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CRISPR-mediated Transfection of Brugia malayi. PLoS Negl Trop Dis 2020; 14:e0008627. [PMID: 32866158 PMCID: PMC7485969 DOI: 10.1371/journal.pntd.0008627] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 09/11/2020] [Accepted: 07/21/2020] [Indexed: 01/25/2023] Open
Abstract
The application of reverse genetics in the human filarial parasites has lagged due to the difficult biology of these organisms. Recently, we developed a co-culture system that permitted the infective larval stage of Brugia malayi to be transfected and efficiently develop to fecund adults. This was exploited to develop a piggyBac transposon-based toolkit that can be used to produce parasites with transgene sequences stably integrated into the parasite genome. However, the piggyBac system has generally been supplanted by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) based technology, which allows precise editing of a genome. Here we report adapting the piggyBac mediated transfection system of B. malayi for CRISPR mediated knock-in insertion into the parasite genome. Suitable CRISPR insertion sites were identified in intergenic regions of the B. malayi genome. A dual reporter piggybac vector was modified, replacing the piggyBac inverted terminal repeat regions with sequences flanking the insertion site. B. malayi molting L3 were transfected with a synthetic guide RNA, the modified plasmid and the CAS9 nuclease. The transfected parasites were implanted into gerbils and allowed to develop into adults. Progeny microfilariae were recovered and screened for expression of a secreted luciferase reporter encoded in the plasmid. Approximately 3% of the microfilariae were found to secrete luciferase; all contained the transgenic sequences inserted at the expected location in the parasite genome. Using an adaptor mediated PCR assay, transgenic microfilariae were examined for the presence of off target insertions; no off-target insertions were found. These data demonstrate that CRISPR can be used to modify the genome of B. malayi, opening the way to precisely edit the genome of this important human filarial parasite. Human filarial parasites are the causative agents of lymphatic filariasis (elephantiasis) and onchocerciasis (river blindness) and are some of the most important causes of morbidity worldwide. A large obstacle to research on these organisms has been the inability to employ reverse genetic methods and to develop integrated transgenic parasite lines. Recently, we developed a piggyBac transposon-based method that employed a co-culture system that permitted the infective larval stage of B. malayi to be transfected by lipofection in culture, resulting in the production of developmentally competent transgenic parasites. However, the piggyBac system cannot be used to precisely edit particular sequences in the genome. Thus, the piggyBac system has generally been supplanted by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) based technology, which permits precise targeting (and editing) of particular sequences in the genome. Here, we report building upon the methods developed for piggyBac mediated transfection of B. malayi to develop a CRISPR mediated method for precise transgenesis in this parasite.
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Liu C, De SL, Miley K, Unnasch TR. In vivo imaging of transgenic Brugia malayi. PLoS Negl Trop Dis 2020; 14:e0008182. [PMID: 32243453 PMCID: PMC7122700 DOI: 10.1371/journal.pntd.0008182] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 02/28/2020] [Indexed: 12/13/2022] Open
Abstract
Background Studies of the human filarial parasite have been hampered by the fact that they are obligate parasites with long life cycles. In other pathogenic infections, in vivo imaging systems (IVIS) have proven extremely useful in studying pathogenesis, tissue tropism and in vivo drug efficacy. IVIS requires the use of transgenic parasites expressing a florescent reporter. Developing a method to produce transgenic filarial parasites expressing a florescent reporter would permit IVIS to be applied to the study of tissue tropism and provide a non-invasive way to screen for in vivo drug efficacy against these parasites. Methodology/Principal findings We report the development of a dual luciferase reporter construct in a piggyBac backbone that may be used to stably transfect Brugia malayi, a causative agent of human filariasis. Parasites transfected with this construct were visible in IVIS images obtained from infected gerbils. The signal in these infected animals increased dramatically when the transgenic parasites matured to the adult stage and began to produce transgenic progeny microfilaria. We demonstrate that the IVIS system can be used to develop an effective method for cryopreservation of transgenic parasites, to non-invasively monitor the effect of treatment with anti-filarial drugs, and to rapidly identify transgenic F1 microfilariae. Conclusions To our knowledge, this represents the first application of IVIS to the study of a human filarial parasite. This method should prove useful in studies of tissue tropism and as an efficient in vivo assay for candidate anti-filarial drugs. The human filarial parasites are responsible for two major debilitating diseases; lymphatic filariasis (elephantiasis) and onchocerciasis (river blindness). Both have been identified as diseases that can be eliminated as a public health problem. However, the current elimination programs rely upon prolonged distribution of a limited number of drugs, a process which is logistically difficult to accomplish and may encourage the development of resistance. Thus, more effective drugs are needed. In other infectious diseases, in vivo imaging systems (IVIS) have proven to be very effective tools to study the pathogenesis of infection and to develop rapid and non-invasive assays for new drugs. Here we report the adaptation of IVIS to a human filarial parasitic infection and demonstrate in principal that it may be used to non-invasively monitor the efficacy of anti-filarial treatment in vivo. This system should prove useful as an in vivo screen for new anti-filarial compounds, as well as studies of the basic biology of these parasites.
