Genetic and antigenic characterization of wild type rubella viruses isolated from India

Rubella, is a contagious disease caused by Rubella virus (RuV) that manifests as fever with skin-rashes in children and adults along with complications in pregnant women. WHO-SEAR has set a target for Rubella elimination by 2023. This is the first report of antigenic characterization and genome sequencing of nine RuVs sampled during 1992, 2007-9, and 2015-17 from four Indian states. Comparative analysis of Indian RuVs (2B) with that of global isolates and vaccine strain RA 27/3 (1a) revealed that the observed mutations in structural proteins have no major impact on the 3D structure, function and antigenicity. Indian RuVs formed three major clusters (Pune-1992, Kannur-2009 and Chitradurg-2007) in genome-based phylogeny of global isolates. Neutralizing antibody titers in a panel of serum samples from measles negative cases were significantly higher to the vaccine strain compared to a wild-type 2B isolate (Kannur) with concordance of 91.9%, thereby substantiating the use of current vaccines.