News Story

Fighting back: HIV is deadly because it destroys the immune system.
But Dr. Paul MacPherson is looking for ways to help the immune system fight back.

A viral infection is a war between a very small, simple invader, and the body’s hugely complex system of defense, the immune system. The immune system usually wins the war, and it’s not hard to see why: it contains hundreds of types of specialized cells, each designed to attack the virus in a different way. It also has a complex network of signals used to recruit various immune cells and order them to adopt certain tactics.

HIV is one of the few viruses that almost always wins against the human immune system. It has less than a dozen genes (compared to the 30,000 human genes) and it is about a thousand times smaller than a single human cell, but it has some tricks up its sleeve. Dr. Paul MacPherson is studying those tricks, and looking for ways to sabotage them. Dr. MacPherson is a Scientist in the Molecular Medicine Program at the Ottawa Hospital Research Institute, an Infectious Diseases Specialist at The Ottawa Hospital, and an Assistant Professor of Medicine at the University of Ottawa.

While it has been known for some time that HIV directly infects the “helper” cells of the immune system, Dr. MacPherson is studying a more subtle viral attack mechanism: He has found that HIV can prevent the body’s main “attack” cells from receiving certain messages. The virus doesn’t have to infect the “attack” cells to do this; it just sends them signals telling them to “turn off” the machinery they use to receive recruitment messages from other immune cells. In effect, the virus gums up the immune system’s communication network.

Most HIV drugs available today work by disrupting replication of the virus, but Dr. MacPherson’s work suggests that it might be useful to also design drugs to disrupt these more subtle viral attack strategies. If HIV is hitting the immune system at many levels, then HIV drugs should be designed to hit back along similar lines.

As a physician-scientist, Dr. MacPherson is able to study HIV both in the test tube, and in patients. For more information, visit his web profile.