Abstract
A comparison of the infectivity titers obtained by concurrently inoculating suckling mice, embryonated hens'' eggs and cultures of various tissues indicates that suckling mice are the most sensitive detector of the presence of this virus in infected materials from human, equine, avian and arthropod sources. Evidence is presented that cultures of embryonic chick tissue can be made as efficacious as suckling mice for the primary isolation of EEE virus by increasing the volume of the inoculum.