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July 01, 2021

USDA develops candidate African swine fever vaccine

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A federal research team reported progress toward creating a commercial vaccine against the devastating African swine fever virus.

An article published in May in the Journal of Virology indicates Department of Agriculture scientists at the Plum Island Animal Disease Center in New York created an attenuated vaccine candidate that can reproduce in a continuous cell line, overcoming a limitation that previous vaccine candidates required fresh macrophages from live swine. USDA Agricultural Research Service scientists had developed a previous vaccine candidate that offered effective protection, but the macrophage requirements prevented large-scale production.

Two of the article authors—USDA ARS research microbiologists Manuel Borca, PhD, and Douglas Gladue, PhD—said in a joint message that the ASF virus requires primary swine macrophages to replicate, and those macrophages do not divide. The researchers adapted an ASF virus to reproduce in a cell line that was developed at the ARS from primary porcine epithelial cells, and the attenuated vaccine candidate they produced with that modified virus protected swine as well as their previous vaccine candidate.

The researchers saw no clinical signs of illness among 20 swine that were vaccinated and experimentally inoculated with live ASF virus.

ASF is highly dangerous to commercial swine breeds, and outbreaks can wipe out entire herds. In 2018, the disease emerged in China, the world’s largest pork producer, killing unknown millions of pigs.

Drs. Borca and Gladue said in their message they were working with a commercial partner to further evaluate the vaccine candidate.