Adaptive evolution of rotavirus VP7 and NSP4 genes in different species.

ABSTRACT

Rotavirus is recognized as the major enteric pathogen associated with high burden of worldwide epidemic diarrhea disease in human and animals. Its outer capsid structural protein VP7 elicits the production of distinct neutralizing antibodies in the host and also determines the serotype of the virus strain. As the diarrhea-related protein of rotavirus, NSP4 is becoming an attractive candidate for vaccine development. It is not clear whether rotavirus VP7 or NSP4 evolved in the same way or not, and how the rotavirus VP7 and NSP4 evolved in specific species. Using the different models, we analyzed Datasets A composed of 12 coding sequences representing 12 species and Dataset B composed of nine coding sequences representing nine species. Computational results indicate that rotavirus experienced strong purifying selection in VP7 and NSP4 across species, and there exist some positive selective sites in specific species by Branch-site model A (119S in Bovine lineage and 199T in Canine lineage for Datasets A, 69Y and 70H in Murine lineage for Datasets B). Since these sites are located in different functional sequence segments, it may be concluded that these sites are crucial to related virus function. Therefore, the results of this study would provide potential values to vaccine research and development.