Low detection of hepatitis B and occult hepatitis B infection in patients with rheumatic diseases

BackgroundA new form of hepatitis B virus (HBV) infection, occult hepatitis B infection (OBI), has been identified and reported among patients with rheumatic diseases.Aim of the workTo determine the incidence of HBV infection and OBI in patients with rheumatic diseases referred to major hospitals in the city of Ahvaz in Iran.Patients and methods136 patients with rheumatic diseases were included. Serological assays for HBV markers (HBsAg, HBcAb and HBsAb) were performed by enzyme-linked immunosorbent assay. All the sera were tested for HBV DNA using nested PCR and real-time PCR. All samples were negative for anti-HCV and anti-HIV antibodies.ResultsThe mean age of the patients was 43.5 ± 12.02 years with a F:M 2.24:1. 2 (1.47%) cases with undifferentiated connective tissue disease tested positive for both HBsAg and HBV DNA. Quantitative HBV real-time PCR was carried out for the 134 negative HBsAg samples and only 1 (0.74%) patient was positive for OBI. The results of sequencing and alignment showed that the detected HBV DNAs belonged to the D genotype, ayw2 subtype. The nucleic acid sequence of OBI case revealed substitution changes in amino acids in the positions of the 171-4 of HBsAg gene.ConclusionA moderate rate of HBV infection and low detection of OBI is found in patients with rheumatic diseases in southwest Iran. The amino acid substitutions and mutation have been observed at the position of 171-4 in the S gene region of HBV DNA which may affect the detection of HBsAg by commercial immunoassay methods.