Project Number: 6612-32000-049-01
Project Type: Specific Cooperative Agreement

Start Date: Sep 27, 2006
End Date: Aug 31, 2009

Objective:
Characterize and compare the pathology of infections with different Newcastle disease viruses and recombinants to define NDV virulence mechanisms.

Approach:
Pathogenesis studies will be conducted in SEPRL SPF leghorn chickens utilizing a previously developed model to characterize the clinical form of any resultant disease and tissue tropism of the infection. Isolates to be tested will include domestic and exotic field isolates with a diverse history based on species of origin, sequence analysis, and virulence testing and those viruses generated by reverse genetics at SEPRL. In brief the protocol is to inoculate 4-wk-old chickens by eye drop, a natural route of infection in contrast to pathogenicity testing done by systemic inoculation. Clinical observations will be recorded over a 14 day period and 2 birds will be euthanized for sampling at 2, 5, 10, and 14 days post inoculation. Birds dying from infection will be included in sampling. Tissues will be collected into 10% formalin for processing, sectioning and staining for histopathology, in situ hybridization (ISH) with a NDV matrix gene riboprobe to detect NDV mRNA, and immunohistochemistry (IHC) with an NDV anti-peptide serum to detect expressed NDV nucleoprotein (N). A riboprobe to detect N mRNA may also be used. Seroconversion detected in blood samples collected on days 10 and 14 and/or virus isolated from oral and cloacal swabs collected at each sampling will confirm infection in sampled birds that display no clinical signs of disease. Selected tissues may also be processed separately for virus isolation. Infections of other birds species may also be evaluated similarly if there appears to be a host predilection for some isolates.