Variations in Specificity and Virulence of Pneumococci During Growth in Vitro

Reimann, Hobart A.

doi:10.1084/jem.41.5.587

Cited by 42 publications

(15 citation statements)

References 7 publications

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“…This was done in order to exclude from the cultures degraded R forms of pneumococci, which are non-encapsulated, non-type-specific, and avirulent. Reimann (6) has pointed out that a pneumococcus culture of low virulence may be one in which R forms predominate over type-specific, encapsulated S forms. According to this view, the repeated passage through mice of a culture containing both forms increases the proportion of S organisms until, with the acquisition of maximum virulence, the culture is theoretically composed entirely of type-specific, encapsulated pneumococci.…”

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confidence: 99%

Studies on Immunity to Pneumococcus Mucosus (Type Iii)

Tillett

1927

Journal of Experimental Medicine

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In a previous paper (1) it was shown, in agreement with the experience of others, that the sera of rabbits immunized with Type III pneumococci failed to agglutinate the homologous organisms. Evidence was offered that the failure in agglutination was due, not to the inagglutinable state of the encapsulated bacteria, but to the actual absence of demonstrable type-specific antibodies. However, the sera of the immunized animals were reactive with pneumococcus nucleoprotein regardless of its type derivation and were capable of agglutinating the non-encapsulated degraded variants of all type-specific strains (R forms). This antibody response is contrary to the usual experience in immunization with type-specific pneumococci, when the cells used as antigen are intact. Although the Type III organisms used were, for the most part, possessed of large capsules, the antibody response, instead of being type-specific, was only species-specific in character and simulated that elicited by immunization with pneumococcus protein or with non-encapsulated R forms. The inference drawn from these results was that rabbits possess some mechanism which is capable of affecting the antigenic integrity of Type III pneumococci and that the alteration which the organisms undergo in the animal body is reflected in the character of the antibody response.Because of the unusual reaction of rabbits to immunization with Type III pneumococci and the implications which these results suggest, investigations have been carried out with regard to the infectivity of this type of pneumococcus for rabbits. The experiments reported in the present paper include observations on the degree of viru-

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confidence: 99%

Studies on Immunity to Pneumococcus Mucosus (Type Iii)

Tillett

1927

Journal of Experimental Medicine

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“…It has been repeatedly shown (1)(2)(3) that by subjecting type-specific (S) pneumococcus strains to various unfavorable cultural environments in vitro, certain biological characteristics of the bacteria are profoundly affected. The changed bacteria no longer elaborate the specific carbohydrate element upon which type specificity depends and they are therefore agglutinable in heterologous as well as homologous antipneumococcus serum (4), they are no longer virulent for mice, and they are easily phagocyted (5,6).…”

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confidence: 99%

The Occurrence of Degraded Pneumococci in Vivo

Reimann

1927

Journal of Experimental Medicine

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It is conceivable that a change from the virulent, non-phagocytable S form of Pneumococcus to the avirulent phagocytable R form may take place in pneumococcus disease, but the experiments here reported do not settle the question whether or not this is an important factor in determining the outcome in natural infection. It has been shown experimentally that the degradation from the S form to the R form actually does take place in cultures of Pneumococcus growing in agar subcutaneously embedded in guinea pigs, in agar enclosed in vials subcutaneously embedded in rabbits, and spontaneously in the blood stream of infected horses. However, it was not possible in any of the experiments here cited to demonstrate the complete change from S to R pneumococci before the bacteria disappeared from the body. When the intermediate or R forms did appear, they were always accompanied and usually exceeded in number by the S forms and all three forms disappeared together. S organisms may disappear entirely without evidence of first going through the intermediate and R stages. On the other hand, contrary to expectations, pure cultures of R forms remained viable in subcutaneous foci for weeks although apparently freely accessible to the action of phagocytes. It seems of some significance that the R forms appeared early in the vials (inoculated with S pneumococci) in immunized and normal rabbits alike, indicating that the presence of demonstrable specific immune bodies was not alone responsible for the variation of the bacteria. Of some importance also is the fact that R forms were never derived from similarly prepared control cultures growing in vitro at the same temperature and immersed in normal serum, although the S forms remained viable and unaltered for 6 weeks. It is likely that variations of pneumococci do not occur readily when S cultures are exposed to normal serum in vitro, especially when growing in closed vials under a diminished oxygen supply, for it has previously been shown (2) that only slight variation occurs even after prolonged (240) transfers in heterologous serum broth in the test-tube. It is possible, therefore, that the variation which occurred among pneumococci growing in agar vials embedded in normal rabbits was actually provoked by unknown influences in the living tissue fluids. Although R forms have been shown to occur in vivo, no positive evidence can be derived from these experiments to prove that recovery from pneumococcus infection depends upon the degradation of the virulent S forms of pneumococci to the avirulent R forms and the subsequent destruction of the latter by phagocytes.

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“…Since these cocci grew poorly and were completely avirulent to mice, their behaviour with the type sera may well have been due to their condition of attenuation, rather than to any abnormality in the sera. Other workers, notably Griffith (1923) and Reimann (1925), have observed similar tendencies with various types of pneumococci which, having lost their virulence and other characters proper to them, show marked cross-agglutination with the other type sera, in addition to a specific reaction to their own type serum. Indeed, Griffith (1928) now claims to have converted one type of pneumococcus into another at will.…”

Section: Virulence In Pneumococczmentioning

confidence: 68%

The Relation of Virulence in Pneumococci to Disease, with a Comparison of Virulence of the Different Types of Pneumococci in various Pathological Conditions

Whittle

1928

Epidemiol. Infect.

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Pneumococci form a group of organisms of which the individual strains exhibit wide differences in character. Like the streptococci, certain types of which they closely resemble, they show a variability in their predilections and behaviour bewildering to those who are attempting to classify them. Not only are pneumococci known to cause a great variety of lesions about the body, but they have also been found in the throats of a large proportion of healthy persons who apparently suffer no inconvenience from their presence—Stillman (1916, 1917), Glynn (1923) and others.

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Variations in Specificity and Virulence of Pneumococci During Growth in Vitro

Cited by 42 publications

References 7 publications

Studies on Immunity to Pneumococcus Mucosus (Type Iii)

Studies on Immunity to Pneumococcus Mucosus (Type Iii)

The Occurrence of Degraded Pneumococci in Vivo

The Relation of Virulence in Pneumococci to Disease, with a Comparison of Virulence of the Different Types of Pneumococci in various Pathological Conditions

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