PROGRESS TOWARD
THE DEVELOPMENT OF SEROLOGICAL TESTS FOR DIAGNOSIS
OF COCCIDIOSIS IN CHICKENS
J.B.Molloy1, C. Constantinoiu2, G. Richards3,
J-M.L. Hewitson1, A.G. Bruyeres1, G. Coleman2 and
W.K. Jorgensen1
1Emerging Technologies, Department of
Primary Industries and Fisheries.
Yeerongpilly, Qld. 2School of Veterinary Science,
University
of Queensland, St. Lucia, Qld.
3Eimeria Pty Ltd, Melbourne, Australia
(medichick@ava.com.au)
Vaccines
comprising attenuated strains of each of the seven
species of Eimeria that cause coccidiosis in Australian
chickens have been shown to be effective in preventing
acute disease. Improved diagnostic tests are now required
for monitoring vaccine efficacy, epidemiological studies
and for the implementation of effective control strategies.
As a first step toward developing species-specific
serological tests we have investigated the chicken
antibody response to infection. Birds infected with
the E. tenella vaccine strain produced parasite-specific
antibodies between 16 and 30 days post-infection.
Experiments with parasite antigens prepared from heavily
parasitized gut linings harvested from birds sacrificed
at varying times post-infection suggested that the
antibodies were directed exclusively against gametocyte
antigens. Immunostaining infected gut sections confirmed
this observation. Merozoites, gametocytes and oocysts
were all present in the sections but antibodies bound
only to gametocytes. Monoclonal antibodies that recognize
E. tenella gametocytes epitopes have been developed
and characterized by immunofluorescent and immunoperoxidase
staining of parasitized tissue and purified gametocytes
and in Western blots. Implications for the development
and application of species-specific serological tests
for coccidiosis are discussed.