Abstract
The inactivating effect of ultraviolet light on viruses as well as bacteria has been observed repeatedly. That viruses so inactivated may be effective as immunizing antigens has already been shown for at least 2 viruses capable of causing disease in man. With a vaccine prepared by irradiating mouse-brain infected with rabic virus, Webster and associates 1 successfully immunized mice and dogs against a subsequent injection of active virus. Salk, Lavin, and Francis 2 compared the antigenic potency of epidemic-influenza virus following irradiation with that of active virus. In high concentrations, irradiated virus was nearly as effective an immunizing antigen as active virus; when lower concentrations were tested, a hundredfold loss in immunizing capacity was found to have occurred during irradiation. Ultraviolet light has been applied to the virus of equine encephalomyelitis, Eastern strain (E.E.E.), by Sharp and associates; 3 they studied the molecular stability of ultraviolet-treated virus. The preparation of an immunizing antigen produced by irradiation of E.E.E. virus with ultraviolet light is reported here.
Chick embryos 7-days-old were inoculated with 0.1 cc 10-3 suspension of E.E.E. virus-infected embryo in 0.85% saline solution. Embryos removed from the egg 18-20 hours after inoculation were rinsed in saline solution, ground in a mortar and made to a 10% suspension in saline or Tyrode's solution. This suspension was centrifuged at 2000 rpm for 10 minutes; the centrifugation was repeated with the supernate; the supernate then obtained was spun in a Swedish angle-centrifuge at 4000 rpm for 45 minutes. About 30 cc of the final supernate were transferred to a quartz test-tube, with an internal diameter of 2.1 cm, which was placed in the center of a quartz-mercury resonance lamp in the form of a spiral∗ with an internal diameter of 9 cm.
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