The African swine fever isolate ASFV-Kenya-IX-1033 is highly virulent and stable after propagation in the wild boar cell line WSL

Hemmink, J.D., Abkallo, H.M., Henson, S.P., Khazalwa, E.M., Oduor, B., Lacasta, A., Okoth, E., Riitho, V., Fuchs, W., Bishop, R.P. and Steinaa, L. 2022. The African swine fever isolate ASFV-Kenya-IX-1033 is highly virulent and stable after propagation in the wild boar cell line WSL. Viruses 14(9): 1912.

We describe the characterization of an African swine fever genotype IX virus (ASFV-Kenya-IX-1033), which was isolated from a domestic pig in western Kenya during a reported outbreak. This includes the efficiency of virus replication and in vivo virulence, together with genome stability and virulence, following passage in blood macrophages and in a wild boar lung cell line (WSL). The ASFV-Kenya-IX-1033 stock retained its ability to replicate in primary macrophages and retained virulence in vivo, following more than 20 passages in a WSL. At the whole genome level, a few single-nucleotide differences were observed between the macrophage and WSL-propagated viruses. Thus, we propose that the WSL is suitable for the production of live-attenuated ASFV vaccine candidates based on the modification of this wild-type isolate. The genome sequences for ASFV-Kenya-IX-1033 propagated in macrophages and in WSL cells were submitted to GenBank, and a challenge model based on the isolate was developed. This will aid the development of vaccines against the genotype IX ASFV circulating in eastern and central Africa.