IgM-specific linear epitopes on the E2 protein for serodiagnosis of Chikungunya

Chikungunya virus (CHIKV) and Dengue virus (DENV) are vector-borne diseases transmitted by Aedes aegypti and Aedes albopictus that pose a significant threat to global public health. Cases of acute Chikungunya fever often present similar clinical symptoms to other vector-borne diseases, such as Dengue fever. In regions where multiple vector-borne diseases coexist, CHIKV is often overlooked or misdiagnosed as Dengue virus, West Nile virus, Zika virus or other viral infections, which delays its prevention and control. However, IgM antibodies directed against the E2 protein of CHIKV have not yet been generalized to clinical settings due to the low sensitivity and high cost in commercial kits. Indirect ELISA with peptides provides an effective supplementary tool for detecting CHIKV IgM antibodies. Our study aims at examining the potential of linear epitopes on the E2 glycoprotein that specifically bind to IgM antibodies as serodiagnostic tool for CHIKV. The sensitivity of the established peptide indirect ELISA method for detecting clinical samples is significantly better than that of commercial kits, realizing a beneficial supplement to the existing IgM antibody assay. It also established the groundwork for comprehending the biological mechanisms of the CHIKV E2 protein and the advancement of innovative epitope peptide vaccines.

Ginsenoside Rg3 endows liposomes with prolonged blood circulation and reduced accelerated blood clearance

PEGylated cholesterol-containing liposomes (Chol-PEG-lipo) have been widely used as a drug carrier for their good stealth property in blood circulation where cholesterol maintains the stability of the liposomal lipid bilayer and PEGylation endows liposomes with long circulation capability. However, cholesterol-related disadvantages and the accelerated blood clearance (ABC) phenomenon caused by PEGylation greatly limit the application of conventional stealth liposomes in clinic. Herein, ginsenoside Rg3 was selected to substitute cholesterol and PEG for liposomes preparation (Rg3-lipo). Rg3 was proved with similar liposomal membrane regulation ability to cholesterol and comparable long circulation effect to PEG. In addition, repeated administrations of Chol-PEG-lipo and Rg3-lipo were performed. The circulation time of the second dose of Chol-PEG-lipo was substantially reduced accompanied by a greatly increased accumulation in the liver due to the induction of anti-PEG IgM and the subsequent activated complement system. In contrast, no significantly increased level of relative plasma cells, IgM secretion and the complement activation in blood circulation was observed after the second injection of Rg3-lipo. As a result, Rg3-lipo showed great stealth property without ABC phenomenon. Therefore, developing liposomes utilizing Rg3 instead of PEG and cholesterol presents a promising strategy to prolong the blood circulation time of liposomes without triggering the ABC phenomenon and activated immune responses.

Association between toxoplasmosis and autoimmune rheumatic diseases in Egyptian patients

PURPOSE

To explore the association between T. gondii and autoimmune rheumatic diseases (ARDs).

METHODS

This study involved 82 patients with ARDs: 44 rheumatoid arthritis (RA), 28 systemic lupus erythematosus (SLE), and 10 systemic sclerosis (SSc) and 61 age- and sex-matched controls. Sociodemographic, clinical, and laboratory data were collected, and disease activity was assessed. Exposure to toxoplasmosis risk factors was investigated. Serological tests for anti-Toxoplasma IgM and IgG antibodies were assessed using ELISA.

RESULTS

In SLE patients, a significant difference of T. gondii IgM versus controls was detected (P=.03). In RA and SLE patients, T. gondii IgG showed a significant difference versus controls (34 (77.3%) P=.001 and 18 (64.3%) P=.03, respectively). There was no significant difference in SSc versus controls. Fetal congenital anomalies displayed a significant difference in IgM seropositive compared to seronegative patients (P=.04). Cat exposure showed a significant difference between IgM and IgG seropositive versus seronegative patients (12 (80.0%) P=.02 and 34 (59.6) P=.04, respectively). There was no significant difference in seropositive patients regarding history of abortion, neuro-psychiatric manifestations, disease activity parameters (ESR, CRP), or different regimens of medications.

CONCLUSION

Toxoplasma IgM seropositivity is associated with SLE patients. T. gondii IgG seropositivity is associated with both RA and SLE patients. However, Toxoplasma seropositivity had no association with SSc patients. An association between fetal congenital anomalies and IgM seropositivity was demonstrated. A linkage between cat exposure as a risk factor and toxoplasmosis was suggested among ARD patiants. Exploration of impact of toxoplasmosis on ARDs is a necessity through randomized controlled trials.

Renin-angiotensin-system blockers and IgG antibodies in end-stage renal disease hemodialysis-receiving patients diagnosed with COVID-19 infection

OBJECTIVES

To evaluate the prevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections among patients receiving in-center hemodialysis (ICHD), the relationship between the IgG antibody levels against the virus and SARS-CoV-2-associated symptoms, hemodialysis adequacy, and the antihypertensives used in order to control blood pressure.

METHODS

A prospective observational study was carried out at a tertiary care center, King Fahad Kidney Center, Riyadh, Kingdom of Saudi Arabia, between November 2020 and January 2021. A total of 214 ICHD patients with end-stage renal disease (ESRD) were included, and the levels of their anti-SARS-CoV-2 IgG antibodies were assessed after obtaining their informed consent.

RESULTS

Our tests indicated that 15% of the patients in the study's population had detectable SARS-CoV-2 IgG antibodies, with more than half of them (53%) being asymptomatic. We also found that ESRD patients on angiotensin converting enzyme inhibitors or angiotensin receptor blockers (ACEIs/ARBs) had higher levels of SARS-CoV-2 IgG antibodies than patients not receiving this group of medications.

CONCLUSION

More studies are required to assess whether patients with a SARS-CoV-2 infection that do not have an indication for being prescribed ACEIs/ARBs would benefit from receiving these medications.

Revision of Cytomegalovirus Immunoglobulin M Antibody Titer Cutoff in a Maternal Antibody Screening Program in Japan: A Cohort Comparison Involving a Total of 32,000 Pregnant Women

Cytomegalovirus (CMV) is associated with congenital infections. We aimed to validate the revised CMV immunoglobulin (Ig) M titer cutoff for IgG avidity measurements as a reflex test in maternal screening to identify women with primary CMV infection and newborn congenital cytomegalovirus (cCMV). We screened maternal CMV antibodies (the Denka assay) in Japan, from 2017 to 2019, using a revised IgM cutoff (≥4.00 index). Participants were tested for IgG and IgM antibodies, and for IgG avidity if IgM levels exceeded the cutoff. We compared these with corresponding results from 2013 to 2017 based on the original cutoff (≥1.21) and recalculated using the revised cutoff. Newborn urine CMV DNA tests were performed for women with low avidity (≤35.0%). Among 12,832 women screened in 2017-2019, 127 (1.0%) had IgM above the revised cutoff. Thirty-five exhibited low avidity, and seven infants developed cCMV. Of 19,435 women screened in 2013-2017, 184 (1.0%) had IgM above the revised cutoff, 67 had low avidity, and 1 had cCMV. The 2017-2019 results were not significantly different from the 2013-2017 results. The revised IgM cutoff improves maternal screening in identifying primary infection and newborn cCMV; however, further study related to other assays than Denka is required.

