Teladorsagia circumcincta is an important parasitic nematode of domestic small ruminants. Drug resistance in this species is common so alternative methods of control are required. As animals develop immunity to T. circumcincta, vaccination is a valid option. Little is known about the
antigens that play a role in stimulating immunity at this host/parasite interface. As responses generated between 1 and 5 dpi are known to affect development of these nematodes in their gastric niche, we focused on
proteins released during the early stages of
infection. To identify molecules potentially involved in immunity, we undertook a proteomics analysis of
proteins released from larvae harvested at 1-, 3- and 5-days post-
infection (dpi). This analysis produced
peptide sequence data that was used to search information available in T. circumcincta expressed sequence tag (EST) databases and enabled identification of a number of excretory/secretory (ES)
proteins. Immunoblots were performed to assess the relative molecular weight of ES
antigens that were targets of local
IgA responses in mucus from sheep rendered immune to
infection. ELISA was performed to assess
antigen-specific mucus
IgA levels in individual sheep. These experiments provided preliminary evidence that the
proteins identified in the larval secretome were subject to these antibody responses.