TITLE:
Genotyping of Occult Hepatitis B Virus in Sudanese Blood Donors by RFLP in the Pre-S Region: Identification of Novel Patterns D-Del 1, D-Del 2, and E-Del
AUTHORS:
Amel Ahmed Alrasheed, Mubark Mustafa Elkarsany, Elsir Ali Mohamed, Nadia Madani Mohamed, Mohamad M. Aboelenin, Ayat Ahmed Alrasheid
KEYWORDS:
Molecular Detection, Occult HBV, Blood Donors, Sudan
JOURNAL NAME:
American Journal of Molecular Biology,
Vol.15 No.4,
October
27,
2025
ABSTRACT: Background: Hepatitis B virus (HBV) infection remains a significant public health concern in developing countries. HBV genotypes influence viral evolution and genetic diversity. This study aimed to genotype occult HBV strains among Sudanese blood donors using RFLP analysis of the Pre-S region. Methodology: This study was conducted for RFLP Genotyping of occult HBV by analysis of patterns obtained after amplifying a fragment in the Pre-S region and digestion of the amplicon by AvaII and DpnII. Results: Out of a total of 44 HBV DNA-positive samples from HBsAg-negative donors with occult hepatitis B, one sample failed to amplify during PCR, likely due to DNA degradation or low viral load resulting from storage or suboptimal sample quality. The remaining 43 samples were successfully genotyped by RFLP after amplification of the pre-S region and digestion of the amplicon by AvaII and DpnII and showed genotype D was the most prevalent (51.16%; 95% CI: 36.5 - 65.5%), comprising subtypes D1, D2, D3, and two novel deletion patterns, D-Del 1 and D-Del 2. Genotype E accounted for (44.19%; 95% CI: 30.2 - 59.1%), including E1, E2, E3, and a novel deletion pattern, E-Del. Genotype A1 was detected at low frequency (4.65%; 95% CI: 0.6 - 15.5%). Pre-S deletion mutants were found in genotypes D and E. D-Del 1, D-Del 2, and E-Del were never reported and showed unique truncated patterns and expanding the understanding of HBV genetic variability in Sudan. Conclusion: The integration of molecular techniques such as PCR and RFLP techniques effectively detected occult HBV genotypes and revealed novel Pre-S deletion variants. These findings enhance knowledge of HBV diversity and may inform future molecular surveillance in blood donors.