Jimenez de Cisneros, J.P., Stear, M.J., Mair, C., Singleton, D., Stefan, T., Stear, A., Marion, G. and Matthews, L.
Journal of the Royal Society Interface 11, 20140416. Royal Society Publshing.
Royal Society Publshing
host-parasite model, approximate Bayesian computation, helminth infections, selective breeding, sheep, nematodes
||Gastrointestinal nematodes are a global cause of disease and death in humans,
wildlife and livestock. Livestock infection has historically been controlled with
anthelmintic drugs, but the development of resistance means that alternative
controls are needed. The most promising alternatives are vaccination, nutritional
supplementation and selective breeding, all of which act by enhancing
the immune response. Currently, control planning is hampered by reliance
on the faecal egg count (FEC), which suffers from low accuracy and a nonlinear
and indirect relationship with infection intensity and host immune responses.
We address this gap by using extensive parasitological, immunological and
genetic data on the sheep-Teladorsagia circumcincta interaction to create an
immunologically explicit model of infection dynamics in a sheep flock that
links host genetic variation with variation in the two key immune responses
to predict the observed parasitological measures. Using our model, we show
that the immune responses are highly heritable and by comparing selective
breeding based on low FECs versus high plasma IgA responses, we show
that the immune markers are a much improved measure of host resistance.
In summary, we have created a model of host-parasite infections that explicitly
captures the development of the adaptive immune response and show
that by integrating genetic, immunological and parasitological understanding
we can identify new immune-based markers for diagnosis and control.