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

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