Susan Hafenstein, PhD, Professor and Cryo-EM Director at The Hormel Institute, University of Minnesota in Austin, and Carol Bator, Cryo-EM Project Specialist, are co-authors of a paper that was recently published in Nature Communications. The paper, entitled “A human monoclonal antibody binds within the poliovirus receptor-binding site to neutralize all three serotypes,” analyzes a human antibody that was observed successfully neutralizing all three serotypes of poliovirus — making it a promising candidate for the future development of antiviral treatments.
While polio cases have dramatically declined over the last several decades, the disease has yet to be eradicated worldwide. Just 33 cases of type 1 wild poliovirus were documented globally in 2018, while type 2 has not been detected since 2012, and type 3 was declared globally eradicated in 2015. Until very recently, the United States had not documented a polio case since 1979, thanks to widespread polio vaccinations. But resurgence remains a risk, as reports of a poliovirus case and presence of the virus in wastewater in New York were described in 2022.
With this in mind, and in the interest of developing the next generation of vaccines and antivirals to protect against the virus, Dr. Hafenstein and Bator, in collaboration with other researchers, studied how a particular antibody and poliovirus would interact. In doing so, they used cryo-electron microscopy (cryo-EM) to develop high-resolution maps of the epitope — the part of an antigen that an antibody attaches itself to in order to defeat it — of a human monoclonal antibody known as 9H2, which can neutralize all three poliovirus serotypes.
Polio is an extremely contagious disease caused by the poliovirus that spreads through person- to-person contact and often arises without symptoms. About 25% of people infected with poliovirus experience flu-like symptoms, according to the Centers for Disease Prevention and Control (CDC), and an even smaller portion of people may experience more severe symptoms affecting the brain and spinal cord, including meningitis and even paralysis, which can ultimately result in death when the muscles that aid in breathing are affected.
Serotypes are distinct groups within a single species of microorganism, like a bacteria or virus. There are three serotypes of poliovirus: type 1, type 2, and type 3, each type with its own slightly different capsid or shell — and immunity to one serotype doesn’t guarantee immunity to another.
Ultimately, by studying structures like these, scientists can develop better understandings of how a virus operates and use its own weaknesses against it to design more effective treatments or preventative measures. This is particularly significant for polio, considering the current lack of effective antivirals available for treatment.
Because the 9H2 antibody can neutralize all three poliovirus serotypes in these wrestling matches, the researchers note it makes a promising possible candidate for the development of biologics that could be used in the treatment or prevention of polio.
The CDC maintains that all individuals in the United States should remain up to date on recommended poliovirus vaccinations. Since 2000, only the inactivated polio vaccine (IPV), which contains no live virus and protects against all three serotypes, has been used in the United States. More information about polio, prevention guidance, and vaccination recommendations are available on the CDC website.