A Bioinformatics Approach to Revealing the Genetic Basis for Host Range Specificity

Bacteriophages, or phages, are viruses that infect bacteria. Mycobacteriophages are bacteriophages that specifically infect the genus Mycobacterium. This genus of bacteria includes human pathogens such as Mycobacterium tuberculosis, Mycobacterium leprae and Mycobacterium ulcerans, which cause tuberculosis, leprosy and Buruli ulcer, respectively. The full genome sequences of 654 mycobacteriophages are currently available. Collectively, these 654 phages encode 69,581 genes. Only 20.25% of these genes have at least one known homologue in NCBI, the National Center for Biotechnology Information, leaving roughly 80% of all known mycobacteriophage genes without even a predicted function. Bacteriophages are highly host-specific and typically only infect a small number of bacterial hosts. The host range of 204 mycobacteriophages, initially isolated on Mycobacterium smegmatis strain mc2 155, was recently determined on three other bacterial hosts: M. tuberculosis and two M. smegmatis strains, Jucho and MKD8. The phages that were capable of infecting one or more of the hosts were of particular interest. The host range information was then used in an association study using Phamerator software to examine the relationship between gene products (protein phamilies) and host range of the corresponding phages. With so many uncharacterized genes encoded by these phages, the potential for elucidating key factors involved in the determination of host range is an exciting prospect