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Affiliation(s)
- Canhui Liu
- Center for Global Health Infectious Disease Research, University of South Florida, Florida, United States of America
| | - Sai Lata De
- Center for Global Health Infectious Disease Research, University of South Florida, Florida, United States of America
| | - Kristi Miley
- Center for Global Health Infectious Disease Research, University of South Florida, Florida, United States of America
| | - Thomas R. Unnasch
- Center for Global Health Infectious Disease Research, University of South Florida, Florida, United States of America
- * E-mail:
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Liu C, Mhashilkar AS, Chabanon J, Xu S, Lustigman S, Adams JH, Unnasch TR. Development of a toolkit for piggyBac-mediated integrative transfection of the human filarial parasite Brugia malayi. PLoS Negl Trop Dis 2018; 12:e0006509. [PMID: 29782496 PMCID: PMC5983866 DOI: 10.1371/journal.pntd.0006509] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/01/2018] [Accepted: 05/08/2018] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND The human filarial parasites cause diseases that are among the most important causes of morbidity in the developing world. The elimination programs targeting these infections rely on a limited number of drugs, making the identification of new chemotherapeutic agents a high priority. The study of these parasites has lagged due to the lack of reverse genetic methods. METHODOLOGY/PRINCIPAL FINDINGS We report a novel co-culture method that results in developmentally competent infective larvae of one of the human filarial parasites (Brugia malayi) and describe a method to efficiently transfect the larval stages of this parasite. We describe the production of constructs that result in integrative transfection using the piggyBac transposon system, and a selectable marker that can be used to identify transgenic parasites. We describe the production and use of dual reporter plasmids containing both a secreted luciferase selectable marker and fluorescent protein reporters that will be useful to study temporal and spatial patterns of gene expression. CONCLUSIONS/SIGNIFICANCE The methods and constructs reported here will permit the efficient production of integrated transgenic filarial parasite lines, allowing reverse genetic technologies to be applied to all life cycle stages of the parasite.
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Affiliation(s)
- Canhui Liu
- Center for Global Health Infectious Disease Research, Department of Global Health, University of South Florida, Tampa, FL, United States of America
| | - Amruta S. Mhashilkar
- Center for Global Health Infectious Disease Research, Department of Global Health, University of South Florida, Tampa, FL, United States of America
| | - Johan Chabanon
- Center for Global Health Infectious Disease Research, Department of Global Health, University of South Florida, Tampa, FL, United States of America
| | - Shulin Xu
- Center for Global Health Infectious Disease Research, Department of Global Health, University of South Florida, Tampa, FL, United States of America
| | - Sara Lustigman
- Molecular Parasitology, New York Blood Center, New York, NY, United States of America
| | - John H. Adams
- Center for Global Health Infectious Disease Research, Department of Global Health, University of South Florida, Tampa, FL, United States of America
| | - Thomas R. Unnasch
- Center for Global Health Infectious Disease Research, Department of Global Health, University of South Florida, Tampa, FL, United States of America
- * E-mail:
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Fang Z, Tong H, Zhang S, Fang H, Lu S, Xu B. Construction of a recombinant plasmid harbouring the glyceraldenyde-3-phosphate dehydrogenase gene of periodic Brugia malayi and observation on DNA immunity. Indian J Med Microbiol 2012; 30:193-7. [PMID: 22664436 DOI: 10.4103/0255-0857.96691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
PURPOSE Controlling and eliminating lymphatic filariasis will require further research of preventative measures and implementation. Parasite is dependent on glycolysis for ATP production. The glycolytic enzyme glyceraldenyde-3-phosphate dehydrogenase (GAPDH) plays an important role in glycolysis and therefore is either a potential target for anti-parasite drug development or a vaccine candidate. Therefore, we tried to investigate the DNA vaccine-elicited immune responses in BALB/c mice. MATERIALS AND METHODS We cloned a gene encoding the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from periodic Brugia malayi into vector pcDNA3.1. Mice were injected at a dosage of 100 μg recombinant plasmid DNA with CpG intramuscular injection and immunized three times at 2-week intervals. pcDNA3.1 and normal saline were used as control. The tissue of muscles at the 4 weeks after the third injection was collected and target genes were detected using RT-PCR. The humoral responses elicited in mice by inoculation with the recombinant plasmid pcDNA3.1-BmGAPDH were detected using a standard ELISA. Two weeks after the third immunization, stimulation index (SI) was measured using the MTT method and the level of secreted IL-4 and INF-g were detected using ELISA. RESULTS Specific gene fragment coding GAPDH was amplified and the recombinant plasmid pcDNA3.1-BmGAPDH was constructed. Post-challenge sera from the mice immunized with the DNA vaccine had specific antibody titres of 1:1600 to 1:6400, and the highest titre was observed in the mice that were inoculated by pcDNA3.1-BmGAPDH/CpG at 6 weeks. At 4 weeks after immunization, the spleens of the mice were obviously enlarged. The proliferation of spleen T lymphocytes seen on the MTT assay was higher in the pcDNA3.1-BmGAPDH group than in the control group (P value <0.05). The levels of IL-4 and INF-γ in serums from the immunized mice were significantly higher than that of the control (P value <0.05). CONCLUSIONS We conclude that the recombinant eukaryotic plasmid pcDNA3.1-BmGAPDH could elicit humoral and cellular immune responses in mice.
