Dynamics of virus infection in a Wolbachia-infected host.

Wolbachia is a bacterium that blocks viruses and protects its arthropod hosts from infection. Whilst Wolbachia blocking is used as a strategy to prevent mosquito-borne disease, the mechanisms of Wolbachia-mediated viral blocking are not well characterised. Several mechanisms have been implicated, but it is often unclear their contribution to the overall blocking and how broadly they apply across host-virus-Wolbachia systems. Wolbachia's impact on viral dynamics and pathogenicity in individual Drosophila hosts was measured to explore what Wolbachia-mediated changes dominate the blocking phenotype. The empirical data was combined with a dynamical model to look at the impact of a series of parameters. This model described changes through time to susceptible cells, infected cells, and free virion particles. Results showed that Wolbachia reduced the accumulation of viral RNA and infectious viruses. The maximum amount of viral RNA was lower in individuals with Wolbachia, while the maximum amount of infectious virus was the same. These viral dynamics of Wolbachia-infected individuals could be recapitulated with a lower rate of viral infection of susceptible cells, lower viral release, a smaller number of susceptible cells or smaller burst size or various combinations of these processes. Experimental testing of the importance of these processes may be required to resolve their contribution to Wolbachia-mediated virus blocking. As further empirical data is added, the dynamical modelling approach may help guide decisions on which large impact mechanisms to focus on for functional approaches.