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SALT LAKE CITY — In a unique twist of scientific genius, University of California at Irvine researchers, Anthony A. James, Alison T. Isaacs, Nijole Jasinskiene, Mikhail Tretiakov, and their international colleague Isabelle Thiery from the Institut Pasteur in Paris France, stand at the edge of one of the most significant medical breakthroughs of this century. They have partially perfected a way to immobilize viral pathogens in wild mosquito populations.
UCI partnered with London based Oxitec to develop a technology that will eventually be licensed. James and his colleagues found a way to introduce foreign DNA into mosquito chromosomes, creating a hybrid or transgenic mosquito.
Mosquitoes worldwide are developing resistance to insecticides. Insecticides also kill beneficial insects and pose a risk for people, animals and the environment. “We have been working… on the individual components of creating a genetically modified mosquito … but this is the first time we have been able to establish this immunity in a wild mosquito population,” James said.
The altered DNA renders the mosquitoes resistant to the dengue virus (and malaria) making the mosquito unable to transmit the disease.
This viral chink in the armor occurs during the replication process. In replication, the virus uses a single strand of RNA – a chemical cousin of DNA – and briefly becomes double–stranded.
“On its own, this process of self-destruction occurs after the virus has already replicated and been transmitted. We found a way to control, regulate and to speed-up the process.”
There is a naturally occurring protein called a “dicer-2” that has no effect on a single strand of RNA, but acts like scissors on the double strand, chopping it up and rendering its genetic material useless. Once this process is started, the single-stranded RNA also becomes vulnerable to dicer-2.
Local mosquito abatement districts will provide free or minimal cost, top feeding minnows that will eat mosquito larvae. Goldfish does not do this job.
The West Nile Virus is mosquito transmitted to humans through birds, both exotic and native, and horses. Health departments encourage citizens to report dead birds, particularly crows and scrub jays like magpies. See recommendations for horse owners .
By cloning a section of the virus RNA and injecting two inverse copies of it into mosquito embryos-the copies form a double-stranded RNA that becomes become vulnerable to the dicer-2 protein” This process, in effect “inoculates” mosquitoes rendering the previously pathogenic status benign.
Oxitec and the Brazilian company Moscamed operate a breeding lab in Juazeiro introducing millions of the modified mosquitoes via trucks. Researchers claim that, at present, 84% of mosquito larvae in Juazeiro (now) carry the modified gene.
Critics like GeneWatch, a British non-governmental watchdog group, say that such programs pose an unjustified risk. The World Health Organization (WHO) estimates that there may be as many as fifty million cases of dengue fever each year and some 20,000 deaths.
Meanwhile, researchers are awaiting approval from the Brazilian Government to introduce the Franken mosquitoes in the nearby city of Jacobina. Jacobina is estimated to be roughly 50,000 people.
“There are always unknowns, so to speak, but we think these are outweighed by the known setbacks of other approaches…most of the concerns are about some unintended off-target effects, (involving the Aedes) but we know exactly what the off-effects of pesticides are” James told the Los Angeles Times.
“There is a radical ecologist wing that thinks you should not get involved with nature no matter what, and there are those of us who think fighting disease is worth it” said Danilo Carvalho--the head of the “Transgenic Aedes Project.”
You can see results of ongoing research reported earlier year in the online edition of the Proceedings of the National Academy of Sciences.
Mel Borup Chandler lives in California. He writes about science-related topics, technological breakthroughs and medicine. His email address is mbccomentator@roadrunner.com.
