Introduction

Hepatitis B virus (HBV) remains a major public health problem worldwide. Implementation of hepatitis B surface antigen (HBsAg) in routine screening of blood donors in the early 1970s has greatly enhanced transfusion safety. The incidence of transfusion-transmitted hepatitis B has been steadily reduced over the last four decades. However, it was demonstrated that HBV transmission by blood components negative for HBsAg can still occur and HBV transmission remains the most frequent transfusion-transmitted viral infection; thus, the term occult hepatitis B virus infection (OBI) was introduced. OBI is simply defined as serologically undetectable hepatitis B surface antigen (HBsAg-ve), despite the presence of circulating HBV DNA with or without the presence of HBV antibodies.

Goal

To determine the prevalence of occult hepatitis B among blood donors and evaluate the presence of HBV DNA in HBsAg negative plasma samples.

Materials and Methods

It includes 16700 samples which donated in NCTM in Ulaanbaatar in 2013. We used to “triplex” PCR assay that included the detect of hepatitis B virus HBV-DNA in addition HCV-RNA and HIV1/2-RNA for whom with absence of serological markers of infection. The studies used molecular biology methods were performed with the help of equipment (ROCHE COBAS S 201) and technology based on Real Time PCR (pool size: 6 donation) Then we choose HBsAg negative, DNA positive samples and determined, anti-HBc and  anti-HBs by serological methods, of ELISA Wantai HBc and HBs 3.0 tests.

Results

The 14948 samples were detected serological negative in the total of 16700 samples. PCR test results show 35 (0.23%) positive by HBV-DNA 29 (82.9%) of the 35 DNA positive blood donors were alone anti-HBc positive and 3 (8.6 %) were anti-HBs, anti-HBc positive. 7(17.1%) were seronegative. Of the 35 OBI cases, 28 (80%) were detected the first time they were screened for HBV DNA while 7 (20%) gave one more HBV PCR-nonreactive results before detection. Callback studies we determined 2 cases were pre-HBsAg window period.

Conclusion:

The prevalence of HBV DNA positive in HBsAg negative blood donors is found 0.2%. HBV NAT needs either extreme sensitivity or to be performed on individual donations to eliminate HBV DNA-containing units. 

Key words: Occult B hepatitis infection, HBV DNA, HBsAg

Pp. 10-13, Table 1, Figures 2, References 12

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