Frequent Occurrence of Simultaneous Infection with Multiple Rotaviruses in Swiss Pigs

Development of a Quadruplex RT-qPCR for the Detection of Porcine Rotaviruses and the Phylogenetic Analysis of Porcine RVH in China

Rotavirus A species (RVA), RVB, RVC, and RVH are four species of rotaviruses (RVs) that are prevalent in pig herds, and co-infections occur frequently. In this study, a quadruplex real-time quantitative RT-PCR (RT-qPCR) for the simultaneous detection of four porcine RVs was developed by designing specific primers and probes based on the VP6 gene of RVA, RVB, RVC, and RVH, respectively. The method showed high specificity and could only detect RVA, RVB, RVC, and RVH, without cross-reaction with other porcine viruses; showed excellent sensitivity, with a limit of detection (LOD) of 1.5 copies/µL for each virus; showed good repeatability, with intra-assay coefficients of variation (CVs) of 0.15-1.14% and inter-assay CVs of 0.07-0.96%. A total of 1447 clinical fecal samples from Guangxi province in China were tested using the developed quadruplex RT-qPCR. The results showed that RVA (42.71%, 618/1447), RVB (26.95%, 390/1447), RVC (42.92%, 621/1447), and RVH (13.68%, 198/1447) were simultaneously circulating in the pig herds, and the co-infection rate of different species of rotaviruses was found to be up to 44.01% (579/1447). The clinical samples were also detected using one previously reported method, and the coincidence rate of the detection results using two methods was more than 99.65%. The phylogenetic tree based on the VP6 gene sequences of RVH revealed that the porcine RVH strains from Guangxi province belonged to the genotype I5, which was closely related to Japanese and Vietnamese strains. In summary, an efficient, sensitive, and accurate method for the detection and differentiation of RVA, RVB, RVC, and RVH was developed and applied to investigate the prevalence of porcine RVs in Guangxi province, China. This study is the first to report the prevalence of porcine RVH in China.

Rotavirus A in Domestic Pigs and Wild Boars: High Genetic Diversity and Interspecies Transmission

Rotavirus A (RVA) is an important pathogen for porcine health. In comparison to humans, RVA in domestic animals and especially in wildlife is under researched. Therefore, the aim of the present study was to investigate the prevalence, genetic diversity, molecular epidemiology and interspecies transmission of RVA in domestic pigs and wild boars. During the three consecutive RVA seasons (2018–2021) we collected 445 and 441 samples from domestic pigs and wild boars, respectively. Samples were tested by real-time RT-PCR, and RVA-positive samples were genotyped in VP7 and VP4 segments. Our results report an RVA prevalence of 49.9% in domestic pigs and 9.3% in wild boars. Outstanding RVA genetic diversity was observed in VP7 and VP4 segments, especially in domestic pigs exhibiting a striking 23 different RVA combinations (G5P[13] and G9P[23] prevailed). Interspecies transmission events were numerous between domestic pigs and wild boars, sharing G3, G5, G6, G9, G11 and P[13] genotypes. Furthermore, our data indicate that such transmission events involved even bovines (G6, P[11]) and, intriguingly, humans (G1P[8]). This study contributes to the basic knowledge that may be considered important for vaccine development and introduction, as a valuable and currently missing tool for efficient pig health management in the EU.