Pathogenic mechanisms of sand tampan toxicoses induced by the tick, Ornithodoros savignyi

Mans, Ben J.; Steinmann, C.M.L.; Venter, Jacobus D.; Louw, Abraham I.; Neitz, A.W.H.

doi:10.1016/s0041-0101(02)00098-3

Cited by 45 publications

(51 citation statements)

References 18 publications

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Section: Discussionmentioning

confidence: 99%

“…TSGP2 is toxic to mice but TSGP3 is not (34). OmCI is highly unlikely to be a toxin because O. moubata does not cause toxicosis (20), whereas O. savignyi causes sand tampan toxicosis in a wide range of mammals (34). Furthermore, intradermal injection of 100 g of purified nOmCI into guinea pigs, in the process of raising antisera, caused no obvious pathophysiological effects (M. Nunn, unpublished observation).…”

Section: Discussionmentioning

confidence: 99%

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Complement Inhibitor of C5 Activation from the Soft Tick Ornithodoros moubata

Nunn

Sharma

Paesen

et al. 2005

The Journal of Immunology

205

186

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Blood-feeding ticks must control C activation or be damaged by the host inflammatory response. We report the characterization and expression of a novel, relatively small, broad-acting C inhibitory protein (termed OmCI) from the soft tick Ornithodoros moubata. The native 17-kDa nonglycosylated protein inhibits both human and guinea pig classical and alternative C activation pathways. The IC50 values for each pathway were 12 and 27 nM, respectively, in hemolytic assays using human serum diluted 40-fold. The cDNA encodes a protein of 168 aa, including an 18-aa secretion signal sequence that is absent in the mature form. The inhibitor has 46% amino acid identity with moubatin, a platelet aggregation inhibitor also from O. moubata that is an outlying member of the lipocalin family. Native OmCI had no inhibitory effect on the addition of C8 and C9 to preformed C5b-C7 and C5b-C8 to form the membrane attack complex and no effect on the rate of C3a production by the C3 convertase enzymes C4bC2a, C3(H2O)Bb, or C3bBb. Both recombinant and native OmCI abolish production of C5a by human classical (C4bC3bC2a) and alternative (C3bC3bBb) C5 convertases. Addition of excess C5 but not C3 competes away the inhibitory activity of OmCI, indicating that OmCI targets C5 itself rather than inhibiting the C5 convertase C4bC3bC2a itself. Direct binding of OmCI to C5 was demonstrated by Western blotting and gel filtration chromatography using 125I-labeled proteins. OmCI is the first lipocalin family member shown to inhibit C and also the first natural inhibitor that specifically targets the C5 activation step.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Complement Inhibitor of C5 Activation from the Soft Tick Ornithodoros moubata

Nunn

Sharma

Paesen

et al. 2005

The Journal of Immunology

205

186

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“…Remarkably, while lipocalins in general are binders of hydrophobic ligands, in all the cases mentioned above they bind hydrophilic molecules. In addition to these small ligand binding activity, some lipocalins also inhibit blood coagulation Ribeiro et al, 1995;Zhang et al, 1998), platelet aggregation (Keller et al, 1993;Waxman and Connolly, 1993), alternative complement activation (Nunn et al, 2005), and have toxic properties (Mans et al, 2003;Mans et al, 2002c). Despite this accumulating functional knowledge on hematophagous arthropods' salivary lipocalins, the vast majority of salivary lipocalins have unknown function.…”

Section: Putative Salivary Secreted Proteins Having Ubiquitous Domainmentioning

confidence: 99%

“…Branch 4 contains several O. parkeri lipocalins as well as the protein named TSGP4 (gi|25991438|), which was also shown to be toxic to mice (Mans et al, 2002c). However, toxic reactions were not observed with closely related O. moubata salivary proteins, indicating that sequence similarity may be a poor predictor of function in tick lipocalins (Mans et al, 2003;Mans and Neitz, 2004a).…”

