Emergence of a novel intergenic region (IGR) IV variant of african swine fever virus genotype II in domestic pigs in Vietnam.

African swine fever virus (ASFV) causes African swine fever (ASF), a deadly disease affecting both domestic pigs and wild boars. ASF has become endemic in Vietnam since its first appearance in early 2019. Our previous molecular surveillance studies revealed that all the ASFV strains circulating in Vietnam belong to p72 genotype II, p54 genotype II, CD2v serogroup 8, and CVR of B602L gene variant type I. However, the genetic analysis based on the tandem repeat sequences located between I73R and I329L genes revealed three different intergenic region (IGR) variants; I, II, and III. In this study, using ASFV field isolates collected from September 24th to December 27th, 2021, we report, for the first time, novel IGR IV variants circulating in the Vietnamese pig population.