Co-circulation of multiple rubella virus strains in Belarus forming novel genetic groups within clade 1

Although the WHO recommends a comprehensive genetic characterization, little is known about circulating strains and genotypes of rubella virus (RUBV) for many European countries. Studies investigating the genetic diversity of a sizeable number of strains from a certain location are rare. This study presents the first molecular characterization of isolates from Belarus. Throat swab and urine samples were collected between 2004 and 2005 from patients presenting in two infectious disease hospitals and three outpatient clinics in and around Minsk. In total, 14 isolates were obtained from this clinical material. Phylogenetic analysis of the E1 gene sequence of these isolates showed that three distinct groups of RUBV strains co-circulated. One group of isolates was assigned to genotype 1E, whereas the other two did not group with any of the recognized genotypes but grouped with a strain belonging to the provisional genotype 1g. Detailed analysis showed that the group comprising 1g strains also contained sequences formerly attributed to genotype 1B and could be divided into four subgroups, one of which might represent a putative novel provisional genotype of clade 1. These findings show that three distinct strains with limited variability are present in Belarus, suggesting independent introductory events. As there currently seem to be misattributions of strains to genotypes and unclear phylogenetic relationships, criteria for genotyping of RUBV should be clarified further.