The Molecules of HIV

Note: this site last updated in 2006

HIV and saliva

An article from "The Molecules of HIV" (c) Dan Stowell

Occasionally I'm asked about whether HIV is present in an HIV-positive person's saliva, and whether it carries a risk of transmission.

The short answer is that saliva virtually never carries any infectious HIV at all.

It does carry detectable "components" of HIV (such as viral RNA and proviral DNA), but these are not infectious on their own. The environment that saliva provides is far too harsh for infectious particles to remain intact and viable.

There are a number of possible mechanisms that have been suggested, which might explain why saliva seems to be so good at destroying HIV. Specific enzymes present in saliva may be important, or the effect of antibodies in saliva. Additionally, the saliva is "hypotonic" and has a tendency to disrupt any cells which may be floating around in it. It's pretty much certain that it's the combination of these factors that mean HIV is not transmitted in saliva.

It may seem strange that such a dangerous virus can't survive in something as "harmless" as saliva. In fact, saliva is a part of the body's natural defences against infection. Additionally, remember that the HIV virus is actually quite fragile.

More information:

  • Shugars DC, Sweet SP, Malamud D, Kazmi S, Page-Shafer K, Challacombe SJ (2002)
    Saliva and inhibition of HIV-1 infection: molecular mechanisms. Oral Diseases 8: 169-175 Suppl. 2 2002
  • Baron S, Poast J, Cloyd MW (1999)
    Why is HIV rarely transmitted by oral secretions? Saliva can disrupt orally shed, infected leukocytes. Archives of Internal Medicine 159 (3): 303-310

Written by
Dan Stowell

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