From: SCW112@psuvm.psu.edu
Newsgroups: sci.skeptic
Subject: Re: AIDS and the CIA (was Question)
Date: 16 Nov 92 00:42:33 GMT
 <92318.150807SCW112@psuvm.psu.edu> <97736@netnews.upenn.edu>
Organization: Penn State University

In article <97736@netnews.upenn.edu>, weemba@sagi.wistar.upenn.edu (Matthew P
Wiener) says:
>
>In article <92318.150807SCW112@psuvm.psu.edu>, SCW112@psuvm writes:
>>Well, what HIV does is it has the ability to insert a copy of it's
>>genetic material into the host's DNA. Most viruses just infect a cell
>>and force it to create a whole lot of copies of itself (killing the
>>cell in the process).  That's why HIV remains dormant -- It's sitting
>>inside your DNA until something (some environmental factor) turns it
>>on and you get AIDS.
>
>This is unknown.  As a retrovirus, HIV forms DNA instructions for itself
>in host cells, and they join in with the rest of the chromosomes.  The
>cell at some point uses the viral DNA as if it were its own, repeatedly.
>It will do this without any special environmental factor.  Retroviral
>infection is, in fact, a common technique in the recombinant DNA world.
>

True, the cell will replicate&all progeny cells will contain the viral genes,
but just because you have lots of these cells doesn't mean you have AIDS,
Something has to make the cell go from the lysogenic to the lytic phase to
create more copies of virus. What? An environmental factor, maybe. We don't
actually know. It could just be a matter of time.

>This, in itself, is no reason why the immune system cannot get at it.
>Foreign bits inside a cell end up having molecular parts show up on
>the surface of infected cells.  The right killer T-cell finds these
>and destroys the cell.  The process is much slower with a retrovirus
>than a normal virus, but otherwise the same.
>

True, if the viral genes are expressed while in the dormant (lysogenic) state.
Are they in HIV, I dunno.

>>As to the reason why we don't have an HIV vaccine, it's easy to make
>>a vaccine.  All a vaccine is is like a part of a virus that provokes
>>the immune system to create antibodies against that virus. We could
>>make an AIDS vaccine right now, I'm sure.
>
>No, we can't.  A vaccine has to induce the correct immune response.
>We do have trial AIDS vaccines though.
>

What's a vaccine? It's something that makes your body produce antibodies. Hell,
_I_ could make an AIDS vaccine. Just take a bunch of HIV viruses and kill 'em.
That, if injected into a human, would provoke an immune response. Of course,
chances are that one of those millions of viruses you inject into the guy will
have lived through the killing process and infect the person with HIV before
the immune response kicks in. So It'd be a pretty damn bad vaccine, but a
vaccine nonetheless, since _some_ (albeit very few) people would have the HIV
antibody but not the disease. As to whether that would make you immune to HIV,
I'm not sure.

>>                                          Thing is, because you're
>>using the virus, there's a chance you might get the disease (a real
>>small one, but a chance). What experimental human subject is gonna
>>take that chance?
>
>Many have taken the chance, so that's not the issue.
>

Sorry. I didn't know that there have been people willing to try experimental
HIV vaccines.

>>                  Plus, a vaccine immunizes a person because that guy
>>will have the antibodies to fight off the virus when he gets exposed
>>to it.
>
>That is correct.
>
>>       Thing is, our HIV antibodies aren't real good at fighting off
>>HIV. So even if we had them, it wouldn't much matter.
>
>It is unknown why our body's response to HIV is a failure.  This unknown
>is a major stumbling block in theorizing, let alone designing, an AIDS
>vaccine.  The models that make the most sense to me say HIV uses judo.
>The immune system is thrown against the virus, and it misses, badly.
>If so, tinkering with this will not be easy.
>

That's why I don't think a vaccine is the way to go. Finding a cure would be
better, I think.

>>So making a vaccine against AIDS is difficult because you want to use
>>a part of the virus that will provoke an immune response but not give
>>you AIDS.
>
>That is only part of the problem, although a minor one according to
>most researchers.  The other difficulty is HIV's high mutation rate.
>It's hard to hit a moving target.
>

True, but it's not mutation _that_ quickly, so it's a problem, but not a huge,
huge problem as long as a new mutation doesn't screw up the part of the virus
that you base your vaccine on.

>>          The fact that HIV is a retrovirus really has nothing to do
>>with it.
>
>That is correct, although it being a retrovirus makes the situation more
>difficult.
>--
>-Matthew P Wiener (weemba@sagi.wistar.upenn.edu)

Steve Wei