SAN ANTONIO (July 23, 2024) — Throughout his 23-year career, Stanton Gray, D.V.M., Ph.D., DACLAM, has sought to improve animal and human health as a veterinarian, colony manager and researcher. Combining both animal care and independent research is often a challenge. Each role requires high levels of dedication, time and energy, and it is rare to find job structures that provide support and protected time for both.

He has found his sweet spot at Texas Biomed and Southwest National Primate Research Center (SNPRC), where he will dedicate one-third of his time to research and two-thirds to managing the center’s three breeding colonies of baboons, rhesus macaques and marmosets.

“This is what I’ve been working towards and hoping for,” says Dr. Gray, who recently began as both Associate Professor and Colony Administrator. “I am thankful I didn’t have to choose one path or the other.”

Dr. Gray’s expertise lies in working with pedigreed nonhuman primate colonies that have been carefully studied over generations. He uses detailed genetic information to investigate how genetic variation influences diseases like obesity and cancer. Teasing apart genetic factors from environmental influences or epigenetics – changes to the genome that occur throughout life – is difficult. But with nonhuman primates, it becomes possible

to get answers that benefit both animals and humans.

“Pedigreed nonhuman primate colonies have this unique ability to answer questions about complex genetic diseases,” he says. “They can answer questions about how genetics contribute to disease risk in ways that you can’t easily answer with human studies.”

Growing up in Oklahoma City, Dr. Gray had considered attending “human medical school,” but at the encouragement of a friend, checked out veterinary medicine. He worked for a local small animal vet who cared for pets, strays and wildlife, so he built up diverse experience in animal care quickly. He studied zoology and population genetics at the University of Oklahoma and veterinary medicine at Oklahoma State University. After a few years working in private practice in California and Oregon, he decided to go back into research.

“I had the fire in my belly to do research,” he says. “I really enjoy the creativity to pose questions that have not been answered and work towards a better understanding.”

He completed his lab animal medicine residency and a Ph.D. in molecular pathology at Wake Forest University. He served as staff veterinarian at Wake Forest University and then Assistant Director at the Oregon National Primate Research Center. For the last 10 years, he managed a colony of 1,000 rhesus macaques at the Keeling Center for Comparative Medicine and Research at The University of Texas MD Anderson Cancer Center. He also researched conditions that affect both humans and macaques, including colon cancer, Lynch Syndrome, chronic colitis and Chagas disease.

Specifically, he and collaborators Eduardo Vilar-Sanchez, M.D., Ph.D., at MD Anderson and Jeff Rogers, Ph.D., at Baylor School of Medicine, are developing an anti-cancer vaccine that could help reduce colon cancer risk for people with Lynch syndrome. Lynch syndrome is a genetic disease that significantly increases the risk of many types of cancer, especially colon cancer. It involves mutations in “mismatch repair genes,” which normally repair mistakes that occur during DNA replication. The mutations result in non-functional proteins that inhibit this repair function and this is connected with cancers developing at earlier ages.

“Instead of getting colonoscopies in your 40s, if you have Lynch syndrome, you are getting colonoscopies in your 20s,” Dr. Gray says.

Colon cancer is also the most common form of cancer in rhesus macaques. Dr. Gray is seeking to understand if mutations in mismatch repair genes in macaques cause colon cancer through the same or similar pathways as people. If so, rhesus macaques would make excellent models for studying the disease and potential interventions for both humans and animals.

“There seems to be an epigenetic inactivation of the mismatch repair genes. And is that a universal pathogenesis for colon cancer? It seems to be a universal mechanism, but we don’t know for sure,” he says.

He is also studying a common problem that occurs in rhesus macaque colonies: colitis, more commonly known as diarrhea. Understanding and addressing this would be extremely beneficial, especially considering that rhesus macaques make up the majority of nonhuman primates in biomedical research.

“It is such a common problem that clarifying what is going on and developing solutions could have an enormous impact on the overall health of rhesus colonies everywhere,” Dr. Gray says.

Part of the work involves investigating a bacteria called Campylobacter, which is the most common culprit causing diarrhea in people in the U.S. and elsewhere. Dr. Gray is interested in working with others to develop a vaccine to protect against the bacteria for both animals and people.

“Developing a vaccine for Campylobacter is something that has worldwide implications for human and animal health,” Dr. Gray says.

Preclinical findings provide strong evidence for moving vaccine candidate forward in first-of-its-kind study

A vaccine against Zika virus is safe and effective when administered both before and during pregnancy, according to new research published in npj Vaccines.

The purified, inactivated Zika vaccine (ZPIV) candidate, developed by Walter Reed Army Institute of Research (WRAIR), is being evaluated in animal models at Texas Biomedical Research Institute (Texas Biomed) in collaboration with WRAIR and Trudeau Institute in New York.

The vaccine candidate has previously been shown to effectively block prenatal Zika virus transmission when given to nonhuman primates prior to pregnancy. This new study goes a critical step further, studying what happens when the vaccine is administered during pregnancy.

“This is a giant step forward,” says Jean Patterson, Ph.D., Professor Emeritus at Texas Biomed. “We have very strong evidence that this vaccine could protect fetal health during the next Zika outbreak.”

Zika virus is primarily transmitted by mosquitoes. It does not typically cause serious illness in most people; the biggest threat is to pregnant women and developing fetuses. During the 2015-2016 Zika outbreak in the Americas, there was a surge in miscarriages and babies born with extremely small heads and other severe birth defects, collectively called Congenital Zika Syndrome. Zika virus continues to circulate at low levels and has been detected in 89 countries and territories to date.

“Zika virus continues to infect people around the world and present a significant risk to maternal-fetal health,” says Stephen J. Thomas, M.D., an inventor of the ZPIV vaccine and a study collaborator. “Because of this, advancing the development of vaccine candidates and studying different use scenarios is incredibly important.”

The vaccine candidate has completed Phase 1 clinical trials in humans and was well tolerated and elicited an immune response. But clinical trials usually exclude pregnant people, leaving key questions unanswered about whether vaccination during pregnancy would be safe and potent. This new study is believed to be the first to evaluate a Zika vaccine during pregnancy in nonhuman primates. Marmosets, a small nonhuman primate that typically has twins and triplets, are sensitive to Zika virus infection and closely mirror what happens in pregnant humans.

Given the drastic changes that the immune system undergoes during pregnancy, the researchers were not sure if the vaccine, when given during early pregnancy, would generate a protective immune response, such as creating protective antibodies.

“The antibody response when given during pregnancy was similar to the level we observed when administered before pregnancy,” says In-Jeong Kim, Ph.D., a principal investigator at Trudeau Institute. “That is very exciting.”

The vaccine candidate prevented placental damage and sufficiently blocked transmission of Zika virus from mother to fetus. The viral load in placentas and fetuses was significantly lower in the vaccinated group versus the unvaccinated group. Growth and development of fetuses of vaccinated adult marmosets exposed to Zika virus were similar to controls not exposed to the virus. No adverse effects were detected.

What remains to be studied is if protection will last throughout pregnancy and whether offspring born from vaccinated females challenged with the virus during pregnancy are free of Congenital Zika Syndrome. 

“We hope to garner more interest and funding to pursue those next steps,” says Dr. Patterson.