Virology Study And The Safety Of Occult Hepatitis B Infection Screening In Blood Donors

ObjectiveTo investigate the prevalence of the presons with hepatitis B virus among blood donors, and explore the safety and reliability of hepatitis B surface antigen screening to blood donors in domestic blood bank. To analysis the PreS-S section in hepatitis B virus to explore the cause of occult infection.Methods1.To collect the plasma screened by domestic blood banks, which is from the blood donors with HBsAg negative, anti-HCV and anti-HIV negative, anti-TP, and alanine aminotransferase (ALT<40 U/ml) negative in normal, and store it in-20℃.2.HBsAg quantitative should be tested with Abbott Architect 12000 electrochemiluminescence and Nested-PCR amplify HBV S, C and X region, to defined as occult HBV infection.3.The Nested-PCR should be used to amplify the PreS-S region of virus from the persons with occult hepatitis B virus infection and PCR products can sequenced directly while contrasting with the standard virus strain and analyzing the variation of virus strain together with it.Results1.6.5% of health donors (64/983) was positive for HBsAg determined through Abbott Architect 12000 chemiluminescence apparatus,60.9%(39/64) of samples was positive in two districts for Nested-PCR HBV S, C, Xregion. the prevalence of occult hepatitis B Virus infection in healthy blood donors was 4.0%(39/983).2.Undetected samples of HBsAg titer, has a median of 0.17IU/ml (0.05-1.14 IU/ml), of which HBsAg positive specimens 60.9%(39/64) virus expands positive, and 9.1% (25/64) virus does negative; HBsAg quantitative:positive group with a median of 0.15IU/ml (0.05-0.96IU/ml) and negative group with a median of 0.18IU/ml (0.05-1.14IU/ml). There are no statistical significances on the HBsAg quantitative between the positive group of virus expansion and the negative group, sex ratio and transaminase level.3.Those with occult infection have low virus load, about 50～1000 copies/ml; virus PreS-S section expands at a positive rate of 35.9%(14/39), of which 60.9%(39/64), at least two district, expands positive, so does the 29.6%(19/64) S region,64.1%(41/64) C region, and the 65.6%(42/64) X region.35.9%(14/39) expands out of the virus PreS-S region.4.Sequencing results peak map shows a average situation without mixed infection. The "a" determinant mutation is not found, which has been proved to be the cause of HBsAg negative or the lowering of secretion volume by existing documents, so the mutation may happen to a small number of amino acid site in S-area relating to HBsAg negative:S45D, N68D, Q129R, F134N, V180S, V190I.ConclusionsAt present, the HBsAg and HBV DNA still can be found from the negative blood in the required standard with more sensitive reagents, which is tested routinely by the Blood Bank, so the risk leading to hepatitis B infection exists in the clinical use of blood. It is difficult to discriminate between the samples of virus in positive and negative when the HBsAg secretory volume can not be justified because of minute amounts, even using highly precise electrochemiluminescence testing technology. The main reason leading to OBI may be the low level replication of HBV, the lack of detection reagent sensitivity and the failure on HBsAg testing led by virus variation.