Molecular epidemiology of avian pneumovirus (APV) in United States

This thesis research has been presented in several individual studies on Avian Pnemovirus (APV) infection in turkeys.; An RT-PCR assay was developed for the specific detection of APV infection in turkeys. Primers derived from the Matrix gene of APV were found to be specific and sensitive for APV.; Comparison of the nucleotide and amino acid sequences of nucleoprotein, phosphoprotein, matrix, fusion and second matrix genes of 15 US APV strains isolated between 1996 and 1999 revealed 81% to 95% as identity among all the US isolates. In contrast, genes from US viruses had 52% to 78% predicted as identity with European subgroup A or B viruses, confirming that US viruses belong to a separate subgroup.; Susceptibility of broiler chickens to APV turkey origin was examined. Birds from APV-inoculated groups exhibited clinical signs and developed antibodies for APV. APV was re-isolated from turbinate samples. Tissues from APV-inoculated group were positive for APV by PCR.; The infectivity of one isolate of APV from turkeys to ducks was studied. Obvious clinical signs were not observed in ducks inoculated with APV. Tissues were examined by RT-PCR and virus isolation. Tissue samples were positive up to 21 days. Virus was isolated from the nasal turbinates of oculonasally-infected birds. Serum samples at 15 and 21 days PI were positive.; APV was isolated from sentinel ducks placed near turkey farms. The APV duck isolate showed 97% to 99% amino acid identity with APV isolates from turkeys in neighboring farms. The results suggest that ducks may be a source of APV infection.; APV was detected from wild birds and they had over 96% predicted amino acid identity with turkey isolates suggesting that wild birds may be involved in spreading APV infection.; Airborne transmission of APV was examined. Airborne contact control birds placed in close proximity to APV infected birds became positive to APV infection.; Turkey poults from some APV-infected breeder flocks showed evidence of APV infection. This suggested a neonatal transmission of APV infection.