Location: Exotic & Emerging Avian Viral Diseases Research
Project Number: 6040-32000-082-006-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jul 1, 2021
End Date: Jun 30, 2026
Objective:
1. Identify the emergence of new virulent Newcastle disease virus (vNDV) strains.
1A. Develop rapid identification assays for variant virulent Newcastle disease virus strains.
1B. Conduct prevalence studies in poultry from countries where virulent Newcastle disease virus strains are endemic to determine the presence of variant and emerging viruses in Newcastle disease virus -vaccinated poultry and the prevalence of Newcastle disease virus (NDV) in wild birds.
2. Develop predictive models for risk assessment of virus evolution.
2A. Develop in vivo and ex vivo systems to understand the mechanisms of Newcastle disease virus evolution and adaptation.
3. Develop improved NDV vaccine platforms.
3A. Determine and compare mucosal, cell, and early immune responses associated with protection elicited by available Newcastle disease virus vaccines to predict protection conferred by vaccination.
Approach:
Improved diagnostic testing using next generation sequencing, specifically the MinION technology, and combining them with portable equipment that can be set up in the field to conduct highly specific diagnosis of Newcastle disease virus (NDV). We have developed protocols for rapid processing, screening and sequencing from clinical samples from animals infected with influenza A virus (IAV). We plan to transfer and adapt these methods developed for IAV to NDV.
In collaboration with other research groups that monitor wild birds for viral diseases in the United States and abroad, we will collect field samples, as well as genetic material. We will obtain Newcastle disease virus RNA from outbreaks of NDV in South and Central American. All detected viruses will be sequenced using Next Generation Sequencing (NGS). Information from this objective will contribute to expanding genetic databases and better understanding of the epidemiology, ecology and evolution of NDV.
NDV adapts to different host species, some NDV lineages are associated with specific hosts, and these lineages still have the capacity to spill over into non-host species. Spill-over from wild bird poses a risk for poultry flocks. To better understand how NDV adapts to specific hosts and to assess the risk host-adapted strains pose to other hosts, we will adapt low virulence avian paramyxovirus from ducks to chickens by serial passage in embryonated specific pathogen free chicken eggs. Adaption will be assessed by virus load in the allantoic fluid. The whole genome of the adapted viruses and selected passages will be determined.
The role differences in the hemagglutinin neuraminidase (HN) protein play in host and tissue specificity, and ultimately pathogenicity, has not been directly explored. To explore the role of changes in the HN protein observed during passage of NDV isolates in embryonated eggs of different species, we plan to develop an in vitro assay for attachment to various chicken tissues based on protein histochemistry. Recombinant, soluble, tetrameric HN proteins produced in a eukaryotic expression system will be generated and used to bind to various chicken tissues, primarily respiratory and enteric tissues known to provide epithelial surfaces through which the virus initially infects the host.
The overall aim is to establish immunological methods to predict protection conferred by vaccination against virulent NDV, specifically by enteric replicating strains, by strains of low virulence genotype X and by combinations of these with traditionally used genotype II strains. We will characterize the different components of the complex immune response to NDV and verify which components provide reliable information on how well protected vaccinated chickens are in the event of having to confront virulent challenge. We will also investigate the role maternal antibodies play in the efficacy of vaccines against NDV.
