Two new retroviruses never before seen in humans have turned up among people who regularly hunt monkeys in Cameroon, researchers reported Friday.
Like the AIDS virus, these viruses insert their genetic material directly into cells and perhaps even into a person’s or animal’s chromosomes. Closely related versions of the viruses cause leukemia, inflammatory and neurological diseases.
The two new viruses are called human T‑lymphotropic virus types 3 and 4 or HTLV‑3 and HTLV‑4. They are closely related to two known viruses called HTLV‑1 and HTLV‑2, which experts believe were transmitted to people, like HIV, from monkeys and apes.
This doesn’t really prove anything about HIV-OPV, but it does bear on the “cut hunter hypothesis.” If you think back to our discussion of Baye’s Rule, you’ll remember that P(H|D)= P(H)P(D|H)/(P(D)P(D|H)+P(not H)*P(not H|D), where P(H) is the prior probability of the hypothesis, P(H|D) is the probability of the hypothesis given the data, and P(not H) is the probability of all other hypotheses. So the more probable other hypotheses are, the less probable your hypothesis.
By showing that humans get viruses from monkeys with relative frequency, the probability that it required some special event reduces.