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Lindholm DE, Licciardi PV, Ratu FT, Kim Mulholland E, Nguyen CD, Russell FM. Predictors of antibody persistence to the 7-valent pneumococcal conjugate vaccine in healthy Fijian infants at 12 months of age. Vaccine 2020; 38:5095-5099. [PMID: 32580918 DOI: 10.1016/j.vaccine.2020.06.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 06/05/2020] [Accepted: 06/08/2020] [Indexed: 10/24/2022]
Abstract
Little is known about the predictors of antibody persistence to pneumococcal conjugate vaccines (PCV) in the context of reduced dose schedules. In Fiji, an RCT investigated 0, 1, 2 and 3 dose schedules of 7-valent PCV administered at 6, 10 and 14 weeks of age in 364 healthy infants. This study was a post-hoc analysis of the predictors of poor antibody persistence at 12 months, prior to a booster, using univariable and multivariable analyses. The strongest predictors of poor antibody persistence as measured by serotype-specific immunoglobulin G (IgG) and opsonophagocytosis (OI) assays were being of Indigenous Fijian ethnicity (IgG: adjusted odds ratio (aOR) 3.43, p < 0.001; OI: aOR 1.96, p = 0.013) and receipt of fewer than 3 doses of PCV. These findings may help to identify which children may be at an increased risk of pneumococcal disease in the context of reduced dose primary series PCV schedules.
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Affiliation(s)
- Daniel E Lindholm
- Infection and Immunity, Murdoch Children's Research Institute (MCRI), Melbourne, Australia; Centre for International Child Health, Department of Paediatrics, The University of Melbourne, Australia
| | - Paul V Licciardi
- Infection and Immunity, Murdoch Children's Research Institute (MCRI), Melbourne, Australia; Centre for International Child Health, Department of Paediatrics, The University of Melbourne, Australia
| | - Felisita T Ratu
- Infection and Immunity, Murdoch Children's Research Institute (MCRI), Melbourne, Australia
| | - E Kim Mulholland
- Infection and Immunity, Murdoch Children's Research Institute (MCRI), Melbourne, Australia; London School of Hygiene and Tropical Medicine, London, UK
| | - Cattram D Nguyen
- Infection and Immunity, Murdoch Children's Research Institute (MCRI), Melbourne, Australia; Clinical Epidemiology and Biostatistics Unit, Murdoch Children's Research Institute, Melbourne, Australia
| | - Fiona M Russell
- Infection and Immunity, Murdoch Children's Research Institute (MCRI), Melbourne, Australia; Centre for International Child Health, Department of Paediatrics, The University of Melbourne, Australia.
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2
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Carreras-Abad C, Ramkhelawon L, Heath PT, Le Doare K. A Vaccine Against Group B Streptococcus: Recent Advances. Infect Drug Resist 2020; 13:1263-1272. [PMID: 32425562 PMCID: PMC7196769 DOI: 10.2147/idr.s203454] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 03/10/2020] [Indexed: 01/12/2023] Open
Abstract
Group B streptococcus (GBS) causes a high burden of neonatal and infant disease globally. Implementing a vaccine for pregnant women is a promising strategy to prevent neonatal and infant GBS disease and has been identified as a priority by the World Health Organisation (WHO). GBS serotype-specific polysaccharide – protein conjugate vaccines are at advanced stages of development, but a large number of participants would be required to undertake Phase III clinical efficacy trials. Efforts are therefore currently focused on establishing serocorrelates of protection in natural immunity studies as an alternative pathway for licensure of a GBS vaccine, followed by Phase IV studies to evaluate safety and effectiveness. Protein vaccines are in earlier stages of development but are highly promising as they might confer protection irrespective of serotype. Further epidemiological, immunological and health economic studies are required to enable the vaccine to reach its target population as soon as possible.
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Affiliation(s)
- Clara Carreras-Abad
- Paediatric Infectious Diseases Research Group and Vaccine Institute, Institute for Infection and Immunity, St George's, University of London, London, UK.,Department of Paediatrics, Obstetrics and Gynecology and Preventive Medicine and Public Health, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Laxmee Ramkhelawon
- Paediatric Infectious Diseases Research Group and Vaccine Institute, Institute for Infection and Immunity, St George's, University of London, London, UK
| | - Paul T Heath
- Paediatric Infectious Diseases Research Group and Vaccine Institute, Institute for Infection and Immunity, St George's, University of London, London, UK
| | - Kirsty Le Doare
- Paediatric Infectious Diseases Research Group and Vaccine Institute, Institute for Infection and Immunity, St George's, University of London, London, UK.,Pathogen Immunity Group, Public Health England, Porton Down,UK.,Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
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3
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Ndungo E, Pasetti MF. Functional antibodies as immunological endpoints to evaluate protective immunity against Shigella. Hum Vaccin Immunother 2019; 16:197-205. [PMID: 31287754 PMCID: PMC7670857 DOI: 10.1080/21645515.2019.1640427] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The development, clinical advancement and licensure of vaccines, and monitoring of vaccine effectiveness could be expedited and simplified by the ability to measure immunological endpoints that can predict a favorable clinical outcome. Antigen-specific and functional antibodies have been described in the context of naturally acquired immunity and vaccination against Shigella, and their presence in serum has been associated with reduced risk of disease in human subjects. The relevance of these antibodies as correlates of protective immunity, their mechanistic contribution to protection (e.g. target antigens, interference with pathogenesis, and participation in microbial clearance), and factors that influence their magnitude and makeup (e.g. host age, health condition, and environment) are important considerations that need to be explored. In addition to facilitating vaccine evaluation, immunological correlates of protection could be useful for identifying groups at risk and advancing immune therapies. Herein we discuss the precedent and value of functional antibodies as immunological endpoints to predict vaccine efficacy and the relevance of functional antibody activity to evaluate protective immunity against shigellosis.
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Affiliation(s)
- Esther Ndungo
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Marcela F Pasetti
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
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4
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LaFon DC, Nahm MH. Measuring quantity and function of pneumococcal antibodies in immunoglobulin products. Transfusion 2019; 58 Suppl 3:3114-3120. [PMID: 30536435 DOI: 10.1111/trf.15015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 10/03/2018] [Indexed: 12/22/2022]
Abstract
BACKGROUND Immunoglobulin replacement therapy is a cornerstone of the treatment of primary immunodeficiencies. Preparations used for replacement therapy are processed by purifying immunoglobulins from large pools of plasma, which were obtained from healthy donors. The constituent antibodies in these products depend on the immune history of the donor pool as well as manufacturing processes that differ among manufacturers. For these reasons various methods have been proposed to examine the levels and function of antibodies to organisms such as Streptococcus pneumoniae, which frequently causes infections in patients with immunodeficiencies. Pneumococcal antibody levels or antibody function can be measured with enzyme-linked immunosorbent assay (ELISA) or multiplexed opsonophagocytosis assay (MOPA). Although these assays were developed initially to assess the immunogenicity of pneumococcal vaccines, the techniques have been adapted to evaluate immunoglobulin products as well. STUDY DESIGN AND METHODS This article provides a concise review of the analytic techniques for measuring pneumococcal antibodies and prior studies of immunoglobulin products utilizing these methods. RESULTS Studies utilizing these assays have demonstrated that antibody levels of immunoglobulin products can vary with time, location, and manufacturer. CONCLUSIONS We highlight current issues and future considerations concerning measurement of pneumococcal antibodies in immunoglobulin products, and the assays used for this purpose.
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Affiliation(s)
- David C LaFon
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Moon H Nahm
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama.,Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama
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5
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Song JY, Lim JH, Lim S, Yong Z, Seo HS. Progress toward a group B streptococcal vaccine. Hum Vaccin Immunother 2018; 14:2669-2681. [PMID: 29995578 PMCID: PMC6314413 DOI: 10.1080/21645515.2018.1493326] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 05/18/2018] [Accepted: 06/19/2018] [Indexed: 01/31/2023] Open
Abstract
Streptococcus agalactiae (group B Streptococcus, GBS) is a leading cause of severe invasive disease in neonate, elderly, and immunocompromised patients worldwide. Despite recent advances in the diagnosis and intrapartum antibiotic prophylaxis (IAP) of GBS infections, it remains one of the most common causes of neonatal morbidity and mortality, causing serious infections. Furthermore, recent studies reported an increasing number of GBS infections in pregnant women and elderly. Although IAP is effective, it has several limitations, including increasing antimicrobial resistance and late GBS infection after negative antenatal screening. Maternal immunization is the most promising and effective countermeasure against GBS infection in neonates. However, no vaccine is available to date, but two types of vaccines, protein subunit and capsular polysaccharide conjugate vaccines, were investigated in clinical trials. Here, we provide an overview of the GBS vaccine development status and recent advances in the development of immunoassays to evaluate the GBS vaccine clinical efficacy.
