Some factors affecting the development of immunity in experimental rabbit-syphilis

Worms, W.

Brit Jour Venereal Dis 18(1/2): 18-34


Accession: 025482550

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The author studied the question of whether a rabbit can develop a pan-immunity to all strains of Spirochaeta pallida or a mono-immunity by observing the results of reinoculation in untreated rabbits with particular attention to 4 factors: the interval between the 1st and 2d inoculation; the quality (the virulence) and the amts. of inocula used in the 1st and 2d inoculation; the methods and sites of the 1st and the superinoculations; and the reaction of the rabbit to the 1st inoculation. Numerous observers have shown that in general superinoculations with homologous strains within 40 days after the first inoculation usually succeed, but the reinoculations become less frequently successful with increase of the interval since the 1st inoculation and after 90 days usually fail. This resistance to superinoculations late in the course of syphilis after a primary testicular or subscrotal infection extends also to other parts of the skin. The time factor seems to play a part between intra-testicular and intracut. 1st infections and intraven. super-inoculations. The immunity of untreated infected rabbits persists for life. In the case of heterologous strains the result of superinoculations carried out > 90 days after the 1st infection varies with the virulence of the strains used in the 1st and 2d inoculations respectively. The quantity of organisms in the inoculum in 1st infections has a variable effect according to different investigators. In 2d infections differences in the number of S. pallida may play an important role. The difference in the large quantity of the infectious material used for reinoculation expts. on syphilitic man, as compared with that occurring in natural reinoculations, may be partly responsible for the successful results in artificial reinoculations. In rabbits a refractoriness develops towards homologous superinoculations, and it makes no difference whether the 1st or 2d inoculations are carried out in the scrotal or the testicular tissue or in the skin elsewhere. The same may be true for heterologous superinoculations, but the data are as yet meager. The question of local immunity is not settled. Protection against a 2d infection is considered by some to be merely an expression of a reaction to a 1st infection. Repeated homologous superinoculations without a local response may affect the result of a subsequent heterologous superinoculation. Worms conducted expts. which seemed to show that the untreated rabbit which reacts very strongly to 1st inoculation-carried out simultaneously with 3 old strains-is able to develop not only a mono-immunity, but a non-strain-specific or pan-immunity. Protective antibodies were not demonstrated by crude methods in pooled serums of rabbits inoculated with 3 old strains and reinoculated with a 4th old strain. Demonstration by various investigators of definite but small amt. of protective antibodies suggests that serums of rabbits inoculated simultaneously with various strains of spiro-chetes might show also a greater amt. of antibodies and thus give further support for the importance of humoral antibodies-in addition to that of fixed cells-in the acquired immunity to syphilis.