McCrae focused on the study of the molecular basis of virus pathogenicity. Attention here is focused on the reovirus mouse model employed to define some of the roles of individual viral genes in the pathogenesis process. Specifically the use of site specific mutagenesis of cDNA clones coupled with gene rescue technologies is under development to generate infectious virions with altered pathogenic potentials as a result of defined mutations introduced into their genomes.

He researches into the molecular characterization of Rotaviruses. Four main themes are being followed: the use of recombinant DNA technology to produce candidate vaccine preparations; molecular epidemiological studies of the nature and extent of virus variation; definition of the cell-mediated immune responses made to the virus and the role they play in protective immunity; study of the molecular mechanism(s) of viral pathogenesis. Other topics under study: structure/function studies on the vif and vpr genes of HIV; molecular characterisation of bovine viral diarrhoea (BVD) virus, a pestivirus.

His publications include:
M. Adekale, M.A. McCrae (2005). Changes in Vif protein associated with development of resistance to inhibitors of viral protease. J. Med Virol 75, 0-0.
J.P. Cook, M.A. McCrae (2004). Sequence Analysis of the Guanylyltransferase (VP3) of Group A Rotaviruses. J. Gen Virol. 85, 929-932.
Ibrahim, M.A. McCrae (2001). High Level Expression of Bovine Rotavirus VP4 protein in E.coli using a Hepatitis B core antigen vector. Biotechnology Letters 23, 643-646.