MOLECULAR CHARACTERIZATION OF THE OUTER CAPSID SPIKE PROTEIN (VP4) GENE FROM HUMAN GROUP-C ROTAVIRUS

A cDNA copy of the third genomic RNA segment of a noncultivatable huma n group C rotavirus (Bristol) was generated by single primer amplifica tion. Human group C rotavirus genome segment 3 contains 2283 bp and en codes the VP4 gene with an open reading frame of 2232 nucleotides (744 amino acids) starting at nucleotide 21 and terminating at nucleotide 2251. PCR primers designed from the 5' and 3' terminal sequences of th e C/Bristol VP4 gene were used to amplify the corresponding VP4 gene o f a human group C rotavirus from Belem, Brazil, Nucleotide sequence co mparisons of the Bristol and Belem VP4 genes revealed 45 differences o f which only 6 were predicted to give amino acid changes. Alignment of the two human VP4 sequences with the prototype porcine group C/Cowden rotavirus VP4 showed only 71.2% nucleotide sequence identity. Protein sequence alignments showed that the human group C rotavirus VP4 seque nces were 8 amino acids longer than the porcine VP4 sequence with an i nsertion of 6 amino acids, (252)NSKLGD(257) adjacent to the proposed p roteolytic cleavage region (amino acids 231-250). The large overall nu mber of differences between the human and porcine VP4 sequences strong ly suggested that the porcine C/Cowden isolate may belong to a differe nt group C rotavirus P ''serotype.'' In contrast the very close simila rity of the VP4 sequences of the UK and Brazilian group C rotaviruses support the hypothesis that these human isolates originate from a rece nt common ancestor. (C) 1994 Academic Press, Inc.