Porcine group a rotaviruses with heterogeneous VP7 and VP4 genotype combinations can be found together with enteric bacteria on Belgian swine farms

- RT-qPCR is most sensitive for diagnosis of porcine RVA infections in Belgium.
- RVA positive samples collected on Belgian swine farms were mostly co-infected with enteric bacteria.
- A high genetic diversity was found for genes encoding VP7 and VP4 with 12 different G/P combinations.
- G2, G3, G4, G5 and G11 genotypes were detected for VP7.
- P[6], P[7], P[13], P[23] and P[27] genotypes were detected for VP4.

Group A rotaviruses (RVA) are an important cause of diarrhea in young piglets, resulting in significant economic losses. However, the role of RVA in the etiology of piglet diarrhea on Belgian swine farms was previously unreported. In the present study, different techniques, including fast antigen detection tests, virus isolation, RT-PCR and RT-qPCR have been applied for detection of RVA in diarrheic (n = 28) and asymptomatic (n = 6) fecal samples collected on Belgian pig farms. RT-qPCR was shown to be most sensitive. Routine bacteriological analysis of the fecal samples showed that most diarrheic RVA positive samples were also co-infected with one or more bacterial species, such as Escherichia coli, Clostridium perfringens, Salmonella sp. and/or Brachyspira sp. Further genetic characterization of the VP7 and VP4 genes of 26 RVA strains resulted in the detection of six different G-genotypes (G2, G3, G4, G5, G9 and G11), and five different P-genotypes (P[6], P[7], P[13], P[23], P[27]), in a total of 12 different G/P combinations. A large intra-genotypic diversity was also apparent. In conclusion, results of the present study help us better understand the role of RVA in the pathogenesis of piglet diarrhea, and provide better insights into the vast genetic diversity present among circulating porcine group A rotaviruses.