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Affiliation(s)
- Z Fang
- Department of Parasitology, School of Basic Medical Sciences, Nantong University, Nantong, Jiangsu - 226 001, China
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Kalyanasundaram R, Balumuri P. Multivalent vaccine formulation with BmVAL-1 and BmALT-2 confer significant protection against challenge infections with Brugia malayi in mice and jirds. Res Rep Trop Med 2011; 2011:45-56. [PMID: 21760754 DOI: 10.2147/rrtm.s13679] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE: Lymphatic filariasis, a mosquito-borne infection, affects 120 million people in 83 different countries. Mass drug administration is fully underway in several parts of the world to eradicate this infection by year 2020. Drugs alone are highly efficient treatments, but long-term sustainable prophylaxis requires an effective vaccine. No vaccines are available for humans and animals despite several potential candidate vaccine antigens having been identified. Brugia malayi vespid venom allergen homolog-like protein (BmVAL-1) and B. malayi abundant larval transcript (BmALT-2) are two of the most promising vaccine candidates. We evaluated various vaccination regimens consisting of DNA and protein antigens and evaluated the potential of monovalent and multivalent vaccine formulations in mice and jird animal models. METHODS: Mice and jirds were vaccinated with monovalent DNA preparations of BmVAL-1 or BmALT-2 in pVAX-1 vector or monovalent protein preparations of rBmVAL-1 and rBmALT-2 in alum using a homologous or heterologous prime boost approach. These vaccine regimens were then compared with a multivalent vaccine formulation consisting of DNA or hybrid protein formulation of the two antigens. Challenge experiments were performed with B. malayi L3 in mice and jirds to evaluate the degree of protection, and immunological parameters were determined in mice and humans to elucidate the characteristics of the protective immune responses. RESULTS: Vaccination with monovalent BmVAL-1 vaccine conferred 39% (DNA vaccine) to 54% (DNA prime and protein boost) protection in mice. A similar degree of protection was observed in jirds (50% to 52%). Monovalent BmALT-2 afforded 51% to 75% protection in mice and 58% to 79% protection in jirds. Our testing of a multivalent formulation of BmVAL-1 and BmALT-2, showed 57% to 82% protection in mice and 77% to 85% protection in jirds. A heterologous prime boost approach using the multivalent vaccine gave the highest degree of protection in both mice and jirds. Serological analysis in mice showed that BmVAL-1 vaccination induced an IgG1, IgG2a, and IgG3 antibody response, whereas BmALT-2 vaccination predominantly induced an IgG1 and IgG3 antibody response. Cytokine responses of antigen-responding cells in the spleen secreted predominantly IFN-γ and IL-5 in response to BmVAL-1, and IL-4, and IL-5 in response to BmALT-2. CONCLUSION: A multivalent vaccine formulation of BmVAL-1 and BmALT-2 given as a prime boost regimen gave significant protection against lymphatic filariasis caused by B. malayi in mice and jirds. Because putatively immune endemic normal subjects also carry protective antibodies against BmVAL-1 and BmALT-2, developing this multivalent formulation as a prophylactic vaccine against B. malayi for human and veterinary use has great potential.
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Xu S, Liu C, Tzertzinis G, Ghedin E, Evans CC, Kaplan R, Unnasch TR. In vivo transfection of developmentally competent Brugia malayi infective larvae. Int J Parasitol 2010; 41:355-62. [PMID: 21118694 DOI: 10.1016/j.ijpara.2010.10.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Revised: 10/25/2010] [Accepted: 10/26/2010] [Indexed: 11/26/2022]
Abstract
Transient transfection of isolated Brugia malayi embryos by biolistics has proven to be useful in defining promoter structure and function in this parasite. However, isolated transfected embryos are developmentally incompetent. A method of producing developmentally competent transfected parasites is therefore needed. We report that L3 parasites can be chemically transfected in situ in the peritoneal cavity of a gerbil with a construct consisting of a secreted luciferase reporter gene containing a promoter, the 3' untranslated region and first intron derived from the B. malayi 70 kDa heat shock protein gene. The in situ chemically transfected parasites are developmentally competent, producing adult parasites with an efficiency similar to that obtained from implanted untreated L3s. Cultured adult parasites and progeny microfilariae (mf) derived from L3s transfected with this construct secreted luciferase into the culture medium. When the transfected mf were fed to mosquitoes and the resulting L3s collected, the L3s also secreted luciferase into the culture medium. Progeny mf from transgenic adult parasites contained transgenic DNA, and the transgenic mRNA produced in these parasites was found to be correctly cis- and trans-spliced. In situ chemical transformation thus results in developmentally competent transfected B. malayi in which the transgenic sequences remain transcriptionally active in all life cycle stages and are present in the subsequent generation.
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Affiliation(s)
- Shulin Xu
- Global Health Infectious Disease Research Program, Department of Global Health, University of South Florida, Tampa, FL 33612, USA
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Li BW, Rush AC, Mitreva M, Yin Y, Spiro D, Ghedin E, Weil GJ. Transcriptomes and pathways associated with infectivity, survival and immunogenicity in Brugia malayi L3. BMC Genomics 2009; 10:267. [PMID: 19527522 PMCID: PMC2708187 DOI: 10.1186/1471-2164-10-267] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 06/15/2009] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Filarial nematode parasites cause serious diseases such as elephantiasis and river blindness in humans, and heartworm infections in dogs. Third stage filarial larvae (L3) are a critical stage in the life cycle of filarial parasites, because this is the stage that is transmitted by arthropod vectors to initiate infections in mammals. Improved understanding of molecular mechanisms associated with this transition may provide important leads for development of new therapies and vaccines to prevent filarial infections. This study explores changes in gene expression associated with the transition of Brugia malayi third stage larvae (BmL3) from mosquitoes into mammalian hosts and how these changes are affected by radiation. Radiation effects are especially interesting because irradiated L3 induce partial immunity to filarial infections. The underlying molecular mechanisms responsible for the efficacy of such vaccines are unkown. RESULTS Expression profiles were obtained using a new filarial microarray with 18, 104 64-mer elements. 771 genes were identified as differentially expressed in two-way comparative analyses of the three L3 types. 353 genes were up-regulated in mosquito L3 (L3i) relative to cultured L3 (L3c). These genes are important for establishment of filarial infections in mammalian hosts. Other genes were up-regulated in L3c relative to L3i (234) or irradiated L3 (L3ir) (22). These culture-induced transcripts include key molecules required for growth and development. 165 genes were up-regulated in L3ir relative to L3c; these genes encode highly immunogenic proteins and proteins involved in radiation repair. L3ir and L3i have similar transcription profiles for genes that encode highly immunogenic proteins, antioxidants and cuticle components. CONCLUSION Changes in gene expression that normally occur during culture under conditions that support L3 development and molting are prevented or delayed by radiation. This may explain the enhanced immunogenicity of L3ir. Gene Ontology and KEGG analyses revealed altered pathways between L3 types. Energy and "immune pathways" are up-regulated and may be needed for L3i invasion and survival, while growth and development are priorities for L3c. This study has improved our understanding of molecules involved in parasite invasion and immune evasion, potential targets of protective immunity, and molecules required for parasite growth and development.
