Infectious Disease Postdoc/Clinician
Department of Pediatrics, University Hospital, Syracuse NY
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Since HIV sequences cannot be found in normal human tissue, it is not endogenous.
Therefore, by definition, it must be exogenous.
Additionally, the fact that the virus can be passaged in culture strongly argues against it being an endogenous virus - this is simple virology. If it can do it in culture, what is stopping it in vivo? If the answer is nothing, then it's an exogenous retrovirus!
The arguments requiring EM-quality isolation from plasma do not stand. There is no logical reason why a virus must display a certain peripheral viral load in order to be pathogenic.
Rabies and influenza will happily kill with zero peripheral viral load. HIV replicates in lymph nodes, away from the peripheral circulation - while viral load is predictive of rate of progression to AIDS (as per Mellors et al) there is no need to expect to see excessive levels of virus. Mr Russell presents an argument that only sounds logical, when it is not! Gelderblom suggests that 10,000 fold higher levels of virus would be required to perform a De Harven-like purification process for HIV from peripheral blood, than are found in the very highest HIV viral loads.
It is a well established scientific process to grow an organism in culture from a sample prior to characterising. The lack of a culture system for Hepatitis C substantially slowed research into the virus. As such, keeping in mind that HIV is not endogenous, most scientists will be hard pushed to justify rejecting analysis of virions prepared in this way - including genetic clones derived from the virions. There is no logical difference between "amplifying" a virus by PCR, or by culture, and "amplifying" a virus using the electron microscope! Any of those techniques permits detection of the very small in the visible world. EM is sufficient to see peripheral isolates of Friend, it is not for HIV - but in the same way as 12x1 is equivalent to 3x2x2, so culture plus EM of HIV is equivalent to EM for Friend.
When referring to animal exogenous viruses I was of course talking about Friend virus and other murine retroviruses, as per the reference provided - since that is an area Mr Russell seems to know something about. Does Mr Russell now deny that Friend virus exists? After all, it is clearly transmitted horizontally. Murine retroviruses can be transmitted sexually and with a preference for male to female transmission, just like HIV. Mr Russell previously stated this wasn't true. If he still refuses to accept this, then how can he claim to use De Harven's protocol for isolating a virus that he doesn't believe in......? It seems unscientific to selectively accept evidence, and ignore that which doesn't fit the theory.
I would have an open mind to HIV being endogenous, were it not for the fact that it clearly isn't. If Mr Russell has Southern Blot evidence of HIV being present in normal human tissue I suggest he publish it and inform the human genome project! He would additionally have to explain why so many researchers prior to him have failed in their attempts to do the same thing (myself included - control cultures of human cells were subjected to the same genetic and protein-based detection methods and yet never displayed evidence of HIV sequences or proteins).
A very Happy New Year to all, by the way,
Nick Bennett firstname.lastname@example.org
Competing interests: None declared