Seroprevalence and geographical distribution of parvovirus B19 antibodies in pregnant women: A-meta analysis

Parvovirus B19 has been identified to infect pregnant women and cause anemia, spontaneous abortion, and fetal death. Given the significance of parvovirus B19 complications, this study aims to determine the seroprevalence and geographical distribution of parvovirus B19 antibodies in pregnant women to improve health control policies in the community. Online international databases and national Persian databases were used to define appropriate studies published between 2000 and January 2021. The quality of all papers was determined by a Newcastle-Ottawa Scale (NOS) checklist. The statistical analyses were performed using the Stata version 11 package (StataCorp, College Station, TX, USA) software. Heterogeneity among the primary studies was calculated using Cochran's Q-test and I2 index. The Egger test and the funnel plot chart with a significance level of less than 0.1 were used to evaluate the publishing bias. The seroprevalence of parvovirus B19 IgG antibodies among pregnant and non-pregnant women in Iran was assessed in 12 primary studies. Our finding showed that the seroprevalence of parvovirus B19 IgG antibodies among pregnant women varies from 21% to 76%. Combining the results of 5 primary studies based on the random effect model, the seroprevalence of parvovirus B19 IgG antibody among pregnant women in Iran was estimated to be 54% (95% CI:33-76). The seroprevalence of parvovirus B19 IgM antibodies has been reported in 9 studies. By combining the results of these studies using a random effect model, the seroprevalence of parvovirus B19 IgM antibody among pregnant women was estimated to be 3% (95% CI: 1-6). Generally, it is suggested that appropriate screening programs should be performed for the treatment and prevention of diseases. According to this point, the prevalence of parvovirus B19 is low among pregnant women, but it can cause serious manifestations such as hydrops fetalis and severe anemia, therefore, antibody determination using ELISA can be recommended for all pregnant women.

Poor accuracy of single serological IgM tests in children with suspected acute Mycoplasma pneumoniae infection in Guangzhou, China

Introduction. Early and accurate diagnosis of Mycoplasma pneumoniae (MP) infection of children with pneumonia is at the core of treatment in clinical practice.Gap Statement. Serological immunoglobulin M (IgM) tests for MP infection of children in south China have been rarely described.Aim. To assess the diagnostic performance and clinical application of serodiagnosis of MP infection in paediatric pneumonia patients.Methodology. Serum samples from 144 children diagnosed with MP pneumonia were subjected to a particle agglutination (PA)-based IgM assay. Meanwhile, we used an established suspension array as the reference standard method for the detection of MP DNA in bronchoalveolar lavage fluid (BALF) from all patients to assess the reliability of serological assays.Results. When running immunological testing in single serum samples, 80.6 %(79/98) of cases were diagnosed with MP infection, whereas only 55 (56.1 %) cases were positive in MP DNA analysis. Furthermore, single serum tests for IgM during acute MP infection resulted in 85.5 % (47/55) sensitivity and 25.6 % (11/43) specificity. Nevertheless, immunological testing and MP DNA analysis yielded the same results when paired sera were available for MP IgM antibody testing.Conclusion. Paired serological IgM assays are necessary for the determination of an acute MP infection, whereas single serological IgM testing is unreliable. Moreover, even a short interval of two MP serological tests works well.

Two pan-SARS-CoV-2 nanobodies and their multivalent derivatives effectively prevent Omicron infections in mice

With the widespread vaccinations against coronavirus disease 2019 (COVID-19), we are witnessing gradually waning neutralizing antibodies and increasing cases of breakthrough infections, necessitating the development of drugs aside from vaccines, particularly ones that can be administered outside of hospitals. Here, we present two cross-reactive nanobodies (R14 and S43) and their multivalent derivatives, including decameric ones (fused to the immunoglobulin M [IgM] Fc) that maintain potent neutralizing activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after aerosolization and display not only pan-SARS-CoV-2 but also varied pan-sarbecovirus activities. Through respiratory administration to mice, monovalent and decameric R14 significantly reduce the lung viral RNAs at low dose and display potent pre- and post-exposure protection. Furthermore, structural studies reveal the neutralizing mechanisms of R14 and S43 and the multiple inhibition effects that the multivalent derivatives exert. Our work demonstrates promising convenient drug candidates via respiratory administration against SARS-CoV-2 infection, which can contribute to containing the COVID-19 pandemic.

Dual blockages of a broad and potent neutralizing IgM antibody targeting GH loop of EV-As

The reported enterovirus A 71 (EVA71) vaccines and immunoglobin G (IgG) antibodies have no cross-antiviral efficacy against other enterovirus A (EV-A) which caused hand, foot and mouth disease (HFMD). Here we constructed an IgM antibody (20-IgM) based on our previous discovery to address the resistance encountered by IgG-based immunotherapy. Although binding to the same conserved neutralizing epitope within the GH loop of EV-As VP1, the antiviral breath and potency of 20-IgM are still higher than its parental 20-IgG1. The 20-IgM blocks the interaction between the EV-As and its receptors, scavenger receptor class B, member 2 (SCARB2) and Kringle-containing transmembrane protein 1(KREMEN1) of the host cell. The 20-IgM also neutralizes the EV-As at the post-attachment stages, including postattachment neutralization, uncoating and RNA release inhibition after internalization. Mechanistically, the dual blockage effect of 20-IgM is dependent on both a conserved site targeting and high affinity binding. Meanwhile, 20-IgM provides cross-antiviral efficacy in EV-As orally infected neonatal ICR mice. Collectively, 20-IgM and its property exhibit excellent antiviral activity with a dual-blockage inhibitory effect at both the pre- and post-attachment stages. The finding enhances our understanding of IgM-mediated immunity and highlights the potential of IgM subtype antibodies against enterovirus infections.

Anti-Nipah Virus Enzyme-Linked Immunosorbent Assays with Non-human Primate and Hamster Serum

Enzyme-linked Immunosorbent assays or ELISAs are a versatile method for detecting various immunological ligands of interest. As the name suggests, ELISAs rely on the interaction between a ligand and an antibody to produce results. In the study of infectious disease, ELISAs are commonly used to determine if a pathogen-specific immune response has occurred in a host organism. These assays can be performed in serosurveys as part of epidemiological investigations during, or following, an infectious disease outbreak. In the research environment, ELISAs are used to quantify the humoral immune response following infection or vaccination of a host organism. Data from these assays can be used to determine the type of immune response elicited (e.g. IgG1 vs IgG2) and the robustness of the response. Here, we describe ELISAs that were developed for the study of either hamsters or non-human primates vaccinated against Nipah virus infection, or infected with Nipah virus. The ELISAs described include assays for both IgG and IgM in the hamster and non-human primate models for Nipah virus-induced disease. An assay was also developed for the detection of IgA in bronchoalveolar lavage from non-human primates.

Seroprevalence of Cytomegalovirus antibodies and primary infection among hemodialysis patients: A systematic and meta-analysis review

BACKGROUND

Patients with end-stage renal failure (ESRD) require hemodialysis. According to this point that CMV infection is related to mortality in immunocompromised, and damages in hemodialysis, this study is designed to survey the seroprevalence of CMV and primary infection in hemodialysis (HD) patients.

MATERIAL AND METHODS

Current cross-sectional studies were found by online reviewing the national and international databases (Web of Science, Pubmed, Scopus, Science Direct, Google scholar), and suitable studies were selected. NOS checklist were used for evaluation of the qualities of all papers. Assessment of heterogeneity among the studies of primary studies was performed using Chi-squared test (Cochran's Q) and I2 index (significance level of 50%). The statistical analysis were performed using Comprehensive Meta-Analysis (CMA) V.2. For assessing publication bias, the Egger test was used by subjective judgment in each study. Also the effect of potential factor on heterogeneity of studies was performed by Meta-regression test and the impact of each study on the overall estimate was assessed by sensitivity analysis.

RESULTS

This meta- analysis included 23 primary studies investigating seroprevalence of Cytomegalovirus antibodies and primary infection among hemodialysis patients. Finding showed that seroprevalence of CMV IgG and IgM antibodies in hemodialysis patients at 95% confidence interval using random effect model was 88.7% (81.7-93.2%) and 10.9% (5.9-19.2%) respectively. Also the frequency of CMV infection among these studies were reported 41% (18.8-67.6%).

