RE: Nick Bennett: Ho and Pantaleo 1 November 2004
Previous Rapid Response Next Rapid Response Top
James I Madigan,
student, MS nutrition
New Brunswick, NJ 08901

Send response to journal:
Re: RE: Nick Bennett: Ho and Pantaleo

"[...]Pantaleo et al looked at lymphoid tissue [1] and saw much >higher numbers and proportions of infected cells than in the periphery - the trouble is that taking lymph node biopsies isn't half as easy as a blood draw. The majority of data therefore comes from a sample set that is arguably not the best place to look for HIV.

>From Pantaleo's work, I think he found HIV in around a quarter of lymphocytes in the lymph nodes. Far higher than the 1 in 40 CD4 cells in the periphery in some other studies. [2].

>I don't think Ho stated he was looking at whole virions, although he does suggest that the levels are indicative of actual infectious virus (i.e. a high level by his measure would imply a high level of virus, but not necessarily a 1:1 relationship! It's far lower than that). However, as an RNA genome it would quickly degrade without some form of protection like a virion capsid and envelope, so it would be a reasonable assumption to state that the RNA levels were representative of whole virions, although statements about infectivity cannot be made without a culture comparison. "

I'm not sure how literally you mean "in" when you say "From Pantaleo's work, I think he found HIV in around a quarter of lymphocytes in the lymph nodes. " If "in" this would imply either unreleased virions or provirus. Similarly you don't believe Ho et al were detecting confirmed free virions. Are we sure they weren't just detecting "HIV genome" "in" lymphocytes? In any event you seem to acknowledge that it was not proven that there were any free virions, let alone that they were infective to others or necessarily even infective through lymphocytes within the same organism. How for example do we know that these aren't (even if virus-like particles are produced) artifacts of ancient harmless "proviruses". They may even have evolutionary functions such as (as has been proposed) mutagenesis to speed evolution, or some other functions not yet investigated such as cell signalling or DNA "repair" or even as some kind of controlled "burn-off" of unhealthy cells (making a viral titre a product rather than cause of disease) - to name a few speculative possibilities - have any of these been disproven?

The next thing of interest to me, is that if the levels of genome are really this high then it should be routine to isolate and EM them I would think. I don't recall the titre required for recovery and EM of a virion, but at 1 in 20 of lymphocytes infected in the blood or 1 in 4 in lymph nodes I'd be surprised if it wasn't possible. I also understand there are now procedures that have improved this sensitivity (for EM photos of virions) by 2 or 3 orders of magnitude. You know the next question.

Competing interests: None declared