Dynamics of ILT spread and role of dust in epidemiology, diagnostics and control

Summary

ILTV is shed in faeces and is detectable at high levels in poultry dust both experimentally and in field samples using qPCR (Roy et al., 2015; 2016). ILTV infection is via the respiratory route and transmission in dust is strongly implicated in its epidemiology (DufourZavala, 2008). This project will determine whether faecally shed ILTV is infective and what its likely epidemiological significance is. We assess the influence of temperature, humidity and sunlight on virus survival in that material using a cell culture assay validated by animal challenge. We have shown that ILTV in dust reflects ILTV shedding rate, and is readily detectable at high levels in field dust samples from vaccinated broiler flocks. We will therefore undertake longitudinal monitoring of vaccinated broiler, breeder and layer flocks (if supported by AECL) to determine if differences in dust levels may usefully indicate differences in shedding in response to stressors or differences in replication rate and transmission potential between vaccines or wildtype genotypes. We will also work with unvaccinated flocks to assess the potential of dust tests as a measure of cleanout success and a means of population level surveillance for ILTV. The project has industry support and UNE will bear the bulk of the salary costs by contributing 40% of a prospective postdoctoral fellow, Dr Priscilla Gerber to the project. We are aware of the Peter Groves ILT proposal and feel that our work is complementary to the work proposed in that project and would happily collaborate with him if required to.

Program

Chicken Meat

Research Organisation

University of New England

Objective Summary

The broad objective of this project is to improve our understanding and management of ILT in Australia by addressing the following specific research questions: a) Is ILTV in faeces infective and does it comprise the bulk of detectable ILTV in dust? b) What is the persistence of infectivity in dust and what factors influence this? c) What are the longitudinal profiles of ILTV in dust in vaccinated broilers, broiler breeders and layers and what factors are associated with spiking in levels (eg. pickup, coming into lay, other stressors)? d) Are differences in ILTV profiles in dust associated with differences in virulence and transmissibility between vaccine strains, and between wildtype strains of different groups? e) Is use of dust testing useful for testing the efficacy of cleanout procedures and as a method for regional surveillance for ILTV in low prevalence areas (eg . Tamworth)? The expected outcomes from addressing these questions are Clear determination of whether the current transmission model for ILT (via respiratory aerosols) requires modification to account for aerosolised faecally shed virus. Determination of extent of ILTV survival in dust (irrespective of respiratory or faecal origin) and factors influencing it (eg. temperature, moisture and light). Determination of whether monitoring of ILTV levels in dust in vaccinated and/or unvaccinated flocks is practicable and useful as either a research or a management tool.

Project Code

PRJ-010639

Project Stage

Current

Project Start Date

Wednesday, May 31, 2017

Project Completion Date

Friday, January 21, 2022

Journal Articles From Project

Not Available

National Priority

An environmentally sustainable Australia

National Priority

Adoption of R&D

National Priority

CME-Improve chicken meat production through the whole supply chain

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