There is a disclosed a method of killing abnormal cells such as malignant cells including melanoma cells, using a virus recognising at least one of a cell adhesion molecule and a complement regulatory protein. The virus may be a member of the Picornaviridae family. Coxsackie A-group viruses have been found to be particularly suitable. The cell adhesion molecule is desirably a member of the immunoglobulin (Ig) superfamily. Typically, the complement regulatory protein will be DAF.