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Title: INDUCTION OF LYMPHOPENIA AND INHIBIITION OF T CELL FUNCTION DURING ACUTE INFECTION OF SWINE WITH FOOT AND MOUTH DISEASE VIRUS (FMDV)

Author
item Bautista Peck, Elida
item Ferman Ii, Geoffrey
item Golde, William

Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2002
Publication Date: 3/20/2003
Citation: BAUTISTA, E.M., FERMAN II, G.S., GOLDE, W.T. INDUCTION OF LYMPHOPENIA AND INHIBIITION OF T CELL FUNCTION DURING ACUTE INFECTION OF SWINE WITH FOOT AND MOUTH DISEASE VIRUS (FMDV). VETERINARY IMMUNOLOGY AND IMMUNOPATHOLOGY. Vol 92: 61-73, 2003.

Interpretive Summary: Published work analyzing the immune response of swine to infection with FMDV has concentrated on the production of antibody, and most notably, neutralizing antibody. Little is known about the effect of the virus on initiation of adaptive immune responses. We now show that infection of pigs with this virus leads to a clearly detectable interruption of ongoing immune responses to stimuli other than viral antigens. This effect delays the initiation of immune responses leading to production of antibody and presumably to production of cellular, T cell mediated, immunity. This is a common mechanism of viruses that cause acute infection allowing for spread of the infection through the herd.

Technical Abstract: Foot and Mouth Disease Virus (FMDV) is a picornavirus that causes acute vesicular disease of cloven-hoofed animals. This virus continues to be a threat to livestock worldwide with outbreaks causing severe economic losses. The present study shows an analysis of immune function during the acute phase of infection with FMDV in swine. In the first days of infection, a significant lymphopenia is observed that involves all T cell subsets, CD4+, CD8+, and CD4+/CD8+. This marked lymphopenia is not a result of infection of PBMC with the virus. Further, the responses of residual peripheral blood T cells to the antigen, chicken ovalbumin (cOVA) and the mitogen, Concanavalin A (Con A), are significantly reduced and occasionally eliminated. Animals usually resolve clinical signs of disease and develop antigen specific T cell responses to the virus and recover cOVA and Con A reactivity. This inhibition of T cell function likely plays an important role in viral pathogenesis, propagation and shedding of viral particles and may be targeted as a way of improving vaccine formulations.