Courtesy: United States Air Force

A young child receiving the polio vaccine in Djibouti.

Poliovirus. Typhoid fever. Yellow fever. Measles.

When was the last time you worried about contracting any of these diseases? Well, for the most part, you never will, and that’s thanks in part to vaccine research with nonhuman primates (NHPs). Being up to 98% genetically similar to people, primates are uniquely capable of revealing how many diseases work in the human body. Due to their similarities to humans, monkeys are irreplaceable for vaccine development because they alone mirror the entire biological process of infections in people. These days, scientists are studying NHPs to develop new vaccines for everything from cancer to Zika to HIV.

An HIV Vaccine

HIV is a virus that attacks the body’s immune system, specifically T cells. There is currently no cure, but HIV can be managed through the use of antiretroviral therapy (ART).

Those who are infected can expect to live normal lifespans if they receive one of the various ART “drug cocktails,” which have proven to be effective for so many.

Although previously considered a death sentence, HIV is now a manageable condition with treatment. An HIV vaccine would prevent further spread of the disease and may even one day eliminate the disease altogether. That’s the ultimate goal of research scientists. In fact, Oregon Health and Science University (OHSU) is recruiting volunteers for HIV vaccine clinical trial in humans, due to start next year. The vaccine is a weakened strain of a common herpes virus, engineered to look like HIV to the immune system.

This vaccine holds promise and is one of several vaccine candidates under review which gives researchers reason to believe that an HIV vaccine could become a reality. Louis Picker, an HIV researcher with OHSU, tested the vaccine first in NHPs. It showed positive results – curing nine of the 16 animals that were infected with HIV. Monkeys are essential for this and future HIV/AIDS research.

Although the HIV vaccine is new, primates’ contributions to HIV/AIDs research are not. NHPs have been a valuable animal model for HIV research for the past 30 years. A zoonotic disease, HIV evolved from the Simian Immunodeficiency Virus (SIV), which can cause acquired immunodeficiency syndrome (AIDS) in monkeys. No other mammals are able to replicate HIV infection in humans. At the National Primate Research Centers (NPRCs), researchers were able to gain insight into viral infection and potential targets for vaccines. They were also able to determine that primates’ immune systems are similar to ours. From better understanding transmission of HIV, to developing ART cocktails that can control HIV, to developing drugs that can help prevent HIV transmission, NHPs have contributed to many breakthroughs in HIV research.

Other Infectious Disease Research with Monkeys

An Aedes aegypti mosquito. This kind of mosquito transmits Zika virus.

An Aedes aegypti mosquito. This kind of mosquito can transmit Zika virus.

Primates also are invaluable research models for the Zika virus and malaria. Three species of NHPs – the owl monkey, the squirrel monkey and the chimpanzee— are vulnerable to the same parasite that causes malaria in humans, and are currently being studied to develop malaria vaccines. Currently, researchers at the University of Wisconsin-Madison are studying pregnant monkeys to better understand how the Zika virus can infect a mother and alter her baby’s development. Humans and NHPs are similar in numerous ways, including nervous system, toxin response and infant development. These similarities help to create animal models that can inform researchers about the effect a certain toxin may have on a developing fetus. Research with primates is enabling scientists to find viable treatments for Zika and better courses of treatment for malaria in order to save human lives.

With the many genetic and physiological similarities between people and primates, these animals essential for halting some of the worst epidemics affecting the world today. So many other diseases have already become something kids only read about in history books thanks to vaccines developed with NHPs. With any luck, and a lot of research, HIV, Zika, malaria and other infectious diseases won’t be a concern to future generations. And we will have monkeys to thank for that.

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