March 23, 2021

Scientists using gene editing tool in development of ASF vaccine


Scientists at the International Livestock Research Institute (ILRI) are employing CRISPR Cas9 editing and synthetic biology to modify the African swine fever virus (ASFV) genome in order to attenuate the virus for a live vaccine to help reduce deaths from the disease.


Up to 10 vaccine candidates have been lined up for tests, in a project that commenced in 2016.


"This is the first test based on a genome to be conducted on genotype IX, which is prevalent in Eastern and Central Africa," Lucilla Steinaa, leading scientist in the vaccine research against African swine fever at ILRI, told the Cornell Alliance for Science. The genetic characterisation of all the ASF virus isolates known so far has demonstrated 23 geographically related genotypes with numerous subgroups, according to the Food and Agriculture Organization (FAO).


"There are seven to 10 candidates, on a variety of stages," Steinaa said. "We have just started the lab experiment, a controlled animal experiment, which I estimate may run until the end of 2022 or thereabouts. By then, we hope to have found a candidate vaccine that can be produced."


ASF is present in 26 African countries, Steinaa said, as well as in parts of Asia and Europe. An effective vaccine could be a breakthrough for pig farmers across the globe.


"The only reason it's not yet a catastrophe here is that the pig production is not one of the biggest commodities in Africa," Steinaa said. "But it's coming on - fast. Africa is doing a lot more pig rearing year by year. It would be a disaster if they had a big production like, say, Europe.


"Right now, it is very difficult for the smallholder farmers because of ASF. If they encounter ASF, they are discouraged from starting again, because it eradicates the whole herd. A vaccine would obviously prevent that. If it can be availed at a price that is affordable, then this would be the easiest way to maintain production."


- Cornell Alliance for Science