Young cynomolgus monkeys inoculated intracerebrally with an attenuated Type 1 polio virus and, after 5 days, with a monkey adapted Coxsackie A-14 virus frequently became paralyzed. Neither virus alone was capable of inducing paralysis.
Similar results were observed when the AB IV strain of Coxsackie A-7 was substituted for the A-14 virus. In this case the 2nd inoculation was made intramuscularly.
Paralytic poliomyelitis may at times represent the summation of two infections, the total of motor neuron destruction by two independent and noninterfering enteroviruses.