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# Discovering the HIV/AIDS Drug "Cocktail" in an Equation

The pioneering HIV/AIDS researcher used high school math in creating a drug "cocktail" to combat the worldwide epidemic.

## TRANSCRIPT

Question: How did your education prepare you for your eventual development of an HIV drug "cocktail?"

This is where my quantitative background in physics applied; we realized that we could actually write that out mathematically in a straightforward differential equation that an AP high school student would be able to do. From there, fitting the data and doing the calculation we were able to come up with the idea. We were using the drugs to block virus infection and production and therefore the precipitous decline reflected the fact that the virus was constantly being cleared at a very rapid rate. So using that quantitative background we were able to calculate what the turnover of virus was all the time in a given infected person and that number turned out to be enormously large, so the virus was just replicating away at a rapid clip.

And from there we also knew that HIV changes every time it replicates, so high replication rate meant high error rate and therefore HIV was able to mutate very quickly. We could then do the additional calculation to show that if you treat this virus with one or two drugs at a time the virus is predictably going to mutate and escape from the action of the drugs. But at the same time we could also calculate what it would take to corner the virus so it’s not able to escape. Those calculations suggested to us that three or more drugs would do the trick. So we knew that by 1995 and launched a series of experiments in patients using what is now called a cocktail therapy of three drugs or more. And immediately within weeks we saw the good result. But we wanted to wait to see if the results could be sustained and it was only by middle of 1996 we realized that we were able to keep the virus below detection level for a good year and that opened up the door for what is called combination therapy today.

Question: When did you first know that you wanted to be a scientist?

David Ho: I’m not sure there was one moment that sparked my interest in math and sciences. I think as far as I could recall I have always had some interest in these areas. I certainly remember being a very curious child and perhaps that is a precursor to pursuing science, but I think there is also quite a bit of family influence that affected me gradually and that has to do with having a number of important family members who pursue science or engineering, including my father and a very important uncle. Their interest in technology and in sciences I think had a great deal of influence on my decision ultimately to pursue science.

Question: How intense was your early education in science and math?

David Ho: In terms of the math education in Taiwan, it was quite intense. So the math that I had learned by sixth grade served me pretty well until about eighth or ninth grade here in the U.S. In terms of science education we didn’t have that much formal science in Taiwan and I began to be exposed to that in the later years in middle school and of course in high school and so I think I was first grounded in math and then gradually shifted into the sciences. That is what I remember.