Activity does not homology make 29 January 2005
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Nicholas Bennett,
Infectious Disease Postdoc/Clinician
Department of Pediatrics, University Hospital, Syracuse, NY

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Re: Activity does not homology make

Alex Russell attempts to say that the telomerase in human cells (usually active at extremely low levels, except in stem cells or cancerous cells) is the same as HIV reverse-transcriptase.

A Blast homology search sadly puts the lie to this.

Human Telomerase Reverse Transcriptase Isoform 1 (the active splice variant): accession AF015950.

HIV-1 HXB2 (reference genome) accession K03455.

"No significant similarity was found." using default settings. As Huxley said: "The great tragedy of Science - the slaying of a beautiful hypothesis by an ugly fact."

There is no evidence that HIV is an endogenous entity. As such, will Mr Russell accept this is why HIV appears to spread to contacts of those currently judged to be infected but is not ubiquitous?

One wonders why he thinks that homosexuals should use condoms far more responsibly, when they do not need to prevent conception. Maybe they are more responsible, but this is a very poor a prior assumption, since without evidence one could in fact assume the opposite!

I'm amazed that Mr Russell considers that the developed world has far more sex than the developing: birth rates are around one third the rate for example. This is high-school geography - it says nothing about morals. One wonders why he quotes from the Padian paper of 1997 which shows 70 transmissions between 442 couples over an average followup period of only 7 months per couple (the study was 10 years, but clearly not all couples were followed for that time!). Risk of transmission was associated with transmission of other STDs, and condom use occurred during the study and increased over time. Hardly an appropriate comparison to Africa, where recent reports in the news suggest that in some areas a man may only have access to three condoms per year.

I may not have shown to Mr Russell's satisfaction that HIV is an STD, but he has done so for me.

Nick Bennett njb35@cantab.net

Competing interests: None declared