by Tri D. Do, MD, MPH
February 2003
Lighthouse Community Center Newsletter
I have heard reports that some gay men are immune to the
AIDS virus. Apparently these men are being intensively studied by medical
science to find out how their bodies protect them from the virus. What
are the latest developments in this area of research?
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Dear reader,
Long-term non-progressors (LTNP) have been touted as being keys to the cure
for HIV & AIDS. As a refresher, or for those of you who haven’t
heard of LTNPs before, let’s go over some basics. In the early 1990s,
after more than a decade into the AIDS epidemic in the United States, some
people noticed that after many years of being HIV infected, they were still
healthy. Many other people whom they had known and who had become HIV-positive
around the same time as they did were either sick or had already passed away.
Usually, a person with HIV progresses to an AIDS diagnosis after 8-10 years,
but LTNPs have gone as long as 20 years without any signs of disease.
As time passed, we found that more and more people who weren’t getting sick.
In fact, anywhere from 1-5% of people who are HIV-positive may be long-term
non-progressors and they never see significant decreases in their CD4 counts.
There are some politically-motivated people out there who don’t believe that
HIV causes AIDS. They think that AIDS is some sort of money-making
conspiracy that doesn’t really exist and have pointed to non-progressors
as evidence that neither HIV nor AIDS are real. Of course, they’re
forgetting about the millions of HIV-positive people who have already died
from the disease, and that this small group of people who carry HIV is not
typical of most people who are HIV-positive.
So why aren’t LTNPs getting AIDS? As the epidemic and our knowledge
of the virus have matured, we have come upon one set of answers or another
to this question. Each time we figure something new out, the scientists
who find an answer may think their answer is the final word in what causes
LTNPs to remain healthy. But this really hasn’t turned out to
be the case.
Basically, there are many different reasons why certain people who are living
with HIV don’t progress to AIDS. Remember that HIV is a virus that
attacks the body’s immune system, and that AIDS is the syndrome of diseases
that can happen when the immune system is wiped out. The main basically
three reasons why people to not progress to AIDS:
1) they may have been infected with a weakened virus that their body is able
to fight,
2) they may have certain protective genetic traits that make it difficult
for the virus to effectively infect them, or
3) they may have super strong or smart immune systems that can fight off
even a hardy virus.
Some LTNPs may have a combination of any of the above. And it’s not
necessarily just gay men who may have one of these traits, although we’ve
heard more news about them in this country. In fact, we’ve seen the
same thing among commercial sex workers in Africa, newborns, and many others.
The bad news is that some LTNPs actually do progress, given enough time,
and the AIDS epidemic is a pretty new epidemic. Some LTNPs who may
have one of the protective traits continue to fight a constant battle inside
their body, and sometimes their own body’s fatigue allows the virus to take
over. Another way that LTNPs may progress is due to the fact that HIV
is a constantly mutating virus, and it may evolve in the body to become very
strong and escape the body’s defenses. By chance, new viral “quasi-species”
may emerge that the body can’t beat down. And it’s also clear that
most of these folks are never fully cleared of HIV—even in people with undetectable
virus in their blood, the virus can still be found in places like the lymph
nodes, brain, or other organs.
Finally, there have been stories of a few newborns that initially had evidence
of virus in their blood at birth. However, after 6 months, they appeared
to have completely cleared the virus from their system! How they accomplished
this seems to be pretty clear now: they had virus in their system at
birth, but they also had protective antibodies from their HIV-positive mothers.
These antibodies successfully neutralized the virus in their system soon
after birth, and the virus was never able to get a foothold in their delicate
young immune systems.
There are several lessons we’ve learned from the long-term non-progressors.
The first is that the way the virus gets into the body and attacks the immune
system is known in much more detail from studying LTNPs. We also know
that there are many complex steps required to get the virus into cells.
As a result, new drugs are coming out that take advantage of this new knowledge.
While a cure is far off, at least we have new medications to help those who
have become resistant to the older medications.
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