Sydney: Scientists have cracked the code of how mosquitoes develop
immunity to virus, potentially opening the way to better vaccines
for diseases such as dengue.
A team from the Commonwealth Scientific and Industrial Research
Organisation (CSIRO) Lab, in Geelong, has shown Vago, a protein
previously identified in fruit flies, is released by infected
mosquito cells, warning other cells to defend against the invading
Mosquito-transmitted emerging viruses, such as dengue, Japanese
encephalitis and West Nile threaten the health of our people,
livestock and wildlife. Globally, dengue infects 50-100 million
people and kills around 22,000 people annually, the journal
Proceedings of the National Academy of Sciences reported.
According to Peter Walker, professor at CSIRO, these insect
vectors present a particular biosecurity risk for Australia as
they are rapidly spreading into new areas driven by a number of
factors including climate change and increased travel and trade.
"Difficulties in generating safe and effective vaccines for many
of these pathogens present significant challenges due to their
complex ecology and the range of hosts the viruses can infect,"
Walker said, according to a CSIRO statement.
"Until now, very little was known about the defensive anti-viral
response of insects. Unlike humans and other mammals, insects lack
key components of the immune response including antibodies,
T-cells and many important cytokines (a category of signalling
molecules), such as interferon."
Using West Nile Virus as their infection model, the research team
has demonstrated that, although unrelated structurally, Vago acts
in mosquitoes like human interferon.
"Mosquito cells can sense the presence of a virus by detecting its
small genome, stimulating the secretion of Vago. The secreted Vago
then binds to receptors on other cells, signalling an anti-viral
defensive response to limit the infection.
"This is the first demonstration that such a mechanism exists in
mosquitoes or any other invertebrate," Walker said.