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Title: Mucosal vaccination with formalin-inactivated avian metapneumovirus Subtype C reduces clinical signs of disease but enhances local pathology of turkeys following challenge

Author
item Kapczynski, Darrell
item PERKINS, LAURA - FORMER USDA, ARS, SEPRL
item SELLERS, HOLLY - UNIVERSITY OF GEORGIA

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2007
Publication Date: 3/1/2008
Citation: Kapczynski, D.R., Perkins, L.L., Sellers, H.S. 2008. Mucosal vaccination with formalin-inactivated avian metapneumovirus Subtype C reduces clinical signs of disease but enhances local pathology of turkeys following challenge. Avian Diseases. 52:28-33.

Interpretive Summary: Avian metapneumovirus (aMPV) is the causative agent of turkey rhinotracheitis (TRT) which results in primarily a respiratory disease. Since there are no treatments available for aMPV infection, efforts to prevent TRT in the U.S. have focused on flock management practices, controlled exposure and vaccine development. The objectives of this study were to determine if mucosal vaccination with inactivated aMPV protects turkeys from aMPV challenge. The results indicate mucosal vaccination with inactivated aMPV does not increase protection from viral infection and can increase histopathologic lesion severity following virus infection.

Technical Abstract: Studies were performed to determine if mucosal vaccination with inactivated avian metapneumovirus (aMPV) subtype C protected turkey poults from clinical disease and virus replication following mucosal challenge. Although decreases in clinical disease were observed in vaccinated groups, the vaccine failed to inhibit virus replication in the trachea of 96 % of vaccinated birds and identification of viral genome in lung tissue was only observed in vaccinated groups. Histopathologically, enhancement of pulmonary lesions following virus challenge was associated with birds receiving the inactivated aMPV vaccine compared to unvaccinated birds. As determined by an enzyme-linked immunosorbent assay (ELISA), all virus challenged groups increased serum immunoglobulin (Ig) G and IgA antibody production against the virus following challenge, however, the unvaccinated group displayed the highest increases in virus neutralizing antibody. On the basis of these results it is concluded that intranasal vaccination with inactivated aMPV does not induce protective immunity and can result in increased severity of histopathologic lesions.