Pathophysiology of the pancreas after oral infection of genetically diverse mice with coxsackievirus B4-E2

Coxsackievirus B4 sewage-isolate induces pancreatitis after oral infection of mice

Numerous serotypes which belong to the genus Enterovirus (EV) show variability in their virulence and clinical manifestations. They are also known to undergo changes caused by mutations and recombination during their circulation in the environment and the population. Various EV serotypes are prevalent in groundwater, wastewater and surface waters. Our previous studies showed that oral infection induces pancreatitis depending on specific conditions, such as gravidity, in an outbred murine model. Our aim in the present study was to further explore the pancreatic histopathology in an outbred mouse model following oral infection with clinical isolates from a patient who had aseptic meningitis and an isolate from a treated-sewage sample recovered from the residential area of the patient. The isolates were identified as coxsackievirus B4 (CVB4) in tissue culture. The CVB4 sewage-isolate induced pancreatitis after oral infection. In contrast, pancreatitis was absent following infection with the clinical isolates. Comparison of polyprotein sequences showed that the treated-sewage strains differed from the patient's isolates by 9 and 11 amino acids. We conclude that the isolates of clinical and environmental origin differed in their pathogenic properties and showed genetic variation.

Impact of coxsackievirus-B4E2 combined with a single low dose of streptozotocin on pancreas of outbred mice: investigation of viral load, pathology and inflammation

Coxsackieviruses B (CV-B) belong to the EV-B species. CV-B and particularly CV-B4 are thought to be involved in the development of chronic diseases like type 1 diabetes (T1D). The mechanisms of the enteroviral pathogenesis of T1D are not well known, yet. The in vitro studies are rich with information but in vivo infection models are needed to investigate the impact of viruses onto organs. Our objective was to study the impact of CV-B4E2 combined with a single sub-diabetogenic dose of streptozotocin (STZ) on the pancreas of mice. The infection with CV-B4E2 of CD1 outbred mice treated with a sub-diabetogenic dose of STZ induced hyperglycemia and hypoinsulinemia. Along with the chemokine IP-10, viral RNA and infectious particles were detected in the pancreas. The pancreas of these animals was also marked with insulitis and other histological alterations. The model combining STZ and CV-B4E2 opens the door to new perspectives to better understand the interactions between virus and host, and the role of environmental factors capable, like STZ, to predispose the host to the diabetogenic effects of enteroviruses.

Pancreas of coxsackievirus-infected dams and their challenged pups: A complex issue

Enteroviral infections are frequent, often asymptomatic in humans and during gravidity.

The present study is an extension of our previous investigations where we had shown pancreatitis in challenged pups of CVB4-E2-infected dams. Present investigation describes the effect of gestational infection with this virus on the pancreas of both dams and their challenged pups. Gravid CD1 outbred mice were orally infected with CVB4-E2 virus at different gestation times. Pups were challenged orally with the same virus after 25 days of birth. Organs were collected at selected intervals postinfection (p.i.), and replicating virus and viral-RNA copies were analyzed. Additional readouts included histopathology and immunohistochemical (IHC) analysis for localization and identification of Ly6G+ cells (neutrophils), CD11b+ cells (macrophages), and viral protein in pancreatic tissue sections of the infected dams and their challenged pups. Our results show the presence of replicating virus in the pancreas of infected dams and their challenged pups, with inflammation leading to chronic necrotizing pancreatitis and atrophy of pancreatic acini of the dams and their offspring. IHC analysis of the infiltrating cells showed pronounced Ly6G+ neutrophils in dams only, whereas CD11b+ macrophages were present in tissues of both, the pups and the dams. Time of infection during gravidity as well as the p.i. intervals when mice were sacrificed influenced the pancreatic pathophysiology in both groups. We conclude that coxsackievirus infection during pregnancy is a risk factor for chronic affliction of the exocrine tissue and could affect endocrine pancreas in the mother and child.

Central nervous system infection following vertical transmission of Coxsackievirus B4 in mice

Coxsackie B viruses (CV-B) are important pathogens associated with several central nervous system (CNS) disorders. CV-B are mainly transmitted by the faecal-oral route, but there is also evidence for vertical transmission. The outcome of in utero CV-B infections on offspring's CNS is poorly explored. The aim of this study was to investigate vertical transmission of CV-B to the CNS. For this purpose, pregnant Swiss albino mice were intraperitoneally inoculated with CV-B4 E2 at gestational days 10G or 17G. Different CNS compartments were collected and analyzed for virus infection and histopathological changes. Using plaque assays, we demonstrated CV-B4 E2 vertical transmission to offspring's CNS. Viral RNA persisted in the CNS up to 60 days after birth, as evidenced by a sensitive semi-nested(sn) reverse transcripton(RT)-PCR method. This was despite infectious particles becoming undetectable at later time points. Persistence was associated with inflammatory lesions, lymphocyte infiltration and viral dsRNA detected by immunohistochemistry. Offspring born to dams mock- or virus-infected at day 17G were challenged by the same virus at day 21 after birth (-+ and ++ groups, respectively). Sn-RT-PCR and histology results compared between both ++ and -+ groups, show that in utero infection did not enhance CNS infection during challenge of the offspring with the same virus.