Cloning, expression and antigenicity of the L. donovani reductase

TY - JOUR

T1 - Cloning, expression and antigenicity of the L. donovani reductase

AU - Jensen, A T

AU - Kemp, K

AU - Theander, T G

AU - Handman, E

N1 - Keywords: Amino Acid Sequence; Animals; Antigens, Protozoan; Base Sequence; Case-Control Studies; Cloning, Molecular; DNA Primers; DNA, Protozoan; Gene Expression Regulation, Enzymologic; Genes, Protozoan; Humans; Leishmania donovani; Leishmania major; Leishmaniasis, Visceral; Leukocytes, Mononuclear; Lymphocyte Activation; Molecular Sequence Data; Oxidoreductases; Species Specificity

PY - 2001

Y1 - 2001

N2 - The protozoan parasite Leishmania undergoes a morphological and biochemical transformation from the promastigote to the amastigote form during its life cycle, which is reflected in the expression of stage-specific proteins. One of these proteins shows homology to a superfamily of reductase proteins. We have cloned the reductase gene from L donovani and have shown that it differs in only one nucleotide from the L. major homologue, resulting in one amino acid change. A cytosine (C) to guanine (G) transposition in the coding sequence leads to a nonconserved substitution of asparagine (N) for lysine (K). Only 2 of 22 plasma samples from patients with visceral leishmaniasis were found to have detectable anti-reductase antibodies and peripheral blood mononuclear cells (PBMC) from one of three individuals previously infected with visceral leishmaniasis proliferated in the presence of recombinant reductase protein. Interestingly, 6 of 10 PBMC isolated from Danish controls proliferated in the presence of the reductase protein. Intracellular IFNgamma was found in a significant percentage of cells in all the tested PBMC cultures from Danes, whereas IL4 was only found in a small proportion of cells, or not at all. The results indicate the presence of cross-reacting CD45R0 memory T-cells in individuals not exposed to Leishmania. Several previous studies have shown that T-cells from nonexposed individuals often respond to crude Leishmania antigen preparations. The present study suggests that this reactivity is partly caused by T-cells recognising L. donovani reductase.

AB - The protozoan parasite Leishmania undergoes a morphological and biochemical transformation from the promastigote to the amastigote form during its life cycle, which is reflected in the expression of stage-specific proteins. One of these proteins shows homology to a superfamily of reductase proteins. We have cloned the reductase gene from L donovani and have shown that it differs in only one nucleotide from the L. major homologue, resulting in one amino acid change. A cytosine (C) to guanine (G) transposition in the coding sequence leads to a nonconserved substitution of asparagine (N) for lysine (K). Only 2 of 22 plasma samples from patients with visceral leishmaniasis were found to have detectable anti-reductase antibodies and peripheral blood mononuclear cells (PBMC) from one of three individuals previously infected with visceral leishmaniasis proliferated in the presence of recombinant reductase protein. Interestingly, 6 of 10 PBMC isolated from Danish controls proliferated in the presence of the reductase protein. Intracellular IFNgamma was found in a significant percentage of cells in all the tested PBMC cultures from Danes, whereas IL4 was only found in a small proportion of cells, or not at all. The results indicate the presence of cross-reacting CD45R0 memory T-cells in individuals not exposed to Leishmania. Several previous studies have shown that T-cells from nonexposed individuals often respond to crude Leishmania antigen preparations. The present study suggests that this reactivity is partly caused by T-cells recognising L. donovani reductase.

M3 - Journal article

C2 - 11506479

SN - 0903-4641

VL - 109

SP - 461

EP - 468

JO - Acta Pathologica Microbiologica et Immunologica Scandinavica

JF - Acta Pathologica Microbiologica et Immunologica Scandinavica

IS - 6

ER -