Mosquitoes are known for transmitting deadly viruses to humans, but the insects themselves are susceptible to viral infection. According to a study published in the open-access journal PLoS Pathogens, researchers at Johns Hopkins University have described a virus that infects the mosquito best known for transmitting malaria – Anopheles gambiae. Malaria kills over one million people worldwide every year, and the researchers believe that the infectious mosquito virus might be used to control malaria by passing on new genetic information to A. gambiae.

AgDNV is a densonucleosis virus (densovirus) – a type common to mosquitoes and other insects but not infectious to humans and other vertebrates. The AgDNV virus does not actually harm mosquitoes, but researchers believe it is highly infectious to larvae and is easily passed to the adults.

Researcher Jason Rasgon, PhD (Johns Hopkins Bloomberg School of Public Health’s Malaria Research Institute) notes that this new finding came about while the investigators were actually trying to use Wolbachia bacteria to infect An. gambiae mosquito cells. Co-author Xiaoxia Ren was analyzing the gel used to detect the bacteria when an “artifact” that appeared as an unexpected prominent band in the gel was noticed.

Ragson admits that, “Finding artifacts such as this one during experiments is not uncommon, but we decided to investigate this one further since we kept observing it over and over. When we sequenced it, we were surprised to learn that we had found a new virus.”

The researchers believe that the virus can be altered to kill the mosquito or make it incapable of transmitting malaria. In order to test how much control the authors had over the virus, the altered the AgDNV so that adult mosquitoes presented a harmless green fluorescent protein that is spotted using a microscope.

“In theory, we could use this virus to produce a lethal toxin in the mosquito or instruct the mosquito to die after 10 days, which is before it can transmit the malaria parasite to humans. However, these concepts are many years away,” concludes Rasgon.

Viral Paratransgenesis in the Malaria Vector Anopheles gambiae
Ren X, Hoiczyk E, Rasgon JL
PLoS Pathogens (2008). 4(8):e1000135.
doi:10.1371/journal.ppat.1000135
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Written by: Peter M Crosta