Abstract
1) The passage of the sheep-pox virus was made through goats in 15 successive cutaneous inoculations with the almost similar eruptions in every generation and we found neither gradual increase of the virulence against goat as it was observed by Konew in his experiment of subcutaneous inoculation on the goat with sheep-pox virus nor gradual decrease of the eruptibility to the goat during certain generations in the primary stage as it was observed by the author in the present experiment, carried out with sheep in successive cutaneous inoculation with the cow-pox virus.
2) The animals employed for the passage of the sheep-pox virus maintain not only perfect immunity against the introduced virus but also remain refractory to the revaccination with sheep-pox virus theretoafter, yet being apparently susceptible to cow-pox virus. Moreover these caprinized sheep-pox virus produce typical eruptions on the normal sheep while no reaction is observed with the sheep immunized previously against sheep-pox. The sheep-pox virus seems, therefore, to be stable with its immunogenic property even after caprinization inoculating cutaneously through many goats.
3) The sheep-pox virus passed through goats by cutaneous inoculation, shows a remarkable decrease in its virulence against the sheep, i. e. no symptom of sheep-pox was observed by injection of the virus by any route, cutaneous, subcutaneous or intravenous, nor it recovers the virulence by inoculating into sheep, even in succession. Thus the author introduced a new vaccine against sheep-pox which has the same character as that of the cow-pox virus against variola, being biologically attenuated and fixed in the virulence against sheep without any change of the original immunogenic property during this procedure.
4) Two out of 17 sheep under immunization with the author's Caprina were kept among the animals infected with sheep-pox and were fonnd insusceptible after all, and the following artificial inoculation with sheep-pox virus upon the all animals resulted in no eruptions on one half the number while another have taken but they were very mild, reminding that the vaccine are potent enough to prevent the spontaneous infection of sheep-pox, although its immunogenic property is naturally much more attenuated than that of the original virus. Comparing the author's own Caprina with Konew's, the former seems to be more ideal as the prophylactic vaccine against shee-pox than the latter.
5) The preventive effect of this Caprina against sheep-pox shows no remarkable differences between the strains derived from the goats and those obtained by goat-sheep method, nor we found any bifference of the effects due to the different method of injection, although this may still be beyond the determination with this minor number of the test animal. Other facts will be claimed on the futher investigation.
