Reactivity of anti-human rotavirus VP4 neutralizing monoclonal antibodies with animal rotaviruses and with unusual human rotaviruses having different P and G serotypes

Characterization of VP4 and VP7 of a murine rotavirus (YR-1) isolated in Japan

Nucleotide and deduced amino acid sequences of the outer capsid proteins VP4 and VP7 of a murine rotavirus strain (YR-1) isolated in Japan were determined. Comparisons of the VP7 amino acid sequence of YR-1 with other murine rotavirus strains (EB, EW, EC, EL and EHP) (1) showed that YR-1 was highly homologous to EB, EW, EC, EL and EHP. Moreover, YR-1 was more closely related to strains representing G3 than to any other G type. Analysis of the VP4 amino acid sequence revealed that YR-1 was highly homologous to EB, EW, EC and EL [tentatively P17 (1)], and more closely related to EHP [tentatively P18 (1)] than to any other P type. Enzyme immunoassay with monoclonal antibodies against G types (KU-4 and BH49 for G1, S2-2G10 and BW36 for G2, YO-1E2 and BC5 for G3; and ST-2G7 and BE18 for G4) and against a P type (YO-1S3, KU-12H and YO-2C2 for P8) showed no reactivity. These results indicate that YR-1 is highly homologous to EB, EW, EC and EL.

Genotypic diversity of reassortants between simian rotavirus SA11 and human rotaviruses having different antigenic specificities and RNA patterns

A total of 200 clones of reassortants were generated in vitro between simian rotavirus SA11 (SA11-L2 strain) and each of five human rotavirus (HRV) strains with different antigenic specificities and RNA patterns. When culture fluid coinfected with parent viruses was subjected to repeated selection with anti-HRV-VP4 and anti-SA11-VP7 neutralizing monoclonal antibodies, all yielded progenies were antigenic mosaic reassortants possessing VP4 and VP7 derived from SA11 and HRV, respectively. In genomic analysis of viral RNA by PAGE, two and five different genotypes were identified in 40 clones, generated between SA11 and HRV strain Hochi (G serotype 4, G4) and between SA11 and KU (G1), respectively. In contrast, 11 and 17 genotypes were found in progenies between SA11 and subgroup I G2 HRV strain HN126 or DS-1, respectively. Although SA11 genes, except for the VP7 gene, were predominant in most reassortants, gene 5 was preferentially selected from HRV. Incorporation of HRV segments 1, 3 and 10 into progenies was more frequent in SA11 x HN126 and SA11 x DS-1 reassortants than in other reassortants. These results indicated that the extent of diversity of reassortant genotypes differs between the two groups of the parental HRV strain; one has subgroup I specificity and a short RNA pattern (DS-1 genogroup), while the other has subgroup II specificity and a long RNA pattern (Wa genogroup).

VP4 typing of bovine and porcine group A rotaviruses by PCR

A PCR typing assay was developed to identify rotavirus P types (VP4 specificity) of bovine NCDV, UK, and B223 strains and porcine OSU and Gottfried strains. Thirty-nine human and animal strains representing all known, and some undefined, rotavirus P types were used to develop and evaluate the specificity of the method. No cross-amplification was observed. The PCR results agreed with previous characterizations by monoclonal antibodies, sequence analysis, and hybridization assays, except for the Gottfried strain, which showed a P type distinct from the human asymptomatic strains. Analysis of a small number of field specimens suggested a high level of VP4 polymorphism among porcine strains. The assay should be of value in typing field isolates and tracing interspecies infections.

Analysis of gene selection in reassortant formation between canine rotavirus K9 and human rotaviruses with different antigenic specificities

A number of antigenic mosaic reassortants which have neutralization proteins VP4 and VP7 derived from different parental strains were analysed in order to study gene selection in reassortant formation between animal and human rotaviruses (HRV). These reassortants were isolated from mixed infection of MA-104 cells with canine rotavirus strain K9 (subgroup I and G serotype 3) and HRV strains (with subgroup I or II antigen and G serotype 1-4, 9 or 12 antigen), through repeated selections with anti-VP4 and anti-VP7 neutralizing monoclonal antibodies directed specifically at HRV and K9, respectively. By serological and genomic analyses, all the isolated clones were found to be antigenic mosaic reassortants possessing VP4 of K9 and VP7 of HRV. In the reassortants between strain K9 and one of the six strains of subgroup II HRV, a single or a few genotypes with particular constellations of RNA segments were predominant, with only a few RNA segments including gene 4 (encoding VP4) being derived from K9. In contrast, in the reassortants between strain K9 and any one of the subgroup I HRV, more than nine different genotypes were identified and various RNA segments, except for segments 8 and 10, were derived from K9. These findings indicated that the RNA segments of K9 might be reassorted more readily with those of subgroup I HRV than with those of subgroup II HRV, suggesting the possible existence of functional mechanisms which determine the extent of diversity of genome selection depending on the pairs of parent strains in the reassortant formation.