Changing the paradigm of virus survival strategies in the Sea

Abstract

In aquatic systems it is described that lysogeny (a prophage inserted in the DNA of the bacterial host) should be the dominant viral life cycle in oligotrophic waters, which are characterized by a low nutrient concentration, low primary production and slow growing bacterial cells. While, according to the kill the winner hypothesis lytic phages prevail in high productive systems where bacterial hosts are abundant. However, the analysis of several public datasets revealed that lysogeny increased in eutrophic systems. These findings are in agreement with the recently proposed Piggyback-the–Winner model, which also suggests that lysogeny is more successful than the lytic cycle when bacterial hosts are abundant. The model assumes that viruses “exploit” their hosts through lysogeny instead of killing them, making this fact advantageous for both. Thus, the prophage stage of the virus is propagated from the “happily” growing bacteria to the new bacterial generations, being the host protected by the prophage from new viral infections and predation by grazers. The finding that aquatic environments with high host abundances has fewer virus per host when the host abundance is low, challenge the paradigm on the relative roles of lytic and lysogeny viral strategies