SEARCH · PubMed Health

Results for “Ornithodoros”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources

PubMed1976

"Karshi" virus, a new flavivirus (Togaviridae) isolated from Ornithodoros papillipes (Birula, 1895) ticks in Uzbek S.S.R.

Three identical strains of an arbovirus were isolated from 475 Ornithodoros papillipes ticks collected in June, 1972, in burrows of the great gerbil (Rhombomys opimus Licht., 1882) in the environs of Beshkent, Karshinsk steppe, Uzbek S.S.R. The isolate was found to range among flaviviruses. Complement-fixation, agar diffusion precipitation and neutralization tests is tissue culture and mice indicated a one-way antigenic relationship between the isolate and West Nile virus. However, the pattern of differences between them made it possible to consider the isolated agent as a new virus, "Karshi" virus. The results of electron microscopic studies of this virus are presented.

Animals↗

PubMed1977

Piroplasmal sporozoites in the Argasid Ornithodoros erraticus (Lucas).

The infective forms of Nuttallia meri, a small-mammal piroplasm, first appear as spindle-shaped sporozoites in and around the salivary glands of Ornithodoros erraticus (small race) 30 days after the ticks had fed on infected blood. O. erraticus is the only soft tick so far proved to transmit a piroplasm.

Animals↗

PubMed1995

Effects of ingested phytoecdysteroids in the female soft tick Ornithodoros moubata.

The effects of the ingestion of some phytoecdysteroids were studied in the soft tick Ornithodoros moubata. Supernumerary moulting and malformations of first leg pairs were obtained with 22-oxo-20-hydroxy-ecdysone, 20-hydroxyecdysone-22-acetate, and 20-hydroxyecdysone-22-benzoate. Egg-yield was reduced with 20-hydroxyecdysone-22-acetate and carthamosterone. Finally, drying-out of eggs was observed with carthamosterone and 22-deoxy-20,26-dihydroxyecdysone. In addition, we demonstrated that there is a correlation between the number of completed gonotrophic cycles and the impossibility of inducing supernumerary moulting.

Animals↗

PubMed1990

Absence of Ornithodoros moubata, the vector of African swine fever virus, from the main pig producing area of Cameroon.

No evidence for the presence of soft ticks of the Ornithodoros moubata complex was found during a survey of African swine fever carried out between 1985 and 1988 in the West Province and southern parts of the North West and South West Provinces of Cameroon. The survey consisted of interviews of veterinary assistants and farmers, distribution of a questionnaire and tick searches both manually and with carbon dioxide traps. The absence of warthogs (Phacochoerus aethiopicus) from these areas was also recorded.

African Swine Fever↗

PubMed1985

Use of a silicone membrane feeding technique in the laboratory maintenance of a colony of Ornithodoros moubata.

Adult Ornithodoros moubata from a laboratory colony were fed on mice or through natural or artificial membranes on pig blood. The rate of feeding and its efficiency as assessed by fecundity were markedly superior when membranes rather than live mice were used. Artificial silicone membranes offer major advantages of both convenience and economy over alternative membranes in the maintenance of soft tick colonies.

Animals↗

PubMed1986

Development and mortality of Ornithodoros moubata after feeding through an artificial membrane.

High mortality rates have often been observed when artificial feeding techniques are used for colony maintenance of Ornithodoros moubata. Such fatalities can be readily controlled by addition of antibiotics to the feeding medium without apparent toxicity to ticks. Comparative results show that for maintaining colonies of O. moubata artificial feeding techniques can be as efficient as direct feeding on swine--the primary hosts of these argasids.

Animals↗

PubMed2003

Up-regulated humoral immune response in the soft tick, Ornithodoros moubata (Acari: Argasidae).

Ticks have an efficient defense system for preventing microbial infection. The antimicrobial peptide defensin is one effective molecule in this system. Here we investigated immune competence and the involvement of defensin in the humoral defense of the soft tick, Ornithodoros moubata. Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) revealed that gene expression of all four defensin isoforms was up-regulated by bacteria or bacterial components. Defensin gene up-regulation by hemocoelic inoculation of bacteria involves the midgut and granulocytes. In immunodetection analysis, immunization by bacterial injection increases the relative concentration of defensin-like material in the hemolymph plasma. Furthermore, elevated antibacterial activity against Gram-positive bacteria but not against Gram-negative bacteria was observed after immunization by a liquid growth inhibition assay. Therefore, enhanced anti-Gram-positive bacterial activity appears to be partially dependent on the release of defensin into the hemolymph. These findings demonstrate that defensin plays an important role in the up-regulated humoral response of O. moubata.

Animals↗

PubMed1985

Ornithodoros moubata: host immunoglobulin G in tick hemolymph.

