FLC | TNPRC scientists detail their primate-based quest for a COVID-19 vaccine

TNPRC scientists detail their primate-based quest for a COVID-19 vaccine

April 23, 2020

This month, the National Institutes of Health, National Institute of Allergy and Infectious Disease awarded a contract to the Tulane National Primate Research Center to test potential vaccines and treatments to combat COVID-19.

The research beginning there in just a few weeks will attempt to answer many vexing questions, said Dr. Chad Roy, director of infectious disease aerobiology at Tulane National Primate Research Center and the project’s director.

“We are looking to really develop the non-human primate model from which we can begin to understand such things as the mode of transmission, the route of exposure, and why some people are getting mild doses of the virus, while others are dying,” Roy said. “We will be utilizing three different primate species closely aligned with the human population, for testing. This includes the rhesus monkey, the rhesus macaque, and the African green monkey. We will be testing both treatments and vaccines, and at this moment there are already over 70 potential vaccines.”

Animal models have always been critical, and in fact private labs all across this country working on their own therapeutics and vaccines are required to show results in monkeys before any FDA approval could ever be granted. Studying the immune responses in primates give a much clearer idea of why and how people are infected, and gives us a window into determining whether a repeated onslaught of the virus makes it more difficult for our own immune systems to fend off this particular coronavirus.

The 4,000 animals who live at the primate center are a hardy bunch. They and their predecessors there have been used in biomedical research for 50 years, so much is known about their genetics, and it’s why they will play a very important first-step in the research.

“We initially need to simulate how this virus affects a normal healthy person, so we use very healthy primates,” Roy said. “These are animals very close to us genetically, so their response to treatments and new vaccines is very closely aligned with ours. Once we establish how a healthy non-human primate responds, then we can factor in comorbidities that arise out of pre-existing conditions in humans, like hypertension, diabetes, COPD, and morbid obesity.”

Assuming COVID-19 will continue to spread, it’s important we learn just how the contagion goes from one individual to another, why everyone responds in a different manner, and how long the virus actually stays in the body, even after symptoms abate.

It’s a question that’s now been posed in light of China’s lifting of its own lockdown, only to see a re-emergence of COVID-19 cases within the first week.

“We know that you can shed virus for two to three weeks after your symptoms resolve,” said Robert Garry, M.D., a virologist and professor of microbiology and immunology at Tulane Medical School. “But does this mean one is still infectious? It’s likely shedding could last a while, but is it days or weeks? We don’t know, and it’s something for which we need an answer before we send anyone back into the community.”

Reactivation has been seen before with Ebola, where patients were supposedly recovering, only to find the virus in what are called “privileged” sites: the brain and testes, which respond less to traditional antivirals.

“There’s no evidence yet that this is happening with COVID-19, but it has happened with SARS, and with AIDS, where there’s sexual transmission,” Garry said.

So, how would a vaccine study work with primates?

“We would try to stay consistent with a human schedule for vaccines,” Roy said. “So, a primary dose, then a waiting period of 30 days before a booster, then another 30 days and maybe another booster. Then we would wait four or five weeks for a challenge study to get an idea of the immediate immunology associated with a response to that vaccine. The animals will be constantly monitored for heart rate, fever, breathing, and we have incredible resources here … PET scanners, CT’s, you name it.”

Although the world demand for a vaccine has reached a fevered pitch, it’s difficult to predict exactly how long it will take for all of the steps required to develop and deploy a vaccine.

“This won’t be an easy virus for which to find a vaccine,” Garry said. “But I’m one of the people who thinks it’s possible, if we put everything we have at it in a Manhattan-style Project, pulling out all the stops. That means getting out of our own way with regulatory issues. It’s important to test treatments and vaccines simultaneously, and certainly test drugs on the sickest patients. And if we do find something effective, we need to gear up manufacturing very quickly. We spent $2 trillion on a stimulus package, so if we spend a fraction of that, we should have a vaccine.”