DNA sequences of rickettsial epitopes can be cloned into the pVAX vector. Constructed plasmids can generate a proliferative response and produce cytokines in vitro, in co-culture of transfected macrophages with sensitized human lymphocytes. Plasmid OmpB-24 proved to be the most immunogenic with respect to plasmids OmpA-49 and OmpB-15.

Las Rickettsiosis son un grupo de enfermedades zoonóticas causadas por las bacterias del género Rickettsia. Transmitidas por vectores ectoparásitos hematófagos como garrapatas, piojos, pulgas y ácaros, cuya incidencia ha aumentado en los últimos años. Debido a su cuadro clínico inespecífico es subdiagnosticada y confundida con otras de mayor influencia. Debido a su creciente incidencia se han estudiado antígenos rickettsiales, asi como la respuesta inmune que generan, para poder desarrollar una vacuna que permita combatir el número de casos de rickettsiosis. De estos estudios se han identificado diversas proteínas de membrana como candidatas para la realización de vacunas, siendo OmpA y la OmpB las más destacadas. Recientes estudios destacan una respuesta inmune efectiva contra esta enfermedad por lo que la presente revisión tiene como objetivo brindar un panorama de los resultados obtenidos en estudios de vacunas generadas a partir de estas dos proteínas.

Background: In recent years, promising vaccination strategies against rickettsiosis have been described in experimental animal models and human cells. OmpB is considered an immunodominant antigen that is recognized by T and B cells. The aim of this study was to identify TCD4+INF-γ+ and TCD8+INF-γ+ lymphocytes in an autologous system with macrophages transfected with the vaccine candidate pVAX1-OmpB24. Lymphocytes and monocytes from 14 patients with Rickettsia were isolated from whole blood. Monocytes were differentiated into macrophages and transfected with the plasmid pVAX1-OmpB24 pVax1. Isolated lymphocytes were cultured with transfected macrophages. IFN-γ-producing TCD4+ and TCD8+ lymphocyte subpopulations were identified by flow cytometry, as was the percentage of macrophages expressing CD40+, CD80+, HLA-I and HLA-II. Also, we analyzed the exhausted condition of the T lymphocyte subpopulation by PD1 expression. Macrophages transfected with pVAX1-OmpB24 stimulated TCD4+INF-γ+ cells in healthy subjects and patients infected with R. typhi. Macrophages stimulated TCD8+INF-γ+ cells in healthy subjects and patients infected with R. rickettsii and R. felis. Cells from healthy donors stimulated with OmpB-24 showed a higher percentage of TCD4+PD1+. Cells from patients infected with R. rickettsii had a higher percentage of TCD8+PD-1+, and for those infected with R. typhi the larger number of cells corresponded to TCD4+PD1+. Human macrophages transfected with pVAX1-OmpB24 activated TCD4+IFN-γ+ and CD8+IFN-γ+ in patients infected with different Rickettsia species. However, PD1 expression played an important role in the inhibition of T lymphocytes with R. felis.