CONCLUSION

We found that frequency of CMV IgG was higher and it was detected in HD patients. The result of our study showed that most patients were exposure to CMV during dialysis may reactivate by various stimulation, including immunosuppression and inflammation, so screening of patients should be performed to prevent future consequences such as kidney transplant rejection during of dialysis.

[Evaluation of efficiency of different anti-cysticercus antibody test kits for serodiagnosis of cysticercosis]

OBJECTIVE

To evaluate the diagnostic efficiency of four anti-cysticercus IgG, IgG4 or IgM antibody test kits (enzyme-linked immunosorbent assay, ELISA) by different manufacturers, so as to provide insights into the epidemiological investigation and clinical detection of cysticercosis.

METHODS

Forty serum samples from cerebral cysticercosis patients, 100 serum samples from healthy volunteers, 30 serum samples from paragonimiasis skrjabini patients, 17 serum samples from cystic echinococcosis and 19 serum samples from subcutaneous or cerebral sparganosis patients were collected and detected using anti-cysticercus IgG, IgG4 or IgM antibody test kits (brand A) and the anti-cysticercus IgG antibody test kit (brand B). The sensitivity, specificity and false negative rate of the four kits for detection of cysticercosis were estimated.

RESULTS

The anti-cysticercus IgG, IgG4 or IgM antibody test kits (brand A) showed 95.00% (38/40), 87.50% (35/40), 7.50% (3/40) sensitivities and 98.00% (98/100), 100.00% (100/100) and 100.00% (100/100) for detection of cysticercosis, while the anti-cysticercus IgG antibody test kit (brand B) presented a 75.00% (30/40) sensitivity and 100.00% (100/100) specificity for detection of cysticercosis. The sensitivity for detection of cysticercosis was significantly higher by the anti-cysticercus IgG antibody test kit (brand A) than by the anti-cysticercus IgG antibody test kit (brand B) (χ² = 6.28, P < 0.05); however, no significant difference was seen in the specificity by two kits (χ² = 2.01, P > 0.05). The four ELISA kits showed overall false positive rates of 37.88% (25/66), 22.73% (15/66), 62.12% (41/66) and 15.15% (10/66) for detection of paragonimiasis, echinococcosis and sparganosis (χ² = 37.61, P < 0.05), and the anti-cysticercus IgG antibody test kit (brand A) presented the highest overall false positive rate for detection of paragonimiasis, echinococcosis and sparganosis (χ² = 7.56, P' < 0.008), while a higher overall false positive rate was seen for detection of paragonimiasis, echinococcosis and sparganosis by the anti-cysticercus IgG antibody test kit (brand A) than by the anti-cysticercus IgG antibody test kit (brand B) (χ² = 8.75, P' < 0.008). The four ELISA kits showed false positive rates of 40.00% (12/30), 16.67% (5/30), 76.67% (23/30) and 13.33% (4/30) for detection of paragonimiasis (χ2 = 32.88, P < 0.05) and 21.05% (4/19), 26.32% (5/19), 73.68% (14/19) and 15.79% (3/19) for detection of sparganosis (χ² = 19.97, P < 0.05), and the highest false positive rates were found by the anti-cysticercus IgM antibody test kit (brand A) for detection of paragonimiasis and sparganosis (all P' < 0.008). However, the four ELISA kits showed comparable false positive rates of 52.94% (9/17), 29.41% (5/17), 23.53% (4/17) and 17.65% (3/17) for detection of echinococcosis (χ² = 8.24, P > 0.05). In addition, the anti-cysticercus IgM anti-body test kit (brand A) showed false positive rates of 76.67% (23/30), 23.53% (4/17) and 73.68% (14/19) for detection of paragonimiasis, echinococcosis and sparganosis (χ² = 14.537, P < 0.05), with the lowest false positive rate seen for detection of echinococcosis (χ² = 14.537, P' < 0.014), while no significant differences were seen in the false positive rate for detection of paragonimiasis, echinococcosis and sparganosis by other three ELISA kits (all P > 0.05).

CONCLUSIONS

The four anti-cysticercus IgG, IgG4 or IgM antibody test kits exhibit various efficiencies for serodiagnosis of cysticercosis. The anti-cysticercus IgG antibody test kit (brand A) has a high sensitivity for serodiagnosis of cysticercosis; however, it still needs to solve the problems of cross-reaction with other parasitic diseases and stability.

Time Course of Severe Fever With Thrombocytopenia Syndrome Virus and Antibodies in Patients by Long-Term Follow-Up Study, China

Objectives: The objective was to describe the changes of severe fever with thrombocytopenia syndrome virus (SFTSV) and antibody in the disease course and explore the relationship between antibody titers and patients’ prognosis.

Methods: The levels of SFTSV, virus-specific immunoglobulin M (IgM), immunoglobulin G (IgG) titers, and cytokines in 37 patients with severe fever with thrombocytopenia syndrome (SFTS) were measured dynamically by real-time PCR and ELISA during the disease course; IgG titers were followed up in 53 cases. The correlation analysis of antibody titers with individual serum cytokines was calculated using the Spearman test.

Results: The average time of SFTSV duration in individual serum was 22.45 ± 7.6 days from onset. We found SFTSV turned negative within the 10th day from the onset in two patients. SFTSV-specific IgM seroconversion occurred as early as within 3 days from the onset, increased gradually within the first 2 months, decreased gradually 3 months later, and disappeared after 6 months in all the patients. The average time of SFTSV-specific IgG antibody seroconversion was at 17 days from onset in the patients; the time was later in severe cases than in mild cases (23 ± 1.4 vs. 14.3 ± 1.0 days, p < 0.0001). IgG titers were maintained at the peak levels during the periods from 6 months to 1 year and decreased from the second year gradually. Severe cases had higher IgG levels than mild cases and also had a slower decreasing trend. During follow-up, only one lost IgG antibody 7 years later; no chronic infection and sequela were found among the 53 patients. None of the patients had SFTSV reinfection even if they were bitten by ticks again. The correlation analysis showed a positive relationship between inflammatory factors and IgG antibody levels.

Conclusion: IgM antibody has important value in early diagnosis of SFTS. A moderate inflammatory response is beneficial for production and duration of IgG antibodies.

A broad and potent IgM antibody against tetra-EV-As induced by EVA71 and CVA16 co-immunization

OBJECTIVE

To determine the potent and broad neutralizing monoclonal antibody (mAb) against enterovirus A (EV-A) in vitro and in vivo induced by enterovirus A71(EVA71) and coxsackievirus 16 (CVA16) co-immunization.

METHODS

The mAb was Generated by co-immunization with EVA71 and CVA16 through hybridomas technology. The characteristics and neutralizing ability of mAb were analysed in vitro and in mice.

RESULTS

We screened three mAb, the IgM antibody M20 and IgG antibody B1 and C31. All three antibodies showed cross-reactivity against tetra-EV-As. However, M20 showed potent and broad neutralizing ability against tetra-EV-As than B1 and C31. Meanwhile, M20 provided cross-antiviral efficacy in tetra-EV-As orally infected mice. Moreover, M20 binds to a conserved neutralizing epitope within the GH loop of tetra-EV-As VP1.

CONCLUSIONS

M20 and its property exhibited potent and broad antiviral activity against tetra-EV-As, and that is expected to be a potential preventive and therapeutic candidate against EV-As.

A pilot study on screening for gestational/congenital toxoplasmosis of pregnant women at delivery in the Eastern Province of Saudi Arabia

BACKGROUND

Globally, congenital toxoplasmosis remains a significant cause of morbidity and mortality, and outbreaks of T. gondii infection represent a major public health threat, especially in developing countries. Evidence in the literature indicates that only a few studies have been conducted on the incidence of maternal and congenital toxoplasmosis in Saudi Arabia. This prospective study aims to measure the overall incidence of congenital toxoplasmosis, both patent and 'silent' infection, among pregnant women in the Eastern Province of Saudi Arabia. The study would attempt to relate the cord blood results with the time of seroconversion in the mother, underlining the importance of early intervention in such cases.

