Molecular and serological characterization of hepatitis B virus in deferred Ghanaian blood donors with and without elevated alanine aminotransferase

Abstract

Candidate blood donors in Ghana are frequent carriers of hepatitis B virus (HBV). A comparative study of 117 donor samples including 46 with alanine aminotransferase (ALT) > or = 60 IU/L and 71 with < or =40 IU/L level was undertaken. S and the basic core promoter-precore regions (BCP/PC) sequencing was used to identify genotypes and variants relevant to HBV natural history, respectively. Age, viral load, HBe status were correlated with molecular data. HBV genotype E (87%) was dominant with little genotypes A (10%) and D (3%). Comparing individuals with or without liver disease, an association between liver disease and older age (P = 0.004) and higher viral load (P = 0.002) whether as a whole population or only genotype E was found. Compared with a commercial assay, BCP/PC sequencing had lower sensitivity to detect mixtures of wild-type and variant viruses but detected BCP deletions. BCP 1762/1764 variants were positively correlated with older age (P < 0.0001) and elevated ALT levels (P = 0.01). PC 1896 stop codon was marginally correlated with viral load (P = 0.09). HBV genotype E infection natural history appears different from genotypes B and C prevalent in Asia. Donors with liver disease being older, with higher viral load and higher BCP variant proportion may be at higher risk of cirrhosis and hepatocellular carcinoma.

Molecular characterization of occult hepatitis B virus in genotype E-infected subjects

“…Two other samples (PW4 and PW5) contained anti-HBe antibodies, in association with either the A 1762 T / G 1764 A double mutation alone or combined with G 1896 A . This seromolecular diversity of OBI strains is not significantly different from that in HBsAg-positive genotype E chronic infections (Allain et al, 2003;Candotti et al, 2006).…”

“…Amino acid substitutions in OBI sample sequences that were not present in any of the reference isolates were designated uncommon mutations. The BCP/ PC sequences were compared with 96 previously characterized partial sequences from HBsAg-positive Ghanaian blood donors infected with HBV genotype E (Candotti et al, 2006).…”

“…The 276 bp basic core promoter/pre-core (BCP/PC) region, including 50 bp separating the binding site of the primers used in the full-length PCR, was amplified by using hemi-nested PCR as described previously (Candotti et al, 2006).…”

“…Previous reports have shown that, during the late stages of the natural history of the infection, OBI in Ghana is characterized by a very low viral load and the presence either of both anti-HBc and antibodies against HBsAg (anti-HBs), or of anti-HBc without anti-HBs, although anti-HBe may or may not be detectable in either of these two categories of infected individual (Candotti et al, 2006). The presence of anti-HBs suggests recovery from an acute infection, although the simultaneous presence of HBV DNA suggests persistence of the virus, as described previously (Rehermann et al, 1996;Yotsuyanagi et al, 1998).…”

“…By age 16, 75 % of the population is anti-HBcpositive and the majority of the 15 % of chronic carriers have already developed anti-HBe [antibodies against the HBV 'e' antigen (HBeAg)] and carry a relatively low viral load (Candotti et al, 2006). It is therefore unsurprising that approximately one in 60 Ghanaian blood donors have been identified as carriers of 'occult' HBV infection (OBI), defined as the presence of HBV DNA without detectable HBV surface antigen (HBsAg) (Owusu-Ofori et al, 2005).…”