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Johns Hopkins scientists have found that a safe and inexpensive antibiotic in use since the 1970s for treating acne effectively targets infected immune cells in which HIV, the virus that causes AIDS, lies dormant and prevents them from reactivating and replicating.

The drug, minocycline, likely will improve on the current treatment regimens of HIV-infected patients if used in combination with a standard drug cocktail known as HAART (Highly Active Antiretroviral Therapy), according to research published now online and appearing in print April 15 in The Journal of Infectious Diseases.

Unlike the drugs used in HAART which target the virus, minocycline homes in on, and adjusts T cells, major immune system agents and targets of HIV infection. According to Clements, minocycline reduces the ability of T cells to activate and proliferate, both steps crucial to HIV production and progression toward full blown AIDS.

If taken daily for life, HAART usually can protect people from becoming ill, but it's not a cure. The HIV virus is kept at a low level but isn't ever entirely purged; it stays quietly hidden in some immune cells. If a person stops HAART or misses a dose, the virus can reactivate out of those immune cells and begin to spread.

This drug strikes a good balance and is ideal for HIV because it targets very specific aspects of immune activation.

Minocycline reduces the capability of the virus to emerge from resting infected T cells, Szeto explains. It prevents the virus from escaping in the one in a million cells in which it lays dormant in a person on HAART, and since it prevents virus activation it should maintain the level of viral latency or even lower it. That's the goal: Sustaining a latent non-infectious state.

The team used molecular markers to discover that minocycline very selectively interrupts certain specific signaling pathways critical for T cell activation. However, the antibiotic doesn't completely obliterate T cells or diminish their ability to respond to other infections or diseases, which is crucial for individuals with HIV.

HIV requires T cell activation for efficient replication and reactivation of latent virus, Clement says, so our new understanding about minocyline's effects on a T cell could help us to find even more drugs that target its signaling pathways.