PubMed Health⌕ Search

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 127 records · Page 7Linked to original sources
PubMed1997

Host immune response evasion strategies in Ornithodoros erraticus and O. moubata and their relationship to the development of an antiargasid vaccine.

We analysed in mice why the salivary gland extract (SGE-2) from Ornithodoros erraticus and O. moubata induce a protective response with Freund's adjuvants (FAs) in swine while the saliva, in natural conditions, does not. