Rotavirus Viremia and Extraintestinal Viral Infection in the Neonatal Rat Model

Abstract

Rotaviruses infect mature, differentiated enterocytes of the small intestine and, by an unknown mechanism, escape the gastrointestinal tract and cause viremia. The neonatal rat model of rotavirus infection was used to determine the kinetics of viremia, spread, and pathology of rotavirus in extraintestinal organs. Five-day-old rat pups were inoculated intragastrically with an animal (RRV) or human (HAL1166) rotavirus or phosphatebuffered saline. Blood was collected from a subset of rat pups, and following perfusion to remove residual blood, organs were removed and homogenized to analyze rotavirus-specific antigen by enzyme-linked immunosorbent assay and infectious rotavirus by fluorescent focus assay or fixed in formalin for histology and immunohistochemistry. Viremia was detected following rotavirus infection with RRV and HAL1166. The RRV 50% antigenemia dose was 1.8 ؋ 10 3 PFU, and the 50% diarrhea dose was 7.7 ؋ 10 5 PFU, indicating that infection and viremia occurred in the absence of diarrhea and that detecting rotavirus antigen in the blood was a more sensitive measure of infection than diarrhea. Rotavirus antigens and infectious virus were detected in multiple organs (stomach, intestines, liver, lungs, spleen, kidneys, pancreas, thymus, and bladder). Histopathological changes due to rotavirus infection included acute inflammation of the portal tract and bile duct, microsteatosis, necrosis, and inflammatory cell infiltrates in the parenchymas of the liver and lungs. Colocalization of structural and nonstructural proteins with histopathology in the liver and lungs indicated that the histological changes observed were due to rotavirus infection and replication. Replicating rotavirus was also detected in macrophages in the lungs and blood vessels, indicating a possible mechanism of rotavirus dissemination. Extraintestinal infectious rotavirus, but not diarrhea, was observed in the presence of passively or actively acquired rotavirus-specific antibody. These findings alter the previously accepted concept of rotavirus pathogenesis to include not only gastroenteritis but also viremia, and they indicate that rotavirus could cause a broad array of systemic diseases in a number of different organs.Rotaviruses, responsible for most cases of gastroenteritis in children under the age of five worldwide, have been thought to cause mucosal infections restricted to the mature, differentiated enterocytes of the small intestine. However, an increasing number of reports indicate that rotavirus escapes the gastrointestinal tract. Rotavirus antigen and RNA were detected in serum samples from approximately 65% of children with rotavirus diarrhea, indicating that antigenemia and possibly viremia occur during rotavirus infection (4, 7, 16). In other reports, rotavirus antigen and/or RNA was detected in the central nervous systems, spleens, hearts, kidneys, testes, and bladders of children who died during rotavirus infections (23, 29-32, 35, 42); in liver biopsies from infants with cholestatic disease (47); and in respiratory secre...

Characterization of Clinical and Immune Response in a Rotavirus Diarrhea Model in Suckling Lewis Rats

“…Thus, RV can be detected in a broad array of organs, and its presence may explain some clinical consequences exhibited by infected children (20,21). Otherwise, protection mechanisms and interaction with the immune system have been less studied, and thus evaluation of cell/humoral and mucosal/systemic immune responses have become the focus of attention in the present work.…”

Intestinal ribosomal p70S6Ksignaling is increased in piglet rotavirus enteritis

“…Furthermore, endotoxemia markedly alters mTOR pathway signaling and translation initiation in pigs (25) and rats (26). During viral enteritis, hormonal or other signals from the gut to muscle have not been investigated but could include cytokines such as IL-6, IL-1␤, TNF-␣, IL-12, IL-10, and IFN-␥ (2, 21); reactive oxygen species; glucocorticoid hormones [which are among the best-established inhibitors of mTOR (50,51)]; and the virus itself (8,12). Among these, the best-recognized inhibitors of protein synthesis and mTOR in inflammatory diarrheas are glucocorticoid hormones (32,48,49,52), which have been shown to inhibit the translational pathway below the level of Akt (most likely at mTOR itself) (31,33).…”

Comparative In Vitro and In Vivo Studies of Porcine Rotavirus G9P[13] and Human Rotavirus Wa G1P[8]

“…There is increasing evidence suggesting that RV can spread extraintestinally (28,29). RVs have been shown to cause persistent infection in immunodeficient mice as well as immunodeficient young children, resulting in diseases such as encephalitis in children (30,31).…”