SEQUENCE CONSERVATION AND EXPRESSION OF THE GENE ENCODING THE OUTER CAPSID GLYCOPROTEIN AMONG HUMAN GROUP-C ROTAVIRUSES OF GLOBAL DISTRIBUTION

Group C rotaviruses have been identified recently from fecal samples o f children with diarrhea in the United States. Using reverse transcrip tase-polymerase chain reaction and sequence analysis, we sequenced gen e 8s encoding VP7 from two U.S. strains (RI-1 and RI-2), and eight oth er strains isolated from patients on four continents, and compared the se with the sequences of four published strains. The gene 8s of the 14 strains were remarkably conserved in size and in predicted primary an d secondary structures. When the sequences of the human VP7s were comp ared with that of the prototype porcine Cowden strain, six regions wer e found variable in both deduced primary and predicted secondary struc tures, four of which were predicted to be hydrophilic and might determ ine serotype specificity. Gene 8 of the human S-l strain was further c haracterized by expression in recombinant baculoviruses. The expressed product was immunogenic but failed to elicit neutralizing antibodies. Our sequence analysis indicates that all the human strains characteri zed to date belong to a single G genotype, which may constitute a sing le G serotype, pending further antigenic analysis. Whether the human s trains and the Cowden strain are the same serotype remains to be deter mined.