| Summary: | Rabbit Passage of the Virus
The hog cholera virus was carried through six alternate passages from pig to rabbit and then top five serial passages in rabbits. The virus could not be demonstrated in rabbit-spleen suspension prepared for the sixth serial passage in rabbits. The lack of pathogenic or antigenic properties for the pig made it impossible to detect the virus, assuming that it was present in the rabbit-spleen suspension, at the sixth serial passage. The virus did not become pathogenic for the rabbit during the alternate and serial passages, although it survived for at least 72 hours in the rabbit. No evidence or attenuation of the virus for the pig was obtained in either the alternate or serial passages.
Ultraviolet Irradiation or the Virus
The hog cholera virus in the form of a pig-spleen suspension was irradiated by the Westinghouse lamps CH4 and Wl793. The virus was irradiated at a distance of 15 centimeters from the lamp. The suspension was placed in an open petri dish, to a depth or l to 2 millimeters, and was constantly agitated during the irradiation. Irradiation by the CH4 lamp for 30 and 60 minutes and irradiation by the WL793 lamp for 15, 30, and 60 minutes failed to attenuate the virus for the pig. Typical hog cholera was produced in pigs injected with the irradiated virus.
Nitrogen Mustard Treatment of the Virus
The hog cholera virus in the form of blood virus was mixed with the nitrogen mustard, methyl-bis (β-chloroethyl)-amine, in the proportion or five milliliters of blood virus to ten milligrams of nitrogen mustard. In one lot of blood virus so treated, the virus was completely destroyed, whereas in a second lot the virus was not affected.
Treatment of five milliliters of the virus, in the form of pig-spleen suspension, with ten milligrams of the nitrogen mustard completely attenuated the virus for the pig, so that, when the virus was injected into pigs, no ill effects appeared. Pigs injected with five milliliters of the mustard-treated pig-spleen virus developed a resistance to the virulent virus. The injected pigs successfully withstood the intramuscular injection or two milliliters of virulent virus, or pen exposure to cholera-infected pigs. The mustard-treated pig-spleen virus produced a satisfactory immunity in pigs injected with the treated virus 24 hours after its preparation. The mustard-treated pig-spleen virus did not spread from injected pigs to non-injected pigs kept in close contact with them. === Ph. D.
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