Illustration of a single poliovirus virionCDC, MEREDITH BOYTER NEWLOVE, JAMES ARCHERPolio is nearly eradicated. Now much of the risk of polio outbreaks comes not from wild poliovirus but from the oral vaccine, which comprises attenuated viruses. These viruses accumulate mutations that allow them to circulate among under-vaccinated populations, regain virulence, and even cause outbreaks. Now, scientists have mapped out a series of mutations that might explain how some cases of vaccine-derived polio can arise, according to a study published today (March 23) in Cell.
Using data from outbreaks of this circulating vaccine-derived poliovirus, researchers at University of California, San Francisco (UCSF), and Tel-Aviv University, in collaboration with others, have identified genetic changes through which they believe the attenuated oral polio vaccine re-evolves virulence. An attenuated vaccine virus genetically engineered to carry the virulence mutations that the researchers identified caused paralysis in mice.
“In polio, we know that viruses that are more replicatively fit in cell culture are usually more paralytic in humans, or more paralytic in mice, for that matter, but it’s been a qualitative relationship,” Mike Famulare, who works on polio at the Institute for Disease Modeling in Washington and was not involved in the study, told The Scientist.
In the past, all three oral polio vaccine (OPV) ...
