Professor Tim Mahony, from the University of Queensland, said tick infestations cost northern beef enterprises more than $160 million in lost production annually, and the development of an annual – or even six‑monthly – vaccine could return huge economic and animal welfare benefits.
An additional benefit is producers could utilise more Bos taurus genetics rather than having to rely on the more tick‑tolerant Bos indicus genotypes.
“There was a tick vaccine brought to the market 30 years ago, however, the major hurdle for extensive northern beef operations was that it required multiple doses – two to three initially to create an immune response and then boosters every three to four months,” Mr Mahoney said.
“While this worked well for Queensland’s dairy industry, it was impractical for extensive production systems. For this project, we wanted to develop a vaccine that would protect animals for up to a year – or even six months from one dose so they had an effective defence during high risk periods (i.e. a warm wet season).”
Mr Mahoney, collaborators from Swinburne University of Technology, and his team working at UQ’s Queensland Animal Science Precinct, formulated a range of single‑dose polymer depot systems that were tested on sheep.
Several of these delivered strong, sustained immune responses for up to a year.
The vaccine formulation was further optimised for testing in Bos taurus cattle – because of their susceptibility to cattle ticks and ability to show a clear immune response – in controlled conditions.
“We vaccinated 40 animals, divided into four different groups. Each of these received different amounts of the BM86 antigen (found to be effective in the earlier vaccine).
“Our single‑dose responses were actually higher in cattle than the responses to a conventional multi‑dose vaccine.
“We believe when the vaccine is injected into animals, the animals get a primary dose and, over time, the polymer formulation starts to break down, creating a continual release process.”
Mr Mahony said that while each animal reacts slightly differently to the vaccine, generally levels of immunity peak at 28 days post‑injection, then drop and stabilise. After about three months, immunity falls further before hitting a trough around four months.
“If they’re still protected at this stage, the animals will be protected throughout the 12 months as, after that, the immune response starts to increase again due to the way the vaccine is formulated with polymers. As it breaks down, it creates its own booster doses.”
What’s next?
The team is now collecting the protection data before moving to talking to veterinary pharmaceutical companies about commercialising a vaccine.
“We’d like to see a vaccine co‑funded by the pharmaceutical industry and see it developed to registration,” he said.
“We see a vaccine as a key element of a successful integrated pest management program, as continued use of chemicals increases the risk of pathogens becoming tolerant to them.
“Producers do need to keep in mind that even if this vaccine is successfully commercialised, it’ll need to be used with other control mechanisms, particularly if a herd is heavily infested.”
Mr Mahoney said if cattle were not being sold in the near future, producers could treat them to get rid of heavy tick infestations and then boost the animals’ immunity to control future infestations with the vaccine.
“Long term, the integrated use of multiple control methods should keep lower levels of pathogens in check,” he said.
