Viremia and Nasal and Rectal Shedding of Rotavirus in Gnotobiotic Pigs Inoculated with Wa Human Rotavirus

Abstract

Group A rotaviruses are the most common cause of dehydrating diarrhea in infants and young children worldwide, with more than 2 million hospitalizations yearly and approximately 440,000 deaths. It is estimated that 82% of rotavirus deaths occur in children in the poorest countries (23). Rotavirus transmission occurs mainly by the fecal-oral route, although respiratory transmission has been suggested to occur (7).Rotavirus infection was thought to be limited to the gastrointestinal tract. However, respiratory symptoms and rotavirus shedding in nasopharyngeal secretions have been reported in children with and without gastrointestinal symptoms (19,26,42). Rotavirus antigen was detected in the lung of 1 of 13 experimentally infected 3-week-old conventional pigs at postinoculation day 2 (30) and in liver and kidney specimens from immunodeficient children (9). Rotavirus RNA has also been detected in cerebrospinal fluid and blood of children with central nervous system disease (20,34). Recently, Blutt and colleagues (2) detected rotavirus antigenemia in the serum of children, mice, rabbits, and calves. They further demonstrated that serum from infected mice induced rectal rotavirus antigen shedding after oral inoculation of rotavirus-negative adult mice with the serum. Previously, another enteric virus, the porcine enteric calicivirus (PEC), has also been associated with transient viremia (infectious virus in serum) after oral inoculation of gnotobiotic pigs (11).We choose gnotobiotic pigs because they constitute an animal model of HRV-induced disease. Their gastrointestinal tract physiology and their development of mucosal immunity resemble that of humans. These similarities with HRV infections of infants allow us to establish correlations which could be applied for rotavirus vaccine development (14,25) The question addressed in our study was whether an attenuated human rotavirus and virulent HRV causes upper respiratory tract infections or viremia in naïve neonatal gnotobiotic pigs after various routes of inoculation. In this study we evaluated nasal and rectal virus shedding and viremia after oral, intranasal, feeding tube (gavage), and intravenous inoculation of neonatal gnotobiotic pigs with the Wa strain of attenuated HRV or virulent HRV. The presence of infectious virus in serum of gnotobiotic pigs after oral inoculation with Wa HRV was also investigated by oral and intravenous reinoculation of gnotobiotic pigs with a pool of the HRV-positive sera. MATERIALS AND METHODSVirus. The attenuated cell culture-adapted Wa strain HRV (P1A [8]G1), derived from the 27th HRV passage in African Green monkey kidney cells (MA104) and the virulent Wa HRV from pooled intestinal contents of gnotobiotic pigs were used for inoculation of the gnotobiotic pigs at doses of 5 ϫ 10 7

Virus-specific intestinal IFN-γ producing T cell responses induced by human rotavirus infection and vaccines are correlated with protection against rotavirus diarrhea in gnotobiotic pigs

“…The trend for the higher frequencies (not significantly vs. VirHRV group) of IFN-γ+ T cell responses in spleen and blood of AttHRV3x pigs may be explained also by the booster doses. Higher rate of nasal virus shedding than fecal shedding was observed after the AttHRV oral inoculation in our previous studies [43]. This fact may also help to explain the higher IFN-γ +CD4+ and IFN-γ+CD4+CD8+ T cell responses observed in the systemic site (spleen) than in the intestine (ileum) after inoculation with the AttHRV3x or 2x vaccine.…”

Pathogenesis of a Genogroup II Human Norovirus in Gnotobiotic Pigs

“…Similar percentages of viremia were detected in P0-, P1-, and P2-inoculated pigs in a more extensive study (Souza, Cheetham, and Saif, unpublished). Viremia has been detected for other enteric viruses such as the porcine sapoviruses (PEC/Cowden) in pigs and human rotavirus in humans, mice, and pigs without causing lesions outside the small intestines (4,5,14). As described for PEC/Cowden (14), we report that one pig inoculated intravenously with P0 showed viral shedding and diarrhea.…”

Cytokine Responses in Gnotobiotic Pigs after Infection with Virulent or Attenuated Human Rotavirus

“…The pair of virulent and attenuated Wa HRV strains provides a valuable tool to study the relationship between cytokine profiles, kinetics, and magnitude of responses and their relationships to the pathogenicity and immunity induced by these two rotavirus strains that differ in virulence (34,35). The pathogenicity of and immune responses to VirHRV and AttHRV have been well defined in gnotobiotic pigs (3,4,45,46,49,51). The VirHRV infection caused diarrhea and villous atrophy and 100% rectal and nasal virus shedding, with the presence of viral antigen within villous epithelial cells and infectious rotavirus in the serum (viremia) (4,45).…”