METHODS

Five hundred paired maternal/cord blood samples were tested for anti-Toxoplasma IgG or IgM antibodies. Samples were collected during delivery from mother and newborn (cord blood) from November 2011 to May 2012. Only positive for anti-Toxoplasma IgG or/and IgM cord blood was processed for real-time PCR for confirmation. The age of mothers ranged from 16 to 45 years.

RESULTS

The sample subjects were tested during child delivery for specific IgG and IgM antibodies against Toxoplasmosis, of which 21.0% (n = 105) mother/baby pairs were found serologically positive for anti-Toxoplasma IgG antibodies. The rate of maternal seropositivity for anti-Toxoplasma IgM antibodies was found among 4 participants (0.8%), who were also seropositive for anti-Toxoplasma IgG antibodies. None of the children tested positive for anti-Toxoplasma IgM antibodies, even those born to mothers with IgM positive. All 105 cord blood tests in the study sample were confirmed negative by real-time PCR. The seroprevalence of Toxoplasma IgG antibodies increased with maternal age, parity, and was significantly higher in women who gave birth to children with congenital anomalies (p = 0.008).

CONCLUSION

The findings of the current study indicate a dire need to develop and implement preventive programs against Toxoplasma gondii infection, as well as a health education program on how to avoid toxoplasmosis for all seronegative women during pregnancy.

Pitfalls in the Serological Diagnosis of Primary Human Cytomegalovirus Infection in Pregnancy Due to Different Kinetics of IgM Clearance and IgG Avidity Index Maturation

Primary infection occurs when seronegative women are infected by human cytomegalovirus (HCMV). Diagnosis of primary infection is based on the following: antibody seroconversion, presence of IgM and low IgG avidity index (AI), and presence of DNAemia. The kinetics of HCMV-specific IgM antibody and maturation of AI might be very rapid or long-lasting during primary infection, which makes serological diagnosis insidious. The aims of this study were as follows: (i) to report atypical kinetics of HCMV-specific IgM antibody and AI early after onset of primary HCMV infection in a population of pregnant women, and (ii) to assess the frequency of such results. Altogether, 1309 sequential serum samples collected from 465 pregnant women with primary HCMV infection were included in the study. As a general rule, using the LIAISON^®CMVIgMII and LIAISON^®CMVIgGAvidityII assays, virus-specific IgM antibody levels decreased, while IgG AI increased over time during the first three months after infection onset. However, early clearance of IgM antibody and/or early IgG AI maturation occurred in 46/426 (10.7%) women. In more details, 20/426 (4.7%) and 26/418 (6.2%) women had undetectable IgM antibody or high IgG AI, respectively, when tested within 1-3 months after well-defined infection onset. Twenty sera from as many women with high IgG AI by the LIAISON assay were further tested for IgG AI by VIDAS^®CMVIgGAvidityII and Mikrogen recomLineCMVIgG Avidity assays. Comparable results were obtained with VIDAS, whereas 14/20 sera gave low AI with the Mikrogen assay. In conclusion, about 11% of pregnant women undergoing a primary HCMV infection showed misleading serological results. Additional and appropriate testing might help in reducing the risk of missing HCMV primary infection in pregnancy. Furthermore, preconceptional testing should be strongly recommended.

Detection and analysis of blood donors seropositive for syphilis

BACKGROUND

The increasing incidence of syphilis worldwide has called attention to the risk of transmission by transfusion.

AIMS

To determine the prevalence of active syphilis in blood donors and characterise the serological profile of syphilis-positive donors.

METHODS

Samples positive for Treponema pallidum using the chemiluminescent microparticle immunoassay (CMIA) during blood donor screening from 2017 to 2018 were tested by the Venereal Disease Research Laboratory (VDRL) non-treponemal test and for anti-T. pallidum IgM by ELISA (Immunoassay Enzyme test for detection of IgM antibodies). The INNO-LIA Syphilis test (Line Immuno Assay solid test for confirmation antibodies to Treponema pallidum) was performed as a confirmatory test on samples that were positive on ELISA-IgM but negative on VDRL. ELISA-IgM (+) samples were also tested for T. pallidum DNA in sera by real-time polymerase chain reaction (PCR).

RESULTS

Of 248 542 samples screened, 1679 (0.67%) were positive for syphilis by CMIA. Further analysis was performed on 1144 (68.1%) of these samples. Of those tested, 16% were ELISA IgM(+)/VDRL(+), 16.5% were ELISA IgM(-)/VDRL(+), 4.1% were ELISA IgM(+)/VDRL(-), and 63.4% were ELISA IgM (-)/VDRL(-). The INNO-LIA Syphilis test results were 33 (3%) positive, 2 (0.2%) undetermined and 12 (1%) negative. Of the 230 EIA-IgM(+) samples (20.1%), 5 (2.2%) were PCR positive. The prevalence of active syphilis in 2017 and 2018 was 0.1% and 0.07%, respectively, and overall prevalence of serologic markers for syphilis was highest among male, unmarried, 25-34-year-olds with a high school education and who were first-time donors.

CONCLUSION

There is a risk of transfusion-transmitted syphilis in blood banks that exclusively use the VDRL test for donor screening, as is currently the situation in some Brazilian blood centres, as well as in other blood centres around the world.

[Preliminary study of the antibody level in confirmed patients with COVID-19 after discharge]

Objective: To analyze the antibody levels and dynamic changes in patients infected with 2019-novel coronavirus(2019-nCoV). Methods: The average age of 72 corona virus disease 2019 (COVID-19) patients was (45.53±16.74)years(median age:47 year), including (44.88±17.09) years(median age:46 year) for 38 males and (46.32±16.52)years (median age:46 year) for 34 females in Loudi City, Hunan Province. There is no significant difference in genders between the severe and mild groups (χ²=0.916, P>0.05). There is a significant difference in the age between the severe and mild groups (F=3.315, P<0.05). The blood samples of 72 discharged patients were collected and the consistence of IgM and IgG antibodies were detected by chemiluminescence method. SPSS25.0 was used for gender, age, case type and antibody analysis of variance, χ² test and other analysis. Results: The average time of the serum samples collection of 72 patients was (34.89±9.02)days (median time: 34 days) from onset of COVID-19, and (14.53±8.35) days (median time: 14 days) from discharge. The positive rate of IgM or IgG was 97.22% (70/72), and the positive rate of IgM and IgG was 48.61% (35/72) and 97.22% (70/72) respectively. Serum COVID-19 antibodies were detected in 72 patients from 1st to 40th days after discharge. The average concentration of IgM in 1-7 days, 8-14 days, 15-21 days, 22-28 days, above 29 days were 21.91(7.07-52.84)AU/ml, 14.16(6.19-32.88)AU/ml, 11.36(6.65-42.15)AU/ml, 8.15(3.66-30.12)AU/ml, 2.98(0.46-6.37)AU/ml. There was no significant difference in the time of IgM antibody concentration (H= 8.439, P>0.05). The average concentrations of IgG in 1-7 days, 8-14 days, 15-21 days, 22-28 days, 29 days and above were 169.90 (92.06-190.91) AU/ml, 163.89 (91.19-208.02) AU/ml, 173.31 (95.06-191.28) AU/ml, 122.84 (103.19-188.34) AU/ml, 101.98 (43.75-175.30) AU/ml, respectively, (H=2.232, P>0.05). The IgM becomes negative after the 3rd week of discharge and decreases rapidly with time. The IgG concentration higher than IgM during the same period, and keep at high level without any change, and decrease in the fourth week. Among them, 5 cases developed "re-infection" within 1-3 weeks after discharge, and the rate of "re-infection" was 6.94% (5/72 cases). Conclusions: After the COVID-19 patients are discharged from the hospital, the level of antibodies produced varies greatly among individuals, but the overall changes in antibodies have a certain pattern. It is recommended to strengthen the antibody monitoring during hospitalization and after discharge from the hospital to reduce the "re-infection" rate and potential risk of infection.

