ORIGINAL ARTICLE: Coinfection rates in φ6 bacteriophage are enhanced by virus‐induced changes in host cells

Abstract

Two or more viruses infecting the same host cell can interact in ways that profoundly affect disease dynamics and control, yet the factors determining coinfection rates are incompletely understood. Previous studies have focused on the mechanisms that viruses use to suppress coinfection, but recently the phenomenon of enhanced coinfection has also been documented. In the experiments described here, we explore the hypothesis that enhanced coinfection rates in the bacteriophage Φ6 are achieved by virus-induced upregulation of the Φ6 receptor, which is the bacterial pilus. First, we confirmed that coinfection enhancement in Φ6 is virus-mediated by showing that Φ6 attaches significantly faster to infected cells than to uninfected cells. Second, we explored the hypothesis that coinfection enhancement in Φ6 depends upon changes in the expression of an inducible receptor. Consistent with this hypothesis, the closely related phage, Φ12, that uses constitutively expressed lipopolysaccharide as its receptor, attaches to infected and uninfected cells at the same rate. Our results, along with the previous finding that coinfection in Φ6 is limited to two virions, suggest that viruses may closely regulate rates of coinfection through mechanisms for both coinfection enhancement and exclusion.

Migration Enhances Adaptation in Bacteriophage Populations Evolving in Ecological Sinks

“…One hypothesis to explain this finding is that host entry by the virus is facilitated by attachment by more than one phage to the host. This contention is supported by evidence from studies showing that 6 attaches to infected cells significantly faster than to uninfected cells (Joseph et al 2009). The presumed mechanism is upregulation of the 6 receptor, the host pilus, by infecting phages.…”

The Double-Edged Sword: How Evolution Can Make or Break a Live-Attenuated Virus Vaccine

“…However it is increasingly clear that, for some viruses, co-infection occurs at rates greater than expected by chance when viral density is very low. Such coinfection enhancement suggests either that a small fraction of appropriate host cells are actually susceptible to infection [45-47] or that viruses may possess mechanisms to enhance coinfection at low viral densities [48]. …”

EDITORIAL: Editorial: evolutionary medicine special issue

“…They also review some exciting recent experimental results that test these predictions using a mouse model system. Joseph et al. (2009) present primary research results from an elegant evolutionary model system of bacteria and phage, demonstrating that bacteria infected with phage can become more susceptible to further infection.…”