Scientists have found a novel strain of the inherited bacteria Wolbachia which can block transmission of dengue and Zika virus among infected mosquitoes, offering a potential alternative to strains already being tested as virus control tools.
Scientists from the University of Glasgow’s MRC Centre for Virus Research (CVR) have carried out the research in the mosquito species Aedes aegypti, which spreads a number of dangerous human viruses, including dengue, Zika, and Chikungunya.
Previous research has shown that transmission of these viruses among mosquitoes is inhibited if the flies are deliberately infected with one strain of Wolbachia bacteria, and several countries are testing whether infecting local mosquito populations with Wolbachia could lower rates of viral disease in humans.
Now University of Glasgow CVR scientists have shown that a novel strain “wAu” is even more effective for virus transmission blocking than strains currently being used, particularly in hot, tropical climates where there is high prevalence of these diseases.
Several Wolbachia strains have already been tested in the field, but there is evidence to suggest that some strains may not block transmission very effectively or may not be inherited efficiently at high ambient temperatures.
In the new study, the research team performed laboratory experiments to test the potential promise of alternative Wolbachia strains.
The researchers introduced four Wolbachia strains into Aedes aegypti mosquitoes, which do not naturally carry these arthropod-infecting bacteria. Two of the strains, wMel and wAlbB had already been evaluated in prior studies, and the scientists wanted to compare their effects with those of two novel strains, wAu and wAlbA.
The analysis revealed particularly promising results for strain wAu. After feeding on blood infected with dengue or Zika virus, mosquitoes infected with wAu had lower levels of viral RNA in their body tissue than did mosquitoes infected with the other strains. wAu also showed very high rates of inheritance, including under high-temperature conditions.
Future research could explore strategies to maximise the effectiveness of wAu in the field, such as combining it with a second strain to help it spread throughout local mosquito populations.
The study, “The Wolbachia strain wAu provides highly efficient virus transmission blocking in Aedes aegypti”, is published in PLOS Pathogens. The work was funded by the Wellcome Trust and the Medical Research Council. M