Transgenic fungus 'could be powerful weapon against malaria'

Daniela Hirschfeld in SciDev.net: Infecting mosquitoes with a transgenic fungus could drastically cut their ability to transmit malaria, according to research published today in Science (25 February). Existing efforts to develop fungal malaria control focus on slowly killing mosquitoes before they have the chance to pass on Plasmodium, the malaria parasite. But they rely on mosquitoes being inoculated with parasitic fungus soon after Plasmodium infection, which limits their use.

In this latest research, scientists have changed tactics and instead focused on reducing the infectiousness of the mosquitoes, so that fungus could be applied later in a mosquito's lifecycle but still cut malaria transmission.

The researchers genetically modified (GM) the fungus Metarhizium anisopliae, which infects mosquitoes on contact, to express molecules which impede the entrance of sporozoites — the cells that malaria parasites produce to infect new hosts — to the salivary gland of the mosquitoes, reducing the number that can be passed to humans through a bite.

The GM fungi reduced the number of sporozoites in mosquito salivary glands by up to 98 per cent compared to those infected with the non-GM fungi. Within just two days of infection 80 per cent of mosquitoes could not transmit malaria anymore compared to only 14 per cent of fungi-free mosquitoes and 32 per cent of those infected with non-GM fungi….

Ring-stage plasmodium in a smear of human blood, shot by Bobjgalindo, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported