Porcine rotavirus groups A, B, and C identified by polymerase chain reaction in a fecal sample collection with inconclusive results by polyacrylamide gel electrophoresis

Abstract

Objective: To evaluate the frequency of groups A, B, and C rotaviruses in diarrheic pigs from Brazilian pig herds. Materials and methods: Fecal samples with inconclusive results when tested by the silver-stained polyacrylamide gel electrophoresis (ss-PAGE) technique were selected for this study (n = 144). Rotavirus A (VP4 and VP7 genes), rotavirus B (NSP2 gene), and rotavirus C (VP6 gene) were identified by reverse transcription-polymerase chain reaction (RT-PCR). Results: Of the 144 fecal specimens analyzed by RT-PCR assays, 103 (71.5%) were positive for rotavirus infection. Single infections were detected in 58 samples (40.3%), with 34 (23.6%), 19 (13.2%), and 5 (3.5%) identified as rotavirus groups A, B, and C, respectively. Mixed infections with two and even three rotavirus groups were identified in 45 fecal samples (31.2%). Rotaviruses B and C were more frequently identified in mixed (65.2%) than in single infections. Implications: The inclusion criteria for sample selection and use of RT-PCR assays for diagnosis in this study contributed to the higher frequencies of rotaviruses B and C, which are sporadically implicated in porcine neonatal diarrhea. The high rate of diagnosis of atypical rotavirus showed that rotaviruses B and C, as well as rotavirus A, are disseminated in Brazilian pig herds. These results suggest that failure to identify porcine rotaviruses B and C in diarrheic fecal samples is primarily due to use of diagnostic methods of low sensitivity, and not to low prevalence of infection.