Impact of Immunoglobulin M-Type Donor-Specific Human Leukocyte Antigen-Antibody Levels in Supernatants from Cultured Peripheral Blood Mononuclear Cells as Predictors of Antibody-Mediated Rejection

Background: Antibody-mediated rejection (AMR) is a crucial barrier in the long-term prognosis of transplant recipients. Methods: Peripheral blood mononuclear cells (PBMCs) were collected from kidney allograft recipients (N = 41) and cultured in vitro for 1 week. Furthermore, the supernatants of the cultured PBMCs were analyzed by Luminex single-antigen beads. Results: Analyses using Luminex single-antigen beads revealed the presence of immunoglobulin (Ig) G donor-specific anti-HLA antibodies (DSAs) was detected in the supernatants of cultured PBMCs collected more frequently than IgM in de novo DSA-sensitized patients with AMR, and IgM were detectable in patients with stable graft function mainly and several IgM DSAs were detectable in the supernatants of the cultured PBMCs before detecting the IgG levels in sera. We also found that the DSA-specific IgM-secreting memory B cells (mBCs) were more sensitive to the chronic use of immunosuppressive agents than to the IgG-secreting mBCs. Conclusions: In the transplant recipients, the assessment of supernatants of cultured PBMCs provide more details of immune reactions than the commonly used method that directly measures IgG DSA levels in patient sera and some IgM DSA detection may be a better predictor of IgG DSAs production, which may cause AMR and enable early intervention, in initial stages of AMR development.

Delayed specific IgM antibody responses observed among COVID-19 patients with severe progression

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly worldwide since it was confirmed as the causative agent of COVID-19. Molecular diagnosis of the disease is typically performed via nucleic acid-based detection of the virus from swabs, sputum or bronchoalveolar lavage fluid (BALF). However, the positive rate from the commonly used specimens (swabs or sputum) was less than 75%. Immunological assays for SARS-CoV-2 are needed to accurately diagnose COVID-19. Sera were collected from patients or healthy people in a local hospital in Xiangyang, Hubei Province, China. The SARS-CoV-2 specific IgM antibodies were then detected using a SARS-CoV-2 IgM colloidal gold immunochromatographic assay (GICA). Results were analysed in combination with sera collection date and clinical information. The GICA was found to be positive with the detected 82.2% (37/45) of RT-qPCR confirmed COVID-19 cases, as well as 32.0% (8/25) of clinically confirmed, RT-qPCR negative patients (4–14 days after symptom onset). Investigation of IgM-negative, RT-qPCR-positive COVID-19 patients showed that half of them developed severe disease. The GICA was found to be a useful test to complement existing PCR-based assays for confirmation of COVID-19, and a delayed specific IgM antibody response was observed among COVID-19 patients with severe progression.

Determination of anti-p52 IgM and anti-gB IgG by ELISA as a novel diagnostic tool for detection of early and late phase of primary human cytomegalovirus infections during pregnancy

BACKGROUND

Dating of primary human cytomegalovirus (HCMV) infection in pregnancy is crucial to define whether infection occurred before or during pregnancy and at which gestational age.

OBJECTIVE

The aim of this study was to identify a diagnostic strategy for determination of early, intermediate and late phase of HCMV primary infection during pregnancy.

STUDY DESIGN

Sequential serum samples from 40 pregnant women with defined onset of HCMV primary infection were tested retrospectively for IgM, IgG and IgG avidity against whole HCMV lysate, along with anti-p52 IgM and anti-gB IgG (Euroimmun AG).

RESULTS

Anti-HCMV IgM were positive in all samples collected within the first 2 months, then decreased remaining weakly positive in about 40% of samples collected within 6-12 months after infection. Anti-p52 IgM followed similar kinetics but decreased earlier, remaining weakly positive only in 20% of late samples. Anti-HCMV IgG were positive in all samples and showed variable kinetics. Their avidity increased from low levels, observed within 2 months, to intermediate/high levels from 4 months onwards. Anti-gB IgG increased over time following kinetics similar to anti-HCMV IgG avidity. By combining results of anti-HCMV IgM plus IgG avidity, and confirming them with anti-p52 IgM plus anti-gB IgG as second-line assays, the early (within 2-3 months) and late (after 3 months) phases of HCMV infection were satisfactorily defined, whereas the intermediate phase overlapped with the beginning of the late phase.

CONCLUSION

Anti-p52 IgM and anti-gB IgG provide additional tools besides classical anti-HCMV IgM, IgG and IgG avidity in dating HCMV primary infections.

Mapping of the binding site for FcμR in human IgM-Fc

FcμR is a high-affinity receptor for the Fc portion of human IgM. It participates in B cell activation, cell survival and proliferation, but the full range of its functions remains to be elucidated. The receptor has an extracellular immunoglobulin (Ig)-like domain homologous to those in Fcα/μR and pIgR, but unlike these two other IgM receptors which also bind IgA, FcμR exhibits a binding specificity for only IgM-Fc. Previous studies have suggested that the IgM/FcμR interaction mainly involves the Cμ4 domains with possible contributions from either Cμ3 or Cμ2. To define the binding site more precisely, we generated three recombinant IgM-Fc proteins with specific mutations in the Cμ3 and Cμ4 domains, as well as a construct lacking the Cμ2 domains, and analyzed their interaction with the extracellular Ig-like domain of FcμR using surface plasmon resonance analysis. There is a binding site for FcμR in each IgM heavy chain. Neither the absence of the Cμ2 domains nor the quadruple mutant D340S/Q341G/D342S/T343S (in Cμ3 adjacent to Cμ2) affected FcμR binding, whereas double mutant K361D/D416R (in Cμ3 at the Cμ4 interface) substantially decreased binding, and a single mutation Q510R (in Cμ4) completely abolished FcμR binding. We conclude that glutamine at position 510 in Cμ4 is critical for IgM binding to FcμR. This will facilitate discrimination between the distinct effects of FcμR interactions with soluble IgM and with the IgM BCR.

Detection of Toxoplasma gondii in Cord Blood Samples from Neonates in Tehran, Iran

BACKGROUND

Toxoplasmosis is an infectious disease caused by the coccidian protozoan parasite Toxoplasma gondii. The infection is life-threatening in congenital form because of transmission of the parasite from mother to fetus. In order to investigate the prevalence of congenital toxoplasmosis, the present study was performed for detection of IgG and IgM antibodies in cord blood samples of newborns by ELISA method in Tehran, Iran.

METHODS

This cross-sectional survey was carried out on 1000 cord blood samples collected from Shahid Mostafa Khomeini Hospital in Tehran, Iran in 2015. Sera were separated and evaluated for the presence of IgG and IgM antibodies against T. gondii by ELISA method. At the same time, whole cord blood samples were stored at -20 °C for complementary PCR test.

RESULTS

From 1000 cord blood serum samples 198 cases (19.8%) were positive for anti T. gondii IgG antibody. IgG positive samples were examined for IgM antibody, among them 1 sample had borderline levels of IgM antibody. PCR was performed for this sample but no positive result was seen.

CONCLUSION

Although congenital toxoplasmosis is of importance, no acute form of infection was seen in pregnant women in this study.

