Researchers have created a powerful tool for studying the Zika virus that should be useful for vaccine and antiviral drug development. The tool creates versions of the virus that are stripped of genes that make them infectious, making them safer to work with.

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One of the replicons the researchers created with their new Zika replicon system could be a powerful tool for vaccine development.

Called a “replicon system,” the new tool is the work of researchers from the University of Texas Medical Branch (UTMB) in Galveston, Southwest University in Chongqing, China, and the University of Leuven in Belgium. They describe how they developed and tested the system in the journal EBioMedicine.

Zika virus is a mosquito-borne member of the genus flavivirus, which includes dengue fever, yellow fever, West Nile virus, and other viruses that cause significant human diseases.

Many people infected with Zika do not have symptoms or only experience mild symptoms, including fever, rash, joint pain, muscle pain, red eyes (conjunctivitis), and headache.

Zika infections are rarely serious enough to require hospitalization, and people very rarely die of it. Once a person has been infected, they are less likely to become infected again.

However, Zika is risky for some people. Infection during pregnancy can cause severe fetal brain defects, such as microcephaly, and other problems that affect the eyes, hearing, and growth. There have also been reports that areas affected by Zika have higher rates of Guillain-Barré syndrome, a rare and serious disorder of the nervous system.

The current epidemic of Zika virus disease in the Americas poses a global public health emergency. Yet despite urgent medical needs, there are no medicines or vaccines against the virus.

Disease viruses spread by infecting host cells and taking over their machinery to make copies of themselves that go on to infect more cells.

Fast facts about Zika
  • Many parts of the United States have the type of mosquitoes that can spread Zika virus
  • Pregnant women are advised against traveling to areas with Zika
  • Couples where one partner lives in or has traveled to a Zika area should use protection during sex.

Learn more about Zika

Replicons are portions of the viral genome that can replicate on their own, without relying on the machinery of the host cell. They are used in research and drug development for studying certain features of viruses, such as their replication machinery.

The authors of the new study note that replicon systems have been widely used for other flaviviruses, such as dengue fever and West Nile virus.

For their study, the researchers created an experimental system that generates replicons of the Zika virus that are stripped of the genes that give the virus its structure and make it infectious. This makes it less dangerous to work with.

Senior author Pei-Yong Shi, a professor in the department of biochemistry and molecular biology at UTMB, explains:

“One of these replicons can be used to locate portions of the viral molecule that block or halt viral replication, making it a powerful tool for vaccine development.”

“The other newly developed replicon was designed to study potential antiviral agents by differentiating between when the virus is making copies of itself and when it’s altering its structure,” Prof. Shi adds.

An important feature of the system is it attaches genes to the replicons so the researchers can tag the parts of the virus they are interested in.

For example, they are able to use Luciferase, the compound that makes fireflies glow, to light up targeted parts of the virus so they can more easily observe particular processes, such as replication.

Knowing when and how the virus is mutating is important, as evolution is what makes viruses more adept at invading hosts like humans or animals or become more damaging once inside the host.”

Prof. Pei-Yong Shi

Learn how Zika genome sequencing revealed an immune-inhibiting viral molecule.