It is of great importance to know (1) how poliomyelitis virus enters the human body and (2) how it passes into the central nervous system. Hurst1 has demonstrated that poliomyelitis can be produced in monkeys by injection of the virus into the sciatic nerve. His results established the theory that poliomyelitis virus spreads by way of axonic pathways. We, as well as others, repeated Hurst's experiments and confirmed his findings. However, we were not uniformly successful when subpassage of the virus was attempted by way of other peripheral nerves (Toomey2).
The fact that poliomyelitis was not uniformly produced when the virus was injected in the peripheral nerves of monkeys was of no particular importance, since it was realized that even in nature the disease does not occur in all animals or human beings. It has been our belief that the virus has nearly an obligate affinity for naked gray fibers
TOOMEY JA, TAKACS WS. SPREAD OF POLIOMYELITIS VIRUS ALONG AXONS OF PERIPHERAL NERVES. Am J Dis Child. 1942;63(3):467-473. doi:10.1001/archpedi.1942.02010030037003