A Type-Specific Immunodiffusion Technique for the California Encephalitis Virus Group

The development and evaluation of a California encephalitis virus (CEV) typespecific immunodiffusion (ID) technique is described. Agreement between this typing method and the more conventional complement-fixation test ranged from 96.2% to 100%. To date, type-specific rabbit antisera used in the system have been prepared against Keystone, trivittatus, BFS 283, snowshoe hare, LaCrosse and Jamestown Canyon antigens. A type-specific reaction was obtained with rabbit anti-San Angelo serum following absorption with BFS 283 antigens. However similar absorption of rabbit anti-Tahyna, anti-Lumbo and anti-Jerry Slough sera failed to produce a type-specific response. By screening isolates initially in the ID test using a CEV grouping serum, reacting isolates can quickly be identified by the typespecific antisera in the ID test. The technique is relatively inexpensive and can be performed readily by a technically competent technician in a modicum of time.