A treatment to protect pigs from the deadly African swine fever (ASF) virus has moved a step closer after scientists in Vietnam claimed to have an effective vaccine ready for commercial use.
The vaccine has been under development since 2019 in a collaboration between Avac Vietnam Company (AVAC Co) and the US Department of Agriculture’s (USDA) Agricultural Research Service.
Vietnam took a leading role in the research after it lost six million pigs to the disease – 20% of its national herd – in 2019.
The country is now gearing up for production and intends to become the first country to manufacture and export the vaccine, Vietnam’s deputy agriculture minister Phung Duc Tien announced.
Mr Phung described the vaccine as a “milestone” in the fight against the disease, which has killed about 500 million pigs worldwide, either directly, as a result of infection, or through culling to contain its spread, according to news agency Reuters.
Mortality rates can reach 100% and the disease has spread rapidly westwards after devastating outbreaks in Asia during 2019 through continental Europe to the German-French border.
The closeness of the most recent cases to the UK makes the prospect of an effective vaccine a significant breakthrough for British producers.
The vaccine uses a weakened or attenuated live virus strain to promote an immune response in pigs and has been declared safe for use by the USDA.
Trials conducted in the US and Vietnam have shown a 95% efficacy in protecting pigs from the disease.
One dose of the product provides immunity for about six months, before any booster jabs might be considered for breeding stock.
The trials were carried out in pigs on four farms with herd sizes of 300 to 20,000 head.
Pigs were vaccinated and infected with a high level of the virus, with control groups infected and left without a treatment.
The pigs treated with AVAC ASF LIVE showed only mild clinical signs, such as a fever and appetite loss, before recovering to normal.
Only one vaccinated pig succumbed to the disease, while all of the animals in the unvaccinated control group quickly died.
UK vaccine in development
A vaccine is also under development in the UK at the The Pirbright Institute in Surrey, but no date for any possible commercial release has been suggested.
Linda Dixon, head of Pirbright’s African Swine Fever Virus Group, said vaccine research was continuing intensively on both gene-deleted modified live vaccines and subunit vaccines.
Candidate live attenuated vaccines, similar to those developed in Vietnam, have been tested for safety and efficacy at several doses and further safety tests are ongoing, Dr Dixon said.
The subunit vaccines are at the stage of identifying pools of protective antigens, she added.