Evidence of transmission of hepatitis B virus to spouses from sequence analysis of the viral genome

Heterosexual contact is one of the common routes of transmission for hepati tis B virus (HBV) among adults in Taiwan, but only a few studies have provi ded direct evidence at the level of the HBV genome of infected couples with acute non-fulminant hepatitis to document a common source. By cloning and sequencing polymerase chain reaction-amplified HBV-DNA, we analysed the seq uences of the conserved region of the surface gene (nucleotide (nt) 305-513 , representing 6.5% of the viral genome) of HBV in five HBV-infected index patients, their spouses and four randomly selected HBV carriers as controls . Risk factors associated with acute HBV infection in index cases were sexu al contact with their spouses within 3 months before the onset of hepatitis . For all five couples, the HBV-infected index patient and the spouse share d a 100% sequence homology of HBV-DNA. In contrast, there was significantly more variation (mean heterogeneity 6.1%, range 1-13.9%) in the amplified r egion between the five couples and between each couple and the controls (P< 0.001). This study demonstrated that sequence analyses can correlate well with epidemiological findings and confirm the value of the molecular approa ch for linked infections of HBV through heterosexual contact between spouse s. Susceptible adults should receive vaccination.