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Gene therapy using an adeno‐associated virus (AAV) vector offers a new treatment option for individuals with monogenetic disorders. The major bottleneck is the presence of pre‐existing anti‐AAV antibodies, which impacts its use. Even very low titers of neutralizing antibodies (NAb) to capsids from natural AAV infections have been reported to inhibit the transduction of intravenously administered AAV in animal models and are associated with limited efficacy in human trials. Assessing the level of pre‐existing NAb is important for determining the primary eligibility of patients for AAV vector‐based gene therapy clinical trials. Techniques used to screen AAV‐antibodies include AAV capsid enzyme‐linked immunosorbent assay (ELISA) and transduction inhibition assay (TIA) for detecting total capsid‐binding (TAb) and Nab, respectively. In this study, we screened 521 individuals with hemophilia A from India for TAb and NAb using ELISA and TIA, respectively. The prevalence of TAb and NAb in hemophilia A patients from India were 96% and 77.5%, respectively. There was a significant increase in anti‐AAV3 NAb prevalence with age in the hemophilia A patient group from India. There was a trend in anti‐AAV3 TAb positivity between the pediatric age group (94.4%) and the adult age group (97.4%). [ABSTRACT FROM AUTHOR]

Adeno-associated virus (AAV) vector-based gene therapy offers a new treatment option for individuals with hemophilia. Pre-existing anti-AAV antibodies significantly impact the use of AAV vectors. Even relatively low titers of AAV neutralizing antibodies (NAb) from natural AAV infections against the capsid have been shown to inhibit the transduction of intravenously administered AAV in animal models and were associated with limited efficacy in human trials. This is important for determining the primary eligibility of patients for AAV vector-based gene therapy clinical trials. Current techniques to screen AAV antibodies include AAV capsid enzyme-linked immunosorbent assay (ELISA) for total antibodies and a transduction inhibition assay (TIA) for NAb. This study developed and screened total capsid binding anti-AAV3 antibodies by using ELISA and determined NAb levels by TIA using mCherry flow cytometry in healthy individuals with hemophilia B in India. One hundred and forty-three apparently healthy controls and 92 individuals with hemophilia B were screened. The prevalence of total and NAb in healthy controls was 79.7% and 65%, respectively; the prevalence of total and NAb in patients with hemophilia B for AAV3 was 92.4% and 91.3%, respectively. [ABSTRACT FROM AUTHOR]

Background: Rapid fluorescent focus inhibition test (RFFIT), a neutralization-based assay for detecting rabies antibodies, is the gold standard. The National Action Plan for Dog Mediated Rabies Elimination (NAPRE) is a national program that strategizes the establishment of enzyme-linked immunosorbent assays (ELISA) to detect rabies antibodies., Objective: We developed an in-house ELISA to screen for rabies antibodies using rabies vaccine antigen to study vaccine response among health care workers (HCWs) who received pre-exposure prophylaxis and a few animal bite victims who received post-exposure prophylaxis with rabies vaccine., Study Design: A prospective study was carried out from April to September 2023 at the Department of Clinical Virology of a tertiary care center in South India. A total of 161 serum specimens, which included 155 serum samples from study participants and 6 samples from a reference laboratory (as controls), were obtained during the study period. Rabies antibody was determined by the in-house standardized ELISA developed using the rabies vaccine and compared with the reference assay, RFFIT. The accuracy indices of the in-house ELISA were estimated by MedCalc software (version 22.023)., Results: A panel of 86 positive and 75 negative serum samples was used for evaluating the in-house standardized ELISA. The sensitivity, specificity, positive and negative predictive values of the in-house ELISA were 98.8 %, 100 %, 100 %, and 98.7 % respectively. The accuracy of the in-house ELISA is 99.4 %., Conclusion: ELISA can be a practically feasible and less expensive assay compared to RFFIT which is a cumbersome procedure with a long turn-around time of 3-4 days., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Based on genetic heterogeneity, hepatitis C virus (HCV) is classified into seven major genotypes and 64 subtypes. In spite of the sequence heterogeneity, all genotypes share an identical complement of colinear genes within the large open reading frame. The genetic interrelationships between these genes are consistent among genotypes. Due to this property, complete sequencing of the HCV genome is not required. HCV genotypes along with subtypes are critical for planning antiviral therapy. Certain genotypes are also associated with higher progression to liver cirrhosis., Methods: In this study, 100 blood samples were collected from individuals who came for routine HCV genotype identification. These samples were used for the comparison of two different genotyping methods (5'NCR PCR-RFLP and HCV core type-specific PCR) with NS5b sequencing., Results: Of the 100 samples genotyped using 5'NCR PCR-RFLP and HCV core type-specific PCR, 90% (κ = 0.913, P < 0.00) and 96% (κ = 0.794, P < 0.00) correlated with NS5b sequencing, respectively. Sixty percent and 75% of discordant samples by 5'NCR PCR-RFLP and HCV core type-specific PCR, respectively, belonged to genotype 6. All the HCV genotype 1 subtypes were classified accurately by both the methods., Conclusion: This study shows that the 5'NCR-based PCR-RFLP and the HCV core type-specific PCR-based assays correctly identified HCV genotypes except genotype 6 from this region. Direct sequencing of the HCV core region was able to identify all the genotype 6 from this region and serves as an alternative to NS5b sequencing., (© 2016 Wiley Periodicals, Inc.)