Equine infectious anemia--Immunological aspects

An antigenic material was extracted from the
leukocytes of horses infected with Equine Infectious Anemia.
In unmodified form, this material was infectious, immunogenic,
and antigenic. After modification by anti-viral agents and cross-linkage
to rabbit gamma globulin, the material retained its
immunogenic and antigenic properties, but became non-infectious.
Inoculation of the non-infectious antigen into experimental
horses elicited antibody production. When these horses were
challenged with live virus, the classical symptoms of the disease
did not appear. The possibility exists that a protective vaccine
was developed from modified antigen preparations.

Leukocytes, harvested from EIA infected horse plasma, were
disrupted and partially purified by differential centrifugation.
This material was assayed for its capacity to inhibit migration
of leukocytes from infected horses. After 6 X 10^6 r of gamma
radiation the material was reassayed and 85% of the initial
activity remained, indicating that little antigenic destruction
had occurred. This material was coupled to rabbit gamma
globulin and used for horse inoculation. The above material,
uncoupled, and a partially purified irradiated normal horse
protein material were used as controls. Responses to
immunizations and challenges were monitored. Uncoupled irradiated
material produced the disease. Coupled irradiated
material did not produce the disease and the immunized horse
was resistant to challenge with 1 ml of a 10^-3
dilution of infectious serum for 30 days and, then, to 1 ml of undiluted
infectious serum for 30 more days .