Affinity maturation occurs in channel catfish (Ictalurus punctaus) following immunization with a T-cell dependent antigen

Affinity maturation of the antibody response, a process of antibody affinity increasing over response, is one of the key features of the mammalian immune system. However, the process is incompletely understood in teleost, including channel catfish (Ictalurus punctaus). In this study, IgM affinity maturation in channel catfish was investigated by estimating the kinetics of antibody affinity using ELISA and ELISPOT assays. Fish were immunized with a T-cell dependent antigen (TNP-KLH), and individual serum IgM antibody titers and affinities, and IgM⁺ antibody-secreting cells (ASCs) in peripheral blood were analyzed over a period of 14 weeks. A detectable serum anti-TNP response developed by 2-weeks post-immunization, and the maximal antibody production was observed by 6-weeks post-immunization. The average affinity of anti-TNP serum antibody increased consistently and reached the maximum by 10-weeks post-immunization. The increase of antibody affinity beyond the point of optimal antibody titer revealed that the affinity maturation of IgM antibody response occurred in channel catfish. Dissection of dynamics of individual affinity subpopulations indicated that a significant proportion of low affinity subpopulations appeared at early response, and high affinity subpopulations appeared predominantly at later, resulting in a 100-fold increase in affinity over response. Additional, TNP⁺ IgM⁺ ASCs was detected by 2-weeks post-immunization and achieved the maximal number by 6-weeks post-immunization. Using an inhibition ELISPOT assay, the findings of a consistent increase in the average affinity of secreted IgM antibody by peripheral blood ASCs, as the immune response progressed, confirmed the occurrence of the affinity maturation. Taken together, the results of this study indicated that affinity maturation occurred in channel catfish following immunization with a TD antigen TNP-KLH.

Simultaneous detection of IgM antibodies against dengue and chikungunya: Coinfection or cross-reactivity?

Background:

Dengue and chikungunya sharing same mosquito vector are two most important arboviruses circulating in northern India including Delhi and are responsible for frequent outbreaks. Antigen and antibodies detection ELISA kits are the major tool to diagnose these viral illnesses, and are sometimes associated with cross–reactivity, giving a false picture of coinfection, although simultaneous harboring of both the viruses is not uncommon. Various studies have reported coinfection up to 25% from the same region.

Procedure:

This study was conducted in the Department of Microbiology, Maulana Azad Medical College, New Delhi, during the month of September 2016 which included 200 blood samples from clinically suspected cases attending Medicine OPD of associated Lok Nayak Hospital, New Delhi. Diagnosis of dengue and chikungunya was made using NS-1 antigen and IgM MAC ELISA for dengue and IgM MAC ELISA for chikungunya as per manufacturer's instructions.

Results:

Out of 200 suspected cases, 34 (17%) were positive for dengue serology, 77 (38.5%) were positive for chikungunya serology, and 29.9% of positive chikungunya cases were simultaneously affected with dengue. This higher percentage of coinfection might be because of cross-reactivity of the ELISA kits.

Discussion:

India being a hyperendemic region for dengue and chikungunya, frequent outbreaks are quite common. Circulation of both the virus and huge susceptible population are the major causes for frequent outbreaks. Restricting our attention to diagnose one of them is not sufficient, and coinfection further complicates the illness.

Conclusion:

Simultaneous diagnosis of dengue and chikungunya is need of time to diagnose dual infection and prevent complications by starting supportive treatment well in time. Molecular technique if ever possible should be employed whenever the coinfection number is higher than expected to rule out cross-reactivity.

IgM response against amyloid-beta in aging: a potential peripheral protective mechanism

BACKGROUND

The immune system plays a major role in the pathogenesis of age-related dementia, including Alzheimer's disease (AD). An insight into age-associated changes in the immune response to amyloid-beta (Aβ) in individuals without AD may be beneficial in identifying mechanisms preventing accumulation of Aβ.

METHODS

We examined the response of human monocyte-derived dendritic cells (DCs), T cells, and peripheral blood mononuclear cells (PBMCs) from healthy aged and young subjects to Aβ peptide 1-42, Aβ fibrils, and recombinant, nonaggregated tau-4 protein with a view to understand the role of peripheral immunity in AD.

RESULTS

Our studies revealed that DCs from healthy aged subjects display weak reactivity towards the Aβ peptide and no reactivity towards Aβ fibrils and tau compared with their young counterparts. An analysis of old and young PBMCs revealed that there is no significant T-cell memory against Aβ peptide, fibrils, or tau. Remarkably, the plasma levels of IgM antibodies specific to Aβ peptide 1-42 were significantly increased in aged subjects compared with young subjects, while IgG levels were comparable. Aβ peptide-specific IgM and IgG levels were also determined in the plasma of AD subjects compared with age-matched controls to demonstrate that the immune response against Aβ is stronger in AD patients. A decline in Aβ peptide-specific IgM antibodies was observed in AD patients compared with age-matched controls. In contrast, the levels of IgG as well as interleukin-21, the major cytokine involved in class switching, were increased in AD and patients with mild cognitive impairment, indicating a strong immune response against Aβ.

CONCLUSIONS

Collectively, low immunogenicity of Aβ in healthy controls may prevent inflammation while the generation of specific IgM antibodies may help in the clearance of Aβ in healthy subjects.

Theranostic-PDT with the antibody anti isoform 4 SOD mitocondrial labeled with PpIX in the lung cancer cell line A-549

BACKGROUND

In this work, a drug product composed of an IgM antibody derived from a hybridoma subclone 4C1F6D5G7B8 was prepared and further labeled with PpIX to be used in cell lines A-549 and MRC-5. The aim of this work was to evaluate the potential theranostic activity of the obtained product together with photodynamic therapy (PDT).

METHODS

The IgM antibody labeled with PpIX was used in different concentrations to perform theranostics with PDT in cell lines A-549 and MRC-5 in order to identify the specificity of IgM antibody in lung cancer cells by means of a LED-irradiation system set at 630 nm. The location of the conjugate was further determined by confocal microscopy.

RESULTS

The theranostic with conjugate Ab-PpIX in the A-549 cell lines showed fluorescence by confocal microscopy, whereas the MRC-5 cell line showed no reactivity. The PDT with the conjugate in the cell line A-549 decreased its viability 70% compared to the control. On the contrary, with the MRC-5 cell line no viability diference was shown. The confocal microscopy applied to the cell line A-549 showed that the Ab-PpIX was majorly located at the cytoplasm.

CONCLUSION

Ab-PpIX showed therapeutical potential in lung cancer cells A-549 and had no activity in non-cancerous lung cells (MCR-5).

Detection of human parvovirus B19 in serum samples from children under 5 years of age with rash-fever illnesses in the Democratic Republic of the Congo

Background

It has been demonstrated that infection with human parvovirus B19 (B19V) is associated with rash–fever illnesses. The present study aimed to investigate B19V as an aetiological agent of rash–fever syndromes in Congolese children confirmed as measles and rubella IgM-negative. An ELISA IgM test and PCR were performed to screen for B19V.

Methods

A total of 177 archived serum samples were randomly selected from the measles biobank of the National Institute for Biomedical Research (INRB). Samples were investigated for anti-B19V IgM and B19V DNA. These samples originated from children <5 years of age with measles-like rashes, previously confirmed as negative for both measles and rubella IgM.

Results

Out of 177 serum samples tested by ELISA and 168 tested by PCR, 109 were positive for B19V IgM antibodies (61.6%) and 87 (51.8%) were positive for B19V DNA. Positive samples in both assays were from all provinces of DRC.

Conclusions

B19V plays a role in rash–fever illnesses in children under 5 years of age suspected of having measles or rubella infections in DRC. As an aetiological cause of rash and fever syndromes, the present study demonstrates that B19V should also be considered during the laboratory investigation of rash–fever illnesses in DRC, particularly in the paediatric population. There is a need to conduct further studies in order to gain a better understanding of the spatiotemporal pattern of B19V and to define the genotype(s) of B19V circulating in DRC.

Prevalence of Toxoplasma gondii Infection among Healthy Blood Donors in Northeast of Iran

BACKGROUND

This cross-sectional investigation aimed to evaluate the prevalence of IgM and IgG anti-Toxoplasma gondii antibodies and the associated risk factors among healthy blood donors in Khorasan Razavi Province, northeast of Iran from Nov 2014 to May 2015.