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Affiliation(s)
- Ben-Wen Li
- Department of internal medicine, Washington University School of Medicine, St, Louis, MO 63110, USA.
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AdultBrugia malayimitochondrial and nuclear fractions impart Th1-associated sizeable protection against infective larval challenges inMastomys coucha. J Helminthol 2009; 83:83-95. [DOI: 10.1017/s0022149x08133582] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractProtective immunity to the subperiodic human filariid,Brugia malayi, was explored in the rodent host,Mastomys couchaafter vaccination with subcellular fractions derived from the adult stage of the parasite. The highest level of protection was conferred in animals vaccinated with the ‘mitochondria rich’ (MT) fraction, in which microfilaraemia and worm burden were markedly reduced by 67.2 and 65.9%, respectively, followed by the ‘nucleus rich’ (NR) fraction, showing reductions of 62 and 52.3%, respectively, over the non-immunized control group. Mastomys vaccinated with MT and NR, displayed a significant increase in the level of antigen-specific serum immunoglobulin G (IgG). The levels of IgG2a, IgG2b and IgM antibody isotypes were remarkably elevated in both the MT and NR immunized groups, while IgG1 and IgG3 levels were low. Apart from antibodies, both these fractions also led to marked antigen-specific lymphoproliferationin vitro, along with enhanced release of nitric oxide by peritoneal macrophages. There was an increased population of CD4+ and CD8a+T-cells in MT immunized animals, as measured by flow cytometry, accompanied by elevated levels of proinflammatory cytokines; interferon gamma (IFN-γ), tumour necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) in the culture supernatants of the activated splenocytes. The results suggest that both NR and MT contain proinflammatory molecules which evoke a protective Th1 type of immune response.
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Molecular cloning and characterization of a novel immunoreactive ATPase/RNA helicase in human filarial parasite Brugia malayi. Parasitol Res 2008; 104:753-61. [DOI: 10.1007/s00436-008-1251-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 10/21/2008] [Indexed: 10/21/2022]
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Molecular cloning, purification and characterisation of myosin of human lymphatic filarial parasite Brugia malayi. Parasitol Res 2007; 102:481-9. [PMID: 18064491 DOI: 10.1007/s00436-007-0786-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 10/30/2007] [Indexed: 10/22/2022]
Abstract
Global efforts have been made towards development of vaccine for prevention of lymphatic filariasis. However, lack of thorough knowledge about developmental biology and pathogenesis of filarial parasite restricts us from developing an effective vaccine. A limited number of immunodominant antigens of human lymphatic filariid Brugia malayi have been characterised; however, none of these recombinant antigens so far induced significant degree of protective immunity to challenge infection. In the present study, we identified a approximately 2.0 Kb cDNA clone by immunoscreening of cDNA library of adult female Brugia malayi. The nucleotide sequence of the identified clone showed 94.3% homology with C-terminal part of myosin heavy chain gene of Brugia malayi. This cDNA insert was sub-cloned into pET28b vector and expressed in BL21(DE3). The recombinant protein was purified to near homogeneity by immobilised metal affinity chromatography (IMAC) with yield of approximately 25 mg/l. The purified protein was recognised in western blot with anti-His tag antibody as also with the antibodies present in the sera of human W. bancrofti patients of all categories and infected/immunized rodent serum demonstrating its functional role. Recombinant myosin induced marked cellular immune response as observed by lymphoproliferation assay. The present findings demonstrate the usefulness of B. malayi recombinant myosin as vaccine candidate against human lymphatic filariasis.
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Li BW, Rush AC, Weil GJ, McCarter JP, Mitreva M. Brugia malayi: Effects of radiation and culture on gene expression in infective larvae. Mol Biochem Parasitol 2006; 149:201-7. [PMID: 16824625 DOI: 10.1016/j.molbiopara.2006.05.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Revised: 05/26/2006] [Accepted: 05/31/2006] [Indexed: 11/13/2022]
Abstract
Third-stage infective larvae (L3i) of Brugia malayi are developmentally arrested in mosquitoes but must quickly adapt to a new environment when they enter mammalian hosts to initiate infections. These changes can be studied by in vitro culture of L3 (L3c) under conditions that permit molting of L3-L4. Irradiated L3 (L3ir) have stunted growth and limited lifespan in mammalian hosts, and they induce high levels of immunity to challenge infections in animal models. This study explored differences in gene expression in L3i, L3c and L3ir by expressed sequence tag EST generation and qRT-PCR. 2506 ESTs generated from cDNA libraries constructed from L3i, L3c and L3ir were grouped into 1309 gene clusters. Despite extensive prior sampling from B. malayi (>22,000 ESTs in dbEST), 73% of the L3 clusters described here are novel. Sixty-three percentage of the clusters have homology to proteins from other species including 187 specific to nematodes and 141 that have to date only been described in non-nematode species. The transcript levels of 62 candidates for up- or down-regulation in L3i, L3c and L3ir based on EST frequencies were evaluated by qRT-PCR. Twenty-eight were confirmed to have > or = 3-fold differences in expression. Genes coding for proteins believed to be involved in establishment of infection, host adaptation and targets of protective immunity were confirmed to have higher expression in L3i than in L3c. Some of the genes that were down-regulated in L3c were highly expressed in L3ir. This study provides an improved description of the adaptations that accompany the transition from L3i to L3c and the special ability of L3ir to induce protective immunity.
