Comparative sequence analysis identified mutations outside the NSP4 cytotoxic domain of tissue culture-adapted ATCC-Wa strain of human rotavirus and a novel inter-species variable domain in its C-terminus

Complete nucleotide sequence of the tissue culture-adapted ATCC*-Wa strain of human rotavirus NSP4 was determined. Sequence analysis detected two alte rnate forms of the gene with a nucleotide difference at position 331 (A or G) in the coding sequence (NSP4-A or NSP4-G) leading to a change from neutr al glutamine(97) in NSP4-A to a positively charged arginine(97) in NSP4-G o riginating from the same ATCC-Wa preparation. In addition to this, both for ms of ATCC-Wa NSP4 revealed three mutations at nucleotide positions 88 (T t o C), 142 (C to T) and 572 (G to A), when compared to the previously report ed NSP4 sequence from virulent Wa strain. The former two mutations were in the coding sequence and resulted in a leucine(16) to serine(16) and a proli ne(34) to leucine(34) change, while the third mutation was in the 3' non-co ding region of the gene. The two amino acid changes may contribute to the ' tissue culture-adaptation' of ATCC-Wa strain. The ATCC-Wa NSP4 sequence was found to differ from the previously reported NSP4 sequence of attenuated W a strain by lacking a mutation at 133 (T to C), though the mutations at 88 and 142 were present in both strains. Furthermore, comparison of deduced am ino acid sequence of NSP4 from human, bovine, porcine and simian rotavirus strains identified a seven-residue (positions 135-141) inter-species variab le domain in its C-terminal region.