METHODS

Overall, 491 serum samples from apparently healthy blood donors referred the six biggest blood centers in Razavi Khorasan, Iran, were screened for IgG and IgM anti-T. gondii antibodies by enzyme-linked immunosorbent assay (ELISA). A structured questionnaire was used to obtain information on risk factors for T. gondii infection. Nested PCR was also used to detect DNA of T. gondii in the IgM-positive samples by using of B1 and RE (Repetitive Element) as marker for amplifying fragment size of 531 bp and 164 bp in PCR method.

RESULTS

Totally, 200 (40.7%) samples were seropositive for anti-T. gondii antibodies; 184 (37.5%) donors tested seropositive for only IgG antibody, 8 (1.6%) tested seropositive for both IgM and IgG and 8 (1.6%) were positive for IgM antibody alone. Several risk factors significantly related to T. gondii seropositivity in the univariate analysis at P<0.05 included age (P<0.001), and raw/half-cocked meat consumption (P=0.015). T. gondii DNA was found in all sixteen IgM-positive samples.

CONCLUSION

T. gondii infection was present among healthy blood donors in northeast of Iran. Thus, it is suggested to design screening programs for preventing transfusion-transmitted toxoplasmosis.

Seroprevalence of Toxoplasma gondii infection among childbearing age women in Kerman city, southeastern Iran

This cross-sectional study aims to determine the prevalence of IgM and IgG anti-T. gondii antibodies and the associated risk factors among childbearing age women referring to counseling centers before marriage in Kerman city, southeast of Iran. Totally, 300 serum samples were collected from women referred to Central Laboratory for Marriage Consultation in Kerman city were screened for IgG and IgM anti-T. gondii antibodies by enzyme linked immunosorbent assay (ELISA). Out of the 300 serum samples, 38 (12.6 %) tested seropositive for anti-T. gondii antibodies; 31 (10.3 %) samples tested seropositive for only IgG antibody, 1 (0.33 %) tested seropositive for both IgM and IgG and 6 (2.0 %) were positive for IgM antibody alone. Statistical analyses also indicated that seroprevalence of anti-T. gondii antibodies increased with age (p < 0.05). Moreover, some risk factors such as, living in rural regions, contact with cats, raw/half-cooked meat consumption, and agricultural activities were significantly (p < 0.05) related to T. gondii seropositivity. The findings revealed that more than three-quarters of the childbearing age women studied in the present investigation are susceptible to infection during pregnancy. Thus, by adopting correct and improved practices we can improve their living conditions, and prevent infection and awareness and control of pathogens associated with disease is recommended.

A new fluorescence/PET probe for targeting intracellular human telomerase reverse transcriptase (hTERT) using Tat peptide-conjugated IgM

Despite an increasing need for methods to visualize intracellular proteins in vivo, the majority of antibody-based imaging methods available can only detect membrane proteins. The human telomerase reverse transcriptase (hTERT) is an intracellular target of great interest because of its high expression in several types of cancer. In this study, we developed a new probe for hTERT using the Tat peptide. An hTERT antibody (IgG or IgM) was conjugated with the Tat peptide, a fluorescence dye and (64)Cu. HT29 (hTERT+) and U2OS (hTERT-) were used to visualize the intracellular hTERT. The hTERT was detected by RT-PCR and western blot. Fluorescence signals for hTERT were obtained by confocal microscopy, live cell imaging, and analyzed by Tissue-FAXS. In nude mice, tumors were visualized using the fluorescence imaging devices Maestro™ and PETBOX. In RT-PCR and western blot, the expression of hTERT was detected in HT29 cells, but not in U2OS cells. Fluorescence signals were clearly observed in HT29 cells and in U2OS cells after 1 h of treatment, but signals were only detected in HT29 cells after 24 h. Confocal microscopy showed that 9.65% of U2OS and 78.54% of HT29 cells had positive hTERT signals. 3D animation images showed that the probe could target intranuclear hTERT in the nucleus. In mice models, fluorescence and PET imaging showed that hTERT in HT29 tumors could be efficiently visualized. In summary, we developed a new method to visualize intracellular and intranuclear proteins both in vitro and in vivo.

Dengue: Lessons of an Outbreak

INTRODUCTION

Since 1967 there have been many outbreaks of dengue in Delhi. In the year 2015 Delhi has suffered it's one of the worst dengue outbreaks, with more than 15000 dengue confirmed cases and the highest number of deaths (60) in recent years.

AIM

To determine the status of Dengue cases as compared to previous six years, the ratio of primary and secondary dengue cases and to review the effectiveness of the one test strategy (either NS1 antigen or IgM antibody) for the confirmation of Dengue.

MATERIALS AND METHODS

A cross-sectional study was performed in the year 2015. A total of 7177 serum samples were tested for the confirmation of suspected cases of dengue at our institute. We performed dengue NS1 antigen and dengue IgM antibody ELISA tests for the confirmation of dengue cases in acute and convalescent fever cases respectively. Hundred random samples negative for NS1 antigen were tested for IgM antibody and 100 random samples negative for IgM antibody were tested for NS1 antigen. For determination of ratio of primary and secondary dengue cases, IgG Avidity ELISA was performed on random 76 dengue positive samples.

RESULTS

Out of 7177 samples tested, 2358 were positive either by NS1 antigen or for IgM antibody from January to December. Percentage positivity rates for IgM antibody detection and NS1 antigen detection tests were 24.8% (626) and 37.1% (1732) respectively. Out of 100 NS1 negative samples 8 were positive for IgM antibody and out of 100 IgM negative samples 6 were positive for NS1 antigen. Among the 76 samples tested for dengue IgG Avidity ELISA 52 (68.4%) were found to be of secondary dengue.

CONCLUSION

Number of dengue cases is constantly rising in Delhi since 2011 and 2014. IgM antibody detection and NS1 antigen detection both the tests should be performed for each patient. Due to the increased prevalence of past infection of dengue, percentage of secondary dengue cases is also increasing in Delhi.

Expression of activation-induced cytidine deaminase enhances the clearance of pneumococcal pneumonia: evidence of a subpopulation of protective anti-pneumococcal B1a cells

We describe a protective early acquired immune response to pneumococcal pneumonia that is mediated by a subset of B1a cells. Mice deficient in B1 cells (xid), or activation-induced cytidine deaminase (AID(-/-) ), or invariant natural killer T (iNKT) cells (Jα18(-/-) ), or interleukin-13 (IL-13(-/-) ) had impaired early clearance of pneumococci in the lung, compared with wild-type mice. In contrast, AID(-/-) mice adoptively transferred with AID(+/+) B1a cells, significantly cleared bacteria from the lungs as early as 3 days post infection. We show that this early bacterial clearance corresponds to an allergic contact sensitivity-like cutaneous response, probably due to a subpopulation of initiating B1a cells. In the pneumonia model, these B1a cells were found to secrete higher affinity antigen-specific IgM. In addition, as in contact sensitivity, iNKT cells were required for the anti-pneumococcal B1a cell initiating response, probably through early production of IL-13, given that IL-13(-/-) mice also failed to clear infection. Our study is the first to demonstrate the importance of AID in generating an appropriate B1a cell response to pathogenic bacteria. Given the antibody affinity and pneumonia resistance data, natural IgM produced by conventional B1a cells are not responsible for pneumonia clearance compared with the AID-dependent subset.

