Persons with Intellectual Disability: A Potential Reservoir of Invasive Strains of Hepatitis B Virus

Background: A higher prevalence of hepatitis B virus (HBV) infection has been reported in persons with intellectual disability as well as the nurses working in closed institutions compared to the general population. Objectives: In the present study, the serological and molecular markers of HBV infection in individuals with intellectual disability of closed institutions were investigated. Methods: Blood samples were derived from 400 persons with intellectual disability living in six institutions in Tehran and tested for HBsAg and HBcAb. Nested PCR, direct sequencing, and phylogenetic analysis were performed to determine the HBV genotypes and mutational patterns of HBsAg. Also, HBsAb was tested for HBV DNA positive cases. Results: Twenty-eight (7.0%) patients were positive for the HBsAg serological test. Furthermore, six HBV occult cases were identified. In total, out of 41 patients with HBV infection markers, 26 cases were positive for HBV DNA. Of these patients, 15 full-length HBsAg were successfully amplified and sequenced. All strains belonged to genotype D and subtypes ayw2 and ayw3. These 15 isolated strains carried several immune escape mutants in the S genes. Surprisingly, mutations related to antiviral resistance were detected in the overlapped pol genes of strains isolated from naïve-treatment patients. Conclusions: The observed frequency of HBV infection in individuals with intellectual disability was higher than the reported estimation of HBV infection in Iranian blood donors and the general population. All HBV isolates from these patients represented a homogenous genotype and corresponded with other reported strains from Mediterranean countries. The high frequency of immune escape strains, despite vaccination and detection of identical mutational patterns in different genes, might indicate that persons with intellectual disability have shared vaccine-escape and drug-resistant HBV strains.