Low Risk of Occult Hepatitis B Infection among Vietnamese Blood Donors
Trần Thanh Tùng, J. Schmid, Vũ Xuân Nghĩa, Le Chi Cao, Le Thi Kieu Linh, Ikrormi Rungsung, Bùi Tiến Sỹ, Truong Nhat My, Nguyen Trong The, Nghiêm Xuân Hoàn, Christian G. Meyer, Heiner Wedemeyer, Peter G. Kremsner, Nguyễn Lĩnh Toàn, Lê Hữu Song, C.–Thomas Bock, Thirumalaisamy P. Velavan
Abstract
Occult hepatitis B infection (OBI) is characterized by the presence of low levels of hepatitis B virus (HBV) DNA and undetectable HBsAg in the blood. The prevalence of OBI in blood donors in Asia ranges from 0.013% (China) to 10.9% (Laos), with no data available from Vietnam so far. We aimed to investigate the prevalence of OBI among Vietnamese blood donors. A total of 623 (114 women and 509 men) HBsAg-negative blood donors were screened for anti-HBc and anti-HBs by ELISA assays. In addition, DNA from sera was isolated and nested PCR was performed for the HBV surface gene (S); a fragment of the S gene was then sequenced in positive samples. The results revealed that 39% (n = 242) of blood donors were positive for anti-HBc, and 70% (n = 434) were positive for anti-HBs, with 36% (n = 223) being positive for both anti-HBc and anti-HBs. In addition, 3% of blood donors (n = 19) were positive for anti-HBc only, and 34% (n = 211) had only anti-HBs as serological marker. A total of 27% (n = 170) were seronegative for any marker. Two of the blood donors (0.3%) were OBI-positive and sequencing revealed that HBV sequences belonged to HBV genotype B, which is the predominant genotype in Vietnam.