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Affiliation(s)
- Joon Young Song
- Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Jae Hyang Lim
- Department of Microbiology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Sangyong Lim
- Biotechnology Division, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
- Department of Radiation Biotechnology and Applied Radioisotope Science, University of Science and Technology, Daejeon, Republic of Korea
| | - Zhi Yong
- Biotechnology Division, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
- Department of Radiation Biotechnology and Applied Radioisotope Science, University of Science and Technology, Daejeon, Republic of Korea
| | - Ho Seong Seo
- Biotechnology Division, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea
- Department of Radiation Biotechnology and Applied Radioisotope Science, University of Science and Technology, Daejeon, Republic of Korea
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6
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Development, Interlaboratory Evaluations, and Application of a Simple, High-Throughput Shigella Serum Bactericidal Assay. mSphere 2018; 3:3/3/e00146-18. [PMID: 29898979 PMCID: PMC6001606 DOI: 10.1128/msphere.00146-18] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 04/28/2018] [Indexed: 12/02/2022] Open
Abstract
Shigella is an important cause of diarrhea worldwide, and efforts are ongoing to produce a safe and effective Shigella vaccine. Although a clear immune correlate of protection has not been established, antibodies with bactericidal capacity may provide one means of protecting against shigellosis. Thus, it is important to measure the functional capacity of antibodies, as opposed to only binding activity. This article describes a simple, robust, and high-throughput serum bactericidal assay capable of measuring Shigella-specific functional antibodies in vitro. We show for the first time that this assay was successfully performed by multiple laboratories and generated highly comparable results, particularly when SBA titers were normalized using a reference standard. The serum bactericidal assay, along with a reference serum, should greatly facilitate Shigella vaccine development. Shigella is an important cause of diarrhea worldwide, with serotypes Shigella flexneri 2a, S. flexneri 3a, and Shigella sonnei demonstrating epidemiological prevalence. Many development efforts are focused on Shigella lipopolysaccharide (LPS)-based vaccines, as O antigen-specific conjugate vaccines are immunogenic and efficacious. Immunization with Shigella vaccines containing LPS can elicit antibodies capable of killing Shigella in a serotype-specific manner. Thus, to facilitate Shigella vaccine development, we have developed a serum bactericidal assay (SBA) specific for three Shigella serotypes that measures killing of target bacteria at multiple serum dilutions and in the presence of exogenous complement. The SBA has a high analytical throughput and uses simple technologies and readily available reagents. The SBA was characterized with human sera with bactericidal antibodies against S. flexneri 2a, S. flexneri 3a, and S. sonnei. Purified LPS of a homologous serotype, but not a heterologous serotype, inhibited bacterial killing. Assessment of precision found median intra-assay precision to be 13.3% and median interassay precision to be 19 to 30% for the three serotypes. The SBA is linear, with slight deviations for samples with low (~40) killing indices. The SBA was sensitive enough to allow about 100-fold predilution of serum samples. Repeat assays yielded results with less than 2-fold deviations, indicating the robustness of the assay. Assay results from four different laboratories were highly comparable when normalized with a reference serum. The Shigella SBA, combined with a reference serum, should facilitate the development of Shigella vaccines across the field. IMPORTANCEShigella is an important cause of diarrhea worldwide, and efforts are ongoing to produce a safe and effective Shigella vaccine. Although a clear immune correlate of protection has not been established, antibodies with bactericidal capacity may provide one means of protecting against shigellosis. Thus, it is important to measure the functional capacity of antibodies, as opposed to only binding activity. This article describes a simple, robust, and high-throughput serum bactericidal assay capable of measuring Shigella-specific functional antibodies in vitro. We show for the first time that this assay was successfully performed by multiple laboratories and generated highly comparable results, particularly when SBA titers were normalized using a reference standard. The serum bactericidal assay, along with a reference serum, should greatly facilitate Shigella vaccine development.
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Abbanat D, Davies TA, Amsler K, He W, Fae K, Janssen S, Poolman JT, van den Dobbelsteen GPJM. Development and Qualification of an Opsonophagocytic Killing Assay To Assess Immunogenicity of a Bioconjugated Escherichia coli Vaccine. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:e00123-17. [PMID: 28971965 PMCID: PMC5717180 DOI: 10.1128/cvi.00123-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 09/20/2017] [Indexed: 12/16/2022]
Abstract
The global burden of disease caused by extraintestinal pathogenic Escherichia coli (ExPEC) is increasing as the prevalence of multidrug-resistant strains rises. A multivalent ExPEC O-antigen bioconjugate vaccine could have a substantial impact in preventing bacteremia and urinary tract infections. Development of an ExPEC vaccine requires a readout to assess the functionality of antibodies. We developed an opsonophagocytic killing assay (OPA) for four ExPEC serotypes (serotypes O1A, O2, O6A, and O25B) based on methods established for pneumococcal conjugate vaccines. The performance of the assay was assessed with human serum by computing the precision, linearity, trueness, total error, working range, and specificity. Serotypes O1A and O6A met the acceptance criteria for precision (coefficient of variation for repeatability and intermediate precision, ≤50%), linearity (90% confidence interval of the slope of each strain, 0.80, 1.25), trueness (relative bias range, -30% to 30%), and total error (total error range, -65% to 183%) at five serum concentrations and serotypes O2 and O25B met the acceptance criteria at four concentrations (the lowest concentration for serotypes O2 and O25B did not meet the system suitability test of maximum killing of ≥85% of E. coli cells). All serotypes met the acceptance criteria for specificity (opsonization index value reductions of ≤20% for heterologous serum preadsorption and ≥70% for homologous serum preadsorption). The assay working range was defined on the basis of the lowest and highest concentrations at which the assay jointly fulfilled the target acceptance criteria for linearity, precision, and accuracy. An OPA suitable for multiple E. coli serotypes has been developed, qualified, and used to assess the immunogenicity of a 4-valent E. coli bioconjugate vaccine (ExPEC4V) administered to humans.
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Affiliation(s)
- Darren Abbanat
- Janssen Research & Development, Raritan, New Jersey, USA
| | - Todd A Davies
- Janssen Research & Development, Raritan, New Jersey, USA
| | - Karen Amsler
- Janssen Research & Development, Raritan, New Jersey, USA
| | - Wenping He
- Janssen Research & Development, Raritan, New Jersey, USA
| | - Kellen Fae
- Janssen Vaccines & Prevention B.V., Bacterial Vaccines Discovery & Early Development, Leiden, The Netherlands
| | - Sarah Janssen
- Janssen Vaccines & Prevention B.V., Statistics & Decision Sciences, Leiden, The Netherlands
| | - Jan T Poolman
- Janssen Vaccines & Prevention B.V., Bacterial Vaccines Discovery & Early Development, Leiden, The Netherlands
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8
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Choi MJ, Noh JY, Cheong HJ, Kim WJ, Lin SM, Zhi Y, Lim JH, Lim S, Seo HS, Song JY. Development of a multiplexed opsonophagocytic killing assay (MOPA) for group B Streptococcus. Hum Vaccin Immunother 2017; 14:67-73. [PMID: 28933634 DOI: 10.1080/21645515.2017.1377379] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Group B Streptococcus (GBS) is a leading cause of sepsis in infants as well as chorioamnionitis in pregnant women. Opsonophagocytic killing assays (OPAs) are an essential technique in vaccine studies of encapsulated bacteria for estimating serotype-specific functional antibody levels in vitro. Here, we developed a three-fold multiplexed OPA (MOPA) to enable practical, large-scale assessment of GBS vaccine immunogenicity, including against serotypes Ia, III, and V. First, three target bacteria strains resistant to streptomycin, spectinomycin, or kanamycin were generated by natural selection through exposure to increasing antibiotic concentrations. Since a high level of nonspecific killing (NSK) of serotype V was observed in a 12.5% baby rabbit complement (BRC) solution, the BRC concentration was optimized. The final GBS-MOPA BRC concentration was 9%, which resulted in less than 20% NSK. The specificity was measured by preabsorbing serum with inactivated GBS. The opsonic index (OI) of preabsorbed serum with the homologous serotype GBS was significantly reduced in all three serotypes tested. The accuracy of the MOPA was compared with that of a single OPA (SOPA) with 35 serum samples. The OIs of the MOPA correlated well with those of the SOPA, and the r2 values were higher than 0.950 for all three serotypes. The precision of the MOPA assay was assessed in five independent experiments with five serum samples. The inter-assay precision of the GBS-MOPA was 12.5% of the average coefficient of variation. This is the first report to develop and standardize a GBS-MOPA, which will be useful for GBS vaccine development and evaluation.
