STUDYING MYCOBACTERIOPHAGE GENOME SEQUENCES TO UNDERSTAND RELATIONSHIPS BETWEEN MYCOBACTERIOPHAGES
Valerie Carrasquillo1, Joel Schildbach2.
1Universidad Metropolitana, San Juan, PR, 2Johns Hopkins University, Baltimore, MD.
Bacteriophages comprise the largest biomass on Earth, with an estimated total of 1031 phages in the biosphere; however, little is known about their diversity. Mycobacteriophages are viruses that infect mycobacterial species such as M. tuberculosis and M. leprae. We use M. smegmatis as a model because it is non-pathogenic and shares some traits with M. tuberculosis. Studying phages that infect M. smegmatis may improve our knowledge about the genetics of other mycobacteria. To date, 3,600 mycobacteriophages have been isolated, but only 530 have been sequenced. To gain insight into mycobacteriophage genetics, phages have been sequenced in order to find genome sequence similarities and cluster them. Relationships among phages are typically analyzed by comparing whole genomes. Currently, 21 clusters have been established, but particular clusters are highly represented among sequenced phages, while other clusters have few members. Sequencing novel phages or phages belonging to rarely sequenced clusters will expand our understanding of mycobacteriophage diversity. The goal of this project is to develop a simple and effective protocol for preliminary cluster determination by cloning and sequencing small fragments of phage genomes. This will serve as a base for a more informed selection of phages for whole genome sequencing, resulting in a broader picture of mycobacteriophage biology.