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Affiliation(s)
- Ben-Wen Li
- Infectious Diseases Division, Campus Box 8051, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA.
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Dixit S, Gaur RL, Sahoo MK, Joseph SK, Murthy PSR, Murthy PK. Protection against L3 induced Brugia malayi infection in Mastomys coucha pre-immunized with BmAFII fraction of the filarial adult worm. Vaccine 2006; 24:5824-31. [PMID: 16757067 DOI: 10.1016/j.vaccine.2006.05.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Revised: 04/29/2006] [Accepted: 05/02/2006] [Indexed: 10/24/2022]
Abstract
The present study was aimed at investigating protective efficacy of BmAFII (Sephadex G-200 eluted fraction of Brugia malayi adult worm extract) against establishment of infective larvae (L3)-induced B. malayi infection in Mastomys coucha and to delineate immunological responses induced in the host. Healthy male M. coucha were immunized with BmAFII and subsequently inoculated with B. malayi L3. Specific IgG and cell mediated immune responses (cellular proliferation) including release of tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), transforming growth factor-beta (TGF-beta) and nitric oxide (NO) from host's cells stimulated with BmAFII or lipopolysaccharide (LPS)/concanavalin A (Con A) in vitro were determined. Immunization with BmAFII reduced the adult worm recovery by 85.7% (P<0.001) and microfilaraemia by 77-95% of unimmunized controls (P<0.05-0.01). Immunization alone resulted in downregulation of responses of cellular proliferation, IFN-gamma, TNF-alpha and NO production (P<0.01) but increased TGF-beta release (P<0.001) whereas the converse was seen after L3 inoculation in these animals. In unimmunized+L3 inoculated animals all the above parameters were found downregulated (P<0.01-0.001). The cell proliferative response of BmAFII immunized+L3 challenged animals was larger for Con A (P<0.001) but not for BmAFII. Specific IgG levels were higher in immunized, immunized+L3 inoculated and unimmunized+L3 inoculated groups (P<0.001) compared to unimmunized animals, the highest level being shown by immunized+L3 inoculated group. In conclusion, immunization with BmAFII suppresses establishment of L3-induced infection in M. coucha by stimulating proinflammatory responses to L3.
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Affiliation(s)
- S Dixit
- Division of Parasitology, Central Drug Research Institute, Lucknow 226001, India
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Rao R, Moussa H, Vanderwaal RP, Sampson E, Atkinson LJ, Weil GJ. Effects of gamma radiation on Brugia malayi infective larvae and their intracellular Wolbachia bacteria. Parasitol Res 2005; 97:219-27. [PMID: 15997407 DOI: 10.1007/s00436-005-1421-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Accepted: 05/10/2005] [Indexed: 10/25/2022]
Abstract
Prior studies have shown that irradiated filarial larvae are developmentally stunted but capable of inducing partial immunity to filariasis in animals. The mechanisms for these effects are poorly understood. Recent studies suggest that intracellular Wolbachia bacteria are necessary for the normal development, reproduction and survival of filarial nematodes. The purpose of this study was to examine the effects of irradiation on Wolbachia in Brugia malayi infective larvae (L3) and on L3 development. The L3 were exposed to 0, 25, 35, 45, 55, 65 or 75 krad of gamma irradiation from a (137) Cesium source and cultured in vitro at 37 degrees C in NCTC/IMDM medium with 10% FCS for 12 days. Irradiation prevented molting of L3 to the L4 stage in a dose-dependent manner. Electron microscopy studies showed that irradiation damaged Wolbachia (25 krad) or cleared them from worm tissues (45 krad). In addition, majority of the irradiated L3s failed to develop the L4 cuticle. Real-time PCR studies showed that irradiation reduced Wolbachia DNA in worm tissues. Parallel in vivo studies confirmed decreased development of irradiated L3 in jirds, with associated effects on Wolbachia. Jirds injected s.c with normal L3 developed antibodies to Wolbachia surface protein (wsp) shortly after the onset of microfilarial patency. In contrast, jirds injected with irradiated L3 did not develop microfilaremia or antibodies to wsp. Additional studies are needed to test the hypothesis that irradiation retards growth and development of filarial L3 by killing Wolbachia.
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Affiliation(s)
- R Rao
- Infectious Diseases Division, Department of Internal Medicine, School of Medicine, Washington University, Campus Box 8051, 660 S Euclid Ave, St. Louis, MO 63110, USA.
