Genetic analysis of Group A rotaviruses: evidence for interspecies transmission of rotavirus genes.

Rotaviruses are the major cause of severe gastroenteritis in young children and animals. The rotavirus genome is composed of eleven segments of double-stranded RNA and can undergo genetic reassortment during mixed infections, leading to progeny viruses with novel or atypical phenotypes. There are numerous descriptions of rotavirus strains isolated from human and animals that share genetic and antigenic features of viruses from heterologous species. In many cases, genetic analysis by hybridization has clearly demonstrated the genetic relatedness of gene segments to those from viruses isolated from different species. Together with the observation that some virus strains appear to have been transmitted to a different species as a whole genome constellation, these data suggest that interspecies transmission occurs naturally, albeit at low frequencies. Although interspecies transmission has not been documented directly, there is an increasing number of reports of atypical rotaviruses that are apparently derived from transmission between: humans, cats and dogs; humans and cattle; humans and pigs; pigs and cattle; and pigs and horses. Interspecies evolutionary relationships are supported by phylogenetic analysis of rotavirus genes from different species. The emergence of novel strains derived from interspecies transmission has implications for the design and implementation of successful human rotavirus vaccine strategies.