Age-stratified adeno-associated virus serotype 3 neutralizing and total antibody prevalence in hemophilia A patients from India.

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%).

Prevalence of Adeno-Associated Virus 3 Capsid Binding and Neutralizing Antibodies in Healthy and Hemophilia B Individuals from India.

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.

Transgenic hepatitis B: a new model of HBV infection.

Chronic hepatitis B infection (HBV) is major cause of morbidity and mortality throughout the world. Currently there is limited understanding on the cellular proteins and related molecules involved in the critical steps of viral entry into the cytoplasm and persistent viral replication in cell culture. In order to address these fundamental questions, we designed and implemented a new model of hepatitis B: infectious transgenic hepatitis B virus composed of a complete virus plus a foreign gene. The foreign gene allows identification of cells that are infected by the transgenic virus. The transgenic virus was used in a functional assay to identify cellular proteins necessary for viral replication. This assay repeatedly identified the protein UQCR10. After restoring UQCR10 levels in HepG2 and Huh7 cells, they can be infected by intact virions of transgenic hepatitis B. These results demonstrate the usefulness of this new transgenic hepatitis B model.

Comparison of Three Different Hepatitis C Virus Genotyping Methods: 5'NCR PCR-RFLP, Core Type-Specific PCR, and NS5b Sequencing in a Tertiary Care Hospital in South India.

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.

Fibrolamellar carcinomas are positive for CD68.

Fibrolamellar carcinomas are a unique type of liver carcinoma that arise in non-cirrhotic livers of young individuals. Despite their distinctive appearance, recent studies have demonstrated a lack of consistency in how fibrolamellar carcinomas are diagnosed by pathologists. As a potential aide in diagnosis, we investigated the staining properties of CD68. The CD68 gene encodes for a transmembrane glycoprotein located within lysosomes and endosomes. Macrophages as well as other cell types rich in lysosomes/endosomes are CD68 positive. Cases of fibrolamellar carcinoma were collected from four academic centers. Control groups included hepatocellular carcinomas arising in both non-cirrhotic livers and cirrhotic livers. A group of cholangiocarcinomas were also stained. CD68 immunostaining was scored for both intensity and distribution on a scale of 0 to 3+. Twenty-three primary fibrolamellar carcinomas and 9 metastases (total of 24 individuals) were immunostained and showed a distinctive granular, dot-like or stippled pattern of cytoplasmic staining in nearly all cases (31/32), with a median distribution and intensity score of 3+. In control hepatocellular carcinomas that arose in non-cirrhotic livers, 10/39 showed CD68 staining with a median distribution and intensity score of 2+. In hepatocellular carcinomas arising in cirrhotic livers, 3/27 cases showed CD68 positivity, all with stippled dot-like cytoplasmic staining similar to that of fibrolamellar carcinomas. All five cholangiocarcinomas were negative. Overall, CD68 positivity was strongly associated with fibrolamellar carcinomas, P<0.001 and had a sensitivity of 96%, a specificity of 80%, and a negative predictive value of 98%. In sum, tumor positivity for CD68 staining was highly sensitive for fibrolamellar carcinoma and a lack of CD68 staining should suggest caution in making a diagnosis of fibrolamellar carcinoma.