Estimation of General Toxicity and Immunological Safety of a Novel Therapeutic Vaccine Against Human Papillomavirus-Assosiated Diseases

Abstract

The aim of the investigation was to study in experiment total toxicity and immunological safety of a novel domestic therapeutic vaccine against recurrent respiratory papillomatosis and anogenital condylomatosis, the vaccine injected intramuscularly. Materials and Methods. We studied acute toxicity of the vaccine by the following parameters: clinical presentation of intoxication, median lethal dose size, the change of body weight of the surviving animals; chronic toxicity — by dynamics of general condition of the animals, body weight, hematological and biochemical indices of peripheral blood, functional status of central nervous system, cardiovascular system, kidneys, as well as pathomorphological changes of viscera. Allergenicity was studied by systemic and active cutaneous anaphylactic tests. We assessed immunotoxicity by direct a hemagglutination assay and a delayed-type hypersensitivity test, as well as by neutrophilic activity using luminal-dependent chemiluminescence. Proliferative activity of Вand Т-lymphocytes to lipopolysaccharides and concanavalin А (ConА) was estimated in a direct immunofluorescence test using immunocytochemical assay with anti-Ki-67 monoclonal antibodies. Results. Mean lethal doses (LD50) were not reached in white outbread rats injected intramuscularly by the tested vaccine at a maximum possible single dose (25 ml/kg). Multi-dose administration to white outbread rats and chinchilla rabbits at doses of 0.043; 0.43; 0.86 ml/kg and 0.023; 0.23; 0.4 ml/kg respectively, did not cause significant damage of functional status of basal organs and systems of experimental animals. The findings of systemic anaphylaxis and active cutaneous anaphylactic response to the vaccine in albino guinea pigs at the doses of 0.033 and 0.33 ml/kg intramuscularly indicated the vaccine to exhibit no allergenic properties. Intramuscular vaccine injected to first filial hybrid mice (СВА×С57BL/6)F1 at the doses of 0.084; 2.5 and 25 ml/kg showed neither significant increase or decrease of inflammatory response intensity relating to reference values. The vaccine at the doses of 0.084 and 2.5 ml/kg did not cause any changes of vaccination titer (IgG), phagocytic activity, spontaneous or induced blastic transformation of lymphocytes compared to the control group. The vaccine administered at the dose of 25 ml/kg significantly reduced the antibody formation level relating to the controls, as well as produced a suppressive effect on spontaneous and induced phagocytic activity resulting in the significant reduction of ConА-induced proliferative activity of Т-lymphocytes by the number of Ki-67 positive cells compared to the control group. Conclusion. The animal study of different types of general toxicity of the vaccine against recurrent respiratory papillomatosis and anogenital condylomatosis, the vaccine injected intramuscularly, showed the vaccine to be low toxic and immunologically safe in the dose range from 0.033 to 2.5 ml/kg.