Mutated poliovirus found to beat vaccine protection

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Though polio has been nearly eradicated from the globe, researchers have made a troubling discovery that underscores the need to boost vaccination rates in countries that have seen recent outbreaks as well as develop new, more potent vaccines.

Detailed in the Proceedings of the National Academy of Sciences, scientists at the University of Bonn uncovered a mutated virus found in polio victims of a 2010 outbreak in the Congo that seemingly resisted vaccine protection.

The polio epidemic in the Congo infected 445 people--most of them young adults--and killed 209 of those. The high mortality rate was troubling, especially since surveys indicated that half of the patients claim to have received the recommended three vaccination dosages against the disease.

While at the Institute for Virology of the University Hospital of Bonn, Dr. Jan Felix Drexler and colleague Christian Drosten as well as collaborators Drs. Gilda Grard and Eric Leroy from Gabon were interested in what caused the virus to seemingly circumvent the vaccine and kill so many people.

After isolating the polioviruses from victims who experienced fatal cases, the researchers tested the samples against a control group of blood samples from 34 medical students at the University of Bonn who had all received the polio vaccine during childhood.

While the antibodies from the blood of the control subjects were able to overtake the poliovirus with ease, the immune reaction from the mutated virus was considerably weaker, according to the study.

"The pathogen carries a mutation that changes its form at a decisive point," Drexler said in a statement. This mutation rendered the antibodies induced by the vaccine essentially useless.

The study authors say the findings point to a need for sustained vaccination coverage and surveillance of the poliovirus. Recent polio outbreaks have occurred in Afghanistan, Nigeria and Pakistan.

- get the abstract in PNAS
- read the press release

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