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Affiliation(s)
- Min Joo Choi
- a Department of Internal Medicine , Korea University College of Medicine , Seoul , Republic of Korea
| | - Ji Yun Noh
- a Department of Internal Medicine , Korea University College of Medicine , Seoul , Republic of Korea
| | - Hee Jin Cheong
- a Department of Internal Medicine , Korea University College of Medicine , Seoul , Republic of Korea
| | - Woo Joo Kim
- a Department of Internal Medicine , Korea University College of Medicine , Seoul , Republic of Korea
| | - Shun-Mei Lin
- b Biotechnology Division, Korea Atomic Energy Research Institute , Jeongeup , Republic of Korea
| | - Yong Zhi
- b Biotechnology Division, Korea Atomic Energy Research Institute , Jeongeup , Republic of Korea
| | - Jae Hyang Lim
- c Department of Microbiology and Tissue Injury Defense Research Center , Ewha Womans University School of Medicine , Seoul , Republic of Korea
| | - Sangyong Lim
- b Biotechnology Division, Korea Atomic Energy Research Institute , Jeongeup , Republic of Korea
| | - Ho Seong Seo
- b Biotechnology Division, Korea Atomic Energy Research Institute , Jeongeup , Republic of Korea
| | - Joon Young Song
- a Department of Internal Medicine , Korea University College of Medicine , Seoul , Republic of Korea
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Position of O-Acetylation within the Capsular Repeat Unit Impacts the Biological Properties of Pneumococcal Serotypes 33A and 33F. Infect Immun 2017; 85:IAI.00132-17. [PMID: 28438972 DOI: 10.1128/iai.00132-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/13/2017] [Indexed: 12/26/2022] Open
Abstract
Streptococcus pneumoniae (pneumococcus) produces many capsule types that differ in their abilities to evade host immune recognition. To explain these serotype-dependent protective capacities, many studies have investigated capsular thickness or the interaction of the capsule with complement proteins, but the effects of small chemical modifications of the capsule on its function have not been studied. One small chemical modification found frequently among pneumococcal capsules is O-acetylation. Pneumococcal serotype 33A has two membrane-bound O-acetyltransferase genes, wciG and wcjE A 33A wcjE-deficient variant, 33F, occurs naturally and is increasing in prevalence in the wake of widespread conjugate vaccine use, but no wciG-deficient variants have been reported. To study the biological consequence of the loss of O-acetylation, we created wciG-deficient variants in both serotypes 33A and 33F, which we named 33X1 (ΔwciG) and 33X2 (ΔwciG ΔwcjE). Serotypes 33X1 and 33X2 express novel capsule types based on serological and biochemical analyses. We found that loss of WcjE-mediated O-acetylation appears not to affect cell wall shielding, since serotypes 33A and 33F exhibit comparable nonspecific opsonophagocytic killing, biofilm production, and adhesion to nasopharyngeal cells, though serotype 33F survived short-term drying better than serotype 33A. Loss of WciG-mediated O-acetylation in serotypes 33X1 and 33X2, however, resulted in a phenotype resembling that of nonencapsulated strains: increased cell wall accessibility, increased nonspecific opsonophagocytic killing, enhanced biofilm formation, and increased adhesion to nasopharyngeal cells. We conclude that WciG-mediated, but not WcjE-mediated, O-acetylation is important for producing protective capsules in 33A and that small chemical changes to the capsule can drastically affect its biological properties.
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10
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Riddle MS, Kaminski RW, Di Paolo C, Porter CK, Gutierrez RL, Clarkson KA, Weerts HE, Duplessis C, Castellano A, Alaimo C, Paolino K, Gormley R, Gambillara Fonck V. Safety and Immunogenicity of a Candidate Bioconjugate Vaccine against Shigella flexneri 2a Administered to Healthy Adults: a Single-Blind, Randomized Phase I Study. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2016; 23:908-917. [PMID: 27581434 PMCID: PMC5139601 DOI: 10.1128/cvi.00224-16] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 08/01/2016] [Indexed: 11/20/2022]
Abstract
Several candidate vaccines against Shigella spp. are in development, but the lack of a clear correlate of protection from challenge with the induction of adequate immune responses among the youngest age groups in the developing world has hampered Shigella vaccine development over the past several decades. Bioconjugation technology, exploited here for an Shigella flexneri 2a candidate vaccine, offers a novel and potentially cost-effective way to develop and produce vaccines against a major pathogen of global health importance. Flexyn2a, a novel S. flexneri 2a bioconjugate vaccine made of the polysaccharide component of the S. flexneri 2a O-antigen, conjugated to the exotoxin protein A of Pseudomonas aeruginosa (EPA), was evaluated for safety and immunogenicity among healthy adults in a single-blind, phase I study with a staggered randomization approach. Thirty subjects (12 receiving 10 μg Flexyn2a, 12 receiving Flexyn2a with aluminum adjuvant, and 6 receiving placebo) were administered two injections 4 weeks apart and were followed for 168 days. Flexyn2a was well-tolerated, independently of the adjuvant and number of injections. The Flexyn2a vaccine elicited statistically significant S. flexneri 2a lipopolysaccharide (LPS)-specific humoral responses at all time points postimmunization in all groups that received the vaccine. Elicited serum antibodies were functional, as evidenced by bactericidal activity against S. flexneri 2a. The bioconjugate candidate vaccine Flexyn2a has a satisfactory safety profile and elicited a robust humoral response to S. flexneri 2a LPS with or without inclusion of an adjuvant. Moreover, the bioconjugate also induced functional antibodies, showing the technology's features in producing a promising candidate vaccine. (This study has been registered at ClinicalTrials.gov under registration no. NCT02388009.).
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Affiliation(s)
- Mark S Riddle
- Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Robert W Kaminski
- Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | | | - Chad K Porter
- Naval Medical Research Center, Silver Spring, Maryland, USA
| | | | | | - Hailey E Weerts
- Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | | | - Amy Castellano
- Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | | | | | - Robert Gormley
- Naval Medical Research Center, Silver Spring, Maryland, USA
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11
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Kim HW, Kim KH, Kim J, Nahm MH. A high throughput serum bactericidal assay for antibodies to Haemophilus influenzae type b. BMC Infect Dis 2016; 16:473. [PMID: 27595992 PMCID: PMC5011942 DOI: 10.1186/s12879-016-1808-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 08/26/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The protective capacities of antibodies induced with Haemophilus influenzae type b (Hib) vaccines can be directly assessed in vitro with a Hib-specific serum bactericidal assay (SBA). However, the conventional SBA requires several tedious steps including manual counting of bacterial colonies, and therefore, it is seldom used. METHODS To overcome these limitations, we have improved the conventional SBA by using frozen target bacteria and by developing an automated colony counting method based on agar plates with the chromogenic dye 2, 3, 5-triphenyl tetrazolium chloride (TTC). RESULTS These changes enabled us to analyze about 100 serum samples per day per person by SBA. When the intra- and inter-assay precisions were studied, this assay showed a coefficient of variation (CV) ranging from 1 to 38 %. To monitor the long term assay stability for assays involving different bacteria lots, complement lots, and operators, we analyzed bactericidal indices of quality control samples obtained over a 6 year period and found the CV to be about 35-50 %. Lastly, our SBA results were compared with the ELISA results obtained using 90 serum samples from children. We showed that the bactericidal index correlated with IgG anti-Hib antibody levels (r = 0.84), with a bactericidal index of 10 corresponding approximately to 0.15 μg/mL IgG, the widely accepted protective level of antibody. CONCLUSION We describe a simple high throughput SBA for anti-Hib antibodies that would be useful for evaluating various Hib vaccines. While additional work will be needed to standardize the assay, this SBA should greatly facilitate studies of Hib vaccines.
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Affiliation(s)
- Han Wool Kim
- Center for Vaccine Evaluation and Study, Medical Research Institute, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Kyung-Hyo Kim
- Center for Vaccine Evaluation and Study, Medical Research Institute, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
- Department of Pediatrics, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - JiHye Kim
- Department of Pediatrics, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Moon H. Nahm
- Department of Pathology and Microbiology, University of Alabama at Birmingham, Birmingham, AL USA
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12
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Jang MS, Sahastrabuddhe S, Yun CH, Han SH, Yang JS. Serum bactericidal assay for the evaluation of typhoid vaccine using a semi-automated colony-counting method. Microb Pathog 2016; 97:19-26. [PMID: 27216239 PMCID: PMC4944902 DOI: 10.1016/j.micpath.2016.05.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 05/18/2016] [Accepted: 05/19/2016] [Indexed: 12/22/2022]
Abstract
Typhoid fever, mainly caused by Salmonella enterica serovar Typhi (S. Typhi), is a life-threatening disease, mostly in developing countries. Enzyme-linked immunosorbent assay (ELISA) is widely used to quantify antibodies against S. Typhi in serum but does not provide information about functional antibody titers. Although the serum bactericidal assay (SBA) using an agar plate is often used to measure functional antibody titers against various bacterial pathogens in clinical specimens, it has rarely been used for typhoid vaccines because it is time-consuming and labor-intensive. In the present study, we established an improved SBA against S. Typhi using a semi-automated colony-counting system with a square agar plate harboring 24 samples. The semi-automated SBA efficiently measured bactericidal titers of sera from individuals immunized with S. Typhi Vi polysaccharide vaccines. The assay specifically responded to S. Typhi Ty2 but not to other irrelevant enteric bacteria including Vibrio cholerae and Shigella flexneri. Baby rabbit complement was more appropriate source for the SBA against S. Typhi than complements from adult rabbit, guinea pig, and human. We also examined the correlation between SBA and ELISA for measuring antibody responses against S. Typhi using pre- and post-vaccination sera from 18 human volunteers. The SBA titer showed a good correlation with anti-Vi IgG quantity in the serum as determined by Spearman correlation coefficient of 0.737 (P < 0.001). Taken together, the semi-automated SBA might be efficient, accurate, sensitive, and specific enough to measure functional antibody titers against S. Typhi in sera from human subjects immunized with typhoid vaccines. Improved SBA against S. Typhi was developed using a colony counting system. The improved SBA was specific to S. Typhi but not to other gram-negative bacteria. There was a good correlation between SBA and anti-Vi IgG titers in vaccinee’s sera. This SBA would be useful for the clinical immuno-monitoring of typhoid vaccines.
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Affiliation(s)
- Mi Seon Jang
- Clinical Immunology, Sciences Unit, International Vaccine Institute, Seoul, Republic of Korea; Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | | | - Cheol-Heui Yun
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Seung Hyun Han
- Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
| | - Jae Seung Yang
- Clinical Immunology, Sciences Unit, International Vaccine Institute, Seoul, Republic of Korea.
