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Immunoparasitology

31 Oct 2007   Unravelling the secrets of parasites

Unravelling the secrets of parasites

Finding new  tools that help farmers sustainably manage internal and external parasites is a major focus for researchers at the Hopkirk.

One such parasite, Trichostrongylus colubriformis, is microscopic in size but has a substantial impact on the New Zealand sheep industry.

More commonly known as the Hair Worm, T. colubriformis is a parasite nematode that lives in the small intestine of sheep. It is just one of several species of nematodes that live in the gut of sheep and other livestock, wasting up to 30% of an animal's available protein and energy and costing New Zealand farmers millions in lost production annually.

About one-third of sheep production in New Zealand would be lost without any drench-based control of nematode infections. The problem, says Professor Tony Pernthaner, is the parasites have developed strategies to protect themselves from the host and a variety of drugs.

At the same time, consumers are demanding more stringent guarantees that animal products are free of chemical residues. There is an increasingly urgent need for alternative parasite control practices that provide a clean, non-toxic solution.

AgResearch scientists are working on this at the Hopkirk's immunoparasitology laboratories.

Boosting the host's immune system with a vaccine is one approach that has shown potential. A team under the leadership of Dr Gavin Harrison has made a significant breakthrough by identifying a protective worm antigen. Further research, commissioned by Orico, is targeted at producing an effective vaccine.

"The aim is to produce a vaccine which induces a strong antibody response against the worm, thereby enabling sheep to resist infection with no subsequent loss of productivity," says Gavin.

An important step has been the development of an experimental model that enables researchers to make discoveries at the location where parasites directly interact with the immune system.

Another project, led by Richard Shaw and with funding from OVITA and Catapult, is aimed at developing a new diagnostic test that identifies lambs with the ability to produce strong protective immune responses to gut nematodes. The new test is currently being evaluated in a number of field trials on AgResearch and commercial farms.

Research in the immunoparasitology laboratories also focuses on parasites that live on the outside of sheep.

"Lice live on the skin surface and cause damage to pelts and wool, while blowfly strike can lead to substantial production losses and deaths," says senior scientist Dr Alex Pfeffer.

For more information: tony.pernthaner@agresearch.co.nz.