A recombinant Leishmania chagasi antigen that stimulates cellular immune responses in infected mice.
Cellular immune mechanisms resulting in gamma interferon production are critical for protection against visceral leishmaniasis. Antigens stimulating T-cell responses are likely present in the intracellular amastigote form of the parasite, since this is the form found in a mammalian host. To identify T-cell antigens of Leishmania chagasi, the parasite causing South American visceral leishmaniasis, we used a double antibody-T-cell technique to screen an amastigote cDNA library. One cDNA selected (Lcr1) encodes an antigen that stimulated proliferation of splenic T lymphocytes from infected mice that were either resistant (C3H.HeJ) or susceptible (BALB/c) to L. chagasi infection. The Lcr1 cDNA contains four highly divergent 201-bp repeats homologous to the 204-bp repeat of a Trypanosoma cruzi flagellar antigen gene. Results are consistent with a single copy of the Lcr1 gene producing an mRNA of > 10 kb and a protein of > 200 kDa. Recombinant Lcr1, cloned adjacent to polyhistidine and purified on a nickel affinity column, stimulated gamma interferon but not interleukin-4 (IL-4), IL-5, or IL-10 secretion by T-cell-enriched splenocytes from either susceptible or resistant mice during L. chagasi infection. Immunization with Lcr1 partially protected BALB/c mice against challenge with L. chagasi, indicating the utility of the double screening approach in selecting relevant T-cell antigens.
Wilson
M E
ME
Department of Internal Medicine, University of Iowa, Iowa City 52242, USA.
Young
B M
BM
Andersen
K P
KP
Weinstock
J V
JV
Metwali
A
A
Ali
K M
KM
Donelson
J E
JE
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D015152:Blotting, Northern; D004926:Escherichia coli / Q000235:genetics; D007111:Immunity, Cellular / Q000276:immunology*; D007114:Immunization; D007891:Leishmania / Q000235:genetics / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000517:prevention & control*; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
D000953:Antigens, Protozoan; C093281:Lcr1 antigen; D015800:Protozoan Proteins; D011994:Recombinant Proteins