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Frost HR, Tsoi SK, Baker CA, Laho D, Sanderson-Smith ML, Steer AC, Smeesters PR. Validation of an automated colony counting system for group A Streptococcus. BMC Res Notes 2016; 9:72. [PMID: 26856815 PMCID: PMC4745170 DOI: 10.1186/s13104-016-1875-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 01/19/2016] [Indexed: 01/06/2023] Open
Abstract
Background The practice of counting bacterial colony forming units on agar plates has long been used as a method to estimate the concentration of live bacteria in culture. However, due to the laborious and potentially error prone nature of this measurement technique, an alternative method is desirable. Recent technologic advancements have facilitated the development of automated colony counting systems, which reduce errors introduced during the manual counting process and recording of information. An additional benefit is the significant reduction in time taken to analyse colony counting data. Whilst automated counting procedures have been validated for a number of microorganisms, the process has not been successful for all bacteria due to the requirement for a relatively high contrast between bacterial colonies and growth medium. The purpose of this study was to validate an automated counting system for use with group A Streptococcus (GAS). Results Methods: Twenty-one different GAS strains, representative of major emm-types, were selected for assessment. In order to introduce the required contrast for automated counting, 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) dye was added to Todd–Hewitt broth with yeast extract (THY) agar. Growth on THY agar with TTC was compared with growth on blood agar and THY agar to ensure the dye was not detrimental to bacterial growth. Automated colony counts using a ProtoCOL 3 instrument were compared with manual counting to confirm accuracy over the stages of the growth cycle (latent, mid-log and stationary phases) and in a number of different assays. The average percentage differences between plating and counting methods were analysed using the Bland–Altman method. Conclusions Results: A percentage difference of ±10 % was determined as the cut-off for a critical difference between plating and counting methods. All strains measured had an average difference of less than 10 % when plated on THY agar with TTC. This consistency was also observed over all phases of the growth cycle and when plated in blood following bactericidal assays. Agreement between these methods suggest the use of an automated colony counting technique for GAS will significantly reduce time spent counting bacteria to enable a more efficient and accurate measurement of bacteria concentration in culture. Electronic supplementary material The online version of this article (doi:10.1186/s13104-016-1875-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- H R Frost
- Group A Streptococcus Research Group, Murdoch Childrens Research Institute, Flemington Road, Parkville, Melbourne, VIC, 3052, Australia. .,Laboratoire de Bactériologie Moléculaire, Université Libre de Bruxelles, Brussels, Belgium.
| | - S K Tsoi
- Group A Streptococcus Research Group, Murdoch Childrens Research Institute, Flemington Road, Parkville, Melbourne, VIC, 3052, Australia.
| | - C A Baker
- Group A Streptococcus Research Group, Murdoch Childrens Research Institute, Flemington Road, Parkville, Melbourne, VIC, 3052, Australia.
| | - D Laho
- Group A Streptococcus Research Group, Murdoch Childrens Research Institute, Flemington Road, Parkville, Melbourne, VIC, 3052, Australia.
| | - M L Sanderson-Smith
- Illawarra Health and Medical Research Institute and School of Biological Sciences, University of Wollongong, Wollongong, Australia.
| | - A C Steer
- Group A Streptococcus Research Group, Murdoch Childrens Research Institute, Flemington Road, Parkville, Melbourne, VIC, 3052, Australia. .,Centre for International Child Health, University of Melbourne, Melbourne, Australia. .,Department of General Medicine, Royal Children's Hospital Melbourne, Melbourne, Australia.
| | - P R Smeesters
- Group A Streptococcus Research Group, Murdoch Childrens Research Institute, Flemington Road, Parkville, Melbourne, VIC, 3052, Australia. .,Illawarra Health and Medical Research Institute and School of Biological Sciences, University of Wollongong, Wollongong, Australia. .,Department of General Medicine, Royal Children's Hospital Melbourne, Melbourne, Australia.
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14
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Vivas-Alegre S, Fernández-Natal I, López-Fidalgo E, Rivero-Lezcano OM. Preparation of inocula for experimental infection of blood with Streptococcus pneumoniae. MethodsX 2015; 2:463-8. [PMID: 26844211 PMCID: PMC4688400 DOI: 10.1016/j.mex.2015.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 11/04/2015] [Indexed: 11/18/2022] Open
Abstract
Experimental infections of either cells or animals require the preparation of good quality inocula. Unfortunately, the important pulmonary pathogen Streptococcus pneumoniae is a fastidious microorganism that suffers an autolysis process when cultured in vitro. Supplementation of Todd–Hewitt broth with a biological buffer (20 mM Tris–HCl, pH = 7.8) promotes a six hours delay in the beginning of the autolysis process. Additional improvements include washing bacteria before freezing, avoiding manipulations after thawing, and the use of glycerol (<18%) as a cryoprotectant, instead of reagents like skimmed milk that may affect cell cultures. With the proposed protocol >70% of the frozen bacteria was viable after 28 weeks at −80 °C, and aliquots were highly homogeneous. We have tested their utility in a whole blood infection model and have found that human plasma exhibits a higher microbicidal activity than whole blood, a result that we have not found previously reported. Additionally, we have also observed significant variations in the antimicrobial activity against different strains, which might be related to their virulence.Media culture buffering extends S. pneumoniae viability for 6 h. Washing before freezing of single use aliquots minimizes manipulation after thawing. Experimental infection with the frozen inocula has shown that plasma has higher bactericidal activity than blood.
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Affiliation(s)
- Santiago Vivas-Alegre
- Servicio de Digestivo, Hospital de León, Altos de Nava s/n, 24008 León, Spain; Institute of Biomedicine (IBIOMED), University of León, León, Spain
| | | | | | - Octavio Miguel Rivero-Lezcano
- Institute of Biomedicine (IBIOMED), University of León, León, Spain; Unidad de Investigación, Hospital de León, Altos de Nava s/n, 24008 León, Spain; Fundación Instituto de Estudios de Ciencias de la Salud de Castilla y León, Spain
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15
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Hall JW, Yang J, Guo H, Ji Y. The AirSR two-component system contributes to Staphylococcus aureus survival in human blood and transcriptionally regulates sspABC operon. Front Microbiol 2015; 6:682. [PMID: 26191060 PMCID: PMC4490255 DOI: 10.3389/fmicb.2015.00682] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/22/2015] [Indexed: 12/14/2022] Open
Abstract
To date, genes identified and transcriptionally regulated by the AirSR TCS have been involved in energy production and cellular homeostasis of the staphylococcal cell. It is well accepted that the state of cellular metabolism impacts the expression of virulence factors in Staphylococcus aureus. For this reason, we conducted experiments to determine if the AirSR TCS contributes to the pathogenesis of S. aureus using an antisense RNA interference technology, an inducible overexpression system, and gene deletions. Depletion of AirSR by antisense RNA expression or deletion of the genes, results in significant decrease in bacterial survival in human blood. Conversely, overexpression of AirR significantly promotes survival of S. aureus in blood. AirR promotes the secretion of virulence factors that inhibits opsonin-based phagocytosis. This enhanced survival is partially linked to the transcriptional regulation of the sspABC operon, encoding V8 protease (SspA), staphopain B (SspB) and staphostatin B (SspC). SspA and SspB are known virulence factors which proteolytically digest opsonins and inhibit killing of S. aureus by professional phagocytes. This is the first evidence linking the AirSR TCS to pathogenesis of S. aureus.
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Affiliation(s)
- Jeffrey W Hall
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN USA
| | - Junshu Yang
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN USA
| | - Haiyong Guo
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN USA
| | - Yinduo Ji
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN USA
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16
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Correlates of Protection for M Protein-Based Vaccines against Group A Streptococcus. J Immunol Res 2015; 2015:167089. [PMID: 26101780 PMCID: PMC4458553 DOI: 10.1155/2015/167089] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/28/2015] [Accepted: 05/03/2015] [Indexed: 11/17/2022] Open
Abstract
Group A streptococcus (GAS) is known to cause a broad spectrum of illness, from pharyngitis and impetigo, to autoimmune sequelae such as rheumatic heart disease, and invasive diseases. It is a significant cause of infectious disease morbidity and mortality worldwide, but no efficacious vaccine is currently available. Progress in GAS vaccine development has been hindered by a number of obstacles, including a lack of standardization in immunoassays and the need to define human correlates of protection. In this review, we have examined the current immunoassays used in both GAS and other organisms, and explored the various challenges in their implementation in order to propose potential future directions to identify a correlate of protection and facilitate the development of M protein-based vaccines, which are currently the main GAS vaccine candidates.
