AIDS Basics

What is 'AIDS'?

It stands for Acquired Immune Deficiency Syndrome and its hallmark is a deterioration, slow and steadily, of our immune system based mainly in its early stages on harm to a central cell of our immune system, and when that cell starts to decline certain important signals to our immune system are lost and important functions to enabling a proper immune response to other things, especially things that don't normally cause problems in a healthy person, start to cause serious problems in a person who is HIV infected.

How did you learn about AIDS?

My interest was drawn to it by an epidemiologist named James Curran of CDC, the Center for Disease Control, in Atlanta, Georgia, when he gave a convincing lecture at the National Institutes of Health. I was in the Cancer Institute, which is part of the National Institutes of Health. And at first when he came, he talked about this new epidemic... well it didn't seem very important, a few cases. When he came back a second time, I heard him give a full lecture and it was clear that it was very important and getting worse. It was also clear in his talk that he was thinking of an infectious agent, though there were other ideas as to what might be going on, including chemicals. And I also think that Curran probably believed it was viral. And I was working in virology, and he made the statement, "Where are the virologists?" like that help was needed, and I began thinking about it. And as I thought about it and returned to my laboratory, I recalled that the characteristics of the disease were that a very particular kind of blood cell, one of our key immune cells that is governing a large part of our immune system, appeared to be slowly disappearing in these patients. And that's a cell we call the T helper cell, now better known as the CD4+ T cell.

How did you determine that AIDS was caused by a virus?

We had just discovered the first and the second human retrovirus and I had reason think that AIDS (the disease we were hearing about) might be due to just this kind of virus, still another human retrovirus. This idea came from discussions with Dr Max Essex at Harvard with me when we began thinking about two things. Essex had great expertise with the leukemia virus in cats and he pointed out that with minor changes in the protein that is one of the surface proteins, called the envelope protein, minor changes of that, of the cat leukemia virus and that virus no longer caused leukemia but could cause immune impairment. Kind of the opposite. Instead of too many cells, too few cells. In our experience with the first human retrovirus, which we named Human T-cell Leukemia Virus 1 (HTLV-1), this virus, my colleagues and I discovered as the first human retrovirus in the period of 1979-1980. It causes an unusual form of cancer, leukemia of T-cells in young adults. And our experience with that virus was as follows: it infected exactly these kinds of cells, CD4 T-cells, T-helper cells. It was transmitted by blood and by sex and by mother to child. Little by little as we heard from the CDC, particularly from Curran this is a disease that seemed to favor certain groups where there was sexual activity or a baby born from a certain mother, who had AIDS, could get AIDS or blood transfusion recipient. So that fit this kind of virus and we also knew that this virus, even when it didn't cause leukemia, could give mild impairment of our immune system. Well, what about a modification of that virus? Might cause major impairment and be transmitted the same way. Furthermore, we were learning that there was a lot of AIDS in Haiti and it seemed to be that the origin might be in equatorial Africa. And we knew that the HTLV-1 was prevalent in Haiti and may have had its origin in Africa, and was common in some tribes in Africa, in the African rainforest and so on. So, we speculated that AIDS might be due to another retrovirus belonging to this greater HTLV family...new...but belonging to that family. This idea, was the one that bore fruit, the only idea that bore fruit but, in its details was wrong because mother nature what didn't turn out to be so simple...it's a retrovirus, the AIDS virus HIV, but it's a whole new family.

Is it possible to be HIV positive but never get AIDS?

In today's world very much so because of the effective therapy that we have -- so called triple drug therapy, or the cocktail that has been available since the middle of 1990's, but an HIV infected person who is not treated properly or does not get drug resistant if treated almost all will go on and get AIDS and die of AIDS if they are not treated. There are exceptions called long term non-progressors that are being studied but they are very very unusual -- suffice that they say it for practical purposes it almost does not exist, I mean I know cases, we all know cases but if that gets out the way that I could live with HIV infection without therapy it would certainly be the wrong message.

How long does it normally take HIV to cause AIDS?

Depends on your criteria. For me, the disease begins on the first day. The first days of infection, you're already seeing changes you can measure. Certainly, in two weeks, you can measure big changes already, serious changes. So, it depends on your sophistication of evaluation. But in the conventional way, when a doctor says you're clinically sick, that's five, six, seven, eight years on average, and some people go much longer before it shows up, and some people faster. Some African strains in some people in Africa seem to develop much quicker. Three, four, five years. In a baby it's quicker. So it also depends on who, who you're talking about. It also depends on what. It also seem that what virus strain may also be dictating a little bit. Cofactors are important. If you have a lot of things that are stimulating your immune system, what we call activating your immune system, if you're hot, souped up immune system, you do worse. The cooler response is better. You see that in animal studies. So it all depends on those factors.

How does a person's level of immune activity affect AIDS?

Perhaps last, and maybe not least, we talked before about an over-activated immune system, a heated up immune system. People exposed more to parasites, and to other infectious agents, as occurs in parts of Africa, particularly equatorial Africa, have a more heated up immune reactivity. When your immune system is more activated, more heated up, more virus can spread, more virus will replicate itself, reproduce itself. You'll have a higher, tighter virus. It'll be easier for you to transmit that virus to someone else. So the contribution of other infectious diseases to AIDS, just as AIDS contributes to other infectious diseases, making TB take off. If you're HIV infected and you have TB, your TB is much worse, and much more spreading. On the other hand if you have other infections that are activating your immune system those infections make HIV worse, more replicating, more easy to transmit.