Briefly, polio is an RNA virus, thus has an error-prone RNA-RNA polymerase, thus acts like a quasispecies like HIV-1. Now, a live attenuated polio vaccine is the ‘best’ because you activate lots of branches of your immune system, which ‘remember’ the polio virus for a really long time. But because of polio’s potential genetic diversity, the attenuated vaccine variant can revert back to the wild-type variant, which is ‘more fit’.
This doesn’t matter to you, because you’ve been vaccinated. But if you shed wild-type virus…
Well, you could make someone else sick. ERV then describes the new polio viruses that have been created and that would make safer and more reliable vaccines:
Vignuzzi et al found they could generate polio viruses that:
- Had a higher-fidelity RNA-RNA polymerase, cutting mutation rates by half or more
- Were almost equally ‘fit’ to wild-type virus, reducing selective pressure to revert
- Did not infect the brain/central nervous system
- Were still susceptible to anti-polio antivirals
- Provided better protective immunity to wild-type polio than even the current ‘live’ polio vaccine
All of these are important, especially in countries where vaccination is spotty and supplies of clean water are less reliable. People die while we sit by and say, “I’m all right, Jack.”
The paper she refers to, Vignuzzi et al., is described here: “Building a better polio vaccine.”
The current post goes on to discuss that concept in relation to a larger parasite: disease-carrying mosquitoes.