Computer Model of Tiny Polio Virus May Lead to Safer Vaccine

Using sophisticated computer graphics, medical researchers have pieced together a model of the virus responsible for polio, a development they say could lead to a safer vaccine for the crippling disease.

The three-dimensional model was mapped out by Scripps Clinic and Research Foundation scientists, who recreated the chemical structure of the virus atom-by-atom.

David J. Filman, a molecular biologist at Scripps, said the model construction is “equivalent to taking a picture without a lens.” He said the virus appears to be a roughly spherical object of 20 faces pitted with intricate peaks and valleys, promontories and ridges.

Mathematical ‘Lens’

“In our experiment, a lens is a physical impossibility. So we have to find a way for a computer to do the mathematics which a lens would do if it were available,” Filman said.

Filman co-authored the five-year study with James M. Hogle, also of Scripps, and Marie Chow of the Massachusetts Institute of Technology. The work is described in the Sept. 27 edition of the journal Science.

Filman said the group’s discovery involved analyzing X-rays deflected from highly purified molecules of protein. Computer graphics then created the image.

Paralytic polio is no longer a public health problem in the industrialized world, but the disease is still a concern in parts of the world where access is limited to the vaccine created 30 years ago by Dr. Jonas Salk.

According to the World Health Organization, there are about 500,000 cases of paralytic polio each year in the developing world. In the United States, there were only 230 cases reported from 1969 to 1985, according to federal figures.

Synthetic Vaccine Possible

The Scripps researchers say a synthetic polio vaccine could come from their work. In addition to the Salk vaccine, which uses an inactivated virus, the Sabin vaccine, which contains a weakened live virus, is in use.

Some cases of polio in recent years have been traced to the use of Sabin’s oral vaccine, health officials have said.

The synthetic vaccine envisioned by the Scripps researchers could be invented only from those parts of the polio virus that actually stimulate the production of antibodies. The scientists are looking at several sites along the surface of the polio virus as potential sources for a synthetic vaccine.