100th anniversary of the isolation of poliovirus

Yesterday, 18 December, marked 100 years since Karl Landsteiner, MD and his assistant E. Popper, identified the viral etiologic agent of poliomyelitis. According to A History of Poliomyelitis by JR Paul:

…at a medical meeting in Vienna on December 18, 1908, the immunologist Landsteiner and his assistant Popper were able to demonstrate microscopic slides of one human and two monkey spinal cords, all showing the familiar histological picture of acute poliomyelitis. Sections from the human infection came from a boy of nine years who had died after an illness of three days. Bacterial cultures of the spinal cord had been sterile, and injection of a suspension of the ground-up cord into rabbits, guinea pigs, and mice also had given negative results. But the team went further than this in their choice of experimental animals. They selected the right ones in the form of two monkeys, animals which probably represented an expensive luxury for these young scientists. Nevertheless, they were willing to risk what might have been considered a useless expense for an experiment which did not have any particular promise of success. The monkeys were of different species, one being a Cynocephalus hamadryas and the other a Macaca rhesus (Macaca mulatta). The choice turned out to be fortunate. Both of these species of primates are known today to be highly susceptible to experimental poliomyelitis, although to somewhat different degrees. The selection of Old World monkeys rather than the relatively insusceptible New World ones was just as fortunate.

The bacteriologically sterile material obtained from the spinal cord of the fatal human case was injected into the two animals intraperitoneally. The Cynocephalus monkey succumbed eight days later… The real test came when histological sections of the spinal cord revealed typical and extensive lesions which had a remarkably close resemblance to the lesion of human poliomyelitis. Similar, though not such widespread, changes were found in the sections of the cord from the second monkey, which developed complete flaccid paralysis of both legs… The authors must have been amazed, and not a little pleased, at the nature of the experimental disease produced in this animal, which resembled so closely the paralytic disease in man. They made the modest suggestion that poliomyelitis might be caused by an invisible virus, an opinion soon confirmed by other experiments.

The identification of poliovirus was an enormous advance that ultimately lead, 50 years later, to the development of two effective vaccines. The use of these vaccines has nearly eradicated poliomyelitis from the globe. Yesterday was truly an important day in virology and medicine.