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17
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Song JY, Cheong HJ, Tsai TF, Chang HA, Choi MJ, Jeon JH, Kang SH, Jeong EJ, Noh JY, Kim WJ. Immunogenicity and safety of concomitant MF59-adjuvanted influenza vaccine and 23-valent pneumococcal polysaccharide vaccine administration in older adults. Vaccine 2015; 33:4647-52. [PMID: 25980426 DOI: 10.1016/j.vaccine.2015.05.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 04/20/2015] [Accepted: 05/04/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Concomitant administration of influenza and pneumococcal vaccines facilitates their uptake by older adults; however, data on immunogenicity and safety of concomitant administration of adjuvanted trivalent inactivated influenza vaccine (aIIV3) and 23-valent pneumococcal polysaccharide vaccine (PPSV23) have not been reported. METHODS Subjects aged ≥65 years (N=224) were randomized 1:1:1:1 to receive MF59-aIIV3 alone, MF59-aIIV3+PPSV23 in contralateral arms, MF59-aIIV3+PPSV23 in the same arm or PPSV23 alone (Clinical Trial Number - NCT02225327). Hemagglutination inhibition assay and multiplex opsonophagocytic killing assay were used to compare immunogenicity after single or concomitant vaccination. RESULTS All groups met immunogenicity criteria for the influenza vaccine in older adults with similar seroconversion rates and geometric mean fold-increases, irrespective of concomitant vaccinations and injection site. For each pneumococcal serotype, opsonic index (OI) increased markedly after the PPSV23 vaccination, irrespective of the concomitant influenza vaccine. All subjects showed an OI≥8 for serotypes 6B, 18C and 19A post-vaccination, with a suggestion that the ipsilateral concomitant vaccination might be associated with higher OIs for some antigens. Local and systemic adverse events were more common in subjects receiving PPSV23 compared to those receiving aIIV3 alone. CONCLUSIONS No interference was observed with antibody responses to influenza or pneumococcal antigens when aIIV3 and PPSV23 were administered concomitantly.
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Affiliation(s)
- Joon Young Song
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea; Asian Pacific Influenza Institute (APII), Korea University College of Medicine, Seoul, Republic of Korea.
| | - Hee Jin Cheong
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea; Asian Pacific Influenza Institute (APII), Korea University College of Medicine, Seoul, Republic of Korea.
| | - T F Tsai
- Novartis Vaccines, Cambridge, MA, USA
| | | | - Min Joo Choi
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Ji Ho Jeon
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Seong Hee Kang
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Eun Ju Jeong
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
| | - Ji Yun Noh
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea; Asian Pacific Influenza Institute (APII), Korea University College of Medicine, Seoul, Republic of Korea
| | - Woo Joo Kim
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea; Asian Pacific Influenza Institute (APII), Korea University College of Medicine, Seoul, Republic of Korea
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18
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Lee H, Cha JH, Nahm MH, Burton RL, Kim KH. The 7-valent pneumococcal conjugate vaccine elicits cross-functional opsonophagocytic killing responses to Streptococcus pneumoniae serotype 6D in children. BMC Infect Dis 2013; 13:474. [PMID: 24112237 PMCID: PMC3852776 DOI: 10.1186/1471-2334-13-474] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 10/03/2013] [Indexed: 11/10/2022] Open
Abstract
Background We investigated the immune response to serogroup 6 with the opsonophagocytic killing assay (OPKA) in children aged 12–23 months of age after immunization with the 7-valent pneumococcal conjugate vaccine (PCV7) containing serotype 6B. Methods Blood samples were obtained from 59 children who had blood sampling for medical examination. Immunization status against PCV7 was confirmed by immunization records and samples were categorized according to immunization status into a booster, primary, or control group. The OPKA was performed for serotypes 6A, 6B, 6C, and 6D. Results Subjects with no previous PCV7 immunization history showed opsonic activity for serogroup 6 in 5-30% (according to serotype). In subjects vaccinated with a 3-dose primary series, 81% showed opsonic activity for serotypes 6B and 6D, and 29% showed opsonic activity for serotypes 6A and 6C. Among subjects vaccinated with a booster dose, all subjects had opsonic activity against serotype 6B. Subjects in the booster group with opsonic activity against serotypes 6A, 6C, and 6D were 100%, 78%, and 89%, respectively. Conclusions In subjects aged 12–23 months, an immune response is elicited after a primary series of immunizations with PCV7 for serotypes 6B and 6D, and a booster dose enhances a cross reactive immune response against serotypes 6A, 6C and 6D.
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Affiliation(s)
- Hyunju Lee
- Department of Pediatrics, Ewha Womans University School of Medicine, Seoul, Korea.
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19
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Abstract
Streptococcus pneumoniae is a major human pathogen responsible for the majority of bacterial pneumonia cases as well as invasive pneumococcal diseases with high mortality and morbidity. Use of conjugate vaccines targeting the pneumococcal capsule has dramatically reduced the incidence of invasive diseases, and there are active efforts to further improve the conjugate vaccines. However, in children new pneumococcal vaccines can no longer be tested with placebo-based clinical trials because effective vaccines are currently available. Thus, vaccine studies must depend on surrogate markers of vaccine efficacy. Although traditional antibody levels (e.g., ELISA) are useful as a surrogate marker of protection, they have limitations, and a bioassay measuring the capacity of antibodies to opsonize pneumococci has been developed. This opsonophagocytosis assay (OPA) replicates the in vivo mechanism of antibody protection and should therefore better reflect protection by vaccine-induced antibodies. Technical improvements of OPA have made this bioassay rapid, multiplexed, and practical for analyzing small samples including those from children. Strong correlations between ELISA and OPA have been observed in many studies of young children. However, poor correlations have been found in some important clinical situations (such as determination of protection by cross-reactive antibodies) and populations (such as elderly adults and immunodeficient patients). In these settings, OPA has become a useful supplementary measure of pneumococcal vaccine immunogenicity. Current efforts to standardize OPA will further expand its uses.
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20
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Brugger SD, Baumberger C, Jost M, Jenni W, Brugger U, Mühlemann K. Automated counting of bacterial colony forming units on agar plates. PLoS One 2012; 7:e33695. [PMID: 22448267 PMCID: PMC3308999 DOI: 10.1371/journal.pone.0033695] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 02/20/2012] [Indexed: 11/30/2022] Open
Abstract
Manual counting of bacterial colony forming units (CFUs) on agar plates is laborious and error-prone. We therefore implemented a colony counting system with a novel segmentation algorithm to discriminate bacterial colonies from blood and other agar plates. A colony counter hardware was designed and a novel segmentation algorithm was written in MATLAB. In brief, pre-processing with Top-Hat-filtering to obtain a uniform background was followed by the segmentation step, during which the colony images were extracted from the blood agar and individual colonies were separated. A Bayes classifier was then applied to count the final number of bacterial colonies as some of the colonies could still be concatenated to form larger groups. To assess accuracy and performance of the colony counter, we tested automated colony counting of different agar plates with known CFU numbers of S. pneumoniae, P. aeruginosa and M. catarrhalis and showed excellent performance.
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Affiliation(s)
- Silvio D Brugger
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland.
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21
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Versleijen MW, Roelofs HM, Rombouts C, Hermans PW, Noakes PS, Calder PC, Wanten GJ. Short-term infusion of a fish oil-based lipid emulsion modulates fatty acid status, but not immune function or (anti)oxidant balance: a randomized cross-over study. Eur J Clin Invest 2012; 42:290-302. [PMID: 21880037 DOI: 10.1111/j.1365-2362.2011.02582.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIMS Studies suggest clinical benefits of parenteral fish oil (FO), rich in n-3 polyunsaturated fatty acids (PUFAs), over soyabean oil (SO), rich in n-6 PUFAs, in patients with pro-inflammatory conditions such as sepsis and trauma. Because the mechanisms behind these observations remain unclear, the present study explored the effects of intravenous infusion of FO and SO on fatty acid incorporation, immune functions and (anti)oxidant balance in healthy human volunteers. METHODS Saline, a SO emulsion and a FO emulsion were administered for one hour on three consecutive days at a rate of 0·2 g/kg BW/h to eight subjects in a randomized cross-over design with a 3-week interval between treatments. Plasma phospholipid and peripheral blood mononuclear cell (PBMC) fatty acid compositions, and leucocyte counts and functions were assessed prior to the first infusion (T = 0, baseline) and 1 day (T = 4, early effects) and 8 days (T = 11, late effects) after the third infusion. RESULTS Fish oil infusion significantly increased n-3 PUFA proportions and decreased n-6 PUFA proportions in plasma phospholipids and PBMCs. There were no differences in immune functions or (anti)oxidant balance between treatments at any time. CONCLUSIONS The present lipid infusion protocol appears to be safe and well tolerated and provides significant incorporation of n-3 PUFAs into plasma phospholipids and PBMCs. In the absence of overt inflammation, no direct effects of FO were observed on immune function or (anti)oxidant balance. This model may be useful to evaluate effects of parenteral lipids in other settings, for example in individuals displaying an inflammatory state.
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Affiliation(s)
- Michelle W Versleijen
- Department of Gastroenterology and Hepatology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Poly-N-acetyl-β-(1-6)-glucosamine is a target for protective immunity against Acinetobacter baumannii infections. Infect Immun 2011; 80:651-6. [PMID: 22104104 DOI: 10.1128/iai.05653-11] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Acinetobacter baumannii has emerged as a highly troublesome, global pathogen. Treatment is complicated by high levels of antibiotic resistance, necessitating alternative means to prevent or treat A. baumannii infections. We evaluated an immunotherapeutic approach against A. baumannii, focusing on the surface polysaccharide poly-N-acetyl-β-(1-6)-glucosamine (PNAG). We used a synthetic oligosaccharide of 9 monosaccharide units (9Glc-NH(2)) conjugated to tetanus toxoid (TT) to induce antibodies in rabbits. In the presence of complement and polymorphonuclear cells, antisera to 9Glc-NH(2)-TT mediated the killing of A. baumannii S1, a high-PNAG-producing strain, but not its isogenic PNAG-negative, in-frame deletion mutant strain, S1 Δpga. Complementing the pgaABCD locus in trans in the shuttle vector pBAD18kan-ori, plasmid Δpga-c, restored the high levels of killing mediated by antibody to PNAG observed with the wild-type S1 strain. No killing was observed when normal rabbit serum (NRS) or heat-inactivated complement was used. Antiserum to 9Glc-NH(2)-TT was highly opsonic against an additional four unrelated multidrug-resistant clinical isolates of A. baumannii that synthesize various levels of surface PNAG. Using two clinically relevant models of A. baumannii infection in mice, pneumonia and bacteremia, antisera to 9Glc-NH(2)-TT significantly reduced levels of A. baumannii in the lungs or blood 2 and 24 h postinfection, respectively, compared to levels of control groups receiving NRS. This was true for all four A. baumannii strains tested. Overall, these results highlight the potential of PNAG as a vaccine component for active immunization or as a target for passive antibody immunotherapy.
