Toxoplasmosis II. Studies of Animal Sera Using Complement-Fixation Tests

Serological studies were performed in guinea pigs, a sheep, calf, goat and two pigs experimentally infected with toxoplasmosis. The direct complement-fixation method was effective in detecting antibodies in guinea-pig, goat and sheep sera. The modified complement-fixation technique supplementing complement with normal bovine serum fraction, was required when testing bovine serum. With swine sera best reactions occurred in the indirect complement-fixation test and definite but low grade reactions were produced in the direct test after pro-complementary activity was removed by pH treatment of the sera. Allergic skin reactions were produced in the experimental animals but improvement in the antigen is necessary before the test could be used generally in the field as a diagnostic method for animal toxoplasmosis.

Comparison of the Complement-Fixation Test and the Microscopic-Agglutination Test (Agglutination-Lysis) for the Detection of Leptospiral Serogroup Antibodies

The MA and CF tests using alcohol extracted antigens have been compared with sera from infected rabbits and calves. The MA test was highly serotype specific with serum from both animal species. The CF test was broadly reactive with serum from rabbits infected with various serotypes. However, when bovine serum was used cross reactivity was reduced and it was necessary to use pooled antigens to detect heterologous serotypes.

Immunological Activity of Leptospira Pomona Bacterins

Seven commercially available leptospiral bacterins were compared in guinea pigs and on that basis two of them, the best and the poorest, were further compared in calves. A wide variation was observed in their antigenicity and in their ability to provide protection. Guinea pigs appeared to be satisfactory test animals for evaluation of bacterins prepared for use in cattle.

Toxoplasmosis I. Studies by the Fluorescein-labelled Antibody Technique

The fluorescein-labelled antibody technique was investigated for the diagnosis of toxoplasmosis. The direct method, the inhibition and indirect modifications are suitable for the demonstration of Toxoplasma gondii in fluid and tissue-impression slides from animals in the acute phase of infection. The method was not applicable with the frozen tissue sections. The fluorescein-labelled antibody inhibition technique detected antibodies in immune sera from various species of animal. However the titres obtained were lower than with the complement-fixation test.

Fluorescein-Labelled Antibody Technique for the Demonstration of Leptospira Pomona

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The Effect of Prolonged Injection of Ethionine on Rabbits and Guinea Pigs on a High Cholesterol Diet

The complement titers, protein and lipid values of the serum, and the pathologic findings were compared in ethionine-injected and untreated rabbits and guinea pigs on cholesterol-supplemented or stock diets. All of the ethionine-injected rabbits when sacrificed after 7–24 week's treatment showed some degree of pathologic change in the liver and kidney or both; in some, other organs as well were affected. Atheromatous lesions in the aorta and vessels of the heart were found in all rabbits that had been on the high-cholesterol diet for periods of 14–24 weeks, their location and extent was similar in the ethionine-treated and control animals. No such lesions were observed in any of the guinea pigs on the cholesterol-supplemented diet, although there was a marked accumulation of lipid in the liver, pancreas and other organs.

The complement titers and total protein content of the serum of the untreated rabbits on the high cholesterol diet tended to be higher than those of the untreated controls on the stock diet; this difference was not observed in the corresponding groups of guinea pigs. Complement titers fell and remained low in both dietary groups of rabbits and guinea pigs during the period of ethionine treatment; in rabbits the total serum protein values were depressed initially but later rose to normal levels; prolonged ethionine treatment had no apparent effect upon the hyperlipemia developing in cholesterol-fed rabbits, but in guinea pigs on the same diet an initial rise in serum lipids was followed by a decline during ensuing months of ethionine injection.

The basic mechanisms underlying these changes observed in ethionine-injected animals are discussed briefly from the physiologic and immunologic standpoint.

The Value of Laboratory Reports on Stools in Cases of Suspected Amœbic Dysentery, and their Interpretation by the Clinician; with a Special Note on the Diagnostic Significance of Charcot-Leyden Crystals

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