Mount Sinai physician spends 20 years investigating HIV


Almost two decades ago, Dr. Kelly MacDonald saw first-hand the devastation AIDS would leave in Africa. Today, she is still dedicated to helping find a cure for HIV.

“When it comes to the world-wide epidemic HIV, research and prevention are essential to stopping its spread,” says Mount Sinai Hospital microbiologist and infectious disease consultant Dr. MacDonald who has been researching AIDS for nearly 20 years. “It’s hard to believe that it has been that long.”

It all began in 1987 when she was a medical student working on a clinical research project in Nairobi with people who had been infected with Sexually Transmitted Diseases (STDs). In 1992 she returned as a research fellow at the University of Nairobi and began studying female sex workers in the poorest region of the country. At this time more than 90 per cent of the sex workers were infected with HIV but there was a puzzling small number who remained uninfected, despite the odds.

“In an attempt to find an explanation for this, we began examining their immune systems to see if there were genetic or functional differences which might account for their apparent resistance to infection,” says Dr. MacDonald. “There were in fact some striking differences that correlated with their resistance to HIV.”

These women had vigorous cellular immune responses that recognized HIV either from exposure to a defective virus or a small aborted previous infection. These rare individuals, who have now been identified in other situations of recurrent high risk behavior, remain the only natural examples of protective immunity to HIV infection.

“This research is critical because in its absence, we have no natural example from which to start creating an effective vaccine for HIV which mutates rapidly and evades the usual immune defenses.”

Today, Dr. MacDonald continues to research new and innovative ways to create vaccines that protect against HIV. She can now be found supervising research labs in Toronto where graduate students and post-doctoral fellows study the immunobiology and epidemiology of HIV infection. A recent study of HIV vaccines, led by Dr. MacDonald examines the chickenpox (Varicella Zoster Virus) vaccine. There is evidence that this vaccine provides life-long protection in healthy people because it reactivates periodically and “self boosts” the individual. The failure of HIV vaccines to date to produce long term immunity led to the consideration of whether the chickenpox vaccine could be a successful vaccine to carry HIV genes.

The study could lead to a vaccine that could potentially be used to immunize kids from both chicken pox and HIV before they are sexually active. This is an example of a strategy that might provide a cost-effective preventative vaccine world-wide, something never far from Dr. MacDonald’s mind.