Immunosuppressive effects of bovine viral pathogens

A review

Abstract

Epidemiologic evidence that viral immunosuppression leads to secondary bacterial pneumonia is established, yet our understanding of the immunosuppressive viral effects that cause this is incomplete. Similar relationships are likely to exist in other disease complexes. This paper reviewed many of the effects of different bovine viral pathogens on the bovine host defenses such as epithelial barriers and ciliary function, macrophages, polymorphonuclear neutrophils, and lymphocytes. For each virus there are voids in our understanding. There are many viruses such as bovine adenovirus, bovine enterovirus, bovine empheral fever virus, bovine papilloma virus, bovine papular stomatitis virus, and bovine parvovirus for which no information is available. The relevance of current in vitro tests to in vivo function is, in many cases, speculative. There are many aspects of the host immune system, such as cell-mediated immunity, for which tests are insufficient or entirely lacking. Continued work is needed to develop means to examine the immunologic interactions of cattle and their viral pathogens. There is currently a great deal of research examining the effects of various immunomodulators in cattle. In order to effectively use these immunomodulators the nature of the immunosuppression that viruses cause must be further characterized.