Quick Dips

FootRot Vaccine

Huitong Zhou, PhD candidate at Lincoln University, is sorting out exactly what strains of bacteria are infecting sheep in New Zealand with footrot.

Footrot control measures have not been entirely effective because people don't know exactly which strains of the bacterium are present here, making targeted control impossible.

Zhou works in Dr Jonathan Hickford's team in the Animal and Food Sciences Division where a number of researchers are working on different aspects of this problem. His work involves taking samples from infected sheep and goats, separating out the bacterial DNA and identifying key features to see what strains are present.

"The results showed a level of variation that was not expected," says Zhou. "86% of footrot samples had two or more strains of the bacterium (Dichelobacter nodosus) with at least 15 strains being present in New Zealand and 11 of these strains not being identified before."

"This is exciting because it means there is now the possibility of being able to design vaccines in the future that target particular strains specifically."

Previously it has been thought that there were strains of the bacterium that ranged from benign to very virulent. While this may still be true, the discovery that there are multiple strains on a single sheep or goat hoof makes this classification more complex. "How do the strains interact? Does one or all of them cause the disease?" This needs to be worked on.

"Current vaccines, while good, do not contain all the strains present in New Zealand and this is why sometimes they do not work as well as they could. Until now we did not know why."