#WorldAIDSDay: Joe’s Take On Great Progress, Great Hurdles
2011 marks roughly thirty years since the identification of AIDS in humans. In that time, more than 25 million people have died as a direct result of having their immune system atrophy to a point that they can no longer fight off even the weakest pathogens.
HIV’s entry into pandemic lore was originally attributed to a gay, extremely promiscuous Canadian flight attendant, but careful research into its history actually traces its path into the US as a result of a single Haitian carrier around 1969. Beyond that, we can trace it to Africa, and at some point around 1910 it could have jumped from primates to man as a result of bushmeat butchering and promiscuous sexual activity (certainly an interesting recipe for a Saturday night). At this point you should go listen to Radiolab’s episode “Patient Zero” and trace this detective story in engrossing detail (I’ll wait).
But AIDS is a syndrome, a result, a manifestation of a greater biology. And that greater biology is the HIV virus. Where does Science (with a big “S”) stand today in the battle against this enemy? Let’s look at a few of today’s prominent developments, in no way to be considered a comprehensive review of anti-HIV efforts.
In the brain of this biologist, the fight against HIV falls into three categories: Preventing transmission, post-infection neutralization, and pre-infection vaccination.
- Preventing transmission: If we lived in Candyland, everything would taste like gumdrops, people would wear condoms every time, they would always work, and abusive sexual practices would be the stuff of fiction. But this is not Candyland. So beyond trying to increase condom use and eliminate the sources of female HIV victimization, what can scientists offer? Currently, various antiviral drugs are being used to target transmission in couples where one partner is infected and another is not. But despite early hopes pinned on this cheap method, a recent clinical trial failure of an antiviral vaginal gel is a major setback in this department. Then again, maybe circumcision could work, and simply. Pros: Cheap, easy to distribute, easy to use. Cons: Ineffective thus far, prophylactic and not curative.
- Post-Infection Neutralization: So people will continue to be infected with HIV for the foreseeable future. How do we help them? By controlling the proliferation of the virus in their bodies. We have HAART (the “drug cocktails” you hear about), but it costs lots of money, can encourage resistant strains, the drugs have really sucky side effects, and it pretty much isn’t feasible in sub-Saharan Africa. Perhaps we can use gene therapy to replicate natural mutations that lead to resistance, eradicating viral loads? Very intriguing, but until we either improve gene editing methods (a real possibility) or decide to make bone-marrow transplants an outpatient procedure (which I’ve discussed the impossibility of before), this is not the stuff that cures are made of. Yet. Pros: Proven elimination of HIV load, established pharma approval system Cons: Expensive or impractical treatments for large scale, selection of resistant strains, not applicable to Third World countries
- Pre-Infection Vaccination: Behold the Holy Grail, the Cup of Kings. A vaccine against HIV would be the most straightforward way to both prevent infection and suppress the virus should it rear its ugly head. But this has proven elusive, as HIV has a nasty habit of mutating to avoid the efforts of antibodies. This means that traditional vaccine methods, like the weakened virus that makes up your flu shot, aren’t effective against HIV. However, an adaptive class of antibodies has been developed that not only broadly neutralizes HIV, but can naturally vary their structure to continue recognizing the virus even as it tries to mutate and evade. Essentially it’s like playing the computer in chess: these antibodies would continue to evolve and always be several moves ahead of the virus. And today, in a very timely publication, David Baltimore’s lab reports that by injecting these antibody genes into mice, just integrating right into the muscle cells, they have created an adaptive, permanent genetic HIV vaccine. Of course, we’ve cured cancer and countless other diseases in mice and failed to translate it to humans. But onward! Pros: Permanent, adaptive antibodies, one-time shot, simple distribution potential Cons: Safety of gene therapy method unknown in humans, we are not mice.
HIV has proven to be a formidable foe, but we’ve got our best men and women on the project. Continue to support basic research this #WorldAIDSDay, and we’ll continue to make progress together.
(image via Wellcome Trust)