repeated non-traumatic exposures to poliomyelitis virus of the mucous membranes of the upper respiratory tract and of various portions of the alimentary tract in 5 cynomolgus monkeys , extending over a period of 9 to 14 months , were followed by a definite , though limited resistance to intracerebral inoculation to the homologous strain of virus in 4 of them .
C0206435
poliomyelitis virus
C0042776
virus