Hemolymph proteins of a soft tick, Ornithodoros moubata, were analyzed immunochemically and biochemically. The components of tick hemolymph proteins were shown to be totally different from the host (rabbit) serum proteins by polyacrylamide gel electrophoresis with sodium dodecyl sulfate and Coomassie blue or silver stain. However, in the hemolymph of ticks engorged from rabbits immunoglobulin G was detected by immunoblotting analysis with goat anti-rabbit immunoglobulin G. The concentration of rabbit Immunoglobulin G in tick hemolymph changed with the physiological stages after a blood meal. Immunoglobulin G was isolated from tick hemolymph by affinity chromatography on a Protein A-Sepharose 4B column. Analysis of the isolated immunoglobulin G from tick hemolymph with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Ouchterlony double diffusion test showed it to be composed of the same subunits as heavy and light chains of host (rabbit) immunoglobulin G. Tracer experiments showed that 125I-labeled heavy and light chains of immunoglobulin G were detected in an intact form in hemolymph from ticks that sucked 125I-labeled rabbit immunoglobulin G through an artificial membrane. These facts suggested that the host rabbit immunoglobulin G ingested in the tick midgut passed through the gut wall without digestion. By solid-phase enzyme immunoassay, immunoglobulin in the hemolymph was shown to retain its antibody activity.

Animals↗

PubMed1985

Ornithodoros moubata: spermateleosis and secretory activity of the sperm.

Cytological aspects of spermateleosis in the tick Ornithodoros moubata were studied by electron microscopy. During spermateleosis, detachment of the operculum from the outer sheath of the prospermium results from the fusion of the plasma and the cisternal membranes. The fusion occurs between the shoulder of the acrosomal vesicle and the electron-dense layer of the operculum. A factor inducing vitellogenesis and egg-laying is secreted by the sperm cell after spermateleosis, and begins after the cell is almost completely devaginated. In vitro, fully devaginated spermiophores secrete most of this factor during the first 12 hr of incubation. The vitellogenesis-inducing activity of the secretion is sensitive to proteinase K (EC 3.4.21.14) digestion and correlates with the presence of two high-molecular-weight proteins in the sperm cell incubation medium.

Animals↗

PubMed1994

NMR solution structure of the recombinant tick anticoagulant protein (rTAP), a factor Xa inhibitor from the tick Ornithodoros moubata.

The solution structure of the recombinant tick anticoagulant protein (rTAP) was determined by 1H nuclear magnetic resonance (NMR) spectroscopy in aqueous solution at pH 3.6 and 36 degrees C. rTAP is a 60-residue protein functioning as a highly specific inhibitor of the coagulation protease factor Xa, which was originally isolated from the tick Ornithodoros moubata. Its regular secondary structure consists of a two-stranded antiparallel beta-sheet with residues 22-28 and 32-38, and an alpha-helix with residues 51-60. The relative orientation of these regular secondary structure elements has nearly identical counterparts in the bovine pancreatic trypsin inhibitor (BPTI). In contrast, the loop between the beta-sheet and the C-terminal alpha-helix as well as the N-terminal 20-residue segment preceding the beta-sheet adopt different three-dimensional folds in the two proteins. These observations are discussed with regard to the implication of different mechanisms of protease inhibition by rTAP and by Kunitz-type protein proteinase inhibitors.

Amino Acid Sequence↗

PubMed1984

Metabolism of ecdysteroids during the vitellogenesis of the tick Ornithodoros moubata (Ixodoidea, Argasidae): accumulation of apolar metabolites in the eggs.

The fate of injected [3H]ecdysone [( 3H]E) and 20-hydroxy-[3H]ecdysone [( 3H]20E) has been investigated in the female tick Ornithodoros moubata (Murray, 1877; sensu Walton, 1962). When injected into fed mated vitellogenic females, [3H]E is converted into [3H]20E and two apolar classes of metabolites, AP1 and AP2. Injected [3H]20E is directly converted into AP1 and AP2. AP2 is incorporated into the ovaries in a high proportion and at the end of the vitellogenic cycle represents about 25% of the total label recovered from the animal. The fate of labeled hormones injected into virgin females which perform an abortive vitellogenic cycle is quite similar. However, the ovaries incorporated less of the AP2 products. Ovaries of mated females cultured in vitro in the presence of [3H]E are able to produce [3H]20E and AP2. AP2 is incorporated, while [3H]20E is mainly found in the medium. Ovaries of virgin females presented a slower rate of transformation and of incorporation of the label. Labeled AP2 is recovered in freshly laid eggs and AP1 in the females after oviposition. AP1 and AP2 can produce [3H]20E, [3H]E, and other minor polar peaks when submitted to hydrolysis by esterase. It is concluded that the female O. moubata possesses a special enzymatic mechanism for transformation of ecdysteroids into apolar products and for selective incorporation of AP2 into the ovaries. These products are present in the freshly laid eggs and could play a role during embryogenesis.

