CHARACTERIZATION OF RUBELLA-VIRUS STRAIN DIFFERENCES ASSOCIATED WITH ATTENUATION

A comparison of the phenotypic properties of three rubella vaccines (HPV77/DE5, RA27/3 and Cendehill) and four wildtype (wt(+)) isolates (M33, Therien, Thomas and IB2) has been carried out. Differences in growth characteristics, plaque morphology and temperature sensitivity were identified. In addition differential reactivity of the strains to polyclonal and a monoclonal anti-E1 antibody were found in immunoperoxidase-staining reactions. The ability of the wt(+) and vaccine strains to infect lymphoreticular cells and chondrocytes, also varied in that the RA27/3 and Cendehill strains were highly restricted in both these cell types while the wt(+) strains and HPV77/DE5 vaccine grew to high titer. This biological variation was associated with differences in E1 and E2 glycoproteins detected on immunoblots.