title: Immune elimination of Leishmania major in mice: implications for immune memory, vaccination, and reactivation disease.
abstract: Infection of susceptible BALB/c mice with a large, moderate, or low number of Leishmania major parasites respectively results in progressive disease, the formation of substantial but stable lesions, denoted as borderline disease, and the absence of a visible lesion. Infection with a low number of parasites results over the long term in either subclinical infections or an asymptomatic state. Subclinical mice produce a predominant Th1 response and are resistant to challenge, in contrast to their asymptomatic counterparts. Statistical and other evidence suggest that the asymptomatic state can arise from a subclinical state following parasite clearance, with consequent loss of resistance. Cell transfer studies demonstrate unequivocally that immune cells from subclinical mice can protect naive mice against a pathogenic challenge and can clear the parasite, leaving the mice susceptible to a rechallenge infection. This susceptibility is associated with the disappearance of both parasite-specific effector and memory T cells from secondary lymphoid organs. These findings have implications for vaccination, maintenance of memory, and prevention of reactivation disease.
authors.affiliation: Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: J E
authors.initials: JE
authors.lastname: Uzonna
authors.forename: G
authors.initials: G
authors.lastname: Wei
authors.forename: D
authors.initials: D
authors.lastname: Yurkowski
authors.forename: P
authors.initials: P
authors.lastname: Bretscher
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D007700:Kinetics; D018320:Leishmania major / Q000276:immunology*; D016773:Leishmaniasis, Cutaneous / Q000175:diagnosis / Q000276:immunology* / Q000469:parasitology / Q000517:prevention & control; D008198:Lymph Nodes / Q000276:immunology; D017780:Malaria Vaccines; D051379:Mice; D008807:Mice, Inbred BALB C; D012008:Recurrence; D013154:Spleen / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000637:transplantation; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D017780:Malaria Vaccines; D015847:Interleukin-4; D007371:Interferon-gamma