Expansion of ASF Recombinant Genotype I/II Strains Threatens Effectiveness of Vaccination

The continued expansion of the recombinant African Swine Fever Genotype I/II strains threatens to undermine the effectiveness of vaccination. Recent reporting on African Swine Fever virus strain circulation has highlighted a concerning expansion of the Recombinant Genotype I/II strains being detected in Asia and now the Russian Far East.

Swine Health Information Center Associate Director Dr. Lisa Becton says changes in globally circulating ASF genotypes represent risks for U.S. introduction.

Quote-Dr. Lisa Becton-Swine Health Information Center:

The concern is this is one of the first times that this virus combination was seen, not only within China and other Asian countries like Vietnam but now in Russia, so indicating a bit of an expansion. This is a concern because, up until recently, the predominant genotype that we were seeing in Europe and even in Asia was the genotype II, however that has started to change over time and now that we're seeing this new strain it raises questions as far as what does this  mean for our prevention and even mitigation strategies and how will this impact what we do for the future?

The change in strain has also had an impact on how pigs respond, if they are infected with this, and how they respond to vaccines that are currently being utilized.The vaccines are a genotype II only strain but the pigs that are infected with genotype 1/II recombinant do not respond the same to that vaccine and that is very concerning.

Over time this will continue to be monitored and other groups that are looking at vaccine development and utilization will also be taking note of the changes may occur.

Dr. Becton says preliminary evidence suggests, current live-attenuated vaccine programs based on genotype II, such as those being implemented in Vietnam and the Philippines, are most likely not protective against these recombinant genotype I/II strains.For more visit Farmscape.Ca.