By Jennifer Nachbur
The University of Vermont Vaccine Testing Center has announced that it will be involved in the clinical trials and research on a vaccine for Zika virus, which was declared a global health emergency by the World Health Organization on February 1, 2016.
UVM Vaccine Testing Center faculty Kristen Pierce (KP), MD, an infectious disease specialist and associate professor of medicine, and Sean Diehl (SD), PhD, an immunologist and assistant professor of medicine, have expertise in the characteristics of flaviviruses—a group of viruses, mostly transmitted via insects, that cause such human diseases as Zika virus, yellow fever, dengue, various types of encephalitis, and hepatitis C—and related vaccines. An infectious disease physician, Pierce has led or co-led several dengue and West Nile virus vaccine–related trials. Diehl studies the basic mechanisms of flaviviruses, vaccines against flaviviruses, and the immune responses triggered by flavivirus natural infection or vaccination. The two researchers provide information about Zika virus in the Q&A below.
Will the Vaccine Testing Center (VTC) be involved in the development of a vaccine for Zika virus?
KP & SD: The VTC has a long-standing partnership with the National Institutes of Health (NIH) lab, which developed a dengue vaccine and is developing the Zika vaccine, and the VTC, together with the Center for Immunization Research at Johns Hopkins University in Baltimore Maryland, will be one of two sites to test the safety and immune response testing of an NIH-developed Zika vaccine candidate in humans. Because of the potential for a link of Zika infection with birth defects, pregnant women or those who may become pregnant will be excluded from the Zika vaccine trials.
What is Zika virus and where did it originate?
KP: Zika virus belongs to a group of viruses known as flaviviruses. Other well-known viruses, such as yellow fever, dengue, and West Nile, all belong to this same group. First isolated in Uganda in 1947, Zika virus has circulated in Africa and Asia since that time. So although Zika is not a “new” virus, its presence in the Americas is.
SD: The name flavivirus comes from the Latin “flavi,” which means “yellow,” because of the yellowing of the skin that can occur during infection with yellow fever virus. Zika virus was first found in the Zika Forest of central Uganda when a sentinel monkey became feverish during a study on the patterns of yellow fever virus circulation. Zika has been circulating beyond this initial area and has been associated with outbreaks as recently as 2007 in Micronesia.
How is Zika virus contracted?
KP & SD: Like the other flaviviruses, Zika is transmitted primarily by the mosquito Aedes aegypti and, to a lesser extent, the related Asian tiger mosquito Aedes albopictus. These mosquitos live primarily in tropical climates. Aedes aegypti is now common in the southeastern US, particularly in Florida, and Aedes albopictus has spread as far north as Washington, DC, and New Hampshire. Humans are infected with Zika when they are bitten by an infected mosquito.
What are the symptoms of Zika virus?
KP: About 80 percent of people who are infected with Zika are asymptomatic. The other 20 percent experience nonspecific symptoms consisting of fever, rash, joint pains, and sometimes an associated conjunctivitis. Symptoms usually begin within a few days after a person has been bitten by an infected mosquito and last up to one week. Symptoms are usually mild. Severe disease leading to hospitalization or death from Zika virus infection is quite rare. Mother-to-child transmission of Zika has been demonstrated throughout all stages of pregnancy, leading to fetal demise and possibly microcephaly. There has been a significant increase in the number of cases of Brazilian children born with microcephaly since the start of the Zika virus outbreak. Studies are currently ongoing to determine whether there is a definite association between the increased incidence of microcephaly and Zika virus infection.
Is there a vaccine for Zika virus?
KP: Currently, there is no available vaccine to prevent against infection with Zika virus. However, the NIH has made the development of an effective Zika vaccine a priority. For now, the most effective way of preventing infection is avoiding mosquito bites by wearing long sleeves and pants, and using effective mosquito repellents.
SD: Because of the Zika virus’ relatedness to dengue virus and the fact that there are dengue vaccine candidates in advanced stages of clinical testing, the new Zika virus vaccine may utilize components of the dengue virus vaccine.
Are there any treatments for patients with Zika virus?
KP & SD: There are no specific treatments for Zika virus infections.
What can an individual do to prevent contracting Zika virus?
SD: Avoid travel to countries where Zika is circulating. Use insect spray containing DEET, and wear clothing that fully covers the skin. Utilize sleeping facilities with air conditioning and insect screens; bed nets can also be used, but Aedes aegypti and Aedes albopictus mosquitos are primarily daytime biters.
-Jennifer Nachbur is a writer for the UVM College of Medicine. This piece was first published on UVM Medicine.