Genotyping of African swine fever virus (ASFV) isolates associated with disease outbreaks in Uganda in 2007

Abstract

Samples from infected domestic pigs associated with an outbreak of African swine fever (ASF) in three districts of
central Uganda in 2007 were confirmed as being infected with African swine fever virus (ASFV) using a P72 genebased polymerase chain reaction amplification (PCR) assay combined with restriction analysis. None of the sera
collected from pigs with clinical symptoms were positive using the OIE serological prescribed tests. However, seven
haemadsorbing viruses were isolated in macrophage culture and genotyped by partial p72 and full length p54-gene
sequencing. Four of these viruses were isolated directly from serum samples. All the viruses were classified within
the domestic-pig cycle- associated p72 and p54 genotype IX which also includes viruses responsible for ASF
outbreaks in Kenya in 2006 and 2007 and Uganda in 2003. To define virus relationships at higher resolution, typing
was performed by analysis of tetrameric amino acid repeat regions within the central variable region (CVR) of the
B602L gene. Ugandan isolates sequences exhibited 100% identity to viruses isolated from outbreaks in Kenya in 2007.
The identity was greater than the viruses obtained from an earlier outbreak in Kenya in 2006. This provides further
evidence that genetically similar ASFV virus within p72 Genotype IX may be circulating between Kenya and Uganda.