The use of COS-1 cells for studies of field and laboratory African swine fever virus samples

Different naturally occurring, cell adapted or genetically manipulated stocks of African swine fever virus were able to infect directly cultures of COS-1 cells, producing extensive cytopathic effects and amounts from 106 to 107 of infective progeny virus per ml. The induction of late virus-specific proteins, demonstrated by RT-PCR and immunoblotting, and the development of lysis plaques by all the virus samples tested so far, allowed the optimization of both titration and diagnostic assays, as well as the proposal of a method for selection of virus clones during the generation of virus mutants with specific gene deletions.