Porcine Reproductive and Respiratory Syndrome (PRRS) could be eliminated at a national level within three to six years using a combination of gene editing and vaccination, according to a study by scientists in New Zealand and Scotland.
Recent years have seen significant genetic breakthroughs in PRRS research, culminating in the development of gene-edited pigs carrying resistance to the disease.
Using a modelling approach drawing from numerous sources, the authors of the latest work concluded that while the use of such pigs alone could result in national elimination of the disease, the vast majority of herds would need to contain such pigs, and within these herds, very high percentages of the animals would need to be of the resistant type.
This scenario is not realistic, they suggested, but by using a more pragmatic scenario of introducing PRRS-resistant stock in combination with mass vaccination, the percentage of herds containing gene-edited animals, and the amount per herd, could be greatly reduced.
A strategy to work without all farmers
Vaccination has been used widely as a tool against PRRS, albeit with mixed results. Much of the success of the dual approach depends on the effectiveness of vaccines available, they said, with the best case scenario for elimination when genetically resistant pigs are distributed optimally across herds alongside mass vaccination using a vaccine which has over 70% effectiveness. This approach could achieve eradication in less than three years, they said.
A dual strategy also offers the possibility of national-level elimination of PRRS without the participation of all farmers in cases, for example, where they are resistant to including gene edited animals in their herds.
“Given that adoption by farmers remains one of the biggest barriers to implementation of biotechnology…blanket distribution of a novel genomic technology seems unlikely under current conditions. Nonetheless, we found PRRS elimination still to be feasible for a more realistic scenario where gene editing and mass vaccination are used conjunctively, allowing individual farmers to choose their management tool,” the authors said.
The success of such an approach would also depend on economic and societal factors beyond epidemiological feasibility, they said. However, with PRRS placing an onerous economic burden on producers in European countries and the United States, cost-benefit analyses may come out in favor of new, novel approaches, they suggested.
You can read the full study report in Proceedings of the National Academy of Sciences