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RrgB321, a fusion protein of the three variants of the pneumococcal pilus backbone RrgB, is protective in vivo and elicits opsonic antibodies. Infect Immun 2011; 80:451-60. [PMID: 22083702 DOI: 10.1128/iai.05780-11] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Streptococcus pneumoniae pilus 1 is present in 30 to 50% of invasive disease-causing strains and is composed of three subunits: the adhesin RrgA, the major backbone subunit RrgB, and the minor ancillary protein RrgC. RrgB exists in three distinct genetic variants and, when used to immunize mice, induces an immune response specific for each variant. To generate an antigen able to protect against the infection caused by all pilus-positive S. pneumoniae strains, we engineered a fusion protein containing the three RrgB variants (RrgB321). RrgB321 elicited antibodies against proteins from organisms in the three clades and protected mice against challenge with piliated pneumococcal strains. RrgB321 antisera mediated complement-dependent opsonophagocytosis of piliated strains at levels comparable to those achieved with the PCV7 glycoconjugate vaccine. These results suggest that a vaccine composed of RrgB321 has the potential to cover 30% or more of all pneumococcal strains and support the inclusion of this fusion protein in a multicomponent vaccine against S. pneumoniae.
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Lee HJ, Park SE, Kim KH. Immune response to 19A serotype after immunization of 19F containing pneumococcal conjugate vaccine in Korean children aged 12-23 months. KOREAN JOURNAL OF PEDIATRICS 2011; 54:163-8. [PMID: 21738550 PMCID: PMC3127150 DOI: 10.3345/kjp.2011.54.4.163] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 10/01/2010] [Accepted: 02/11/2011] [Indexed: 11/27/2022]
Abstract
Purpose The purpose of this study was to evaluate the immune response to serotype 19A in children aged 12-23 months after immunization of the 19F containing 7-valent pneumococcal conjugate vaccine (PCV7). Methods Blood samples from a total of 45 subjects (age 12-23 months) were included in the study. Subjects were categorized according to immunization status into three groups as follows: 18 subjects with 3 primary doses and 1 booster dose of PCV7 (booster group), 21 subjects with 3 primary doses before 12 months of age (primary group), and 6 subjects with no vaccination history of PCV7 (control group). An ELISA and opsonophagocytic killing assay (OPKA) was done to evaluate the immune responses against serotypes 19F and 19A. Results According to the ELISA, all subjects had antibody titers ≥0.35 µg/mL for serotypes 19F and 19A in the booster and primary group and 83.0% and 66.7% in the control group, respectively. According to the OPKA, subjects with opsonic activity (≥20) against serotypes 19F and 19A were 100% and 61.1% of the subjects in the booster group and 66.7% and 19.0% in the primary group, respectively. No subjects in the control group had opsonic antibodies against both serotypes. Conclusion In conclusion, in children 12-23 months age who were previously vaccinated with PCV7, a cross-reactive immune response is elicited against serotype 19A after a primary series of 3 doses in a small proportion of subjects, and this response is amplified after booster vaccination.
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Affiliation(s)
- Hyun Ju Lee
- Department of Pediatrics, Ewha Womans University School of Medicine, Seoul, Korea
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Russell FM, Carapetis JR, Burton RL, Lin J, Licciardi PV, Balloch A, Tikoduadua L, Waqatakirewa L, Cheung YB, Tang MLK, Nahm MH, Mulholland EK. Opsonophagocytic activity following a reduced dose 7-valent pneumococcal conjugate vaccine infant primary series and 23-valent pneumococcal polysaccharide vaccine at 12 months of age. Vaccine 2011; 29:535-44. [PMID: 21044669 PMCID: PMC3011050 DOI: 10.1016/j.vaccine.2010.10.046] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 09/28/2010] [Accepted: 10/18/2010] [Indexed: 01/07/2023]
Abstract
Opsonophagocytic activity (OPA) was measured following reduced infant doses of 7-valent pneumococcal conjugate vaccine (PCV-7) with or without 23-valent pneumococcal polysaccharide vaccine (PPV-23) at 12 months, and subsequent re-exposure to a small dose of pneumococcal polysaccharide antigens (mPPS) at 17 months. Fijian infants were randomized to receive 0, 1, 2, or 3 PCV-7 doses. Half received PPV-23 at 12 months and all received mPPS at 17 months. OPA was performed on up to 14 serotypes. Three and 2 PCV-7 doses resulted in similar OPA for most PCV-7 serotypes up to 9 months and for half of the serotypes at 12 months. A single dose improved OPA compared with the unvaccinated group. PPV-23 significantly improved OPA for all serotypes tested but in general, was associated with diminished responses following re-challenge.
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Affiliation(s)
- F M Russell
- Centre for International Child Health, Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Australia.
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26
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Versleijen MW, Roelofs HM, te Morsche RH, Simonetti ER, Hermans PW, Wanten GJ. Parenteral lipids impair pneumococcal elimination by human neutrophils. Eur J Clin Invest 2010; 40:729-34. [PMID: 20561031 DOI: 10.1111/j.1365-2362.2010.02320.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Lipid-induced modulation of phagocyte function seems to contribute to increased susceptibility to infections in patients on parenteral nutrition, and an increased risk for development of pneumonia has been observed in this group. The role of various structurally different lipid emulsions, however, remains unclear. In this study, we therefore assessed phagocyte function, as the capacity of neutrophils to eliminate Streptococcus pneumoniae (i.e. combined result of phagocytosis and killing), in the presence of these lipids. MATERIALS AND METHODS Neutrophils from six healthy volunteers were incubated for 1 h in emulsions (5 mmol L(-1)) derived from soybean- (LCT), fish- (VLCT), olive- (LCT-MUFA), mixed soybean/coconut oils (LCT/MCTs) or structured lipids (SL). After opsonization of the pneumococci (strain OREP-4) by human immunoglobulins, bacteria and neutrophils were incubated in the presence of complement. Next, pneumococcal elimination was evaluated and expressed as the percentage of bacteria eliminated relative to the initial bacterial numbers in neutrophil-free samples. RESULTS Neutrophils that were not exposed to lipids showed a pneumococcal elimination capacity of 75 +/- 3% (mean +/- SD). This significantly decreased after exposure to LCT-MUFA (70 +/- 6%), VLCT (67 +/- 2%), SL (63 +/- 9%), LCT (66 +/- 10%) and LCT/MCT (47 +/- 15%). CONCLUSION These data demonstrate that parenteral lipids impair the microbial elimination capacity of neutrophils in a structure-dependent manner. In accordance with our previously reported in vitro effect on a range of phagocyte functions, LCT/MCT is by far the most potent in this respect.
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Affiliation(s)
- Michelle W Versleijen
- Department of Gastroenterology and Hepatology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
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Clarke ML, Burton RL, Hill AN, Litorja M, Nahm MH, Hwang J. Low-cost, high-throughput, automated counting of bacterial colonies. Cytometry A 2010; 77:790-7. [PMID: 20140968 PMCID: PMC2909336 DOI: 10.1002/cyto.a.20864] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Research involving bacterial pathogens often requires enumeration of bacteria colonies. Here, we present a low-cost, high-throughput colony counting system consisting of colony counting software and a consumer-grade digital camera or document scanner. We demonstrate that this software, called "NICE" (NIST's Integrated Colony Enumerator), can count bacterial colonies as part of a high-throughput multiplexed opsonophagocytic killing assay used to characterize pneumococcal vaccine efficacy. The results obtained with NICE correlate well with the results obtained from manual counting, with a mean difference of less than 3%. NICE is also rapid; it can count colonies from multiple reaction wells within minutes and export the results to a spreadsheet for data processing. As this program is freely available from NIST, NICE should be helpful in bacteria colony enumeration required in many microbiological studies, and in standardizing colony counting methods.
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Affiliation(s)
- Matthew L. Clarke
- Optical Technology Division, Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
| | - Robert L. Burton
- Departments of Pathology and Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294 USA
| | - A. Nayo Hill
- Optical Technology Division, Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
| | - Maritoni Litorja
- Optical Technology Division, Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
| | - Moon H. Nahm
- Departments of Pathology and Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294 USA
| | - Jeeseong Hwang
- Optical Technology Division, Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
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28
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Buzalewicz I, Wysocka-Król K, Podbielska H. Image processing guided analysis for estimation of bacteria colonies number by means of optical transforms. OPTICS EXPRESS 2010; 18:12992-13005. [PMID: 20588428 DOI: 10.1364/oe.18.012992] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A novel method for evaluation of bacterial colonies number (Colony Forming Units--CFU), is described. Proposed algorithm, based on the Mellin transform, allows the CFU evaluation, invariant for the spatial orientation and scale changes. The proposed method involves image recording of bacteria grown in Petri dishes, calculation of the Fourier spectrum followed by coordinates transformation, and determination of the Mellin transform. It was proved that there is a high correlation between CFU and maxima of Mellin spectra. The method was practically implemented for evaluation of antibacterial activity of silver-based nanomaterials and the effect of an additional laser light irradiation.
