Philip J. Griebel, DVM, Vaccine and Infectious Disease Organization, University of Saskatchewan, says a combination of psychological and nutritional stressors associated with abrupt weaning significantly enhanced fatal BRD. These stressors appeared to have a direct effect on the amplitude of antiviral responses. Surprisingly, these stressors enhanced, rather than inhibited, innate immune responses to BHV-1 infection.

At the 2009 AABP, Griebel said functional genomic analyses suggest antiviral responses were linked to an increased capacity to respond to Gram-negative bacterial respiratory infections through increased expression of TLR4 and CD14.

These analyses provide evidence for a novel mechanism by which stress may enhance the risk of fatal BRD. In addition, modulation of TLR expression during viral infection may be of relevance for both Gram-negative and Gram-positive bacterial infections. These molecular analyses should facilitate the identification of appropriate therapeutic targets for the prevention or treatment of stress-enhanced BRD infections.