Genetic heterogeneity of porcine enteric caliciviruses identified from diarrhoeic piglets

Enteric caliciviruses (noroviruses and sapoviruses) are responsible for the majority of non-bacterial gastroenteritis in humans of all age groups. Analysis of the polymerase and capsid genes has provided evidence for a huge genetic diversity, but the understanding of their ecology is limited. In this study, we investigated the presence of porcine enteric caliciviruses in the faeces of piglets with diarrhoea. A total of 209 samples from 118 herds were analyszd and calicivirus RNA was detected by RT-PCR in 68 sample (32.5%) and in 46 herds (38.9%), alone or in mixed infection with group A and C rotaviruses. Sequence and phylogenetic analysis of the calicivirus-positive samples characterized the majority as genogroup III (GGIII) sapoviruses. Unclassified caliciviruses, distantly related to the representatives of the other sapovirus genogroups, were identified in five herds, while one outbreak was associated with a porcine sapovirus related genetically to human GGII and GGIV sapovirus strains. By converse, norovirus strains were not detected. Altogether, these data suggest the epidemiological relevance of porcine enteric caliciviruses and suggest a role in the etiology of piglets diarrhoea.