Key points are not available for this paper at this time.
Experiments were carried out in mice in which an inactivated suspension of the MEFl newborn-mouse adapted strain of Type 2 poliomyelitis virus was used as an immunizing agent. It was found that 1) the adapted strain had a far greater immunogenic potency than the standard when the animals were challenged with the homotypic strain; and 2) a significant and reproducible cross-protection was detected when the mice were challenged intraspinally with a heterotypic, Type 3 (Leon) strain.
Casals et al. (1952) studied this question.