The Brazilian Journal of Infectious Diseases The Brazilian Journal of Infectious Diseases
Braz J Infect Dis 2017;21:620-6 - Vol. 21 Num.6 DOI: 10.1016/j.bjid.2017.09.001
Original article
Humoral and cellular immune response of mice challenged with Yersinia pestis antigenic preparations
Elida A. Leala,, , Josimar D. Moreirab, Fernanda F. Nunesb, Larissa R. Souzab, Janaina M. Martinsb, Vicente P.C. Toledob, Alzira M.P. Almeidac, Tania M.P. Guimarãesb
a Instituto Octavio Magalhães, Divisão de Epidemologia e Controle de Doenças, Serviço de Doenças Bacterianas e Fúngicas, Belo Horizonte, MG, Brazil
b Universidade Federal de Minas Gerais, Faculdade de Farmácia, Departamento de Análises Clínicas e Toxicológicas, Belo Horizonte, MG, Brazil
c Fundação Oswaldo Cruz, Centro de Pesquisa Aggeu Magalhães, Departamento de Microbiologia, Recife, PE, Brazil
Received 05 April 2017, Accepted 26 September 2017
Abstract
Objectives

The plague, which is an infectious disease caused by Yersinia pestis, still threatens many populations in several countries. The worldwide increase in human plague cases and the potential use of the bacteria as a biological weapon reinforce the need to study the immunity that is induced by potential vaccine candidates. To determine the immunogenicity of antigenic preparations based on the F1 protein and the total extract from Y. pestis, we assessed the role of these antigens in inducing an immune response.

Methods

The immunogenicity of antigenic preparations based on the Y. pestis (YP) total extract and the Y. pestis fraction 1 capsular antigen protein (F1) was determined in Swiss-Webster mice immunized with 40μg or 20μg for each preparation. Immunophenotyping was performed by flow cytometry.

Results

Animals immunized with the YP total extract did not elicit detectable anti-F1 antibodies (Ab) in the hemaglutination/inhibition (HA/HI) test. Animals immunized with 40μg or 20μg of the F1 protein produced anti-F1 Abs, with titres ranging from 1/16 to 1/8132. The average of CD3+–CD4+ and CD3+–CD8+ T cells did not differ significantly between the groups. Neither YP total extract nor F1 protein induced a significant expression of IFN-γ and IL-10 in CD4+ T lymphocytes. In addition, F1 failed to induce IFN-γ expression in CD8+ T cells, unlike the YP total extract.

Conclusion

The results showed that F1 protein is not an immunogenic T cell antigen, although the YP total extract (40μg dose) favoured CD8+ T cell-mediated cellular immunity.

Keywords
Yersinia pestis, Antigens, Mice, Immune response, Vaccines
Braz J Infect Dis 2017;21:620-6 - Vol. 21 Num.6 DOI: 10.1016/j.bjid.2017.09.001