Brand-New Vaccine Strategy Works Against Herpes, And Potentially HIV

Coaxing T cells to combat genital herpes at the source is good. Talking them into blocking HIV is even better.

Yale researchers developing a new technique for vaccination against genital herpes have succeeded, but their research may have implications far beyond what they set out to accomplish. Employing a two-part immune-system-boosting strategy known as “prime and pull,” the researchers have effectively coaxed the body’s own antibodies into setting up a defensive blockade in tissues that formerly were not conducive to such immune responses. In doing so, they may have found a mechanism that is effective in preventing not only herpes, but other sexually transmitted infections as well–infections like the AIDS-causing HIV-1.

Vaccines generally work by boosting the bodies own inherent immune responses to certain pathogens, but for certain kinds of infections this kind of vaccination has proven difficult. This has to do with the body’s so-called “memory” T cells. These antibodies deploy when a foreign pathogen is found within the body, and when they do battle with a given pathogen they do what any good soldier would do: They learn from their adversary. These memory T cells can “remember” how to defeat a certain kind of infection, allowing them to mount increasingly stronger immune responses to fight certain pathogens the body has seen before.

But though these memory T cells circulate throughout the body, certain tissues don’t readily harbor them. As such, these tissues are more susceptible to certain kinds of infections, and they are in some places you really don’t want to see infected–places like the central nervous system, the intestines, some regions of the respiratory system, and critical for the Yale researchers’ purposes, some tissues in the female genital tract.

That makes these regions susceptible to infection–unless T cells can be coaxed into taking up residence there. The Yale team’s “prime and pull” method is focused on exactly that. Working with mice, the researchers found a way to “prime” T cells to fight a certain kind of infection (in this case, genital herpes) through conventional vaccination that causes a system-wide immune response. Then, via a topical application of chemokines–chemical agents that initiate movement in immune cells–they were able to “pull” these T cells into tissues where they normally don’t take up residence, like those peripheral tissues in the vagina that are usually susceptible to infection from various sexually transmitted infections.

These primed T cells effectively took up residence in these tissues where they are usually restricted and have shown to increase immunity toward genital herpes by putting up a wall between the herpes simplex virus (HSV) and the cells they infect. That’s good for HSV vaccination, but the implications may be far greater. The “prime and pull” technique could potentially be used to combat any infectious agent that enters the body through any specific tissue–agents like the human immunodeficiency virus (HIV) that causes AIDS. That’s not to say that this is a cure by any means, but it opens the door to a possible HIV inhibitor.

In fact, prime and pull could go even further. “The prime and pull may not be restricted to fighting infections,” lead researcher Akiko Iwasaki told PopSci via email. “One can imagine prime and pulling T cells into solid tumors to facilitate T cell based tumor killing.”

Potential treatments to help stymie both cancer and HIV; not bad for a single vaccine study.