African Swine Fever Virus Mutations May Pose Detection Challenges

Media reports of African swine fever virus (ASFV) variants emerging in China and a recent China Harbin Laboratory paper describing its analysis of ASFV variants prompted the Swine Health Information Center (SHIC) to dig into the topic with ASF expert Dan Rock of the University of Illinois. [Source: Farm Journal's Pork, 23 April 2021, by Jennifer Shike]

Rock shared his perspective in a recent SHIC newsletter about his interpretation of the paper and insight into attenuating mutations of the ASFV genome and also those that could be used in unapproved vaccines.

In "Emergence and prevalence of naturally occurring lower virulent African swine fever viruses (ASFV) in domestic pigs in China 2020," the authors describe genetic changes in all 22 ASFV field isolates collected from June to December 2020 when compared to the virulent field strain, HLJ/18 2020.

In the study, 11 of the viruses isolated from two provinces with high pig density contained mutations in the EP402R gene (encoding for the CD2v protein) and exhibited a non-hemadsorbing phenotype (non-HAD), he explained. Similar mutations were observed in a number of the viruses suggesting they were of the same lineage expressing a truncated CD2v protein of 44 AA.

What does this mean? He said it is likely these represent spontaneous mutations in the CD2v gene occurring on pig passage rather than engineered mutations in a vaccine virus.

Read more at Farm Journal's Pork.