Latent Cytomegalovirus Infection May Exacerbate IBS

Latent cytomegalovirus (CMV) infection can alter mucosal immunity, thus potentially increasing the "tendency of CMV-infected hosts to develop colitis, according to study results recently published in the American Journal of Pathology.

Researchers at Emory University, led by Dr. Andrew T. Gewirtz in the department of pathology, examined the impact of murine CMV (MCMV) on wild-type mice and L-10-/- mice that were "highly prone" to developing colitis. Mice that were given MCMV in an acute or latent state developed signs of viral infections-malaise and weight loss-and "had MCMV loads that were readily detected in numerous organs including the intestine," according to the researchers.

Though these types of MCMV infection did not induce colitis in either category of mice, acute or latent MCMV infection "exacerbated the severity of colitis induced by dextran sodium sulfate (DSS)," occurring without viral reactivation.

Further, results show that the initial infection that resulted from MCMV also resulted in "lasting elevation of antibodies to commensal bacterial antigens." According to the researchers, this could mean that "MCMV infection may have potentiated colitis via priming of the intestinal immune response to gut microbiota," and that underlying MCMV infections could then change mucosal immunity, which may lead to an increased tendency in these patients with cytomegalovirus infections to develop colitis.

The next step for the researchers is to use retrospective serologic analysis to confirm that latent CMV infections do, in fact, lead to exacerbations of IBD. According to Gewirtz, "[Although vaccines to CMV are not yet available, these results suggest that] it may be advisable to consider vaccinating healthy young populations against this virus, even in the absence of any risk factors that such individuals are ever likely to be in an immunocompromised state."