Parasitology
Identification
of vaccine candidates for Teladorsagia circumcincta
Matthews, JB
Teladorsagia circumcincta is a nematode parasite (roundworm)
that is a major cause of economic loss and suffering in sheep. Currently,
these parasites are controlled using repeated treatments with anti-parasitic
drugs (anthelmintics). Resistance to these anthelmintics is increasing,
so alternative methods of control must be sought. One major alternative
to chemotherapy is vaccination.
Despite the importance of this parasite, little research has been
published with regard to the investigation of vaccine candidates.
Excretory/secretory (ES) products, released by parasites in their
host, have been identified as important sources of protective antigens
in other worms. The protective capacity of ES components has not been
assessed for T. circumcincta. Previous studies, which have
focused on the immunology of this infection, showed that local antibody
responses in the stomach wall are important in preventing parasites
reinfecting immune sheep.
The objective of this project is to use antibody responses as probes
to identify proteins recognized by immune sheep during the critical
early stages of infection. Local antibody responses are being compared
in immune versus non-immune sheep and antigens that are recognized
solely by immune sheep are being analyzed using state-of-the-art mass
spectrometry techniques (in collaboration with the Protein Function
Group, University of Liverpool) to provide information on their protein
sequences. Using these sequences to search public databases, scientists
at Moredun are identifying the nature and possible function of these
parasite-released antigens. The availability of the sequences will
also facilitate the isolation of the genes that encode these molecules.
In future, isolated genes will be used for the large scale production
of these proteins for use in vaccine trials.