in february 1997 , rotavirus infection was diagnosed ( by page analysis ) in a 2-year - old child hospitalized with severe acute diarrhea at the  g. di cristina the virus , pa260/97 , exhibited a long e - type and was recognized by an sg - specific monoclonal antibody ( mab ) and by a vp7-specific mab as sgi and g3 ( 6 ) . accordingly , strain pa260/97 displayed a genetic / antigenic constellation that is usually observed in animal - like viruses . for confirmation of the initial antigenic characterization and information about the vp4 ( p ) genotype , strain pa260/97 was characterized at the molecular level . by pcr genotyping of the vp7 and vp4 genes with panels of primers specific for various human g and p types ( 3,7,8 ) , the vp7 was characterized as g3 and the vp4 was untypeable . to characterize strain pa260/97 in more detail , we determined the sequence of the vp7 , vp4 ( vp8 * ) , vp6 , and nsp4 genes . we also determined the vp7 , nsp4 , and vp6 sequences of human strain pah101/97 ( g3p , sgii , long e - type ) , detected in palermo in the same year , as well as the sequences of the vp8 * , vp6 , and nsp4 genes of 2 g3p , sgi , long e - type strains , rv198/95 , and rv52/96 , isolated from dogs in italy in 1995 and 1996 , respectively ( 9 ) . the sequences of human strains pa260/97 and pah101/97 and of canine strains rv198/95 and rv52/96 have been deposited in genbank . the accession numbers are as follows : ef442738 ( vp6 ) , ef442733 ( vp7 ) , ef442735 ( vp8 * ) , and ef442741 ( nsp4 ) for strain pa260/97 ; ef534715 ( vp6 ) , ef442734 ( vp7 ) , and ef534716 ( nsp4 ) for strain pah101/97 ; ef442737 ( vp6 ) , ef442736 ( vp8 * ) , and ef442739 ( nsp4 ) for strain rv198/95 ; ef442742 ( vp6 ) , ef442740 ( vp8 * ) , and ef442743 ( nsp4 ) for strain rv52/96 . the vp8 * of strain pa260/97 displayed the highest amino acid ( aa ) identity ( 98% ) to the canine strain rv52/96 , g3p , isolated in italy in 1996 ( figure 1 ) . similar , the vp7 of strain pa260/97 displayed the highest identity to g3 rotaviruses , with the best match ( 99% nt and aa ) to the canine strain rv52/96 ; identity to reference human g3 strains ( yo , au-1 , ma09004 , tk28 ) and to the human g3 strain pah101/97 , isolated in palermo in 1997 , ranged from 77% to 78% nt and from 88% to 90% aa . in the phylogenetic vp7-based analysis ( figure 2 ) , human strain pa260/97 clustered with animal g3 strains . species - specific patterns have been demonstrated in the vp7 gene of g3 human and animal rotaviruses ( 9 ) . these patterns are suggestive of mechanisms of host - species restriction and are useful for tracing the origin of unusual rotavirus strains . phylogenetic analysis of the deduced amino acid sequence derived from vp4 gene of the pa260/97 human rotavirus strain and other p rotavirus strains . the tree was generated by the neighbor - joining method using the clustalw program ( http://dambe.bio.uottawa.ca/dambe.asp ) . phylogenetic analysis of deduced amino acid sequence derived from vp7 gene of the pa260/97 human rotavirus strain and other g3 rotavirus genotypes . the tree was generated by the neighbor - joining method using the clustalw program ( http://dambe.bio.uottawa.ca/dambe.asp ) . scale bar indicates nucleotide substitutions ( 100 ) . a close genetic relationship between human strain pa260/97 and canine strain rv52/96 was also observed by comparing the genes that encode vp6 and nsp4 . on the basis of mab reactivity , sequencing of an informative fragment of the vp6 gene ( 10 ) showed a close genetic relationship ( 97% aa ) between strain pa260/97 and canine strain rv52/96 and only 86% aa identity with strain pah101/97 . sequence analyses of nsp4 enabled characterization of strains pa260/97 , rv198/95 , and rv52/96 into the nsp4 genotype c ; strain pah101/97 ( g3p ) was characterized as nsp4 b genotype . the highest identity was observed between strains pa260/97 and rv52/96 ( 98% nt and 99% aa ) . rotavirus strains with a g3p combination are usually detected in cats and dogs . despite only a few reports of rotavirus isolation from dogs with gastroenteritis , all canine strains identified thus far in the united states , japan , and europe ( cu-1 , a79 - 10 , lsu79c-36 , rs15 , rv198/95 , and rv52/96 ) display g3 and p specificities ( 9 ) . more recently , g3p rotaviruses have also been identified in monkeys and goats ( 1,11 ) . in contrast , detection of g3p in humans is uncommon ; only 4 g3p strains hcr3a , hcr3b ( 4,12 ) , ro1845 ( 5 ) , and cmh222 ( 13)have been reported . by sequence analysis and by rna - rna hybridization , strains hcr3a and ro1845 were found to be related to canine and feline rotaviruses rather than to human g3 rotaviruses ; strain cmh222 appeared to be genetically related to both simian and caprine g3p rotaviruses ( 13 ) . the mexican rotavirus strain 7177 - 1042 bears a common human vp4 gene , p , in conjunction with a canine - like vp7 gene , closely related to the vp7 of canine strain rv198/95 ( 14 ) . canine rotavirus infection is considered a minor disease in young dogs ( pups ) because it is usually mild or unapparent ; however , serologic investigations have shown a high prevalence of antibodies to rotavirus in adult dogs ( 15 ) . previous documented examples of infections in humans by canine - like rotavirus strains have been associated with either asymptomatic ( strains hcr3a and hcr3b ) or symptomatic ( strain ro1845 ) clinical forms of disease ( 4,5,12 ) . strain pa260/97 in the 2-year - old child was associated with enteritis severe enough to require hospitalization . therefore , the results of this study reinforce the hypothesis that canine - like rotaviruses may be able to not only cross the species barriers but also to induce severe disease forms in children . the lack of systematic surveillance of rotavirus infection in small animals ( e.g. , dogs and cats ) and the fact that most rotavirus infections in such animals may go undetected hinder the ability to establish firm epidemiologic connections . in conclusion , complementing the human rotavirus surveillance programs with surveillance in animals is paramount to understanding the global ecology of rotaviruses and to identifying and characterizing interspecies transmission events and virus evolution