Improved protection of cattle against anaplasmosis in tick-infested areas of Australia
The Improved protection of cattle against anaplasmosis in tick-infested areas of Australia project compared experimental chilled and frozen vaccines with the current registered chilled and frozen trivalent tick fever vaccine.
A. marginale causes significant economic loss to the cattle industries and causes Anaplasmosis. The current vaccine for anaplasma spp uses the Anaplasma centrale strain, and only provides partial and variable immunity against the Australian isolates of A. marginale. Furthermore, A. centrale is not completely benign and can cause anaemia, and also rapidly loses potency.
An isolate of A. marginale (Dawn strain) indicated to be as mild as A. centrale and provide almost total protection against Australian field isolates of A. marginale. Given the mild nature of Dawn strain, the advantages it offered in terms of better protection of cattle against anaplasmosis and the potential to extend the shelf life.
The intention of this project was to evaluate this strain for registration; to clarify tick transmissibility; and to find a molecular marker that would allow differentiation of Dawn strain A. marginale in the vaccine from A. marginale field isolates.
Trial steers were inoculated with three different batches of both experimental chilled and frozen trivalent vaccines. Safety, virulence, infectivity, and efficacy were compared to the current registered vaccine. Whilst there was no difference in safety and virulence of the experimental vaccines, infectivity of the A. marginale was poor in some of the vaccines, and unexplained lack of virulence makes interpretation of some aspects of the trial difficult. Dawn strain A. marginale was also shown again to be poorly tick transmissible. It will not be possible to register Dawn strain A. marginale as a vaccine strain without further evaluation.
When: 13 June 2011 to 28 April 2014
Contact: Peter Rolls
Collaborator: Department of Agriculture and Fisheries
For more information, please read the final report summary and download the final report (B.AHE.0060) (PDF, 236.0 KB) from Meat & Livestock Australia.