Scientists at UC Davis and the University of Wisconsin are using primates to study the Zika virus in the hopes of developing a vaccine and understanding the virus’s impact on developing fetuses.
Koen Van Rompay, a prominent HIV researcher, is leading the effort at UC Davis’ California National Primate Center. He plans to use up to eight rhesus macaque monkeys to learn more about the poorly understood Zika virus.
The World Health Organization has declared the rapid spread of the Zika virus a global emergency. Between January 2014 and February 2016, 33 countries reported cases of Zika. As of Feb. 12, the U.S. Centers for Disease Control and Prevention had tallied 52 reports of travel-associated Zika cases, including two in California. One of those was in Yolo County, a person whose identity was not released, who traveled recently outside of the U.S.
Van Rompay and specialists in mosquito-borne diseases at UC Davis will work with blood specialists from the University of California, San Francisco. The UC researchers will collaborate with researchers at the Wisconsin National Primate Research Center, which focuses on the transmission of diseases and viruses during pregnancy.
Van Rompay said the goal is to build a two-phase research model to study how the infection causes the disease. In the first phase, four non-pregnant monkeys will be infected with the virus and daily blood samples taken to assess how and when the monkeys contract the disease.
“We think this should work because this is the way the Zika virus was first detected in 1947,” said Van Rompay.
That year, researchers from the Rockefeller Foundation were working in Uganda studying yellow fever using rhesus monkeys. The research was done in the Zika forest, the locale that gave the virus its name. The monkeys were put in cages in the forest, and one took ill with the then-unknown virus. The new virus was later injected into mice, which also developed the illness. The first case of Zika in humans was identified in Nigeria seven years later.
Once the monkeys at the UC Davis primate center get infected and it is understood why, the next stage will involve infecting up to four pregnant monkeys during the first part of gestation to observe Zika’s effects on growing fetuses, Van Rompay said.
It is not clear how the virus is transmitted from mother to fetus. Von Rompay’s research may go a long way to understanding that process and how, or whether, having the virus leads to microcephaly – a rare condition associated with incomplete brain development and babies born with a smaller heads than normal.
To date, roughly 4,000 cases of microcephaly recently reported in Brazil may be a result of the fast-spreading virus. “Right now it seems there is a strong link between Zika and infection and the microcephaly, but it has not been 100 percent established,” said Van Rompay.
Research published Friday in the New England Journal of Medicine is being touted as the “smoking gun” establishing that Zika is at the root of the microcephaly cases, said David O’Connor, virologist and associate director of the Wisconsin National Primate Research Center.
That research, conducted at the University of Ljubljana in Slovenia, involved a woman who had been infected with the Zika virus in Brazil during the first trimester of pregnancy. After she returned home to Slovenia, the woman terminated her late-term pregnancy. An autopsy showed a high concentration of Zika virus in the fetus’s brain.
That single incident study suggests more research needs to be done. “It’s complicated, because microcephaly can have a variety of causes, of which viruses are just one,” said O’Connor.
O’Connor said he will start his research with the rhesus monkeys next week. He said using nonhuman primates will be vital to finding more answers about Zika, because primate research allows the introduction of a virus at differing stages of a pregnancy, something that cannot be done on human subjects.
The researchers will also examine the immune response triggered when the Zika virus is detected so a vaccine can be created to mimic that protective response.
“We will infect macaques, let them develop immune responses that we can measure, and then re-challenge some period of time later. If the animals are protected from reinfection, we will know that the measured immune responses can be protective,” said O’Connor.
Such experimentation on primates is controversial, but researchers see it as necessary given the animals’ similarity to humans. Treatments for diseases such as polio and measles were first tested and developed using primates.
At Davis, Von Rompay is interested in establishing whether the Zika virus shares traits with other viruses, especially ones in which the virus causes a direct infection of the fetus and causes brain damage. “A possibility is that somehow the host mother develops an immuno-response against the virus, and that immuno-response may somehow cause the harmful effects in the fetus,” he said.
Zika infection in adults has also been implicated in development of Guillain-Barré syndrome. That autoimmune disease can lead to total paralysis and develops as a result of the immune system attacking a host’s nervous system because of the presence of the viral infection.
The expectation is that a vaccine can be developed for the Zika virus rather quickly. The virus is in the same family as yellow fever, for which there is a vaccine, Van Rompay said.
He said it could take a year or so to develop a vaccine to use in human trials.
Edward Ortiz: 916-321-1071, @edwardortiz