Do you guys remember how Per Ahlberg got his big break? He sifted through the fossil collection at the London Natural History Museum, found friggen tetrapod?
Someone just did the same thing with HIV-1.
Michael Worobey dug through prehistoric (1960s hehe) tissue samples hunting for early HIV-1 sequences.
Now by ’tissue samples’ I dont mean nicely labeled bits of tissue, organized and cataloged in bright fluorescent boxes, in perfect little cryovials, stored at -80 C.
I mean dude dug through chunks of flesh soaked in formaldehyde and embedded in wax, and have been sitting at room temperature for, um, *looks at watch* 48 years, looking for HIV sequences… and he found some.
Direct evidence of extensive diversity of HIV-1 in Kinshasa by 1960
I repeat: Holy crap.
If youve read ERV for a while, youre probably aware of the fact that HIV is not just ‘HIV’. There is HIV-1 (the one causing a mess) and HIV-2 (causes a smaller, less deadly mess). HIV-1 is split into Group M, N, and O– representing 3 different crossover events from chimpanzees to humans. Group M is the ‘bad’ one, and is further divided into subtypes– A, B, C, D, etc. Each of those subtypes has distinctive features, which are the result of decades of evolution within humans (ie, differences in Subtype B vs C Vpu sequence and function).
The oldest HIV-1 sequence weve found was fished out of a 1959 blood sample. This sequence is closely related to Subtype D HIV-1.
Worobey found this new sequence in a lymph node biopsy from 1960. It is more closely related to Subtype A HIV-1.
This means that by 1960, HIV-1 Group M had been in the human population long enough to evolve into distinguishable subtypes.
Previous estimates placed the initial introduction of HIV-1 into humans between 1915 and 1941, probably at ~1931.
Using new evolutionary models with this new sequence, that date has been pushed back a bit– 1902-1921, no later than 1933.
While this information is undeniably cool, you might be wondering why this kind of paleovirology matters. Why does it matter what the virus looked like 50 years ago? Its not like we can just bop on back to 1902 and vaccinate everyone against a less diverse HIV-1. A fellow at the Pasteur Institute had a nice analogy for our logic:
Collecting information about old strains of HIV — even those that disappeared over time — can help researchers learn how successful strains broke through, says Wain-Hobson. “For every star in Hollywood there are fifty starlets,” he says. “We would love to know what it was that caused this strain to move out of starlet phase and to the big time.”
Im not sure if you need a subscription to read these (your local library probably does if you do), but I strongly encourage you all to read the PR article and the Sciency PR article accompanying this paper!