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Affiliation(s)
- Igor Buzalewicz
- Bio-Optics Group, Institute of Biomedical Engineering and Instrumentation, Wroclaw University of Technology, WybrzeSe Wyspiańskiego 27, 50-370 Wroclaw, Poland.
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Lee H, Nahm MH, Kim KH. The effect of age on the response to the pneumococcal polysaccharide vaccine. BMC Infect Dis 2010; 10:60. [PMID: 20219110 PMCID: PMC2856571 DOI: 10.1186/1471-2334-10-60] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Accepted: 03/10/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Streptococcus pneumoniae is a leading cause of morbidity and mortality in the elderly. To prevent invasive pneumococcal diseases, the 23-valent pneumococcal polysaccharide vaccine (PPV) is recommended in subjects over 65 years of age. Although it has been reported to provide approximately 50-80% protection against invasive disease in the general elderly population, there is still controversy as to the effectiveness of the PPV in the elderly. METHODS To evaluate the immune response to the pneumococcal polysaccharide vaccine in the elderly, samples from young adults and elderly were obtained before and one month after vaccination. The quantitative and qualitative response to the vaccine were measured by the ELISA and opsonophagocytic killing assay for eight vaccine type serotypes (4, 6B, 9V, 14, 18C, 19A, 19F, 23F) and one vaccine-related serotype (6A). RESULTS The response to the pneumococcal polysaccharide vaccine showed a similar response between adults and elderly when evaluated by the ELISA, however the functional activity of the antibodies elicited after vaccination were lower in the elderly group for more than half of the serotypes evaluated. In comparison of the antibody needed for 1:8 opsonic titer, more antibodies were needed in the elderly for serotypes Pn 4, 19F, 23F and 6A, suggesting the functional activity of antibody detected by the ELISA was lower in the elderly compared with the adult group for these serotypes. As for subjects with an opsonic titer <8 after vaccination, only one subject each for serotypes Pn 4, 9V and 6A were found in the adult group. However, up to 10 (30.3%) of the subjects did not show opsonic activity after vaccination in the elderly group for serotypes Pn 4, 9V, 14, 19A and 6A. CONCLUSIONS Although the amount of antibodies elicited were similar between the two age groups, distinct differences in function were noted. This report highlights the importance of a quantitative and qualitative evaluation of the immunogenic response to the PPV in the elderly age group. TRIAL REGISTRATION This trial is registered with Clinicaltrials.gov. Registration number NCT00964769.
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Affiliation(s)
- Hyunju Lee
- Department of Pediatrics, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
- Center for Vaccine Evaluation and Study, Ewha Medical Research Institute, Ewha Womans University, Seoul, Republic of Korea
| | - Moon H Nahm
- Departments of Pathology and Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kyung-Hyo Kim
- Department of Pediatrics, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
- Center for Vaccine Evaluation and Study, Ewha Medical Research Institute, Ewha Womans University, Seoul, Republic of Korea
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Immune response in infants to the heptavalent pneumococcal conjugate vaccine against vaccine-related serotypes 6A and 19A. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2009; 16:376-81. [PMID: 19144787 DOI: 10.1128/cvi.00344-08] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The currently available 7-valent pneumococcal conjugate vaccine (PCV7) elicits good immune response to and is effective against vaccine serotypes. However, its effectiveness against vaccine-related serotypes is variable. Serum samples were obtained 1 month after the last vaccination from 31 infants immunized with PCV7 at 2, 4, and 6 months of age. The sera were used to determine immunoglobulin G antibody levels to eight serotypes (seven vaccine serotypes and serotype 19A) with enzyme-linked immunosorbent assay (ELISA) and opsonic capacity against 11 serotypes (seven vaccine serotypes, serotypes 19A and 6A, and nonvaccine serotypes 5 and 7F) using a multiplexed opsonization assay. ELISA results showed antibody concentrations varied between 1.84 and 10.49 microg/ml, and all subjects had antibody concentrations of >or=0.35 microg/ml for all serotypes, including serotype 19A. In contrast, the opsonic index was detectable (i.e., opsonic index >or= 8) in all children for the seven vaccine serotypes, 81% for serotype 6A, and merely 19% for serotype 19A. PCV7 shows good immunogenicity for vaccine serotypes in infants after a primary series. PCV7 does not elicit opsonic antibodies to serotype 19A. ELISA may thus be an inadequate surrogate assay for evaluating the response for cross-reactive serotypes in infants.
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31
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Musher DM, Rueda AM, Nahm MH, Graviss EA, Rodriguez-Barradas MC. Initial and subsequent response to pneumococcal polysaccharide and protein-conjugate vaccines administered sequentially to adults who have recovered from pneumococcal pneumonia. J Infect Dis 2008; 198:1019-27. [PMID: 18710324 PMCID: PMC2631393 DOI: 10.1086/591629] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Controversy persists over the benefits of pneumococcal polysaccharide vaccine (PPV) for adults at high risk for pneumococcal disease. We studied PPV, protein-conjugate pneumococcal vaccine (PCV), and immunologic "priming" with PCV followed by "boosting" with PPV in adults who had recovered from pneumococcal pneumonia. METHODS Subjects received PPV followed by PCV 6 months later, or vice versa. The levels of IgG to capsular polysaccharide and opsonophagocytic killing activity (OPK) were studied at baseline and at 4-8 weeks and 6 months after each vaccination. RESULTS PPV and PCV stimulated similar IgG levels and OPK at 4-8 weeks after vaccination. Six months after receipt of PPV, the antibody levels declined to baseline but remained modestly elevated after receipt of PCV. PCV administered 6 months after PPV stimulated modest increases in IgG level that failed to reach the peaks observed after receipt of PPV. In contrast, PPV administered 6 months after PCV caused dramatic increases in the levels of IgG and OPK for all polysaccharides at 4-8 weeks, consistent with a booster effect. Six months after receipt of the second vaccination, however, levels of IgG and OPK fell precipitously in all patients, approaching baseline levels. CONCLUSIONS In these high-risk subjects who have recovered after treatment for pneumonia, the effect of PPV is short-lived; PCV stimulates a more prolonged response. The use of PPV as a booster following PCV causes early increases in antibody levels, but the level of IgG declines rapidly thereafter, consistent with induction of suppressor cells or tolerance. Protein vaccines may be needed for high-risk adults.
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Affiliation(s)
- Daniel M Musher
- Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas 77030, USA.
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32
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Comparisons of titer estimation methods for multiplexed pneumococcal opsonophagocytic killing assay. Comput Stat Data Anal 2008. [DOI: 10.1016/j.csda.2008.04.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Wang D, Burton RL, Nahm MH, Soong SJ. A four-parameter logistic model for estimating titers of functional multiplexed pneumococcal opsonophagocytic killing assay. J Biopharm Stat 2008; 18:307-25. [PMID: 18327723 DOI: 10.1080/10543400701697182] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In vitro opsonophagocytosis killing assay (OPA) is widely accepted to quantitate Streptococcus pneumococcal antibodies to serotype-specific pneumococcal capsular polysaccharide (PS). A titer estimation method is needed for large scale data generated by OPA, and it is one component of OPA standardization. In order to improve the reliability of OPA results, we developed a nonlinear fitting method using the Levenberg-Marquardt algorithm with an option of a robust procedure to estimate titers of OPA data. Performance of the proposed method was evaluated by comparing precision and accuracy of titer estimation with traditional methods used in the literature by analyzing real experimental data sets. Goodness-of-fit to experimental data for the two model-based methods was also assessed. We conclude that the four-parameter logistic model is an alternative choice for titer estimation of OPA data. Computer software using the statistical language R and Microsoft Excel was developed to implement our calculation algorithm for OPA data.
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Affiliation(s)
- Deli Wang
- Biostatistics and Bioinformatics Unit, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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Yang JS, Kim HJ, Yun CH, Kang SS, Im J, Kim HS, Han SH. A semi-automated vibriocidal assay for improved measurement of cholera vaccine-induced immune responses. J Microbiol Methods 2007; 71:141-6. [PMID: 17888533 DOI: 10.1016/j.mimet.2007.08.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Revised: 08/13/2007] [Accepted: 08/20/2007] [Indexed: 10/22/2022]
Abstract
Vibriocidal antibody assay has been a surrogate standard assay in the evaluation of cholera vaccine efficacy because it has a good correlation with protection. Although the optical density-based vibriocidal assay in a 96-well microtiter-plate format is widely used in clinical trials, it has limitations as vibriocidal titers are altered by incubation time and samples with the same end-point titers could have potentially different vibriocidal kinetics. In the present study, we developed an improved agar-plate assay coupled with an automated colony counting system. Through testing 30 pairs of human sera from vaccinees administered with a cholera vaccine or placebo, these two assays showed good correlations for the vibriocidal titers and fold increases in titers between pre- and post-vaccinated sera as determined by the Pearson correlation coefficient and the Regression coefficient. Notably, the newly-developed semi-automated assay demonstrated that serum samples with the same end-point titers turned out to have distinct vibriocidal kinetics that were not distinguishable by the microtiter-plate assay. The semi-automated assay responded specifically to Vibrio cholerae but not to irrelevant bacteria such as Salmonella typhi and Escherichia coli. These results demonstrate that the semi-automated assay provides better sensitivity, accuracy, and stability of the assay results with minimized efforts than conventional microtiter-plate assay and could provide a useful tool as an in vitro surrogate assay for the evaluation of cholera vaccine efficacy.
