As important predators of bacteria, phages (viruses that kill bacteria) influence the structure of natural microbial communities and how they evolve. Yet the fundamental features of these virus-bacteria interactions in nature are poorly understood, limiting the ability to use viruses as targeted therapies against unwanted bacteria.

In a study published online on January 18 in Nature Communications, the lab of Libusha Kelly, Ph.D., worked with colleagues at the Massachusetts Institute of Technology who isolated from seawater samples more than 1,400 strains of coastal marine bacteria known as Vibrionaceae. Using those bacterial strains as bait, the researchers then quantified the concentrations of viruses present for each bacterial strain. The numbers of viruses corresponding to most bacterial strains were low and their host ranges narrow—evidence indicating that virus-bacteria interaction networks in the marine environment are generally sparse. However, the researchers observed that recombination among viruses was common. (Viral recombination occurs when two different viral strains infect the same host cell and interact during replication to yield viral offspring containing genes from both parents.) The findings suggest that recombination may be an important mechanism for virus survival in the face of bacterial anti-virus defenses.

Dr. Kelly is an associate professor of systems & computational biology and of microbiology & immunology at Einstein.