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Dengue virus increases mosquito’s lust for blood

May 6, 2012 1 comment

Between 50 million and 100 million dengue infections occur each year, according to the World Health Organization.

VIRUS CARRIER: This picture shows the presence of the dengue virus in the mosquitoes’ chemosensory (antennae and palp) and feeding organs (proboscis). (Photo: Johns Hopkins Bloomberg School of Public Health)

Mosquitoes are already blood-sucking machines, but new research indicates that the dengue virus, which the mosquitoes transmit to humans, makes them even thirstier for blood.

The virus specifically turns on mosquito genes that make them hungrier for a blood meal; the activated genes also enhance mosquitoes’ sense of smell, something that likely improves their feeding skills. The result is a mosquito better able to serve the virus by carrying it more efficiently to human hosts.

“The virus may, therefore, facilitate the mosquito’s host-seeking ability, and could — at least theoretically — increase transmission efficiency, although we don’t fully understand the relationships between feeding efficiency and virus transmission,” study researcher George Dimopoulus, of the Johns Hopkins Bloomberg School of Public Health, said in a statement. “In other words, a hungrier mosquito with a better ability to sense food is more likely to spread dengue virus.”

Dengue dangers

The virus doesn’t hurt the mosquitoes that carry it, a specific species called Aedes aegypti, but it lives in them. When the mosquito bites a human, it spreads the deadly disease through its saliva. More than 2.5 billion people live in areas where dengue fever-infected mosquitoes live. The World Health Organization estimates that between 50 million and 100 million dengue infections occur each year.

The researchers analyzed the mosquito genes before and after being infected with the virus, finding changes in 147 genes. These post-infection genes make proteins that are involved in processes that include virus transmission, immunity, blood feeding and host seeking, they found.

“Our study shows that the dengue virus infects mosquito organs, the salivary glands and antennae that are essential for finding and feeding on a human host,” Dimopoulus said. “This infection induces odorant-binding protein genes, which enable the mosquito to sense odors.”

Zombified behavior

“We have, for the first time, shown that a human pathogen can modulate feeding-related genes and behavior of its vector mosquito, and the impact of this on transmission of disease could be significant,” Dimopoulos said.

This is just one of many recent examples of a parasite taking control of an animal for its own benefit. Other examples include a fungus that turns ants into zombiesand a virus that causes caterpillars to dissolve and then rain virus particles down on other potential hosts.

The study was published on March 29 in the journal PLoS Pathogens.

Source:

http://www.mnn.com/earth-matters/animals/stories/dengue-virus-increases-mosquitos-lust-for-blood by Jennifer Welsh, LiveScience

Reference:

Sim S, Ramirez JL, Dimopoulos G (2012) Dengue Virus Infection of the Aedes aegypti Salivary Gland and Chemosensory Apparatus Induces Genes that Modulate Infection and Blood-Feeding Behavior. PLoS Pathog 8(3): e1002631. doi:10.1371/journal.ppat.1002631

http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1002631

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Debating research into mutant H5N1 flu virus

February 8, 2012 1 comment

On 2 February, scientists and public health officials squared off in a panel discussion at the New York Academy of Sciences. At stake, the fate of two papers which describe a mutant strain of the avian influenza virus H5N1. The virus is capable of mammal-to-mammal transmission, which has raised concern that it might be transferable to humans. Several panelists sat down with Nature News to discuss their positions prior to the panel discussion.

For more on the NYAS debate, visit Nature’s blog:

http://blogs.nature.com/news/2012/02/emotion-runs-high-at-h5n1-debate.html

and see web special about the ongoing controversy over H5N1:

http://www.nature.com/news/specials/mutantflu/index.html

Or see NYAS.org where the NYAS has posted two hours of video from the H5N1 event. Now everyone can see exactly what Mike Osterholm said to Peter Palese. Highly unprofessional, in my opinion, and not conducive with a good scientific discourse. Laurie Garrett was not much better.

“Dual Use Research: H5N1 Influenza Virus and Beyond” Panel Sparks Lively Debate | The New York Acade