title: Humoral and cellular immune responses against Type I cysteine proteinase of Leishmania infantum are higher in asymptomatic than symptomatic dogs selected from a naturally infected population.
abstract: Canids are natural reservoirs of Leishmania infantum and have been promoted as experimental hosts to decipher the pathogenesis of human visceral leishmaniasis (VL). In this study, the presence of IgG antibodies as well as the presence of mononuclear leukocytes reactive to different cysteine proteinases (CPs) were examined in 13 L. infantum-infected dogs (six with symptoms, seven asymptomatic). Cysteine proteinases which belong to papain-like enzymes known as clan CA are the most studied CPs of parasite protozoa. These molecules are expressed by the intracellular stages of the parasite and could be immunogenic. We studied Type II CP (CPA) and Type I CP (CPB) with its long C-terminal extension (CTE) which could be highly immunogenic. We showed that the level of antibodies reactive to rCPA is low in both symptomatic and asymptomatic dogs. In contrast, when CPB and CTE were used as antigens, the level of total IgG (with IgG2 superior to IgG1) reached higher values in asymptomatic dogs than in dogs with VL. While the peripheral blood mononuclear cell (PBMC) reactivity was significant when cultured in the presence of freezed/thawed (F/T) lysate, it remained low in presence of CP although always higher for PBMC recovered from asymptomatic dogs. We showed the importance of CPB and CTE in particular as a target of immune response and their potential use for serodiagnosis in asymptomatic dogs.
authors.affiliation: Department of Clinical Biochemistry, School of Medical Sciences, Tarbiat Modarres University, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Nakhaee
authors.forename: Tahere
authors.initials: T
authors.lastname: Taheri
authors.forename: Mohammad
authors.initials: M
authors.lastname: Taghikhani
authors.forename: Mehdi
authors.initials: M
authors.lastname: Mohebali
authors.forename: Ali-Hatef
authors.initials: AH
authors.lastname: Salmanian
authors.forename: Nicolas
authors.initials: N
authors.lastname: Fasel
authors.forename: Sima
authors.initials: S
authors.lastname: Rafati
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D003546:Cysteine Endopeptidases / Q000276:immunology*; D004283:Dog Diseases / Q000276:immunology / Q000469:parasitology*; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D007132:Immunoglobulin Isotypes; D007156:Immunologic Memory / Q000276:immunology; D007527:Isoenzymes / Q000276:immunology; D018314:Leishmania infantum / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D007898:Leishmaniasis, Visceral / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007132:Immunoglobulin Isotypes; D007527:Isoenzymes; D011994:Recombinant Proteins; D003546:Cysteine Endopeptidases