A new vaccine for poison ivy, poison sumac and poison oak is going to Phase 1 clinical trials later this year.

The chemical compound, which desensitizes the immune system against the agent in poison ivy that causes a rash and itching, is the brainchild of Mahmoud ElSohly, a professor and researcher at the University of Mississippi and founder of ElSohly Laboratories.

ElSohly, who has done extensive work with medical marijuana as well as the anti-cancer drug Taxol, began researching poison ivy in the mid 1970s when he first joined the university, working with another professor who was trying to find the key to stopping the annoying effects of poison ivy.

The harmless-looking green plant is the bane of many during the spring and summer months. Once exposed to it, poison ivy can cause painful itching and a rash on the skin.

That research didn’t pan out, ElSohly said, but it got him thinking about whether there was a way to desensitize the body to poison ivy. After years of research, he found a way to do just that, he said.

When someone is exposed to poison ivy for the first time, there usually isn’t a reaction; it is only the second or third time they are exposed that the immune system reacts.

So ElSohly and his team of researchers — both at the University of Mississippi and at his private laboratory — began looking at a way to turn off this mechanism.

What they found was if they masked the active chemical or compound of poison ivy and then got it to bind to plasma proteins, it would then circulate throughout the body, he explained.

Once there, it binds to cell membranes, where an enzyme eats away the mask and the active chemical works its way into the immune system and turns off the reactivity to poison ivy.

The chemical compound — known as HPT-721 — was found extremely effective in tests on guinea pigs, whose skin is similar to humans, ElSohly said.

The vaccine, which would be injected, has been licensed to Hapten Sciences Inc. of Memphis, Tenn., and clinical trials are expected to start later this year, ElSohly said.

It will be at least two years before it would be available for use in humans.