Threat of Occult Hepatitis B Virus Infection: A Major Issue in Blood Transfusion Services

Abstract

Occult hepatitis B virus infection is the existence of hepatitis B virus DNA in blood and liver tissues of hepatitis B surface antigen-negative individual as detected using molecular analysis (PCR). It is so far one of risk factor involved in transmission of HBV from blood and organ donations. Healthy individual that harbors occult HBV DNA may reactivate and yield hepatitis in potential organ and/or blood recipients depending upon host immune response and viral load. Therefore, it is pertinent to ascertain the quality of blood before blood transfusion. An18% prevalence was reported in HBV seropositive individuals, and only 8% among seronegative individuals. In 2015, a research conducted in Nigeria revealed a prevalence of 17%. Several molecular mechanisms including deletions, gene splicing, point mutations, co-infection with HCV and Lamivudine associated mutations are implicated in pathogenesis of occult hepatitis B virus infection. Pathogenesis of HBV infection is influenced by multiple cytokines. Tumor necrotic factor (TNF) induces innate immune response and causes destruction of virally infected hepatocytes. Interleukin 12 (IL-12) functions in viral clearance and seroconversion. Interferon gamma (IFN-γ) has antiviral activity, while Interleukin 10 (IL-10) has anti-inflammatory and immunosuppressive function. Diagnosis of occult HBV infection is carried out by detecting circulating HBsAg, HBV DNA, anti-surface antibody, and anti-core antibody. This infection may be treated using several approaches including INF-α, Lamivudine, Entecavir, Adefovir and pegylated INF-α therapies. However, advanced approach to treatment involves employing ‘Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas9)’. This review is aimed at highlighting the risk associated with transfusing blood screened only with HBsAg assays, because health conditions demanding blood transfusion is high in Nigeria, and so the need to initiate HBV DNA screening in blood transfusion services.