Shortly after the introduction of antibiotics in the 1940's, strains of bacteria that were resistant to these drugs began to emerge. Today, the continued emergence of bacterial strains that are resistant to multiple broad classes of antibiotics has raised significant concern among the general medical community, some even suggesting we may be about to enter a post-antibiotic era. Among resistant bacteria, methicillin-resistant Staphylococcus aureus (MRSA) is an agent of major concern. Bacteriophages, viruses that infect bacteria, have been proposed as biological control agents for the treatment of bacterial infections in humans and animals. Phage therapy against S. aureus and MRSA is facilitated by their broad susceptibility to a single type of phages, referred to as the Twort-like group. While there is considerable interest in the use of phages as therapeutics, an important but currently underdeveloped field of research is the biology of the phages themselves. This proposal is divided into two major aims: the first is to study the genetics and biology of the Twort-like phage K, and the second is to leverage this study to develop methods that can be used to engineer or further study the biology of this phage. In the first aim, the library of suppressible mutants will be generated, providing a map of most of the essential genes in this phage and allowing functions to be assigned to a number of unknown genes.
The second aim of the project is to develop new methods for genetic manipulation of phages, primarily by developing a selectable marker system that can be used in the phage genetic context. This system will allow phage genes to be inactivated or replaced at will, allowing a number of future fundamental studies to be conducted. The strategies developed here should also be useful in other phage systems, thus catalyzing progress in the field of phage biology as a whole.
Staphylococcus aureus is a major opportunistic pathogen of humans. Antibiotic resistant forms of this pathogen, including methicillin-resistant S. aureus (MRSA) may be either hospital or community acquired and are a significant cause of morbidity and mortality in the US and worldwide. Outside of S. aureus and MRSA, antibiotic resistance in a variety of pathogenic bacteria is a health threat that becomes more substantial each year. Bacteriophages, or the viruses that infect bacteria, have been proposed as an alternative form of antibacterial therapeutic, but the implementation of such a therapy may be hampered by our lack of understanding of the basic biology of these diverse organisms. This proposal aims to develop novel methods for the study and manipulation of bacteriophages using S. aureus and phage strain K as a model system. Findings of this study are expected to be applicable for work in the biology of bacteriophages outside of those infecting S. aureus.