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Rao RU, Atkinson LJ, Vanderwall RP, Weil GJ. Brugia malayi: effects of gamma radiation on adult worms and their intracellular Wolbachia bacteria. Exp Parasitol 2005; 109:87-93. [PMID: 15687015 DOI: 10.1016/j.exppara.2004.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Revised: 11/22/2004] [Accepted: 11/24/2004] [Indexed: 10/26/2022]
Abstract
Prior studies have shown that intracellular Wolbachia endobacteria are necessary for the normal development, reproduction, and survival of filarial nematodes. The purpose of this study was to examine effects of gamma radiation on Wolbachia and reproduction in Brugia malayi adult worms. Worms were exposed to 0, 10, 25, 45, 75, and 105 krad of gamma radiation from a 137cesium source and cultured in vitro for 10 days. Irradiation reduced production of microfilariae in a dose-dependent manner. Embryograms of irradiated female worms showed dose-related abnormalities with arrested development at the early embryo stage. Irradiation reduced the viability of adult worms in a dose-dependent manner, but no lethal effect was observed. Electron microscopy studies showed that irradiation cleared Wolbachia from worm tissues. Real-time polymerase chain reaction studies demonstrated greatly reduced Wolbachia DNA in irradiated worms. These effects are essentially the same as those observed in adult worms treated with doxycycline. These studies suggest that effects of irradiation on reproduction in Brugia malayi may be caused by effects of irradiation on Wolbachia.
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Affiliation(s)
- Ramakrishna U Rao
- Department of Internal Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO 63110, USA.
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15
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Li BW, Rush A, Zhang SR, Curtis KC, Weil GJ. Antibody responses to Brugia malayi antigens induced by DNA vaccination. FILARIA JOURNAL 2004; 3:1. [PMID: 14738569 PMCID: PMC343290 DOI: 10.1186/1475-2883-3-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2003] [Accepted: 01/22/2004] [Indexed: 01/14/2023]
Abstract
Background DNA vaccination is a convenient means of immunizing animals with recombinant parasite antigens. DNA delivery methods are believed to affect the qualitative nature of immune responses to DNA vaccines in ways that may affect their protective activity. However, relatively few studies have directly compared immune responses to plasmids encoding the same antigens after injection by different routes. Therefore, the purpose of this study was to explore the influence of the route of administration on antibody responses to plasmids encoding antigens from the filarial nematode parasite Brugia malayi. Methods Four B. malayi genes and partial genes encoding paramyosin (BM5), heat shock protein (BMHSP-70), intermediate filament (BMIF) and a serodiagnostic antigen (BM14) were inserted in eukaryotic expression vectors (pJW4303 and pCR™3.1). BALB/c mice were immunized with individual recombinant plasmids or with a cocktail of all four plasmids by intramuscular injection (IM) or by gene gun-intradermal inoculation (GG). Antibody responses to recombinant antigens were measured by ELISA. Mean IgG1 to IgG2a antibody ratios were used as an indicator of Th1 or Th2 bias in immune responses induced with particular antigens by IM or GG immunization. The statistical significance of group differences in antibody responses was assessed by the non-parametric Kruskal-Wallis test. Results Mice produced antibody responses to all four filarial antigens after DNA vaccination by either the IM or GG route. Antibody responses to BM5 paramyosin were strongly biased toward IgG1 with lower levels of IgG2a after GG vaccination, while IM vaccination produced dominant IgG2a antibody responses. Antibody responses were biased toward IgG1 after both IM and GG immunization with BMIF, but antibodies were biased toward IgG2a after IM and GG vaccination with BMHSP-70 and BM14. Animals injected with a mixture of four recombinant plasmid DNAs produced antibodies to all four antigens. Conclusions Our results show that monovalent and polyvalent DNA vaccination successfully induced antibody responses to a variety of filarial antigens. However, antibody responses to different antigens varied in magnitude and with respect to isotype bias. The isotype bias of antibody responses following DNA vaccination can be affected by route of administration and by intrinsic characteristics of individual antigens.
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Affiliation(s)
- Ben-Wen Li
- Infectious Diseases Division, Campus Box 8051, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Amy Rush
- Infectious Diseases Division, Campus Box 8051, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Shaorong R Zhang
- Infectious Diseases Division, Campus Box 8051, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Kurt C Curtis
- Infectious Diseases Division, Campus Box 8051, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Gary J Weil
- Infectious Diseases Division, Campus Box 8051, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
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Bal MS, Beuria MK, Mandal NN, Das MK. Antigenemia is associated with low antibody response to carbohydrate determinants of a filarial surface antigen. Parasite Immunol 2003; 25:107-11. [PMID: 12791107 DOI: 10.1046/j.1365-3024.2003.00604.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The IgG response to a filarial surface antigen (DssdI) was evaluated in circulating antigen (Og4C3 test) positive and negative individuals from the Wuchereria bancrofti endemic region of Orissa, India. Circulating filarial antigen (CFA) positive individuals exhibited depressed antibody levels to DssdI and individuals with high antibody levels were invariably CFA negative. Low IgG levels to DssdI are associated with CFA positivity irrespective of microfilaraemia and clinical status. Thus asymptomatic microfilaraemic individuals with antigen positivity exhibited low IgG levels similar to symptomatic (chronic filariasis with elephantiasis, hydrocele) or asymptomatic amicrofilaraemic individuals with antigenemia. Western blot analysis revealed a band of approximately 210 kDa reactive with CFA-negative, but not with CFA-positive sera. DssdI was subjected to mild periodate oxidation to investigate the role of carbohydrate epitopes. The treatment considerably reduced the antigenic recognition of DssdI, stressing the immunodominance of carbohydrate residues of DssdI in infection-free individuals. In contrast, individuals with active infection failed to produce such antibodies to filarial surface carbohydrates.
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Affiliation(s)
- M S Bal
- Immunology Division, Regional Medical Research Centre (ICMR), Chandrasekharapur, Bhubaneswar - 751023, Orissa, India
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17
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Ravindran B. Are inflammation and immunological hyperactivity needed for filarial parasite development? Trends Parasitol 2001; 17:70-3. [PMID: 11228012 DOI: 10.1016/s1471-4922(00)01835-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Immune-dependent growth and development of infectious agents and pathogenesis of disease are increasingly being recognized. It is proposed that the development of filarial larvae to adult stage parasites takes place in an ambiance of inflammatory T helper cell type 1 cytokines in mammalian hosts, and that susceptibility to filarial infections could be governed by the status of macrophage-derived nitric oxide and host ability to produce antibodies to filarial T-independent (carbohydrate) antigens.
