U.S. scientists develop
mouse model to test Zika vaccines, drugs
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[March 29, 2016]
By Julie Steenhuysen
CHICAGO (Reuters) - 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
Testing on the mice showed virus particles in many major organs,
including high concentrations in the spleen, brain and testes.
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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)
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