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Avatar universal

HIV Transmission Qs

I posted the same question in general forum but didnt really get the answers i need so i am posting in expert form now.  Sorry for the double post

I do have several questions i am seeking answers for.  I understand saliva might contains small qty of virus but will not cause HIV infection due to virus in saliva inability to reproduce itself as well as small qty of active virus also cant cause infection.  I also read that small qty of blood w/ active also will not cause infection.  So i am not here to debate but looking for the actual how/why factors (because they just confused me) which i cant seems to find anywhere.  Its for one of my study.

1. Why can't small qty of active HIV virus cause infection (for example, during unprotected intercourse)?  

2. Since small qty of active virus will not cause HIV infection, what will happen to those small qty of virus (that are capable of reproducing itself) once it enters a human's body?  I read that it will be eliminated by human's immune system and gone?  if so, wouldn't the immune system build anti-body to destroy them and doesnt that trigger initial positive result on HIV testing then followed by negative result once these virus are gone?  

2. Based on the information i studied online and on this board, saliva has ingredients that inactive the virus.  once the saliva / HIV virus mixture enters body, wouldn't the saliva part and the virus part get separated?  since saliva will stay in place while virus will try to get through the membrane.

3. What about Blood in Saliva?  are the virus in the blood also disabled by saliva?

4. If saliva has ingredients that can inactive the virus, why cant researcher use this to build a vaccine?

5. Correct me if i am wrong but i assume once the virus is inactivated by ingredients in saliva, it will not become active again?  I read somewhere online that Saliva cracked the virus and leave only RNA and DNA which isn't infectious.  What does this mean?  
5 Responses
239123 tn?1267651214
Welcome to the forum.  Directly to your questions.

1) HIV transmission is a very complex event, biologically speaking.  The susceptible cells typically are internal, and even if enough virus can arriive at those sites -- which typically are protected by physical, chemical, and immunologic barriers -- then it generally still takes lots of virus to initiate infection.  Certainly a single virus could do it, but the odds are overwhelmingly against it.  In a way it's like fertilization.  You've probably seen those films of myriads of sperm trying to get inside the ovum; only one makes it.  That's why men with sperm counts of "only" a few million per ml usually are infertile.  Or to look at it another way:  maybe only a single virus needs to get into the right kind of cell -- but the odds of that virus contacting that cell are so low that millions and millions of viral particles have to be placed in the vicinity for the odds to favor infection.  That's why even the highest risk sexual exposure -- desposition of infected semen into the rectum -- has an average infection rate of only 1 in 200 exposures.

2) HIV is very fragile; it litereally falls apart.  Saliva speeds up that process.  Once exposed to saliva; the virus is destroyed and cannot infect.  I don't know the biological mechanism of saliva's activity against HIV, but my guess is that it involves the digestive vaccines in saliva.  As suggested in your last question, it probably dissolves the outer membrane of the virus.

3) Probably blood mixed with saliva would be quickly rendered non-infectious -- but I don't know if such an experiment has actually been done.

4) Vaccines work by stimulating the immune system.  Simply having some sort of chemical reaction or enzyme in saliva that inactivates HIV doesn't mean you can make a vaccine with the same capability.

5) Correct.  Once inactivated by saliva, the virus is dead as a doornail.  For most viruses, if the outer membrane is destroyed, the virus cannot survive, replicate, or infect.

You don't describe the exposure(s) that concern you, if any.  As you will see in most questions on this forum, we generally don't deal with the biological explanations.  The fact is that, whatever the reasons, exposure to saliva -- and therefore oral sex -- carries little or no risk for HIV transmission.  The biological reasons for it really don't matter.

Regards--  HHH, MD
Avatar universal
Hi Dcotor

Thanks for the comprehensive answers and i apologize, i didnt know this site doesn't get into biological explanation.  I am a male and had a risk via oral sex (from female CSW) last year but already tested negative.  Since then, i am interested in studying more about HIV.  I then search this site for more information about HIV transmission.  I found it very surprising that the rate of infection is low , even for unprotected sex anal/vagina.  I always thought its a one time exposure w/ one virus then jackpot.  

it sounds like the HIV virus does not get to pick which cell it infects?  Can HIV virus infect any cell to cause infection or only white blood cell?

I think i get the idea now.  Because during sex(any sex) virus has to break through layers of barriers before it can infect the cell, thats why the rate is so low?  Then injection drug is directly into blood stream so the rate is higher?

Thanks again for the assistance.
239123 tn?1267651214
The only cells in the body that are susceptible to HIV are those that have proteins on their surface called CD4 and CCR5.  Only a few kinds of cells have those characteristics, specifically certain lymphocytes (not all of them), macrophages, and a few others.  Most white blood cells are not susceptible.

Injection of HIV infected blood into the bloodstream is the only near-certain route of HIV transmission, about 90% of people who receive a transfusion with HIV infected blood.

Here is another thread that discussed the biology of HIV/STD transmission.  Start reading with the follow-up comment dated December 14:    http://www.medhelp.org/posts/show/1119533

That will end this thread.  If you need more detail than this, I suggest more sophisticated research via the web or a medical library.  The bottom line remains that receiving oral sex carrlies little or no risk for HIV (truly no risk, according to some experts).
Avatar universal
Thanks for all the information.  That helped me greatly.  One last question if you dont mind.  When i took the rapid test last time, they used a exposed blade finger prick device (it was all white) opposed to the normal spring loaded units i am familiar with.  I did however see the nurse grab one out of the box and kinda twisted it open.  The result came back negative.  I assume i have nothing to worry about the exposed blade finger prick device either being containmented or re-used ?
239123 tn?1267651214
Oh come on.  Of course not.  You assume correctly.  No more comments on this thread.
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