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Affiliation(s)
- Jae Seung Yang
- Laboratory Sciences Division, International Vaccine Institute, Seoul 151-600, Republic of Korea
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35
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Jackson LA, Neuzil KM, Nahm MH, Whitney CG, Yu O, Nelson JC, Starkovich PT, Dunstan M, Carste B, Shay DK, Baggs J, Carlone GM. Immunogenicity of varying dosages of 7-valent pneumococcal polysaccharide-protein conjugate vaccine in seniors previously vaccinated with 23-valent pneumococcal polysaccharide vaccine. Vaccine 2007; 25:4029-37. [PMID: 17391816 DOI: 10.1016/j.vaccine.2007.02.062] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 02/13/2007] [Accepted: 02/15/2007] [Indexed: 10/23/2022]
Abstract
In this dose-ranging study 220 seniors who had received the 23-valent pneumococcal polysaccharide (PnPS) vaccine at least 5 years prior to enrollment were assigned to receive one of four volumes (0.1, 0.5, 1 or 2 ml) of 7-valent pneumococcal conjugate (PnC) vaccine or a 0.5 ml dose of 23-valent PnPS vaccine. All participants received a reduced challenge dose of 0.1 ml of PnPS vaccine 1 year after enrollment. There was evidence of a dose response to PnC vaccine and antibody levels in the 1 ml PnC group tended to be significantly higher than in the PnPS group. A booster response to the challenge vaccination was not observed. Administration of a 1 ml dose of PnC vaccine is more immunogenic than 0.5 ml of PnPS vaccine in elderly adults previously vaccinated with PnPS vaccine.
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Affiliation(s)
- Lisa A Jackson
- Group Health Center for Health Studies, 1730 Minor Ave, Ste 1600, Seattle, WA 98101, USA.
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36
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Burton RL, Nahm MH. Development and validation of a fourfold multiplexed opsonization assay (MOPA4) for pneumococcal antibodies. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2006; 13:1004-9. [PMID: 16960111 PMCID: PMC1563573 DOI: 10.1128/cvi.00112-06] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Opsonophagocytic killing assays (OPAs) are essential for developing and improving pneumococcal vaccines. There is a need for a high-throughput, reliable, standardized, and fully characterized OPA for pneumococcal antibodies. To meet the need, we have developed and characterized a fourfold multiplexed OPA (MOPA4) against 13 serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) of pneumococci. Thirteen target bacteria were made resistant to only one of the following antibiotics: optochin, streptomycin, spectinomycin, and trimethoprim. Following optimization of assay conditions, accuracy of MOPA4 was determined by testing 30 sera from old adults in the MOPA4 and the single-serotype assays. The opsonization titers obtained with both assays agreed well (r(2) > 0.95). Although 22 (out of 390; approximately 6%) results differed more than twofold, the differences were not reproducible. The assay was specific: preabsorbing test sera with homologous polysaccharide (PS) completely abrogated opsonic activity, but a pool of unrelated PS (5 mug/ml of each) had no effect. Intra- and interassay coefficients of variation were 10 and 22%, respectively. MOPA4 results were unaffected by having different target pneumococcal serotypes in each assay group. Also, HL60 cell-to-bacteria ratios could be varied twofold without affecting the results. We conclude that MOPA4 is sensitive, accurate, specific, precise, and robust enough for large-scale clinical studies. Furthermore, MOPA4 should allow evaluation of multivalent pneumococcal vaccines with the limited volume of serum typically available from young children.
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Affiliation(s)
- Robert L Burton
- Department of Pathology, University of Alabama, 845 19th Street South, BBRB 614, Birmingham, 35294, USA
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37
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Romero-Steiner S, Frasch CE, Carlone G, Fleck RA, Goldblatt D, Nahm MH. Use of opsonophagocytosis for serological evaluation of pneumococcal vaccines. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2006; 13:165-9. [PMID: 16467321 PMCID: PMC1391943 DOI: 10.1128/cvi.13.2.165-169.2006] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Martinez JE, Clutterbuck EA, Li H, Romero-Steiner S, Carlone GM. Evaluation of multiplex flow cytometric opsonophagocytic assays for determination of functional anticapsular antibodies to Streptococcus pneumoniae. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2006; 13:459-66. [PMID: 16603613 PMCID: PMC1459634 DOI: 10.1128/cvi.13.4.459-466.2006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 12/15/2005] [Accepted: 02/22/2006] [Indexed: 11/20/2022]
Abstract
The determination of functional antipneumococcal capsular polysaccharide antibodies by sequential testing of pre- and postvaccination serum samples one serotype at a time is sample-intensive and time-consuming and has a relatively low throughput. We tested several opsonophagocytic assay (OPA) formats, including the reference killing method, a monovalent bacterium-based flow method, a trivalent bacterium-based flow method, and a tetravalent bead-based flow method using a panel of sera (4 prevaccination and 16 postvaccination, from healthy adults immunized with the 23-valent pneumococcal polysaccharide vaccine). The trivalent and tetravalent methods allow simultaneous measurements of opsonic antibodies to multiple pneumococcal serotypes. The trivalent bacterial-flow OPA had significant correlation to the reference OPA method and to a previously published flow cytometric OPA (r values ranged from 0.61 to 0.91, P < 0.05) for serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F. The tetravalent OPA had significant correlation to all OPA method formats tested (r values from 0.68 to 0.92, P < 0.05) for all seven serotypes tested. This tetravalent OPA is an alternative to other OPA methods for use during vaccine evaluation and clinical trials. Further, the flow cytometric multiplex OPA format has the potential for expansion beyond the current four serotypes to eight or more serotypes, which would further increase relative sample throughput while reducing reagent and sample volumes used.
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Affiliation(s)
- Joseph E Martinez
- Respiratory Diseases Branch, Immunology Section, Division of Bacterial and Mycotic Diseases, MS-A36, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
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Bieging KT, Rajam G, Holder P, Udoff R, Carlone GM, Romero-Steiner S. Fluorescent multivalent opsonophagocytic assay for measurement of functional antibodies to Streptococcus pneumoniae. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2005; 12:1238-42. [PMID: 16210490 PMCID: PMC1247838 DOI: 10.1128/cdli.12.10.1238-1242.2005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We developed fluorescent mono- and multivalent opsonophagocytic assays (fOPA and fmOPA, respectively) specific for seven Streptococcus pneumoniae serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F). Bacterial survival was quantitated with alamar blue, a fluorescent metabolic indicator. Both fOPA and fmOPA allow for determination of viability endpoints for up to seven serotypes with high levels of agreement to the reference method. The fmOPA eliminates colony counting, reduces serum volume, and produces results in 1 day.
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Affiliation(s)
- Kathryn T Bieging
- Division of Bacterial and Mycotic Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333, USA
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40
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Putman M, Burton R, Nahm MH. Simplified method to automatically count bacterial colony forming unit. J Immunol Methods 2005; 302:99-102. [PMID: 16002082 DOI: 10.1016/j.jim.2005.05.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 05/02/2005] [Accepted: 05/03/2005] [Indexed: 11/29/2022]
Abstract
Bacterial colony counting is a significant technical hurdle for vaccine studies as well as various microbiological studies. We now show that an automated colony counter can process images obtained with a digital camera or document scanner and that any laboratory can efficiently have bacterial colonies enumerated by sending the images to a laboratory with a colony counter via internet.
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Affiliation(s)
- Michael Putman
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Fleck RA, Romero-Steiner S, Nahm MH. Use of HL-60 cell line to measure opsonic capacity of pneumococcal antibodies. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2005; 12:19-27. [PMID: 15642980 PMCID: PMC540204 DOI: 10.1128/cdli.12.1.19-27.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- R A Fleck
- National Institute of Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, United Kingdom.
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42
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Liu X, Wang S, Sendi L, Caulfield MJ. High-throughput imaging of bacterial colonies grown on filter plates with application to serum bactericidal assays. J Immunol Methods 2004; 292:187-93. [PMID: 15350523 DOI: 10.1016/j.jim.2004.06.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2004] [Revised: 06/23/2004] [Accepted: 06/29/2004] [Indexed: 11/27/2022]
Abstract
The ability to accurately enumerate viable bacteria has applications in antibiotic screening assays, toxicology testing, and serological assays for functional antibodies. An impediment to high-throughput bacterial assays is the requirement to grow bacteria as individual colonies on semisolid media containing agar. We have now developed a method for growth, staining, and counting of bacterial colonies in 96-well filter plates. A unique feature of the method is that colony size is inversely proportional to the number of colonies in each well, presumably due to nutrient depletion. As a result, as many as 300 colony-forming units (cfu) can be detected as discrete colonies within a single assay well. The resulting colonies can be counted automatically using an imaging system originally developed for ELISPOT assays. The method has been applied to the measurement of serum bactericidal activity (SBA) in human sera.
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Affiliation(s)
- Xu Liu
- Department of Vaccine and Biologics Research, Merck Research Laboratories, Merck and Co., Inc., WP26B-1123, P.O. Box 4, West Point, PA 19486, USA
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