MOLECULAR-BIOLOGY OF ROTAVIRUSES .9. CONSERVATION AND DIVERGENCE IN GENOME SEGMENT-5

Nucleotide sequencing of RNA segment 5 from seven strains of group A rotavirus has been carried out to investigate the extent of diversity and conservation, as well as possible selective pressures involved in driving the fixation of sequence changes in this gene. Analyses of the derived sequences revealed that sequence conservation could not be correlated either with rotavirus serotype or the species of origin of the virus strain. These sequences together with other published and unpublished sequences of this gene have raised the total number available for comparison to 17. Alignment of all the available sequences revealed that only 88 amino acid positions (17.6%) in the protein encoded by gene 5 (VP5) are absolutely conserved but that the metal-binding motif reported by others is conserved in all sequences. Despite the high degree of sequence divergence, alignment of secondary structure predictions for VP5 showed a high level of conservation, suggesting that constraints on sequence divergence may operate at the level of overall higher-order structure of the encoded protein.