About the presence of a thermolabile (TL) antigenic fraction in Leptospira interrogans.

Antisera prepared with living serovars of Leptospira interrogans have a fraction anti-TL able to neutralize TL antigen of Leptospira strains. After neutralization, any leptospiral serovar is able to adsorb heterologous antisera prepared with living strains.

Detection of an antigenic protein of Leptospira interrogans which shares epitopes with the equine cornea and lens.

A protein epitope which is involved in an antigenic relationship between equine ocular tissues and Leptospira interrogans was detected in homogenates of the bacterium. The antigenic determinant was harboured on a peptide structure which was shown to be sensitive to the action of denaturing and reducing agents by means of Western blotting. The outer surface of the leptospires appeared to be free of this epitope as was proved by dot-blot and electron microscopic studies.

[Studies on the antigens of leptospires (author's transl)]. / Recherches sur les antigènes des leptospires

The authors show the existence of a TR (thermoresistant) antigen capable to withstand heating at 100 degrees C for 30 minutes. This antigen is present in Patoc I, serogroup Semaranga. It absorbs the corresponding immune serum at rates exceeding 99%, and appears to be the only antigen playing a part in the absorption of agglutinins. The existence of a TR antigen was demonstrated in various pathogenic serotypes. This antigen withstands heating at 80 degrees C for 10 minutes. The TR antigen absorbs antibodies of immune sera of the corresponding strains; and, in cross agglutination reactions, antibodies of the other immune sera of the studied pathogenic leptospires. the TR antigen of serotypes icterohaemorrhagiae Wijnberg, australis Ballico and pyrogenes Salinem are not able to absorb agglutinins of sera anti-Patoc I, whereas TR/Hebdomadis and TR/Pomona absorb as much as 20%. tr/hond Utrecht IV and TR/Patoc I (by absorbing their immune sera in cross agglutination) act as homologous strains with an absorption rate of 99%. The capability of absorption of TR changes according to the composition of culture media. This antigen, heated at 80 degrees C for 10 minutes and obtained pyrogenes Salinem is used for macroscopic diagnosis in slide test procedure by mixing equal proportions of antigen and serum. A positive reaction is indicated by distinct agglutination clumps.

Determination of the heat labile point of leptospiral antigens.

Pyrogenes Salinem antigen, prepared at different temperatures, is used to adsorb heterologous anti-Chiffon and anti-Pomona sera, and the lability point of the antigen is determined by the macroagglutination test. Results show that the effect of this thermolabile antigen starts to be destroyed after 10 min at 60 degrees C with anti-Pomona serum and at 65 degrees C with anti-Chiffon serum. The method of measurement is not sensitive enough and the lability point would probably be lower than that obtained in these tests. The authors consider a more accurate method to be the combined use of the adsorption and microagglutination tests, with comparative titration of an heterologous antiserum.

Evaluation of the leptospiral protein-free medium.

Bey and Johnson's leptospiral protein-free medium is evaluated and some modifications to it are introduced. Different serovars have shown good growth in this medium, but generally it is necessary to adapt it before obtaining success. When adapted, the serovars, subcultured serially, have a long term survival, with a good bacterial density. Some serovars, such as tarassovi and grippotyphosa exhibited irregular results.

[Biological diagnosis of the leptospiroses: technics and interpretations]. / Diagnostic biologique des leptospiroses: techniques et interpretation.

According to the chronological data of Physio-Pathology of leptospiroses, diagnosis is: Direct: isolation of the germ in the beginning of the acute phase of the disease: blood culture, culture of cerebrospinal fluid, animal inoculation. Identification is the work of a specialized laboratory. Indirect: demonstration of antibodies. Immunological tests are divided into two groups: Screening tests, available for all laboratories: they give an indication of Leptospirosis. They are carried out during the acute phase: slide macroscopic agglutination test, hemagglutination test, complement fixation test. Confirmatory tests, performed only by specialized laboratories. Interpretation is dependent on the case history of the patient.