Newly Patented Virus Could Help Control Disease-Carrying Mosquitoes

By Jim Core
April 23, 2003

As surely as swallows return to Capistrano around mid-March each year, mosquitoes will arrive in force again this spring. Mosquitoes, however, have become more than just a nuisance. They can transmit diseases such as West Nile virus (WNV).

One mosquito genus, called Culex,has been found to transmit WNV and the closely related St. Louis encephalitis (SLE). Now Agricultural Research Service scientists have received a patent for a baculovirus--a virus specific to arthropods--that kills Culex mosquitoes. The patent also includes a method for transmitting the baculovirus to them. The baculovirus infects only Culex mosquitoes--not other insects, plants, wildlife or people.

Most people who become infected with WNV or SLE have no symptoms, or only mild ones, but last year WNV killed 277 people and made more than 4,000 clinically ill, according to the U.S. Centers for Disease Control and Prevention. The largest outbreak of SLE in 15 years occurred in 1990. On average, about 128 cases of SLE are reported annually.

Baculoviruses are extremely uncommon in mosquitoes. However, James J. Becnel, an entomologist with the ARS Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Fla., discovered a novel baculovirus in 1997. Called CuniNPV, it is very stable and persistent and is a promising candidate to develop into a larvicide.

The baculovirus is activated when it's mixed with magnesium. When the mixture is added into any body of water where mosquitoes breed, larvae ingest it. According to Becnel, the virus can kill 85 to 95 percent of mosquitoes in their natural habitat after two to three days. And the magnesium won't harm the water.

ARS, the U.S. Department of Agriculture's chief scientific research agency, is seeking partners to license the technology and bring it to the market. Interested parties should contact ARS' Office of Technology Transfer.