Presence and characterization of pig group A and C rotaviruses in feces of Belgian diarrheic suckling piglets.

The importance of group A and C rotaviruses (RVA and RVC) in the pathogenesis of diarrhea in Belgian suckling pigs is poorly investigated, and it is not known which strains are circulating in the Belgian suckling pig population. Obtaining better insights in the occurrence of both viral species in the swine population is essential in order to develop accurate diagnostic, therapeutic and prophylactic strategies to protect suckling pigs against diarrhea in a durable manner. In the present study, viral loads of RVA and RVC were quantified in diarrhea samples of suckling piglets less than 2 weeks old, collected on 36 different Belgian farms. On 22 of 36 farms tested (61%), high viral loads of RVA (6.96-11.95 log10 copies/g feces) and/or RVC (5.40-11.63 log10 copies/g feces) were detected. Seventeen RVA isolates were genotyped for their outer capsid proteins VP7 and VP4. Four different G-genotypes (G3, G4, G5 and G9) for VP7 were found together with 4 different P-genotypes (P[6], P[7], P[13] and P[23]) for VP4, in 8 different G/P combinations. All characterized RVC strains belonged to genotype G6 (VP7), except for one strain possessing the G1 genotype. VP4 genes of Belgian RVC strains were genetically heterogeneous, but were classified in the genotype P5. Most rotavirus positive samples also contained Escherichia coli, whereas Clostridium perfringens infections were mainly detected in rotavirus negative samples. Results of the present study offer better insights in the occurrence of RVA and RVC infections in Belgian diarrheic suckling piglets. As a conclusion, routine diagnostic testing for both viral species in cases of diarrhea in suckling pigs is highly recommended. Furthermore, the present findings also offer valuable information for the development of new prophylactic measures against rotavirus. Finally, the relatedness between RVC strains from pigs and other host species is described, and their possible implications in interspecies transmission events are discussed.