Animals↗

PubMed1991

Cuticle deposition and ecdysteroid titers during embryonic and larval development of the argasid tick Ornithodoros moubata (Murray, 1877, sensu Walton, 1962) (Ixodoidea:Argasidae).

Timing of embryonic and larval molts at the ultrastructural level and presence of ecdysteroids (ES) during embryonic and larval development of the argasid tick Ornithodoros moubata were studied. Embryonic "cuticles" A, B, and C were deposited 24-30 hr, 48-56 hr, and 6 days after oviposition, respectively. Deposition of the larval cuticulin layer started on Day 8 of embryonic development and procuticle deposition continued after hatching until apolysis of the larval cuticle 40 hr posthatch. Plaques of cuticulin formed on tips of microvilli 48-56 hr after hatching and procuticle was deposited until after ecdysis. Radioimmunoassay (RIA) was used to determine the ES titer in methanolic extracts of various ages of embryos and larvae. No peaks of RIA-positive material were detected during deposition of envelopes A, B, and C. However two peaks of ES were observed during embryonic development, one which coincided with the shortening of the germ band and a second which coincided with the deposition of the larval epicuticle on Day 8. During larval development, a peak of ES was observed on Day 3 (48-56 hr posthatch) and was correlated with nymphal epicuticle deposition. HPLC-RIA revealed that these last two peaks consisted mainly of 20-hydroxyecdysone together with a small quantity of ecdysone. Conjugated RIA positive material was present in freshly laid eggs and an augmentation of this esterase hydrolysable material was noted at the appearance of each ES peak. Thus the embryos did not appear to be hydrolyzing the maternal apolar conjugates to release ES during embryonic development; on the contrary, they appeared to be conjugating the newly synthesized hormones.

Animals↗

PubMed1996

Photoperiodic response in the soft tick, Ornithodoros turicata.

The effects of photoperiod on the feeding, development and quiescent behavior of the burrow-dwelling soft tick, Ornithodoros turicata (Dugès) were investigated. Ticks were assigned randomly to either continuous darkness (DD), a short-day photoperiod (L:D 10:14), a long-day photoperiod (L:D 14:10) or constant light (LL). Ticks reared under constant light succumbed to much higher mortality than those reared under the other conditions. However, photoperiod did not induce quiescent behavior in O. turicata; the ticks were active and fed regularly throughout the study. Also, ticks reared in continuous darkness developed more slowly than those reared under short-day or long-day conditions. In contrast, pre-oviposition period was significantly longer for ticks reared in long-day conditions. Egg-hatch success was significantly higher for ticks reared in continuous darkness than for those reared under the photoperiods. The stage-specific effects of photoperiod on O. turicata are adaptive; these ticks very likely utilize photoperiod information to predict seasonal conditions.

Animals↗

PubMed1982

Scanning electron microscopy of post-ejaculatory spermiogenesis in the tick Ornithodoros moubata.

The final stages of spermiogenesis in ticks occur in the female genital tract. Scanning electron microscopy was used to follow the morphologic changes that occur in the sperm during this post-ejaculatory spermiogenesis in the African soft tick, Ornithodoros moubata, and to determine a time sequence for its occurrence in vivo. Characteristic features of the maturing and mature cell described include (1) differentiation and detachment of the operculum, (2) changes in cell shape corresponding to different developmental stages, (3) passive migration of the nucleus and acrosome from an anterior to a posterior position, and (4) eversion of that portion of the acrosomal canal containing the nucleus and acrosome. A possible fate for the remainder of the acrosomal canal is suggested by extrusion and detachment of spherical structures, the 'posterior bubbles', from the posterior end of the mature supermatozoon. A mechanism for cellular elongation resulting from contractions of the outer sheath is proposed.

Acrosome↗

PubMed1991

Saliva of the soft tick, Ornithodoros moubata, contains anti-platelet and apyrase activities.

1. Pilocarpine-induced saliva of the soft tick Ornithodoros moubata inhibits platelet aggregation induced by ADP or collagen, even when diluted 2000 times into platelet rich plasma. 2. Saliva contains apyrase (ATP-diphosphohydrolase) activity, which has an optimal pH of 7.0 for ADP and of 8.0 for ATP hydrolysis, respectively. Both Ca2+ and Mg2+ activate the reactions. 3. The mean specific activities for ATP and ADP hydrolysis at pH 7.5 were 0.97 and 0.74 mumoles orthophosphate/min/mg protein. 4. These results, which demonstrate for the first time such activities in the saliva of soft ticks, support the hypothesis that the saliva of blood sucking arthropods serves an anti-hemostatic role during feeding and that large amounts of salivary apyrase activity have evolved independently in hematophagous arthropods.

