AIM

To study the HBV D4 isolates molecular genetic structure first identified in the Russian Federation.

MATERIALS AND METHODS

Blood plasma samples of patients from the Dagestan Republic with previously detected HBV subgenotype D4 were used. For amplification and sequencing reactions, overlapping pairs of specific primers were used, jointly flanking the complete HBV genome.

RESULTS

For the first time in the Russian Federation, isolates of HBV subgenotype D4 were detected. All three isolates are ayw2 serotype. The pharmacoresistance mutations L80V and M204I were detected in an HIV-infected patient with HBsAg-negative occult HBV. The high frequency of natural polymorphic variants of the Pol gene was shown in all three isolates. In the Precore/Core region, all isolates detected Precore A1846T, C1858T, and Core E40D, N74T, N87S, and I97F mutations. In the X region, mutations V5L and P38S were detected in all three isolates. Phylogenetic analysis of the HBV full-sized genome showed that the isolates are grouped together with the D4 subgenotype isolate from South Africa.

CONCLUSION

The origin of all three patients with the above isolates from the same geographical region, the phylogenetic proximity of nucleotide sequences, and a series of identical mutations and polymorphic variants in different genes in all three isolates indicate independent single importation of the virus with subsequent spread. The distribution routes, as well as the frequency of HBV D4 occurrence in the Dagestan Republic remain unknown and need further research.