Immunogenicity of Conjugates of Protective Antigen Complexes of Tularemia Microbe with Gold Nanoparticles

Abstract

Conjugates of gold nanoparticles with two isolated tularemia microbe antigens, a protective antigen complex and a glycosylated protein complex, are used to obtain anti-tularemia sera and to vaccinate animals. A conjugate of gold nanoparticles with the glycosylated protein complex during the subcutaneous immunization of mice is more effective than the unconjugated antigen, which is evident from the increase in protectiveness and antibody titers. The use of conjugates of both antigens with gold nanoparticles during the immunization of rabbits makes it possible to obtain sera with a high titer of specific antibodies (1/64–1/128 titer in the diffusion precipitation reaction and 1/5120–1/10240 in the reaction of indirect hemagglutination) during a relatively short period of time and with minimal antigen consumption (1.8–10 mg). The use of immunoglobulins extracted from sera during the enzyme-linked immunosorbent assay makes it possible to detect Francisella tularensis cells of different subspecies in the amount of (5.2 ± 0.5) × 10⁵ MC/mL with 100% specificity for heterologous strains at a concentration of 10⁸ MC/mL, which enables their subsequent application in the production of preparations for the diagnostics of tularemia.