Comparison of the Bactericidal Activity of Different Vertebrate Sera

Schwab, G. E. (University of Adelaide, Adelaide, South Australia), and P. R. Reeves. Comparison of the bactericidal activity of different vertebrate sera. J. Bacteriol. 91:106–112. 1966.—The bactericidal activity for gram-negative bacteria of normal sera from eight species of vertebrates was investigated to compare complement-mediated killing in sera from animals representing various classes of vertebrates. Although all the sera were bactericidal, there was considerable variation in the range of bacterial species killed and in the bactericidal titers. The temperature dependence of the bactericidal and hemolytic complement activities was also studied. The curves relating activity to temperature were similar in shape for sera from a homeotherm and poikilotherms, but those for the homeotherm reached their maximum at temperatures of 5 to 10 C higher than the poikilotherms. The role of lysozyme and complement in killing rough gram-negative bacteria was examined, and the results suggest that, as for smooth organisms, killing is due to antibody plus complement. These natural antibodies, like those for smooth strains, were shown to be specific.