Section: Putative Salivary Secreted Proteins Having Ubiquitous Domainmentioning

confidence: 99%

“…Also indicated (with a red circle marker) are two histamine and serotonin binders that are closely related, DERRE_18032205 (gi|18032205), from the hard tick Dermacentus reticulatus, and RHIAP_8470381 (gi|8470381) from Rhipicephalus appendiculatus; these last two proteins have no close relatives among the soft ticks. Except for biogenic amine binding functions proposed for group 1 other lipocalins can work at low concentrations as ligands in host receptormediated interactions, as is the possible mode of action of the toxic lipocalin of the African soft tick, O. savigny (Mans et al, 2003;Mans et al, 2002c). …”

Section: Putative Salivary Secreted Proteins Having Ubiquitous Domainmentioning

confidence: 99%

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An insight into the sialome of the soft tick, Ornithodorus parkeri

Francischetti¹,

Mans²,

Meng

et al. 2008

Insect Biochemistry and Molecular Biology

103

104

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While hard ticks (Ixodidae) take several days to feed on their hosts, soft ticks (Argasidae) feed faster, usually taking less than one hour per meal. Saliva assists in the feeding process by providing a cocktail of anti-hemostatic, anti-inflammatory and immunomodullatory compounds. Saliva of hard ticks has been shown to contain several families of genes each having multiple members, while those of soft ticks are relatively unexplored.Analysis of the salivary transcriptome of the soft tick Ornithodorus parkeri, the vector of the relapsing fever agent Borrelia parkeri, indicates that gene duplication events have led to a large expansion of the lipocalin family, as well as of several genes containing Kunitz domains indicative of serine protease inhibitors, and several other gene families also found in hard ticks. Novel protein families with sequence homology to insulin growth factor-binding protein (prostacyclin-stimulating factor), adrenomedulin, serum amyloid A protein precursor and similar to HIV envelope protein were also characterized for the first time in the salivary gland of a blood-sucking arthropod.The sialotranscriptome of O. parkeri confirms that gene duplication events are an important driving force in the creation of salivary cocktails of blood-feeding arthropods, as was observed with hard ticks and mosquitoes. Most of the genes coding for expanded families are homologous to those found in hard ticks, indicating a strong common evolutionary path between the two families. As happens to all genera of blood-sucking arthropods, several new proteins were also found, indicating the process of adaptation to blood feeding still continues to recent times.

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Morphological and molecular description of immature stages of Ornithodoros savignyi (Acari: Argasidae)

et al. 2016

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This study was designed to provide more details about larva, first nymph, and second nymph of Ornithodoros savignyi using a combination of light microscopy (LM), scanning electron microscopy (SEM), and partial sequence of mitochondrial 16S ribosomal ribonucleic acid (rRNA). The main characteristics of larva are wrinkled integument with many grooves, gnathosoma without camerostome cheeks, hypostome with a pair of large teeth apically, and tarsus without humps. The comparisons between the first and the second nymphs are different shape and distribution of dorsal grooves; a few spots without mammilla on the dorsal surface of the second nymph; 27 and 63-65 pairs of setae on the dorsal surface of the first and second nymphs, respectively; small holes on mammillae that are more dense in the second nymph; basis capitulum with two pairs of small setae in the second nymph; and one pair of sate in the first nymph, hypostome with dental formula 2/2 in the first nymph, and 3/3 in the second nymph. The partial 16S rRNA sequence of the second nymph that was determined as O. savignyi (450 bp) was deposited in GenBank under the accession number KU163242.

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Pathogenic mechanisms of sand tampan toxicoses induced by the tick, Ornithodoros savignyi

Cited by 45 publications

References 18 publications

Complement Inhibitor of C5 Activation from the Soft Tick Ornithodoros moubata

Complement Inhibitor of C5 Activation from the Soft Tick Ornithodoros moubata

An insight into the sialome of the soft tick, Ornithodorus parkeri

Morphological and molecular description of immature stages of Ornithodoros savignyi (Acari: Argasidae)

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