Unveiling the secrets of tick resistance

Research to improve the resistance of Australia’s northern beef herds to cattle ticks received a boost recently with the discovery that tropically-adapted cattle breeds have a different immune response to tick infestation than more susceptible European breeds.

CSIRO Livestock Industries scientist, Dr Ian Sutherland, says that while research has traditionally focused on the genetics of tick resistance, little was known about the underlying immune mechanisms involved.

Now, however, Dr Sutherland’s parasitology team in Rockhampton has found that tropically-adapted (Bos indicus) cattle, such as Brahmans, which are known for their high tolerance to cattle ticks (Boophilus microplus), switch off parts of their immune system in response to tick infestation.

“We hypothesise that this response may prevent some of the more damaging side-effects of the immune response that much less resistant European (Bos taurus) breeds, such as Herefords, experience,” Dr Sutherland says.

’It could also be that by shutting down one part of the immune system, another part is up-regulated.’

While the exact nature of the immune response is yet to be deduced, Dr Sutherland says the preliminary results demonstrate observable differences between the two types of cattle and open the door to research aimed at increasing Bos taurus resistance to ticks by modulating the host immune response.

To help characterize the differences in immunity further, the team is now comparing the response to tick strikes of cross-bred cattle with varying degrees of Bos indicus content.

’This research should give us an idea of how much Bos indicus content is needed for a more favourable immune response,’ Dr Sutherland says.

More information:

Dr Ian Sutherland, CSIRO Livestock Industries, 07 4923 8187

Media assistance:

Veronica Toohey, CSIRO Livestock Industries, 07 3214 2960