U.S. scientists have identified a genetically modified strain of mice that develop Zika, an important tool needed for testing vaccines and medicines to treat the virus that is rapidly spreading across the Americas and the Caribbean.
CHICAGO: U.S. scientists have identified a genetically
modified strain of mice that develop Zika, an important tool needed for
testing vaccines and medicines to treat the virus that is rapidly
spreading across the Americas and the Caribbean.
Early tests on the mice show the virus growing in the
testes, offering clues about how a virus typically spread by mosquito
bites can be transmitted sexually.
"We are going to do experiments to see if we can produce
sexual transmission" in these mice, said Scott Weaver, a virologist at
the University of Texas Medical Branch in Galveston who worked on the
study published on Monday in the American Journal of Tropical Medicine
and Hygiene.
Weaver said the Zika mouse model will provide a critical
tool to allow companies and scientists to test vaccines and antiviral
drugs against Zika, which has been linked with thousands of cases of
microcephaly, a rare birth defect marked by unusually small head size
and possible developmental problems.
Zika has not been proven to cause microcephaly, but strong
evidence connecting Zika infections with microcephaly cases in Brazil
prompted the World Health Organization to declare Zika a global health
emergency on Feb. 1.
Normally, creating this kind of mouse model would take
several months. But the urgency of the Zika outbreak called for rapid
response, and the team put together the results in just three weeks,
said Shannan Rossi, a UTMB virologist who led the study.
Normally, mice do not become sick from a Zika infection. The
team tested the virus on several genetically altered mice that had
weakened immune systems. The young mice quickly succumbed to the virus,
becoming lethargic, losing weight and typically dying six days later.
Testing on the mice showed virus particles in many major organs, including high concentrations in the spleen, brain and testes.
While Weaver says there are limits to what mouse models can
tell about human infections, they may at least provide some early clues
that could be followed up in non-human primates, a more costly animal
model that is a better predictor of human disease.
"The mouse will mainly be used to do the very earliest
testing of vaccines or drugs where the mechanism of disease doesn't have
to be a perfect model to what happens in humans," Weaver said.
Brazil has confirmed more than 900 microcephaly cases and
considers most related to Zika infections in the mothers. It is
investigating nearly 4,300 additional suspected cases of microcephaly.
(Reporting by Julie Steenhuysen; Editing by Dan Grebler)
- Reuters
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