Summary

Caprine arthritis-encephalitis (CAE) virus is an important cause of disease in goats and can have a profound impact on dairy goat production. This project will develop new strategies to carry out testing of goats to support disease control programs, herd monitoring and health certification. These will include the application of highly sensitive and specific tests for the detection of antibodies and viral nucleic acid (DNA/RNA) in either blood or milk samples. These tests will be the key tools to be employed to support new test strategies. The use of milk samples for testing individual animals will also simplify sample collection. Based on the level of reactivity in a bulk milk sample, it may be possible to broadly estimate the proportion of infected animals in a herd. The application of new nucleic acid detection tests as an alternative to antibody detection will also provide an option to test samples of blood or milk from individual animals (either singly or in pools) or to screen tank milk and allow detection at a very early stage of infection, before an animal has produced antibodies. This would then identify an infected animal at an earlier time and, by early segregation or culling, limit further spread of the virus to uninfected animals. Period testing of bulk milk samples for antibodies will allow low cost monitoring of the status of a herd and would be an efficient method to survey the status of the Australian dairy goat population.

Program

New and Emerging Animal Industries

Research Organisation

(DPIE) The Crown in right of the State of NSW acting through the DPI within the Department of Planning, Industry and Environment

Objective Summary

The objectives of this project are:
a) for the detection of antibodies to CAE virus:
– to evaluate the analytical sensitivity of a range of existing enzyme linked immunosorbent assays (ELISAs) used for the detection of antibodies to CAE virus to determine the levels of antibodies that can be detected;
– to investigate the potential to increase the sensitivity of ELISAs for the detection of antibodies;
– to compare the ability to detect antibodies to CAE virus in milk and serum from goats of different ages and stages of lactation;
– to determine the limits of detection of a single infected sample in pools of individual samples of serum or milk;
– to determine the limit for the detection of CAE infected animals based on testing of tank milk
b) for the detection of DNA and RNA from CAE virus:
– develop a real time PCR assay for the detection of Australian strains of CAE virus;
– to compare the ability to detect nucleic acids of CAEV in milk and serum from goats of different ages and stages of lactation;
– to determine the limits of detection of an infected animal in pools of individual samples of serum or milk;
– to determine the limit for the detection of CAE infected animals based on testing of tank milk
– to compare testing for nucleic acid and antibodies in newly infected animals;
c) to investigate the practical application of a suite of new diagnostic assays in a pilot CAE control program.