Hepatitis B virus genotype D strains from Estonia share sequence similarity with strains from Siberia and May specify ayw4

Abstract

The genotypes and subtypes of 205 HBV isolates collected during 1989-2002 in Estonia and 14 other regions of the former USSR were determined by sequencing and phylogenetic analysis of the S gene. The in Europe prevailing genotypes, A and D, were also circulating in the whole territory of the former USSR including Estonia and accounted for 18.5 and 81% of the strains, respectively. All genotype A strains specified adw2, and a single genotype C strain specified adrq+. Most genotype D strains specified ayw3 and ayw2, although, three strains from Estonia and Siberia specified ayw4. Due to unique substitutions, Ser122 and Ala127, four strains could not be classified according to the subtype. One strain specifying ayw3 encoded Leu143 and Ala145 and was possibly an immune "escape" mutant. At phylogenetic analysis 93% of the Estonian genotype D strains belonged to a cluster specifying mainly ayw3 and were more similar to isolates from Siberia and the Far-East of Russia than to isolates originating from Central Russia which belonged to another cluster of strains specifying mainly ayw2. This pattern might be explained by part of the Estonian population, has roots east of European Russia, based on linguistic evidence. Eight dominant HBV strains represented by identical S gene sequences were identified, one within genotype A and seven within genotype D, three of which included isolates from Estonia and Siberia. Some of these strains were collected over a period of at least 13 years indicating there are genetically stable variants of HBV that remain conserved over decades.

D2: major subgenotype of hepatitis B virus in Russia and the Baltic region

“…The complete or almost complete P genes AB104709 AB078032 AJ131956 AB033559 DQ315779 AB104711 AB078033 AJ344117 AB048702 AB104712 AB090270 AY233291 AB048703 AB126581 AB109475 AY233292 AB188244 AB109476 AY233293 AB222710 AB110075 AY233294 AB222711 AB116266 AY233295 AB222712 AB120308 AY233296 AB222713 AB205126 DQ111987 AB246347 AB205127 V01460 AB246348 AB210822 AF121240 AB267090 AF121241 AJ627220 AF280817 AJ627223 AY161157 AY090453 AY721605 Z35716 AY721606 AY721607 AY721608 AY721609 AY721612 AY741797 AY945307 X02496 Y07587 Strains in this studycould be sequenced for another nine strains, which could be used for subgenotyping of these strains. Two of these had identical S genes encoding ayw4 within clade III (Tallo et al, 2004; Table 1). …”

“…One hundred and twenty six HBV strains, 26 genotype A and 100 genotype D strains obtained from patients and blood donors, were selected for sequence analyses of complete HBV genomes from the 205 strains previously published (Tallo et al, 2004). Fifteen of the selected genotype A strains had identical S gene sequences and 59 selected genotype D strains belonged to seven clades, each formed by strains with identical small S gene sequences (Table 1; Tallo et al, 2004). Criteria for selection were inclusion of strains with identical and divergent small S genes encoding subtypes ayw2, ayw3, ayw4 and adw2 originating from European, Siberian, Middle Asia and Far-Eastern regions of the former USSR (Table 1).…”

“…Genotype D was found to be dominating. However, an unexpectedly high number of strains were found to have identical S gene sequences, even though they were collected in geographically distant regions over a 13 years period (Tallo et al, 2004). The aim of this study was to characterize the complete genomes of representative strains from the different regions to classify them into subgenotypes and to further investigate the subclades of strains with identical S genes.…”

The Trends and Risk Factors for Hepatitis B Occurrence in Estonia

“…The genetic analysis of Estonian HBV virus strains revealed that genotype A, subtype adw2 (14%) and genotype D, subtype ayw3 (73%), subtypes ayw2 (3%) and ayw4 (9%) are circulating in Estonia (30). Infection with genotype D was mainly associated with IDUs, sexual contacts and medical procedures.…”

Tracing the history of hepatitis B virus genotype D in western Japan

“…These genotypes have a distinct geographical distribution, with genotypes A (HBV/A) and HBV/ D predominant in Europe, Middle East, Central Asia, Siberia, and America, HBV/B and HBV/C in East Asia, and HBV/E in Africa. In addition, HBV/F has been reported in Central America, and HBV/G in the United States and France [Norder et al, 1993;Lindh et al, 1997;Sanchez-Tapias et al, 2002;Chu et al, 2003;Miyakawa and Mizokami, 2003;Deversa et al, 2004;Mulders et al, 2004;Tallo et al, 2004]. In Japan, HBV/C is the most prevalent, followed by HBV/B, while others are encountered very rarely.…”