[Immunochemical study of the type-specific polysaccharides of pneumococcus]

Polysaccharide-containing preparations obtained from pneumococci, serovars 3, 6B, 9N, V and 23F, were studied by the methods of immunodiffusion and rocket immunoelectrophoresis (RIE). The tests were carried out with the use of rabbit antisera to formol vaccines prepared from serovars 3, 6, 9, 10, 12, 14, 18, and 23. The highly purified preparations of each of these serovars were shown to possess strict serological specificity. The results of RIE and chemical analysis permitted the selection of the preparations which served as reference antigens for 5 above-mentioned pneumococcal serovars. The calibrating curves plotted with the use of the reference antigens helped calculate the relative quantitative content of specific polysaccharide in preparations of different batches. The antigenic preparations were shown to differ in the content of specific polysaccharide and the degree of their purification. The authors recommend that double immunodiffusion and RIE should be used in combination in the study of the serological specificity of pneumococcal polysaccharide-containing preparations. The latter may be used as a rapid method for the standardization of the above-mentioned pneumococcal preparations and their mixtures. To achieve greater objectivity in the analysis of the mixtures, the use of sectional RIE, a variant of RIE proposed by the authors, is probably expedient. The present work also shows the possibility of using RIE for evaluating the level of the accumulation of specific polysaccharide during the cultivation of pneumococci in a liquid culture medium.