The potential use of arginine kinase from the brown tick Rhipicephalus sanguineus as a biomarker for vector exposure in the surveillance of Rocky Mountain spotted fever

•The dog tick, Rhipicephalus sanguineus, is a significant health problem as a vector for RMSF.•There is scarce data on the effect of tick bites on the immune response in humans.•The highly antigenic arginine kinase is present in ticks and many invertebrates. The brown dog tick (Rhipicephalus sanguineus) is the vector of Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever (RMSF) in Northern Mexico and Southwestern United States. The immune response to a tick protein in the sera of humans or animals may reveal the zones with a high propensity to acquire RMSF, and vector control strategies may be focused on these zones. Arginine kinase (AK) is a highly antigenic invertebrate protein that may serve as a marker for tick exposure. We used R. sanguineus recombinant AK in an indirect ELISA assay with RMSF-positive patient sera. The response to AK was significantly higher against the sera of RMSF patients than the control sera from healthy participants without contact with dogs. To validate the antigenicity of tick AK, we mutated one predicted conformational epitope to alanine residues, which reduced the recognition by RMSF patients’ immunoglobulins. This preliminary result opens a perspective towards the development of a complimentary technique based on RsAK as an antigen biomarker for vector serological surveillance for Rickettsia RMSF prevention. En el norte de México y el suroeste de Estados Unidos, la garrapata café del perro (Rhipicephalus sanguineus) es el vector de la bacteria Rickettsia rickettsii, causante de la fiebre manchada de las Montañas Rocosas (RMSF). La respuesta inmune a una proteína de garrapata puede revelar la exposición al vector, sugiriendo zonas en las que hay mayores posiblidades de contraer RMSF, y puede proporcionar mejores estrategias para el control de estos vectores en dichas zonas. La arginina quinasa (AK) es una proteína altamente antigénica que puede servir como marcador de exposición a garrapatas. Algunos experimentos con enzyme-linked immunosorbent assay (ELISA) indirecto empleando AK recombinante de R. sanguineus mostraron que la respuesta a AK con sueros de pacientes positivos para RMSF fue significativamente mayor que con sueros control (participantes sanos sin contacto con perros). Para validar la antigenicidad de la AK de la garrapata, se evaluó la misma respuesta a una AK mutante (E1), donde un epítopo conformacional se sustituyó por residuos de alanina, lo que redujo el reconocimiento por parte de l