name:   Actinobacteriophage_1321
version:    2
date:   2018-09-26
owner:
    name:   Graham Hatfull
    email:  gfh@pitt.edu
    url:    https://www.biology.pitt.edu/person/graham-hatfull
description: >
    This database contains the 1321 manually annotated Actinobacteriophages analyzed
    in Mavrich & Hatfull 2019.
publications:
    1:
        doi:    10.1128/mBio.00971-19
        pmid:   31164468
        title:  >
            Evolution of Superinfection Immunity in Cluster A Mycobacteriophages
        authors:    >
            Travis N Mavrich and Graham F Hatfull
        abstract:   >
            Temperate phages encode an immunity system to control lytic gene expression during
            lysogeny. This gene regulatory circuit consists of multiple interacting genetic
            elements, and although it is essential for controlling phage growth, it is subject
            to conflicting evolutionary pressures. During superinfection of a lysogen, the
            prophage’s circuit interacts with the superinfecting phage’s circuit and prevents
            lytic growth if the two circuits are closely related. The circuitry is advantageous
            since it provides the prophage with a defense mechanism, but the circuitry is also
            disadvantageous since it limits the phage’s host range during superinfection.
            Evolutionarily related phages have divergent, orthogonal immunity systems that no
            longer interact and are heteroimmune, but we do not understand how immunity systems
            evolve new specificities. Here, we use a group of Cluster A mycobacteriophages that
            exhibit a spectrum of genetic diversity to examine how immunity system evolution
            impacts superinfection immunity. We show that phages with mesotypic (i.e., genetically
            related but distinct) immunity systems exhibit asymmetric and incomplete superinfection
            phenotypes. They form complex immunity networks instead of well-defined immunity
            groups, and mutations conferring escape (i.e., virulence) from homotypic or mesotypic
            immunity have various escape specificities. Thus, virulence and the evolution of new
            immune specificities are shaped by interactions with homotypic and mesotypic immunity
            systems.
resources: ~