Re: Still no in vivo images of 'HIV'! 15 October 2004
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Nicholas Bennett,
Infectious Disease Postdoc/Clinician
Department of Pediatrics, University Hospital, Syracuse NY

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Re: Re: Still no in vivo images of 'HIV'!

Upon re-reading Mr Russell's latest contribution it seems that he is fixated upon getting the virus into the blood stream.

"Why should 'HIV' be more readily transmitted male to female but not female to male? In which case where do heterosexual males get 'HIV' from? Also, where does the active (insertive) homosexual get 'HIV' from? How does a passive (receptive) homosexual transmit 'HIV' to an active (insertive) homosexual? I want the precise mechanism please. "

For starters "more readily" implies that it is not "exclusively", and female to male transmission clearly occurs. One does not need an explanation when the observeration is staring you in the face (when someone comes up with an explanation for gravity, then let me know). It is fairly obvious that the exposure occurs at the point of contact between penile and vaginal mucosal surfaces. Micro-abrasions likely play a large role (hence why anal intercourse is more likely to transmit the virus). Getting to the blood stream is actually a fair way downstream from the initial infection of the mucosal cells, trafficking to the lymph nodes, and then migration around the body. The large innoculums are to ensure that experimentally an infection will occur: he is well aware I'm sure that the lower innoculums found in real life infections do not result in 6/7 contacts being infected! There's a decent review diagram in [1] which is available fulltext online that explains the route of infection, from mucosa to bloodstream.

I suggest that if Mr Russell has time, and I suggest perhaps 1-2 hours (the amount of time one might take to read the paper prior to presenting at a journal club) to seriously devote to disentangling the language (as intended, not as understood by him currently), he'd get a proper grasp for why HIV infection via sexual intercourse is not just true by observational epidemiology, but also has sound biological reasons behind it.

If he finds the mechanism slightly unlikely, then I refer him to examples such as rabies, CMV, HSV, polio and other viruses which wander far from their portal of entry: some with particularly ingenious methods. Once again, HIV is far from unusual.

Nick Bennett njb35@cantab.net

1. Weissman and Fauci Clin Microbiol Rev. 1997 Apr;10(2):358-67. Role of dendritic cells in immunopathogenesis of human immunodeficiency virus infection.

Competing interests: None declared