Molecular characterization of rotaviruses with distinct group antigens.

Comparative serological and nucleic acid studies were carried out on rotavirus isolates, with and without the original group antigen. Indirect immunofluorescence allowed the atypical isolates to be divided into two groups each with its own distinct group antigen hence giving a total of at least three distinct rotavirus groups. Genome profile analysis of the atypical isolates again divided them into two groups which corresponded with those obtained by immunofluorescence and within which the overall pattern of genome segments was similar. A more rigorous examination of the degree of difference between the three virus groups was carried out using single-dimension terminal fingerprint analysis. This indicated that the viruses in the three groups did not carry any genome segments in common with each other. Therefore, experimental criteria have been established which allow the division of rotaviruses into three groups. Analysis of further atypical isolates, as they become available, will establish whether the division of rotaviruses into a number of separate groups, of the type seen in influenza virus, is justified.