A Complement-Fixing Antigen from Trypanosoma Cruzi Grown in Cell Cultures

Franklin A. NevaLaboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Tropical Public Health, Harvard School of Public Health, Bethesda, Maryland 20014

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Albert A. GamLaboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Tropical Public Health, Harvard School of Public Health, Bethesda, Maryland 20014

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A complement-fixing (CF) antigen was prepared from amastigotes and trypomastigotes of Trypanosoma cruzi (Ernestina strain) grown in beef embryo cell cultures. Multiple lots of the antigen, which consisted of a supernate of washed and disrupted organisms, required material from 106 to 107 total organisms per ml for optimum CF activity. Antibody at dilutions up to 1:256 was demonstrable in various sera from infected animals or patients. Contaminating beef cells from infected cultures were shown to be partly responsible for cross-reactions of the antigen by CF with sera from cases of cutaneous leishmaniasis in whom concomitant infection with T. cruzi could be excluded. There were no cross-reactions with syphilitic sera and the frequency of positive reactions with normal sera was very low. Some characteristics of the antigen included stability to storage at -20° C and -70° C for months, inactivation at 60° C and by lyophilization, and an estimated molecular size of between 50,000 and 100,000 on the basis of membrane filtration.

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