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Affiliation(s)
- B Ravindran
- Division of Immunology, Regional Medical Research Centre, Indian Council of Medical Research (ICMR), Bhubaneswar-751023, India.
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18
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Le Goff L, Loke P, Ali HF, Taylor DW, Allen JE. Interleukin-5 is essential for vaccine-mediated immunity but not innate resistance to a filarial parasite. Infect Immun 2000; 68:2513-7. [PMID: 10768938 PMCID: PMC97453 DOI: 10.1128/iai.68.5.2513-2517.2000] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The study of protective immune mechanisms effective against filarial nematodes has been hampered by the inability of these important human pathogens to infect laboratory mice. Recently, Litomosoides sigmodontis, a natural parasite of rats, has been developed as a valuable model for the study of filarial infection. BALB/c mice are fully susceptible to infection with L. sigmodontis third-stage larvae and develop patent infection. In contrast, mice on the C57BL background are resistant, and parasites undergo only a single molt and do not mature to adulthood. We used interleukin-5 (IL-5)-deficient mice on the C57BL/6 background to address the role of IL-5 and eosinophils in the innate resistance of C57BL/6 mice. We found no differences in parasite survival between IL-5-deficient and C57BL/6 mice. However, when these mice were used for the analysis of vaccine-mediated immunity, a critical role for IL-5 was elucidated. Mice genetically deficient in IL-5 were unable to generate a protective immune response when vaccinated with irradiated larvae, whereas C57BL/6 mice were fully protected from challenge infection. These studies help to clarify the highly controversial role of eosinophils in filarial infection.
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Affiliation(s)
- L Le Goff
- Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
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19
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Helmy H, Weil GJ, Faris R, Gad AM, Chandrashekar R, Ashour A, Ramzy RM. Human antibody responses to Wuchereria bancrofti infective larvae. Parasite Immunol 2000; 22:89-96. [PMID: 10652121 DOI: 10.1046/j.1365-3024.2000.00280.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Human IgG antibody responses to Wuchereria bancrofti third stage infective larvae (L3) surface and somatic antigens were studied by indirect immunofluorescence (IFA) and immunoblot with endemic Egyptian sera (n = 115) with the aim of identifying targets of protective immunity. Human sera variably recognized 14 major bands in L3 by immunoblot. The statistical significance of group differences in antibody prevalence was assessed by the chi-squared test. Children and young adults (aged 10-20 years) tended to have antibodies to more L3 somatic antigens than older adults, with significant differences for bands at 66, 60 and 5 kDa. Infected subjects had more consistent antibody responses to antigens at 55, 50 and 6 kDa than endemic normal subjects with negative serum filarial antigen tests, who are presumed to be uninfected. A 5 kDa antigen was preferentially recognized by the latter group. Antibodies to L3 surface antigens were equally prevalent in uninfected children (75%) and adults (90%) but less prevalent in people with microfilaremia (38%) than in amicrofilaremic subjects with or without filarial antigenemia (81%) (P < 0.001). IFA-positive sera showed significantly enhanced recognition of antigens at 66, 40 and 14 kDa in immunoblots relative to IFA-negative sera. Additional studies are needed to further characterize antigens identified in this study and to establish whether they are indeed targets of protective immunity in humans.
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Affiliation(s)
- H Helmy
- Research and Training Center on Vectors of Diseases, Ain Shams University, Cairo, Egypt
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20
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Raghavan N, Ghosh I, Eisinger WS, Pastrana D, Scott AL. Developmentally regulated expression of a unique small heat shock protein in Brugia malayi. Mol Biochem Parasitol 1999; 104:233-46. [PMID: 10593178 DOI: 10.1016/s0166-6851(99)00150-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A screen of an expression library from the fourth larval stage (L4) of the parasitic nematode Brugia malayi resulted in the identification of a 727 bp full-length cDNA with 29-40% identity to members of the small heat shock family of proteins (Bm-hsp-s1). The open reading frame encoded a protein of approximately 18 kDA (Bm-HSP-s1). An alignment of the Bm-HSP-s1 sequence with the sequences of small HSPs from vertebrate and invertebrate species demonstrated that a majority of the identity was concentrated in the central alpha-crystallin domain. Bm-HSP-s1 was constitutively produced by L4 and adult parasites and at low levels by third-stage larvae (L3), but not by first-stage larvae (microfilariae). In adult parasites, Bm-HSP-s1 was localized to the body wall muscle cells and to the cells of the hypodermis/lateral cord. Bm-HSP-s1 production was induced in adult and L3 incubated at 42 degrees C and in L3s during the developmental transition from vector-stage to vertebrate-stage parasites at 37 degrees C. Neither increased nor decreased temperatures induced Bm-HSP-s1 production in microfilariae. Nitric oxide induced low-level, transient Bm-HSP-s1 synthesis in adults, but not in microfilariae. Bm-HSP-s1 did not function as a molecular chaperone to prevent heat-induced aggregation of a test substrate. The developmentally regulated expression and inducable nature of Bm-HSP-s1 suggests that it may have a stage-restricted role in maintaining parasite homeostasis.