Adenosine Diphosphate↗

PubMed1990

Evaluation of an enzyme-linked immunosorbent assay to detect specific antibodies in pigs infested with the tick Ornithodoros erraticus (Argasidae).

Ornithodoros erraticus is known to transmit the virus that causes the highly contagious disease, African Swine Fever, in Spain. As part of the disease eradication campaign, an ELISA test to detect specific antibodies against the tick was developed. The ELISA, using salivary gland preparations as an antigen, showed high sensitivity and was able to detect as few as 10 adult ticks. The specific antibodies were detected in the sera 6 weeks after the primary infestation and strongly increased after the challenge. The utility of this test under field conditions was also tested.

Animals↗

PubMed1994

Detection of pig farms with Ornithodoros erraticus by pig serology. Elimination of non-specific reactions by carbohydrate epitopes of salivary antigens.

Ornithodoros erraticus is the European vector of African Swine Fever. It is therefore essential to know on which pig farms the tick is present in order to prevent contact with swine. Currently, studies are being made to ascertain this through the detection of anti-O. erraticus antibodies in the sera of swine, using three extracts from the salivary glands of the parasite (SGE): a complete extract (SGE-1), a soluble antigens extract (SGE-2), and a tissue antigens extract (SGE-3). The results of the present work show that SGE-2 gives the best differentiation between swine bitten by O. erraticus and unbitten swine in the enzyme-linked immunosorbent assay (ELISA). Using this extract, an optical density (OD) five-fold higher than the basal OD indicates that the pigs carry anti-O. erraticus antibodies. A serological study carried out in Salamanca with 8083 sera from 1756 pig farms revealed the presence of the parasite on 135 farms. However, during this study we noticed that some sera of unbitten animals gave false-positive reactions. Western blot analysis of SGE-2 of these false-positive sera demonstrated the same bands (except for two) as the real anti-O. erraticus sera. We observed, in ELISA and Western blot analysis, that such false-positive sera only recognised carbohydrate epitopes on SGE-2. This reactivity disappeared on deglycosylated SGE-2 (SGE-2-P). Therefore, SGE-2-P is the antigen that confers the greatest specificity to serology. In this study it was also observed that the low levels of anti-O. erraticus antibodies found in some cases may be because the swine were bitten some months previously on a different farm or that the current farm harboured only a few specimens of O. erraticus, so pig-tick contact is unlikely and hence the pigs either only develop a primary response or the time between contacts is very long and the levels of antibodies fall. Since pigs could be bitten on a different farm, the presence of low levels of anti-O. erraticus antibodies in pig sera do not necessarily indicate the presence of the tick on the farm where sampling was carried out.

African Swine Fever↗

PubMed2002

Tissue distribution and characterization of predominant hemolymph carrier proteins from Dermacentor variabilis and Ornithodoros parkeri.

The tissue distribution of the predominant hemolymph protein found throughout tick development was examined in the hard tick, Dermacentor variabilis, and in the soft tick, Ornithodoros parkeri. In D. variabilis, the predominant (purified) hemolymph protein was a lipoglycoheme-carrier protein (DvCP) with a molecular weight of 200K. A protein with a similar mobility on native-PAGE was found in fat body, salivary gland, muscle and ovary from partially fed females which was most abundant in the plasma and salivary gland. DvCP from plasma, salivary gland and fat body of partially fed females consisted of two subunits on SDS-PAGE (98 and 92K). In replete females, only salivary gland exhibited protein subunits equivalent to hemolymph CP. CP in salivary gland and fat body stained positive for lipids. The concentration of CP in tissues varied between partially fed and replete females, indicating a difference in the expression and/or sequestration of CP during adult development. The predominant hemolymph carrier protein from O. parkeri (OpCP) was purified to homogeneity for the first time and is presumed to have similar functions to CP from D. variabilis. Purified OpCP exhibited a molecular weight of 668K by native-PAGE. Unlike CP from D. variabilis, OpCP was not detected in fat body or salivary gland tissues but occurred abundantly in coxal fluid. By SDS-PAGE, purified hemolymph OpCP consisted of two major subunits (114 and 93K) and a less abundant protein with an apparent molecular weight of 48K. Purified native OpCP was a lipoprotein like DvCP. A spectral analysis of purified OpCP failed to demonstrate the presence of heme like that found for CP from D. variabilis, purified by the same methods. However, plasma from O. parkeri contained heme with a lambda(max) of 410nm.

Journal Article↗