Molecular cloning of a novel protein antigen of Leishmania major that elicits a potent immune response in experimental murine leishmaniasis.
BALB/c mice are highly susceptible to infection with the protozoan parasite Leishmania major. This susceptibility has been attributed, in part, to the expansion of parasite-specific CD4+ Th2 cells that antagonize Th1 responses and promote humoral immunity. In the present study, we have utilized sera from L. major-infected BALB/c mice to screen an L. major amastigote cDNA expression library. One of the clones detected encodes a novel Ag designated as L. major stress-inducible 1 (LmSTI1). LmSTI1 contains six copies of the tetratricopeptide consensus motif and is highly related to a family of stress-inducible proteins that is conserved from yeast to humans. Sera from L. major-infected BALB/c mice have LmSTI1-specific Ab titers in excess of 1:200,000, comprised predominantly of IgG1, IgG2A, and IgG2B isotypes. Recombinant LmSTI1 protein elicited strong proliferative responses from draining lymph node cells of L. major-infected BALB/c mice at both early (10 days) and late (28 days) stages of infection and elicited production of high levels of IFN-gamma and low levels of IL-4. In contrast, soluble leishmanial lysate elicited high levels of IL-4 and low IFN-gamma production. Thus, we have identified an Ag of Leishmania capable of eliciting a mixed cellular response that is skewed toward a Th1 phenotype in susceptible BALB/c mice with advanced infections. In addition, analyses of sera from human patients with cutaneous, visceral, and post-kala azar visceral leishmaniasis indicated that a majority of individuals from all three clinical groups mounted strong humoral responses against LmSTI1.
Webb
J R
JR
Infectious Disease Research Institute, Seattle, WA 98104, USA.
Kaufmann
D
D
Campos-Neto
A
A
Reed
S G
SG
D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis; D000953:Antigens, Protozoan / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D016054:DNA, Protozoan / Q000235:genetics; D004195:Disease Models, Animal; D005260:Female; D017125:Genes, Protozoan; D006801:Humans; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D018320:Leishmania major / Q000235:genetics* / Q000276:immunology*; D016773:Leishmaniasis, Cutaneous / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D013601:T-Lymphocytes / Q000276:immunology
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D016054:DNA, Protozoan; D015847:Interleukin-4; D007371:Interferon-gamma