Exploiting insect-specific viruses as a novel strategy to control vector-borne disease

Abstract

Novel insect-specific viruses (ISVs) are being discovered in many important vectors due to advances in sequencing technology and a growing awareness of the virome. Several in vitro and in vivo studies indicate that ISVs are capable of modulating pathogenic arboviruses. In addition, there is growing evidence that both vertical and horizonal transmission strategies maintain ISVs in vector populations. As such there is potential to exploit ISVs for stand-alone vector control strategies and deploying them in synergy with other symbiont control approaches such as Wolbachia-mediated control. However, before the applied potential can be realized, a greater understanding of their basic biology is required, including their species range, ability to be maintained and transmitted in native and non-native vector hosts, and the effect of infection on a range of pathogens.

Figure 1.

Putative overview of using Insect-specific viruses for vector control. ISVs have been discovered in arthropod vectors. There is evidence that ISVs modulate arbovirus infections. Many modes of transmission may be used in natural and laboratory settings, but aspects of the natural biology of ISVs remain unknown. Combining these attributes will inform methods used for vector control.

Figure 2.

Midpoint-rooted phylogeny of 875–910 nt dual-host flavivirus and insect-specific flavivirus (ISF) NS5 gene sequences. Virus designations followed by GenBank accessions and mosquito species from which they were isolated are indicated. Key interactions of ISFs that inhibit or enhance arbovirus transmission are indicated in green and blue, respectively. The phylogeny was generated using PhyML version 3.0 [61], employing the Akaike information criterion [62] for automatic selection of the general time reversible (GTR) sequence evolution model. Tree topologies were estimated using nearest neighbour interchange (NNI) improvements over 1000 bootstrap replicates. The branch length scale represents substitutions per site.