ORIGINAL PAPER Leishmania major infection in susceptible and resistant mice elicit a differential humoral response against a total soluble fraction and defined recombinant antigens of the parasite Virginia Iniesta & Inés Corraliza & Jesualdo Carcelén & Luis Gómez Gordo & Javier Fernández-Cotrina & Juan Carlos Parejo & Javier Carrión & Manuel Soto & Carlos Alonso & Carlos Gómez Nieto Received: 3 October 2007 / Accepted: 4 December 2007 / Published online: 10 January 2008 # Springer-Verlag 2007 Abstract In the present work, we analyzed the humoral response of Leishmania major experimentally infected BALB/c and C57BL/6 mice against three Leishmania antigens: total soluble antigen (soluble leishmania antigen (SLA)), a chimerical recombinant protein formed by the genetic fusion of four cytoplasmic proteins (PQ), and a kinetoplastic membrane protein (Kmp-11). We determined the correlation between the immune response against these proteins and the histopathological changes induced in the susceptible and resistant mice after infection. The data showed the existence of wide differences in the recognition of SLA, PQ, and Kmp-11 by the sera from both strains. The anti-SLA titer of BALB/c was 100 times higher than that of C57BL/6 mice. Antibodies against the recombinant Kmp- 11 were detected only in infected BALB/c during the first stage of the infection. In contrast, the PQ protein was recognized by the sera from infected BALB/c mice but exclusively when they were in a late-lesion period. The data suggest that the response against the membrane Kmp-11 protein is transient and correlates with early developmental stages of the infection, whereas the response against cytoplasmic proteins as those present in PQ is sustained and could be considered as a marker of an advanced stage of the infection and disease. Introduction Leishmania protozoa are intracellular parasites that infect and replicate inside the mononuclear phagocyte system of their vertebrate host. Infection causes a wide range of animal and human diseases characterized by a high variety of symptoms and clinical manifestations. The importance and complexity of the host immune response against the parasite has been extensively reviewed (Liew and O'Donnell 1993). It has been shown that the response is dependent on the Leishmania species infecting the host and the form of the disease it Parasitol Res (2008) 102:887–893 DOI 10.1007/s00436-007-0844-9 V. Iniesta : J. Carcelén : J. Fernández-Cotrina : C. Gómez Nieto Unidad de Parasitología y Enfermedades Parasitarias, Universidad de Extremadura, Avda. de la Universidad s/n, 10.071, Cáceres, Spain I. Corraliza Departamento de Bioquímica y Biología Molecular, Universidad de Extremadura, Avda. de la Universidad s/n, 10.071, Cáceres, Spain L. Gómez Gordo Unidad de Anatomía Patológica, Universidad de Extremadura, Avda. de la Universidad s/n, 10.071, Cáceres, Spain J. C. Parejo Unidad de Genética, Facultad de Veterinaria, Universidad de Extremadura, Avda. de la Universidad s/n, 10.071, Cáceres, Spain J. Carrión : M. Soto : C. Alonso Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Cantoblanco, 28049 Madrid, Spain V. Iniesta (*) Unidad de Parasitología y Enfermedades Parasitarias, Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de Extremadura, Avda. de la Universidad s/n 10.071, Cáceres, Spain e-mail: viniesta@unex.es