Characterization of a secreted macrophage migration inhibitory factor homologue of the parasitic nematode Strongyloides acting at the parasite-host cell interface.
Strongyloidiasis is a tropical parasitosis characterized by an alternation between free-living and parasitic stages, and by long-term infection via autoinfection. Since invasion and evasion processes of helminth parasites are substantially attained by the involvement of excretory-secretory products, we identified and characterized the 13.5 kDa macrophage migration inhibitory factor (MIF)-like protein in Strongyloides ratti. Sra-MIF is mainly secreted from the infective stage larvae (iL3), while the transcript was found at lower levels in parasitic and free-living females. Sequence analysis of the full-length cDNA showed the highest homology to the human pathogen Strongyloides stercoralis, and both are related to the MIF type-2. Unlike other mif genes, the Sra-mif includes no intron. The protein was recombinantly expressed in Escherichia coli and purified. Sra-MIF exhibited no in vitro tautomerase activity. The exposure of Sra-MIF to the host immune system is confirmed by high IgG reactivities found in the hosts' sera following infection or immunization. Flow cytometric analysis indicated the binding of Sra-MIF to the monocytes/macrophage lineage but not to peripheral lymphocytes. After exposure to Sra-MIF, monocytes released IL-10 but not TNF-alpha suggesting the involvement of the secreted parasite MIF in host immune responses.
Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany. abssan2000@yahoo.com
Abuelhassan Elshazly
AE
Younis
Hanns
H
Soblik
Irene
I
Ajonina-Ekoti
Klaus D
KD
Erttmann
Kai
K
Luersen
Eva
E
Liebau
Norbert W
NW
Brattig
D000595:Amino Acid Sequence; D000818:Animals; D000947:Antigens, Helminth / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D002465:Cell Movement; D003429:Cross Reactions; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D005260:Female; D005434:Flow Cytometry; D015801:Helminth Proteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D006790:Host-Parasite Interactions; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D016753:Interleukin-10 / Q000378:metabolism; D008263:Macrophage Migration-Inhibitory Factors / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D008264:Macrophages / Q000276:immunology; D008297:Male; D008969:Molecular Sequence Data; D009000:Monocytes / Q000276:immunology; D010802:Phylogeny; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D017170:Strongyloides ratti / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D013322:Strongyloidiasis / Q000276:immunology / Q000469:parasitology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
D000947:Antigens, Helminth; D015801:Helminth Proteins; D007074:Immunoglobulin G; D008263:Macrophage Migration-Inhibitory Factors; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10