A changing hepatitis B virus genetic diversity pattern in North-western Tanzania: Is it a concern for Tanzania?

Background Frequent evaluation and understanding of the genetic diversity of the HBV virus in different affected global settings is essential towards the elimination of infection by 2030. In this regard, HBV genetic diversity evaluation is scarcely done in Tanzania, imposing a crucial knowledge gap. We serologically and genetically characterized the HBV from 21 chronically HBV-infected patients attending Bugando Medical Centre to determine the HBV genetic diversity. Methods This cross-sectional study was conducted on the selected 21 plasma samples with high HBV-deoxyribonucleic acid (DNA) levels of > 300,000IU/mL. DNA extraction was done using Qiagen DNA Blood Mini Kit (Qiagen, Hilden, Germany). The Partial amplification of HBV DNA, sequencing and analysis was done at Institute of Virology, Giessen Germany. Results The mean age of 21 HBV chronically infected patients was 41 ± 11 years with HBV-DNA median of 979 [185.5–8457.5] IU/mL. Majority (85.7%, 18/21) were males from Mwanza. The genotypes detected were HBV/A; 76.2% (16/21), all being A1, followed by HBV/D; 19% (4/21), all being D4 and lastly HBV/G, 4.8% (1/21). The HBV/A1 serotypes were Adw2; 81.3% (13/16), followed by Ayw2; 12.5% (2/16) and all 4 HBV/D4 genotypes were serotype Ayw2. Overall, 19% (4/21) of the patients had HBV escape mutations (T123V, Y134N, P120T and T123A). The HBV/A identified in this study were distributed randomly among other HBV/As from all regions of Tanzania reported previous. On the other hand, HBV/D identified in this study were distributed among HBV/Ds from the North-western Tanzania identified previously. However, most of the HBV/As and all of the HBV/Ds identified in this study did not mix-up with HBV/As and HBV/Ds from other parts of the world. Conclusion HBV/A (HBV/A1) is predominant over time in North-western Tanzania. Most HBV/A1 and all HBV/D are unique to Tanzania as had been previously reported. However, the molecular epidemiology of HBV in this region is changing with occurrence of HBV/G as a new genotype and increasing HBV escape mutations which are mostly not due to drug pressure selection. The observation of HBV escape mutations threatening the future efficacy of serologic diagnostic tests and HBV vaccination in Tanzania underscoring the continuous monitoring of these mutants.