HIV (Apparently) Comes From Gorillas: What This Means for the HIV Community

By Myles Helfand

August 5, 2009

Ann Darrow: the Fay Wray edition

Look out! You can get HIV from a gorilla! Somebody warn Ann Darrow!

OK, OK, let's all calm down. Yes, scientists have apparently found that HIV can make the leap from gorillas into humans. But what does it mean for someone living with HIV -- or even for the human race in general? For now, at least, it means pretty much nothing -- unless, of course, you're fascinated by cool developments in HIV science.

This latest bout of overblown HIV-related news comes to you from France, where scientists have found the first case in which a human was apparently infected with a gorilla-like strain of HIV. Here's the gist of the story, as published in the online edition of Nature Medicine on Aug. 2:

Once upon a time (OK, it was 2004), a woman in her late 50s/early 60s moved from Cameroon to Paris. Upon her arrival in Paris, the woman (who the researchers lovingly nicknamed "subject number RBF168") was diagnosed with HIV. Bienvenue en France!

Several different HIV tests repeatedly came up positive, but her Western Blot results were a little weird. Scientists decided to investigate.

They isolated her HIV and coded its genetic sequence. (Isn't science amazing?)

Verdict: The scientists discovered that her strain was most similar to a strain of SIV found in gorillas.

OK, let's stop a moment for a bit of background.

As far as we've been able to figure, HIV is a human-only virus. But it evolved from SIV, which is found in a bunch of primates, including chimpanzees, monkeys and gorillas.

To read more about HIV types, groups, subtypes and all that good stuff, read this terrific overview from Avert.org.

The most common type of HIV, called HIV-1, is believed to have evolved from SIVcpz, which is found in chimps. There are actually many types of HIV-1, so having a new form HIV-1 is not such big news. HIV-1 is divided into three groups -- group M (for "major"), N (for "new") and O (for "outlier" -- incredibly, I'm not even making this up). Each group is supposed to represent separate introductions of SIV from chimpanzees into humans. Most people with HIV-1 have a strain that's part of group M.

(Even within group M, there are at least nine subtypes, or "clades," of virus that are slightly different from one another. These clades are named A, B, C and so forth -- so a person can have, for instance, HIV-1 group M clade A. Does your head hurt after reading all this? Because mine sure does after writing it.)

That's HIV-1. There's also HIV-2, a type of HIV found mostly in Africa. HIV-2 is thought to have come from SIVsm, a virus in sooty mangabeys (a type of monkey).

The virus found in this woman is the first that appears to be most closely related to SIVgor, a strain that scientists discovered in gorillas a few years ago. The researchers have decided to call this newly found virus HIV-1 group P. (Oddly, the P doesn't appear to stand for anything. I think we should have a contest to name it; I vote for "pusillanimous." Or maybe "portly.")

Got all that? Me neither. Let's trudge on:

Standard PCR viral load tests showed that the viral load of Ms. RBF168 has consistently hovered around 100,000 since her diagnosis.

Her CD4 count has remained around 300 since her diagnosis.

She has never shown a symptom of advanced HIV/AIDS.

She has never been on HIV treatment -- or, at least, she wasn't on treatment when this study was first received by Nature Medicine, which was back on April 2.

As far as we know, she never ate a gorilla, had sex with one or shared needles with one.

Before Paris, the woman had lived in Cameroon all her life. Her husband died in 1984 (his HIV status was unknown), and she had six kids, all of whom were born before 1980. (She said two of them have since died, but not from HIV; the other four are HIV negative.) She's had sex partners since her husband died, but never knew any of their HIV statuses.

Where does all this leave us? Nowhere, really -- at least for the average Joe or Jane. There's very little takeaway here, regardless of whether you're HIV negative and you're getting tested for HIV, or whether you're someone living with HIV. Standard HIV tests were able to spot Ms. RBF168's virus, and standard viral load tests seem to work fine as well. She's never been on HIV meds, so we don't know how well they'd work. She was just diagnosed in 2004, and we don't know how long she's been HIV positive, so we can't be sure whether the long-term effects of her HIV strain will be any different than they are for anyone else's HIV strain, although we already know that HIV's effects can differ widely from person to person.

All we really have at this point are a whole bunch of questions, such as:

How did Ms. RBF168 get this strain of HIV? (And how did that person get it?)

How many other people might have this strain, and how long has it been around?

Is this strain any more infectious than the strains of HIV we already know about?

What happens if someone who's already HIV positive is infected with this strain as well?

How well will this strain respond to HIV meds?

How many other, currently undiscovered strains of HIV might be out there?

Are new strains of HIV still evolving from primates today?

We just don't know the answers to many of these questions. We'll probably learn more over time, as scientists poke around down in Cameroon and doctors continue to follow Ms. RBF168, who most likely has gotten a lot more attention than she bargained for when she decided to move to Paris five years ago.

For now, all we in the HIV community can do is wait. For most of us, this is just another piece of random HIV-related news floating its way through the ether, with no real impact on our daily lives. If nothing else, the lesson here is that even though we've known about HIV for more than 25 years, we still have an awful lot to learn about how it works.

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