Hepatitis B virus infection in post-vaccination South Africa: Occult HBV infection and circulating surface gene variants

Abstract

Background and objective The aim of this study was to investigate the prevalence of occult hepatitis B virus (HBV) infection and the HBV surface (S) gene variants circulating in the South African population after nearly two decades of universal hepatitis B vaccination. Study design From a previous serosurvey, 201 serum samples with serological evidence of exposure to HBV were identified and these were stratified into post- and pre-vaccine introduction populations. For all samples, HBV DNA was screened and quantified using a real-time PCR assay and results analysed together with HBV serological markers. Where HIV results were available, subset analysis was performed. The HBV S gene was PCR-amplified and sequences analysed for a total of 37 isolates. Results The prevalence of occult HBV infection reduced from 70.4% in the pre-vaccine introduction era to 66.0% post-vaccine introduction. There was an association between HIV infection and an increase in prevalence of occult HBV infection within the post-vaccine introduction population, although this was not statistically significant. Furthermore, sequence analysis revealed the following HBV subgenotypes; A1 (n = 34), A2 (n = 2) and a rare D4 isolate. HBV S gene variants, including diagnostic escape mutants were isolated. Conclusion There was a decline in the prevalence of occult HBV infection in post-vaccination South Africa, although the disease burden remains significant in the HIV co-infected population. After nearly two decades of a universal hepatitis B vaccination programme, no positive selection of vaccine escape mutants were observed.

Broad Range of Hepatitis B Virus (HBV) Patterns, Dual Circulation of Quasi-Subgenotype A3 and HBV/E and Heterogeneous HBV Mutations in HIV-Positive Patients in Gabon

“…Consistently with other studies conducted either in Africa [ 10 , 35 ] or Asia [ 36 ], HBcAb was a reliable surrogate marker of OBI. Unexpectedly, among our patients with HBcAb ‘alone’, ~20% (44/228) showed HBV DNA levels above 100 IU/mL.…”

Hepatitis B virus strains from Rwandan blood donors are genetically similar and form one clade within subgenotype A1

“…In this study, about one quarter (23%) of the HBsAg negative blood donors, who may be representative of the wider adult population in the country, have been exposed to HBV and cleared the infection. This is a relatively lower prevalence of anti-HBc and anti-HBs compared to many other Sub-Saharan African countries especially those in West Africa [29], which suggests that a large part of the Rwandan adult population is susceptible to hepatitis B. In addition, the vaccination coverage seems to be low among adults in Rwanda, with 4.3% of the blood donors in this study having only anti-HBs, indicating immunity obtained by HBV vaccination.…”

Update of the statements on biology and clinical impact of occult hepatitis B virus infection

“…[80][81][82] Mother-to-child transmission OBI may occur in newborns from HBsAg positive mothers despite proper active/passive immunoprophylaxis at birth. [83][84][85][86][87][88][89][90][91] HBV vaccination is one of the most important and most successful accomplishments in medical science. The World Health Organization has proposed goals to eliminate HBV by 2030.…”