[Rubella in Russia: variability of the infectious agent during the period of vaccine prophylaxis].

AIM: To assess influence of vaccination against rubella on the genetic diversity of rubella virus.

MATERIALS AND

METHODS

Vaccine strains of rubella virus Wistar 27/3 and Orlov-B as well as sera from patients with rubella obtained in Perm region during 1999 - 2005 period and standard serologic, molecular, epidemiologic and statistical methods were used. The study was performed according to the WHO recommendations on the genotyping of wild rubellavirus strains.

RESULTS

Strains of rubella virus isolated in Perm region, vaccine strain Orlov-B (Saint Petersburg), and 4 Russian strains isolated in 1967-1997 before vaccine introduction belong to the same genetic group with high degree of homology - genetic divergence do not exceed 0 - 1%. This group was identified as genotype 2c which, according to WHO's data, circulates only in Russia. Periods of epidemic peaks of rubella incidence and its falls as well as selective immunization of girls and women of childbearing age did not influence on the genetic stability of the virus (divergence did not exceed 0.6 - 2.0%). On the contrary, mass immunization of children aged 1 - 2 years during 4 years resulted in statistically significant changes of rubella virus subtype inside the genotype 2c.

CONCLUSION

Ten-year experience of rubella vaccination in Perm region demonstrates necessity of inclusion of monitoring for rubella virus variability in the system of epidemiological surveillance and control for rubella infection during period of its prevention by vaccine.