Rotavirus-Like, Calicivirus-Like, and 23-nm Virus-Like Particles Associated with Diarrhea in Young Pigs

Abstract

Virus particles morphologically similar to caliciviruses and rotaviruses were detected by electron microscopy (EM) in the intestinal contents of a 27-day-old diarrheic nursing pig. A third small spherical 23-nm virus-like particle was also observed. Calicivirus-like particles averaged 33 nm in diameter. Similar to rotaviruses, rotavirus-like particles were present as single-capsid 55-nm forms or double-capsid 70-nm particles. Most gnotobiotic pigs orally exposed to samples containing these three viruses developed diarrhea and villous atrophy of the small intestine, and all shed the three viruses in their intestinal contents. Attempts to propagate these viruses in cell culture were unsuccessful. The antigenic relationship of the rotavirus-like particles to known rotaviruses was explored by immune EM and immunofluorescent staining. By these techniques, the rotavirus-like particles did not cross-react with antisera to porcine, bovine, or human rotaviruses or to reovirus type 3. Antisera from gnotobiotic pigs exposed to all three viruses had enzyme-linked immunosorbent assay and virus neutralization titers of <4 against porcine rotavirus. Previous infection of gnotobiotic pigs with the mixture containing rotavirus-like particles failed to protect them against a subsequent challenge with porcine rotavirus. The antigenic relationship of the calicivirus-like particles to known caliciviruses was investigated by immune EM and virus neutralization. By these tests, the calicivirus-like particles did not react with antisera against feline calicivirus strain 255 or M-8. In a study conducted at Plum Island Animal Disease Center, antiserum against the three combined agents did not specifically neutralize any serotype of swine vesicular exanthema virus.

Genetic diversity of porcine sapoviruses

“…Since a porcine SaV infection was first reported in the US in 1980s (Saif et al, 1980), it has only been reported in a few countries including the US, Netherlands, Venezuela and the United Kingdom (Bridger, 1990;Martínez et al, 2006;Saif et al, 1980). However, the precise epidemiology of porcine SaV infections in the other countries is not known.…”

“…Porcine SaVs circulating in the US have been genetically analyzed using the major strains classified as SaV/GIII (Guo et al, 1999;Wang et al, 2005a), though one strain represents a potential new genogroup of porcine SaVs (Wang et al, 2005a). Since the discovery of porcine SaVs in the 1980s (Saif et al, 1980), only a few additional studies of their genetic diversity have been reported (Farkas et al, 2004;Guo et al, 1999;Schuffenecker et al, 2001;Wang et al, 2005a). In South Korea, we demonstrated that porcine SaVs cause diarrhea outbreaks .…”

“…Noroviruses and sapoviruses have emerged as the leading cause of food-and waterborne, acute, nonbacterial gastroenteritis in humans worldwide (Green et al, 2001). Animal SaVs and NoVs also cause gastroenteritis in swine, calves and mink (Bridger, 1990;Guo et al, 2001a,b;Saif et al, 1980). Several of porcine SaVs and NoVs are closely related to human SaVs and NoVs genetically, which has raised public health concerns of potential cross-species transmission and animal reservoirs for SaVs and NoVs related to human SaVs and NoVs (Guo et al, 1999;Wang et al, 2005a,b).…”

Detection and molecular characterization of porcine group C rotaviruses in South Korea

“…Group C rotavirus (GCRV) was first detected in pigs in 1980 (Saif et al, 1980) and has been subsequently identified in humans, ferrets, and cattle (Rodger et al, 1982;Torres-Median, 1987;Tsunemitsu et al, 1991). Since then, the global distribution of human GCRVs has been established; they are suspected of being an emerging pathogen Caul et al, 1990;Esona et al, 2008;Iizuka et al, 2006;Kuzuya et al, , 2007Medici et al, 2009;Steyer et al, 2006).…”

Molecular detection and characterization of unclassified bovine enteric caliciviruses in South Korea

“…In humans, NoVs and SaVs have been associated with enteric diseases only, and are the most common cause of food-and waterborne, acute, non-bacterial gastroenteritis in humans worldwide (Green et al, 2001). Animal SaVs and NoVs also cause gastroenteritis in swine, calves and mink (Bridger, 1990;Guo et al, 2001;Saif et al, 1980).…”