Is "passaging" the origin of AIDS?

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The New York Review of Books had a review two or three years ago of a long book promoting the theory that AIDS was spread to humans by experiments with polio vaccines in the Belgian Congo in the 1950's.

The reviewer discounted this theory, but had a similar theory. According to this reviewer there is a well established medical phenomenon called passaging. It works like this. Take a harmless virus. Inject it into the host (to whom it is currently harmless). Before the immune reaction is complete, take a sample and inject it into a second member of the host species. Repeat. After a few repetitions, sometimes as few as three hosts, the virus has mutated to be harmful to the host. This reviewer thought early African innoculation efforts reusing needles could have been unwitting experiments in passaging with simian viruses with the HIV virus as one outcome.

I had never heard of passaging. Is it really a well-established phenomenon? In that case why encounter it only in a book review?

-- dandelion (golden@pleurisy.plant), August 30, 2001

Answers

Howdy Dandelion:

You should try getting your scientific opinions from the scientific literature and not from the New York Review of Books.

There is a good time estimate for the origin of HIV. Before WWII. Based on typical molecular genetics; you know frequency of base changes and all of that.

You are sounding like Sherri Naked! :)

Best Wishes,,,,,

Z

-- Z1X4Y7 (Z1X4Y7@aol.com), August 30, 2001.


Z, *grin*

-- Cherri (jessam6@home.com), August 30, 2001.

Naturally Z has the documentation to back up his claim.

-- KoFE (your@town.USSA), August 30, 2001.

KOFE:

Of course, I could tell you to go to places like the Journal of Molecular Evolution. I won't: I know that you only read tax nut web sites :).

Best Wishes,,,,,

Z

-- Z1X4Y7 (Z1X4Y7@aol.com), August 30, 2001.


By-the-by KOFE:

The information is in a number of Journals. Go to your local research university and do a search. It isn't publically available on the web.

Hell, I called a meeting for tomorrow morning. The main agenda is to deal with stem cell research. I still don't know what the administration policy is. People at NIH don't either. I am talking details here. Then, I am off to the PNW.

Best Wishes,,,,

Z

-- Z1X4Y7 (Z1X4Y7@aol.com), August 30, 2001.



Evolution of the RDNA spacer, ITS 2, is examined by comparing 17 DNA sequences of the ticks, Ixodes scapularis and L pacificus. The distribution of fixed interspecific differences and the relative frequency of base changes vs. insertions/deletions (indels) matches the distribution and relative frequency for intraspecifically variable sites. This suggests that most intraspecific variation is not effectively selected against. The base composition of the ITS 2 transcript is G- and U-biased. But, 5-base regions enriched (> 80 per cent) for A or U occur more frequently than expected while G- and C-enriched regions occur less frequently than expected. Enriched sequences may be prone to replication slippage, accounting for the A/T bias in insertions. Slippage-mediated gains and losses of A/T-rich tandem repeats apparently account for most indels. Minimum-energy conformations of the two species folded transcripts share major structural features. Structural inertia arises from intramolecular base pairing within stems that allows most mutations to be absorbed as new bulges off stems. Yet, there is evidence of selection to maintain the conformation. First, intraspecifically variable sites are concentrated at the ends of stems in loops and intersections, structures that do not contribute to intramolecular base pairing. Moreover, some indels that ha-N-e become fixed in one species compensate for the presence of conformation-destabilizing indels. However, high rates of sequence evolution within stems and absence of compensatory base evolution contraindicates selective constraint. Degenerate dispersed and tandem copies of two subrepeats, each approximately 20 bases long, may account for much of the ITS 2 sequence. These are approximate inverses of each other and are, consequently, capable of significant intramolecular hydrogen bonding to produce folded transcripts of low energy. Evolution of the ITS 2 sequence may largely entail replication slippage-mediated gains and losses of these repeats or their composite subrepeats.

-- Cherri (jessam6@home.com), August 30, 2001.

Also see Rethread HIV/AIDS on this forum.

-- David L (bumpkin@dnet.net), August 30, 2001.

Z,

Presumably passaging would speed up the rate of base changes, making the pre-WWII date too old. But I think you are saying that passaging is a figment of the reviewer’s imagination. Is there an archival site for biology preprints similar to the archive at xxx.lanl.gov for physics and mathematics?

-- dandelion (golden@pleurisy.plant), August 30, 2001.


Z, Don't forget your bumpershoot, word has it you'll need it this coming week.

-- Cherri (jessam6@home.com), August 31, 2001.

Heck, Z, answer is obvious.

Maximize profit for all mega corps, maximize taxpayer money going to same. Minimize results, to keep the Christian Right Wing happy.

Since the Bush supporters will be all over this one, I'll just ask ahead of time for a decision of his that did something besides funneling money towards the mega corps. And, for those who answer, again, ahead of time, please to take into account all monies spent on US military material' will go to large corps. Unless, of course, you can show a major procurement effort from some "mom and pop" operation.

And, of course, in this case, Bush wants as few results as possible, to keep from actually having to make a real decision on the matter.

-- Paul Davis (davisp1953@yahoo.com), September 02, 2001.



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