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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.
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.
Médici KC, Barry AF, Alfieri AF, et al. Porcine rotavirus groups A, B, and C identified by polymerase chain reaction in a fecal sample collection with inconclusive results by polyacrylamide gel electrophoresis. J Swine Health Prod. 2011;19(3):146–150.
