Vaccines rock.
So many diseases my mom and dad, my grandparents had to deal with, had to fear– I never have to even think about. Viruses I read about in books, like a 5-year-old reads about dinosaurs.
And I really, really appreciate this fact.
Nowhere is this appreciation more vivid than with the HPV vaccine. Gardasil became widely available when I was 23, so I was still young enough that insurance humored me and covered the series of shots (though I had to harass the hell out of my OB/GYN at the time to actually get them). I feel like Indiana Jones, like I barely slid under a stone door before it trapped me in a room full of snakes.
I pretty much never have to worry about one of the major causes of cancer in women. Hell, Im never even really going to have to deal with ‘abnormal’ pap-smears (though I still get them annually anyway).
It feels amazing (YAY! I get to die from something else instead! LOL!).
But I learned something really cool about the HPV vaccine at that last conference I went to: The vaccine? It gives you a ‘better’ immune response than actually getting infected with HPV.
This is weird. Normally, a ‘natural’ infection from, say, chickenpox, activates every possible branch of your immune system. The ‘natural’ virus replicates over and over, over a period of time, and your immune response really has to rev up and think hard to ultimately fight it off. Once it does, you really dont need to worry much about getting chickenpox again. Contrast that to the best possible vaccine, a live attenuated virus, in the VZV vaccine. Live attenuated vaccines cover more bases than dead viruses/viral proteins, but even then, you have to readminister the VZV vaccine to keep immune protection.
And then weve got the HPV vaccine. Its not a live attenuated virus. Its not a killed virus. Its made of viral structural proteins mushed into a membrane (virus-like particles). This should be an ‘adequate-but-not-ideal’ vaccine, but its perfect. You make lots of antibodies to these structural proteins, get exposed to a ‘real’ virus, and it cant infect your cells. Hurray!
… But this isnt the case with a ‘natural’ HPV infection. HPV has evolved all kinds of these wonderful ways of dampening your immune response to it. Some people dont develop antibodies to HPV until months after they are exposed, and even then, they dont make very much, and even then, the antibodies dont really stick around long. I dont think there is any reason to think these antibodies provide much protection at all against future infection. Furthermore, there is evidence that in the ‘natural’ chain of events, from HPV–>cancer, ‘natural’ HPV proteins create an environment that is (accidentally) conducive to tumor formation:
In this model the potent immunosuppressive activity of iNKT cells is induced by epithelial hyperplasia as a result of persistent viral oncoprotein expression. This finding suggests that in skin settings of chronic infection, tumors or autoimmune disorders, where alteration or disruption of local epithelial architecture and physiology leads to hyperplasia, recruited iNKT cells may be acting via IFN-{gamma} to protect the tissue from a deleterious immune response, by generation of a local immunosuppressive site. Although this effect may be useful in dampening autoimmunity, the site also creates an immune privileged niche allowing further immune evasion by viruses and tumors, and generation of escape variants.
*blink* Yeah… ‘Natural’ is not better.