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Affiliation(s)
- N Raghavan
- Department of Molecular Microbiology and Immunology, Johns Hopkins School of Hygiene and Public Health, Baltimore, MD 21205, USA
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21
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Li BW, Zhang S, Curtis KC, Weil GJ. Immune responses to Brugia malayi paramyosin in rodents after DNA vaccination. Vaccine 1999; 18:76-81. [PMID: 10501237 DOI: 10.1016/s0264-410x(99)00182-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Immunization with recombinant Brugia malayi paramyosin protein (BM5) induces partial immunity to this filarial nematode in jirds. The present study examined the effects of intramuscular immunization with plasmid DNA that encodes BM5. DNA-immunized mice produced strong antibody and cell-mediated responses to paramyosin. The protective activity of DNA vaccination with BM5 was tested in jirds. Vaccinated jirds produced strong antibody responses to paramyosin, but adult worm recoveries after challenge were not decreased in vaccinated animals relative to controls. These studies show that DNA vaccination can induce immune responses to filarial antigens in rodents. Further efforts will be needed to achieve the goal of inducing protective immunity to filariasis with this promising new technology.
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Affiliation(s)
- B W Li
- Washington University School of Medicine and Barnes-Jewish Hospital, Infectious Diseases Division, St. Louis, MO 63110, USA
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22
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Abstract
Human antibody responses to Brugia malayi antigens were studied with sera from a Brugia endemic area in South India. Patients with clinical filariasis had significantly higher IgE and lower IgG4 levels to adult worm antigens than people with asymptomatic microfilaraemia. Intermediate antibody levels were observed in endemic normals. A majority of sera from each clinical group contained IgG antibodies to surface antigens of infective larvae (L3) by IFAT. IgG immunoblot studies did not reveal group differences in L3 antigen recognition. IgE antibodies bound to a subset of antigens bound by IgG. IgE antibodies in sera from clinical filariasis patients preferentially bound to L3 antigens at 200, 97, 68 and 58 kDa compared with sera from microfilaria carriers. These results are consistent with prior studies of antibody responses in filariasis and add new information on the targets of IgG and IgE antibodies to L3 antigens in brugian filariasis.
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Affiliation(s)
- S Zhang
- Department of Internal Medicine, Washington University School of Medicine and Barnes-Jewish Hospital, St. Louis, MO 63110, USA
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23
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Kurniawan-Atmadja A, Sartono E, Partono F, Yazdanbakhsh M, Maizels RM. Antibody responses to filarial infective larvae are not dominated by the IgG4 isotype. Parasite Immunol 1998; 20:9-17. [PMID: 9491413 DOI: 10.1046/j.1365-3024.1998.t01-1-00118.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The humoral immune response in humans to filarial parasites is generally dominated by the IgG4 isotype, when measured by ELISA against somatic adult worm extract. In contrast, as we report here, antibodies reactive to somatic extracts of infective larvae are more equally represented by IgG1 and IgG4. Moreover, binding to surface exposed epitopes in immunofluorescence on larval stages is mediated foremost by IgG1 and IgM, secondarily by IgG2 and IgG3, and very little by IgG4. Both anti-L3 surface and somatic antibodies are strongest in elephantiasis patients, and tend to increase with age. Antibody to the L3 surface is also present in most microfilaraemic individuals who bear no detectable antibodies to the surface of the microfilarial stage. These results demonstrate that a stage- and isotype-specific response is mounted to the L3 surface which should be considered as a possible mediator of concomitant immunity in filariasis.
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Affiliation(s)
- A Kurniawan-Atmadja
- Department of Parasitology, Faculty of Medicine, University of Indonesia, Jakarta, Indonesia
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24
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Li BW, Hoppe PE, Weil GJ. Cloning of an early immunodominant filarial antigen: a member of the Brugia malayi myosin heavy chain gene family. Int J Parasitol 1995; 25:611-9. [PMID: 7635639 DOI: 10.1016/0020-7519(94)00164-j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Partial protective immunity to filariasis can be achieved in animals by vaccination with irradiated infective larvae. A Brugia malayi cDNA expression library was screened with serum pools from vaccinated and infected jirds to select clones that expressed potentially protective recombinant antigens that were preferentially recognized by sera from vaccinated animals. Bmmyo-2, the largest of a group of related clones, was studied in detail. Jirds produced strong antibody responses to the protein product of Bmmyo-2, Bmmhc-B, as early as 1 month after vaccination with irradiated larvae. Antibody responses to Bmmhc-B in infected jirds were weaker than those of vaccinated jirds, and they developed somewhat later. Antibodies produced to Bmmhc-B were reactive with a 200 kDa native B. malayi antigen by immunoblot and with muscle bands in the body wall of microfilarial by indirect immunofluorescence. Sequence analysis of the 1454 bp cDNA insert of Bmmyo-2 showed that it codes for a portion of the rod region of a B. malayi myosin heavy chain isoform. The deduced amino acid sequence of Bmmyo-2 is 74.6% identical with that of the corresponding region of Caenorhabditis elegans myosin heavy chain B, but only 64.6% identical with a recently described B. malayi myosin heavy chain, Bmmhc-A.
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Affiliation(s)
- B W Li
- Department of Medicine, Washington University School of Medicine, St Louis, MO, USA
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25
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Abstract
Parasitic helminths continue to be a major cause of morbidity in human populations, particularly in the tropics and subtropics. The need for effective vaccines that minimize worm burdens, thus reducing associated pathology, is evident. With this goal in mind, an intense research effort is in progress to characterize immune responses to helminths, especially in the context of recent developments in our understanding of the cytokine network. The growing realization that the parasites can themselves subvert host immune responses to their own advantage makes the task of vaccine development that much harder.
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Affiliation(s)
- R A Wilson
- Department of Biology, University of York, UK
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