Isolation, serologic and molecular characterization of the first G3 caprine rotavirus

We isolated a rotavirus in cell culture, named the GRV strain, from a stool specimen of a Korean goat with diarrhea, and performed an in-depth characterization. At various passage levels in cell culture, the GRV strain retained its pathogenicity for goat kids, thereby for the first time establishing that a caprine rotavirus can cause diarrhea in goat kids. The GRV strain grew to a high titer and agglutinated group O human erythrocytes. The GRV VP7 protein was 96% identical with the RRV (simian rotavirus) and R2 (lapine rotavirus) VP7 proteins, and slightly less similar to the SA11 (simian rotavirus) and HCR3 (feline/canine-like human rotavirus) VP7 proteins. The GRV VP4 protein was 93% identical with the RRV VP4 (P[3]) and 90% identical with the SA11 VP4 (P[2]). However, phylogenetic analysis including more VP4 sequences from representative P[3] strains unambiguously placed the GRV VP4 in the cluster of P[3] VP4s. A high level of two-way cross neutralization with RRV substantiated that GRV was a G3P5[3] strain, thus identifying GRV as the first caprine rotavirus with such a phenotype. The GRV NSP4 sequence belonged to the AU-1 allele, as does the RRV NSP4 sequence. Genetic analysis by RNA-RNA hybridization revealed that the overall genomic RNA constellation of the GRV strain was unique among mammalian rotavirus genogroups and that it was almost equally related to, yet distant from, simian rotavirus RRV, feline/canine rotavirus FRV64 (or CU-1), feline/human rotavirus FRV-1 (or AU-1), and lapine rotavirus R2. The availability of the GRV strain will further expand our limited knowledge of caprine rotaviruses.