Detection of substantial porcine group B rotavirus genetic diversity in the United States, resulting in a modified classification proposal for G genotypes

Abstract

Rotavirus (RV) is an important cause of gastrointestinal disease in animals and humans. In this study, we developed an RT-PCR to detect RV group B (RVB) and characterized the VP7 (G) gene segment detected in porcine samples. One hundred seventy three samples were tested for RV group A (RVA), RVB, and C (RVC) by RT-PCR and examined for RV-like lesion using histopathology. A majority (86.4%) of the samples had mixed RV infections and co-infections of RVA/RVB/RVC were detected at a higher rate (24.3%) than previously reported. RVB was identified in 46.8% of the 173 samples. An adapted VP7 classification was developed using previously published (n=57) and newly sequenced (n=68) RVB strains, resulting in 20 G genotypes based on an 80% nucleotide identity cutoff value. Our results revealed a broad genetic diversity of porcine RVB strains, suggesting RVB has been the cause of common/pre-existing, yet undiagnosed, disease in pigs.

Diarrhea outbreaks in suckling piglets due to rotavirus group C single and mixed (rotavirus groups A and B) infections

“…The majority of the surveys evaluated only one pathogen, resulting in insufficient information about the frequency and severity of diarrhea caused by concomitant infections with multiple enteropathogens (Barreiros et al 2003, Linares et al 2009); however, more recently some studies have identified several different enteric agents in pig fecal samples (Martella et al 2007, Jeong et al 2009, Halaihel et al 2010, Médici et al 2011, Marthaler et al 2012. In Brazil, the association of different PoRV groups in piglet enteritis has been reported in transversal epidemiological studies carried out in distinct pig farms, not all of which were involved in a diarrhea outbreak (Médici et al 2011).…”

“…Single infections of PoRVC have been detected in piglets, but this PoRV group was more frequently detected in piglets in association with other PoRV groups or with other enteric viruses (Médici et al 2011, Marthaler et al 2012. Martella et al (2007) reported that in piglets, PoRVC was more frequently detected in association with other viruses, such as PoRVA and calicivirus, than as a single infectious agent.…”

“…Newborn piglets are susceptible to infection by several enteric microorganisms, including bacteria (enterotoxigenic Escherichia coli and Clostridium perfringens type C), protozoans (Cryptosporidium spp and Isospora suis), and viruses (rotavirus, coronavirus, and calicivirus) , Zlotowski et al 2008, Jeong et al 2009, Linares et al 2009, Médici et al 2011, Marthaler et al 2012.…”

“…Porcine group A rotavirus (PoRVA) infections are most frequently identified in episodes of diarrhea in piglets worldwide, including in Brazil (Linares et al 2009, Halaihel et al 2010, Médici et al 2011, Lorenzetti et al 2011; however, the involvement of porcine rotavirus groups B and C (PoRVB and PoRVC) in weaning and post-weaning piglets with diarrhea has also been reported mainly in transversal epidemiological studies (Magar et al 1991, Zlotowski et al 2008, Médici et al 2010a, 2010b, Médici et al 2011, Marthaler et al 2012.…”

“…A combination of different groups of PoRVs can intensify the severity of the piglets' diarrhea, although mixed infections have been detected in piglets without these clinical signs (Marthaler et al 2012).…”