His principal research interests are particularly focused on virus-receptor interactions, basic puzzles of virus assembly and studying virus evolution. His team are studying several viral proteins and enzymes which are potential drug targets and/or illuminate how viruses modulate host responses. For example, the immune modulators of pox viruses.

He is a world leader in structural biology, distinguished by contributions to viral crystallography. Since his 1989 Foot-and-Mouth Disease Virus structure he has extended the complexity of known structures with several milestone determinations; notably of bluetongue virus core and PRD1 (the first structure of an enveloped virus), providing the bedrock for advances in understanding viral assembly, replication and infection.