Vaccine against specific strain of ASF developed in the US
The US Department of Agriculture (USDA) has announced that its Agricultural Research Service (ARS) has developed a vaccine that protects pigs from a specific strain of ASF. This is a very important advance, although it has been pointed out that it is the beginning of a long journey before it can be used.
In autumn, a team of researchers presented results that indicate pigs administered the candidate vaccine not only survived but often remained free of clinical signs of illness when experimentally inoculated with an ASF virus strain that has been circulating in Vietnam. The work follows previous results, published in April 2020 in the Journal of Virology, that indicated the candidate vaccine was effective against a strain first identified in 2007 in the country of Georgia.
Researchers tested the candidate vaccine on two sets of mixed-breed pigs, some of them Yorkshire and Landrace crossbred pigs and some of them Vietnamese Mong Cai crossbred with either Landrace or Yorkshire pigs. The researchers checked for effectiveness of four different doses of the vaccine as well as how quickly the vaccine offered protection.
When challenged with ASF inoculation 28 days after vaccination, three of five pigs in the lowest-dose group developed the disease and were euthanized, but all pigs in the remaining three groups survived, which aligns with previous results. In a second experiment, the researchers found that the vaccine protected only half of the pigs challenged 14 days after vaccination, but all of the pigs challenged after 21 or 28 days survived without clinical signs of disease. According to the researchers, before being manufactured on a large scale, the vaccine must be tested for years to prove that it is safe and fully works. USDA indicates that the outlook is good since the first laboratory tests have shown the efficacy of the vaccine in pigs immunized and later exposed to that strain of the virus.
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