Prevalence, genotype distribution and mutations of hepatitis B virus and the associated risk factors among pregnant women residing in the northern shores of Persian Gulf, Iran

BACKGROUND: Considering perinatal transmission and the high rate of chronic hepatitis B virus (HBV) infection in infants, diagnosis of HBV infection during pregnancy and timely interventions are of great importance. Therefore, this study was performed to investigate the prevalence and genotype distribution of HBV infection and the associated risk factors among pregnant women in the northern shores of the Persian Gulf, South of Iran. METHODS: Serum samples of 1425 pregnant women were tested for the presence of HBsAg and HBcAb by ELISA (HBsAg one—Version ULTRA and HBc Ab ELISA kits, DIA.PRO, Milan, Italy). The seropositive samples were tested for the presence of HBV DNA by nested PCR, targeting S, X, pre-core (pre-C), and basal core promoter (BCP) regions of the HBV genome. The amplified fragments were sequenced by Sanger dideoxy sequencing technology to evaluate the genotype distribution and mutations of HBV infection by using the MEGA 7 software. The HBV seropositive pregnant women were tested for HCV and HIV coinfections by ELISA (HCV Ab and HIV Ab/Ag ELISA kits, DIA.PRO, Milan, Italy). RESULTS: Of 1425 participants, 15 pregnant women (1.05%, 95% CI: 0.64%-1.73%) were positive for HBsAg, 41 women (2.88%, 95% CI: 2.10%-3.88%) were positive for HBcAb, and 5 women (0.35%, 95% CI: 0.15% –0.82%) had HBV viremia with genotype D, sub-genotype D3 and subtype ayw2. One of the viremic samples was positive for HBcAb but negative for HBsAg, which is indicative of an occult HBV infection. HBsAg seroprevalence was higher among pregnant women aged 20 to 29 years, women in the third trimester of pregnancy, residents of Khormuj city, Afghan immigrants, illiterate women, and pregnant women with a history of tattoo and HBV vaccination. The highest rate of HBcAb seroprevalence was observed in residents of Borazjan city, Turk ethnicity, the age group >39 years, and those women with more parities and a history of abortion. Nevertheless, HBV seroprevalence among pregnant women was not statistically associated with these variables. In contrast, HBcAb seropositivity was significantly associated with the history of tattoo (P = 0.018). According to mutations analyses, seven amino acid substitutions in the HBsAg, one point mutation in the pre-C region, and five points mutations in the BCP region were detected. Besides, the BCP mutations caused amino acid substitutions in the X protein. Of note, the conversion of Ala → Val at amino acid 168 (A168V) and Thr → Pro at amino acid 127 (T127P) were detected in HBsAg of the occult HBV strain. CONCLUSION: These results indicate a relatively low prevalence of HBV infection among pregnant women in the South of Iran, while tattooing is a risk factor for exposure to HBV infection. Moreover, all of the HBV-positive pregnant women were asymptomatic and unaware of their infection. Therefore, routine screening for HBV markers during pregnancy, appropriate treatment of HBV-infected women, and HBV vaccination are recommended to decrease mother-to-child transmission of HBV.