Various ammonium sulfate concentrations and reaction conditions were employed in the fractionation of sera from rabbits, sheep, horses, and goats. Precipitates and supernatant fluids were analyzed by electrophoresis to study the effects of the controlled variables. At room temperature, the third precipitate in 35% saturated (NH)2SO4 was the best fraction from both rabbit and sheep sera; 80 to 90% of the gamma globulins were recovered. The second and third precipitates of horse sera proteins in 30% saturated (NH),2SO0 were both satisfactory, but only 44% of the gamma globulin was recovered after three precipitations. Goat sera yielded a very satisfactory fraction; 80% of the gamma globulin was recovered after two precipitations-the first in 30% and the second in 45% saturated (NH,)2SO. The composition of these fractions was not MATERIALS AND METHODS Antisera. The antisera used in these studies were produced in rabbits, sheep, horses, and goats against a variety of bacterial antigens including Bacillus anthracis, Bordetella bronchiseptica, Bordetella pertussis, Escherichia coli, Pseudomonas pseudomallei, Salmonella, Shigella dysenteriae, Shigella sonnei, and Yersinia pestis. Some normal sera were also used. Ammonium sulfate. A stock solution of saturated ammonium sulfate (SAS) was prepared and stored at room temperature (approximately 25 C). Working solutions of 50, 60, 70, 80, and 90% SAS were prepared (v/v) fresh as needed from the stock saturated solution. Equal volumes of these solutions and various antisera resulted in reaction mixtures of 25, 30, 35, 40, 45, and 50% SAS (6). Fractionation. The following procedure for frac

When the data from performance and physicochemical studies of conjugates are combined for analysis, the performance data and specific titers show a direct relationship to the physicochemical data (Table 2). These reagents were prepared from the same lot of antiserum. The specific titers are very misleading without the accompanying data (Table 2). The protein concentrations range from 4 to 10 mg/ml, the F/P ratios from 10 to 30, and CASE shows gamma-globulin to constitute 30 to 100% of the protein. CASE also shows the gamma-globulin F/P ratio to be only 10 to 20. Using these data, we calculated the concentrations of the gamma-globulins and normalized their titers to 10 mg/ml. The value of good fractionation procedures for recovering gamma-globulin and the desirability of obtaining optimal F/P ratios are reflected in the adjusted titers. Physicochemical characterization of conjugates identifies superior and deficient reagents and frequently reveals the cause of inadequate performance. In this way it serves as a quide for improving reagent quality.

Various ammonium sulfate concentrations and reaction conditions were employed in the fractionation of sera from rabbits, sheep, horses, and goats. Precipitates and supernatant fluids were analyzed by electrophoresis to study the effects of the controlled variables. At room temperature, the third precipitate in 35% saturated (NH 4 ) 2 SO 4 was the best fraction from both rabbit and sheep sera; 80 to 90% of the gamma globulins were recovered. The second and third precipitates of horse sera proteins in 30% saturated (NH 4 ) 2 SO 4 were both satisfactory, but only 44% of the gamma globulin was recovered after three precipitations. Goat sera yielded a very satisfactory fraction; 80% of the gamma globulin was recovered after two precipitations—the first in 30% and the second in 45% saturated (NH 4 ) 2 SO 4 . The composition of these fractions was not influenced by the p H of the sulfate solutions ( p H 5.8 and 7.2), by a range of normal room temperatures (20 to 30 C), or by diluting the sera before fractionation. Crude globulins and fluorescein isothiocyanate-labeled globulins were successfully refractionated by one precipitation in the optimal sulfate concentration for the appropriate animal species. The refractionated products contained considerably less beta and alpha globulins than did the original crude fractions and little or no albumin.

Few studies have been conducted to determine the lipid composition of Listeria monocytogenes cells. Implications of the importance of this class of compounds in the pathogenesis of listeriosis was suggested by the early study of Stanley (5), who found a lipid component from bacterial cells that incited monocyte production in monogastric animals. The chemical nature of this component was not determined, but it was readily extracted with chloroform and later was suggested by Keeler and Gray (1) to be a constituent of the bacterial cell wall or membrane. It is possible that the monocyte-producing activity of the lipid component could be due to the nature of its fatty acid moiety which may be manifest by uncommon or previously unknown fatty acids. This study was initiated to provide basic information of the cellular fatty acids of L. monocytogenes. This report describes the results from 33 strains representing ten serological types of L. monocytogenes (J. Donker-Voet, Proc. Third Intern. Symp. Listeriosis, Rijka Instituut Voor De Volksgezondheid,

The use of fluorescent-antibody and cultural-precipitin grouping procedures for identifying Group A streptococci from throat swabs was evaluated with paired throat swabs. The sensitivity of the fluorescent-antibody technic was equivalent to or greater than that of cultural-precipitin technics. The importance of a number of conditions and factors for successful use of fluorescent-antibody tests on a routine basis is emphasized.