Prevalence and genotype distribution of hepatitis B virus among migrant workers in Lombok Island, Indonesia

Objective: To examine the potential risk of hepatitis B virus (HBV) spread in Indonesia by migrant workers, based on the molecular characteristics of HBV strains. Methods: Sera collected from migrant workers traveling to their destination countries (pre-migrant workers) and those returning to Indonesia (post-migrant workers) were screened for HBsAg by ELISA, followed by HBV DNA detection by PCR and (sub) genotype/subtype determination according to surface region and whole genome sequencing. Results: Of 87 pre-migrant workers, 15 (17.24%) were HBsAg-positive, whereas 15 (12.10%) of 124 post-migrant workers were HBsAg seropositive. HBV genotype analysis based on the S region showed that HBV-B3/adw2 was predominant (96.15%, 25/26) whereas 3.85% (1/26) of isolates were HBV-C3/adrq+. Whole genome sequencing of selected strains and phylogenetic tree analysis identified subgenotype B7 in three samples previously categorized as subgenotype B3 based on S region analysis, supporting a recent argument that subgenotypes B5/B7/B8/B9 could be considered as a quasi-subgenotype of B3. Conclusions: A high prevalence of HBsAg carriers was detected among migrant workers from Lombok Island, with no significant difference in prevalence between before and after returning to Indonesia. All strains were classified into genotypes common in Indonesia, and the results suggested that migrant workers are not a risk factor for HBV transmission into Indonesia.