Multiple Administrations of Viral Nanoparticles Alter in Vivo Behavior-Insights from Intravital Microscopy

Multiple administrations of nanoparticle-based formulations are often a clinical requirement for drug delivery and diagnostic imaging applications. Steady pharmacokinetics of nanoparticles is desirable to achieve efficient therapeutic or diagnostic outcomes over such repeat administrations. While clearance through mononuclear phagocytic system is a key determinant of nanoparticle persistence in vivo, multiple administrations could potentially result in altered pharmacokinetics by evoking innate or adaptive immune responses. Plant viral nanoparticles (VNPs) represent an emerging class of programmable nanoparticle platform technologies that offer a highly organized proteinaceous architecture and multivalency for delivery of large payloads of drugs and molecular contrast agents. These very structural features also render them susceptible to immune recognition and subsequent accelerated systemic clearance that could potentially affect overall efficiency. While the biodistribution and pharmacokinetics of VNPs have been reported, the biological response following repeat administrations remains an understudied area of investigation. Here, we demonstrate that weekly administration of filamentous plant viruses results in the generation of increasing levels of circulating, carrier-specific IgM and IgG antibodies. Furthermore, PVX specific immunoglobulins from the serum of immunized animals quickly form aggregates when incubated with PVX in vitro. Such aggregates of VNP-immune complexes are also observed in the mouse vasculature in vivo following repeat injections when imaged in real time using intravital two-photon laser scanning microscopy (2P-LSM). The size of aggregates diminishes at later time points, coinciding with antibody class switching from IgM to IgG. Together, our results highlight the need for careful in vivo assessment of (viral) nanoparticle-based platform technologies, especially in studying their performance after repeat administration. We also demonstrate the utility of intravital microscopy to aid in this evaluation.

Seroprevalence and risk factors of Toxoplasma gondii infection among healthy blood donors in south-east of Iran

This prospective cross-sectional study was aimed to evaluate the prevalence of IgM and IgG anti-T. gondii antibodies and the associated risk factors among healthy blood donors in Kerman province, south-eastern Iran. Structured questionnaires (before the donors gave blood) were used to obtain information on risk factors for infection. Totally, 500 serum samples from healthy blood donors of Kerman Blood Transfusion Organization (KBTO) at Kerman, Iran, were screened for IgG and IgM anti-T. gondii antibodies by enzyme-linked immunosorbent assay (ELISA) and Roche Elecsys Toxo IgM assay. Real-time PCR was used to detect DNA of T. gondii in the IgM-positive samples. Seroprevalence of IgG and IgM anti-T. gondii antibodies was 28.8% and 3.2%, respectively. In the multiple logistic regression, it could be observed that living in rural regions, having B blood type, being in contact with cats, consuming raw vegetables and raw milk/egg and doing agricultural activities were independent risk factors for Toxoplasma seropositivity. T. gondii DNA was also found in one (9.0%) of IgM-positive samples. In this study, it was found that T. gondii infection was present among healthy blood donors in south-east of Iran. Therefore, it is suggested to design screening programmes for preventing transfusion-transmitted toxoplasmosis.

Seroprevalence of toxoplasma-specific antibodies in patients suspected to have active toxoplasmosis: A cross-sectional survey

Background:

The aim of this study was to investigate the presence and distribution of anti-toxoplasma-specific IgM and IgG tantibodies in patients suspected to have toxoplasmosis and investigate for any association between IgM and IgG antibodies and some toxoplasmosis risk factors as well.

Materials and Methods:

In a comparative cross-sectional study, 70 patients suspected to had active toxoplasmosis and 30 control volunteers, who gave informed consent, entered the study. In each group, patient age, sex, signs of appearance, education level, residency status (urban / rural), occupation, frequency of toxoplasma-specific IgG and IgM antibodies, abortion history, and some risk factors (Direct cat exposure, Occupational exposure to raw meat, and Raw vegetable consumption) were recorded. The enzyme-linked immunosorbent assay (ELISA) kits (EUROIMMUN^®, United Kingdom) were used for the evaluation of anti-toxoplasma IgG and IgM antibodies according to the manufacturer's instructions. All analyses were done using SPSS-20.

Results:

The frequency of toxoplasma-specific IgG and IgM antibodies like: Direct cat exposures, Occupational exposure to raw meat, and Raw vegetable consumption were not statistically significant between the two groups (P > 0.05). The history of previous abortions in women in the toxoplasmosis-suspected group was significantly higher than that in the controls (31.4% versus 6.7%; P = 0.009).

Conclusion:

The frequency of specific IgM and IgG antibodies in toxoplasmosis suspected in the toxoplasmosis and control groups was not statistically significant.

Clinical applicability of various dengue diagnostic tests in resource-limited endemic settings

Introduction:

Dengue is one of the most important arboviral infections caused by one of the four dengue serotypes, 1-4.

Objective:

To study the applicability of different diagnostic methods in diagnosis of dengue viral infection.

Materials and Methods:

A total of 2101 blood samples were collected for confirmation of dengue viral infection. All the samples were tested by dengue-specific IgM ELISA, of which 111 were also tested for NS1 antigen detection and 27 acute samples (≤5 days) were further subjected for viral RNA detection by RT-PCR and isolation in C6/36 cell line. To detect the sensitivity of NS1 antigen for different dengue virus serotypes, four dengue serotype 1 and 12 dengue 3 were subjected for the NS1 antigen assay.

Results:

Most common age group affected was 16-45 years, with male to female ratio of 2.8:1. During first 3 days of illness virus isolation and RT-PCR were the most sensitive (83%) followed by NS1 antigen detection (75%) and IgM detection (37.5%). The positivity of IgM detection was found to be significantly higher as compared to NS1 detection during 4 to 5 days and also after 5 days of illness (P < 0.05). Dengue serotypes 1 and 3 were found to be co-circulated, dengue 1 being the predominant serotype.

Conclusion:

Virus isolation and RT-PCR were the most sensitive tests during the early period of illness whereas beyond third day, IgM antibody detection was found to be the most sensitive method of dengue diagnosis.

Outbreak of Kyasanur Forest disease in Thirthahalli, Karnataka, India, 2014

Kyasanur Forest disease virus (KFDV) was first identified in 1957, when it was isolated from a sick monkey from the Kyasanur Forest in Karnataka State, India. Since then it has been reported to be enzootic in five districts of Karnataka State, India. Recent reports of human infections have reached an alarming level, in spite of the availability of a vaccine. This disease has also been reported from new areas, such as Tamil Nadu and Kerala State. During January-March 2014, KFDV-positive cases were detected in Thirthahalli taluk, Shimoga District, Karnataka State, India. Here, we report an outbreak of Kyasanur Forest disease occurring in the Kannangi and Konandur area, Thirthahalli taluk in Karnataka State, India, with sporadic cases from eight other areas.

Association between E-selectin expression and histopathological modification of glomerular lesions by non-nephritogenic IgM antibodies in experimental lupus nephritis

OBJECTIVE

To examine the role played by E-selectin in bystander IgM-mediated modification of glomerular lesions in experimental lupus nephritis.

METHODS

Experimental lupus SCID mice were induced by an intraperitoneal injection of clone 7B6.8, which was derived from a MRL/lpr mouse and shown to induce wire-loop type glomerular lesions. Mice were subsequently administered clone Sp6, a non-nephritogenic IgM antibody- producing hybridoma. E-selectin expression was then evaluated in glomeruli showing histopathological conversion of lesions from wire-loop-like to a cell-proliferative form. We also investigated the effects of a circulating soluble form of E-selectin (sE-selectin) on the modification of glomerular lesions in this lupus model.

RESULTS

In experimental lupus mice, glomerular E-selectin expression significantly increased during the conversion from wire-loop-like glomerular lesions to a cell-proliferative type mediated by a non-nephritogenic bystander IgM antibody in presence of a nephritogenic antibody. Intraglomerular infiltration of CD68 + macrophages correlated significantly with the glomerular level of E-selectin expression. In addition, overexpression of circulating sE-selectin significantly suppressed conversion to cell-proliferative glomerular lesions and glomerular macrophage infiltration in these lupus model mice.

CONCLUSIONS

The histopathological modification of lupus nephritis by non-nephritogenic bystander IgM antibodies is associated in part with glomerular E-selectin expression.