Indicators of postvaccination humoral immunity in immunization with anti-pseudomonas vaccines

Abstract

Introduction. The problem of Pseudomonas aeruginosa infection remains relevant worldwide, since the etiological role of P. aeruginosa as one of the main causative agents of purulent inflammatory diseases has not decreased, but has only increased in the context of military conflicts, and the effectiveness of means of combating it, on the contrary, is of concern. The study of the toxicity and reactogenicity of the obtained batches of the purulent vaccine confirmed their harmlessness to laboratory animals (vital signs and weight of animals in the experimental group did not differ compared to the control group). To scientifically substantiate the protective activity of the vaccines obtained by the proposed method, it is necessary to study such important indicators of vaccine immunity as titers of specific immunoglobulins, which was the main objective of this study. Materials and methods. P. aeruginosa cultures freshly isolated from patients and wounded with complications were used as candidate strains. Three series of vaccines from the actual strains were obtained using the developed method. In experiments on laboratory animals (white laboratory mice), a comparative study of the immunostimulatory activity of anti-pseudomonas vaccines obtained by two methods was carried out: thermally inactivated (TIV) and photodynamic inactivation of regionally circulating and nosocomial strains of P. aeruginosa (PIV). The criteria for immunogenicity were indicators reflecting seroconversion - maximum (max) and average titers of specific antibodies after the first and second immunization with these vaccines; the multiplicity of titers; the percentage of animals that responded with antibody production in the maximum titer. The evaluation was based on the results of the hemagglutination inhibition reaction (HIR) with a specific antigen of P. aeruginosa obtained from the same strain used to infect vaccinated and control (unvaccinated) animals. Results and discussion.  As a result of a single immunization with PIV, the maximum titers of specific antibodies were 16 times higher than the control values in most mice (80.0%). In the TIV-vaccinated mice, the level of homologous antibodies to the purulent antigen in 70.0% of mice was 8 times higher than the control values.  After the second immunization, PIV again demonstrated performance superior to that of the comparison product (average PIV titer 1:620 vs. 1:260 for TIF). Conclusions. The production of homologous antibodies caused by immunization of animals with photoinactivated vaccine significantly exceeds the results of similar exposure to heat-inactivated vaccine. Based on the average titer level, this occurred already at the stage of a single (first) immunization.  Thus, the determination of the immunostimulatory properties of the vaccine developed using the photodynamic method of inactivation of candidate strains in the experiment proved its high activity and predominant effectiveness in the production of specific immunoglobulins against P. aeruginosa, which indicates the prospects for its further comprehensive study.