Characterisation and follow-up study of occult hepatitis B virus infection in anti-HBc-positive qualified blood donors in southern China

Abstract

Background: Most major Chinese blood centres look for hepatitis B surface antigen (HBsAg) and perform nucleic acid testing to screen blood for hepatitis B virus infection. The search for antibodies to the core of hepatitis B virus (anti-HBc) has not been implemented because it would lead to a high rate of discarded blood units. The aim of this study was to evaluate the prevalence of occult HBV infection among anti-HBc-positive qualified blood donors in southern China.

Materials and methods: We tested anti-HBc-positive blood donations negative for HBsAg and HBV DNA by standard NAT from Shenzhen for the presence of HBV DNA by sensitive nested and quantitative polymerase chain reactions. Anti-HBs titres were quantified. HBV DNA-positive donors were traced and followed-up.

Results: Of the 1,033 qualified donors, 47.4% (95% CI: 44.4 to 50.5%) carried anti-HBc as evidence of exposure to HBV. The rate of anti-HBc positivity increased steadily with age, ranging from 32.6% in the age group <30 years to 69.8% in the age group <50 years (p<0.001). Of the 1,033 donors, 777 (75.2%; 95% CI: 72.4 to 77.8%) carried anti-HBs (>10 IU/L). HBV DNA was detected in 14 donors who were anti-HBc-positive, HBsAg-negative and negative by routine NAT. Seven of those 14 specimens had an anti-HBs titre above 100 mIU/mL. The prevalence of OBI in anti-HBc-positive qualified blood donors was 2.86% (95% CI: 1.57 to 4.75%). Eight of the 14 OBI cases were genotype B and one was genotype C; 7/14 cases were followed-up, one case converted to anti-HBe. HBV DNA became undetectable in all follow-up samples.

Discussion: A small proportion of anti-HBc-positive qualified donors carry HBV DNA after HBsAg and NAT screening. This finding suggests the possibility of HBV transmission from asymptomatic donors, especially in areas of high HBV prevalence. More sensitive NAT rather than anti-HBc testing should be considered to improve blood safety.