The in vivo early transcriptional intestinal response to rotavirus infection in germ-free piglets

Th. Niewold, M.M. Hulst, H.H.D. Kerstens, A.A.C. de Wit, M.A. Smits, J. van der Meulen

Research output: Contribution to journalAbstractAcademic

Abstract

Rotaviruses are a major cause of severe diarrhea in young children worldwide. Most studies regarding the molecular mechanism underlying rotavirus induced disease focus on isolated enterocytes or enterocyte cell-lines. In vivo, mature enterocytes lining the intestinal epithelial layer are the primarily target cells for rotavirus replication, however, the different types of cells that compose the intestinal mucosal layer are probably also involved in anti-viral responses. The in vivo system is also much more complex for the presence of the intestinal microbiota. In order to separate rotavirus specific effects from microbiota associated effects, we used germ-free piglets. Piglets housed in sterile incubators were orally infected with virulent group A rotavirus at 3 weeks and whole mucosal gene expression vs uninfected controls was analyzed by cDNA microarray on 12 and 18 h post infection. IFN-¿ mRNA levels were 10¿50-fold higher in infected piglets. Microarray analysis identified 13 down-, and 19 up-regulated genes in infected piglets. Microarray data were validated by Northern blot analysis of nine selected genes. Regulated genes were functionally clustered in interferon-regulated genes, signal transduction and apoptosis genes, (enterocyte) metabolism and cell maintenance genes, and genes without a known function. Up-regulation was observed for several genes associated with the innate defense against viral infections, such as IFN-¿ induced guanylate binding protein 2 (GBP-2), a protein that was described earlier to effectively inhibit VSV and EMCV virus replication in vitro. Furthermore, a gene coding for an uncharacterized hypothetical protein was upregulated, carrying a phospholipase A2 inhibitor domain, suggesting involvement in (anti-) inflammatory pathways. We hypothesize that both these proteins participate in cellular mechanism(s) that provide the intestinal mucosa protection to the effects of rotavirus in the jejunum. Histological analysis showed a significant reduction of villus length due to rotavirus infection. It is concluded that differential expression reflects in part a shift in the relative contribution of certain cell types (e.g. loss of mature epithelial cells), and in another part represents induction by rotavirus itself. Finally, a most striking finding is the limited number of differentially expressed genes in intact mucosa in vivo compared to those obtained in in vitro enterocyte cultures. Dilution of expression may play a role in that, but our findings are probably also consistent with modulatory effects of the heterogenous cell population in vivo
Original languageEnglish
Pages (from-to)262-263
JournalVeterinary Immunology and Immunopathology
Volume128
Issue number1-3
DOIs
Publication statusPublished - 2009

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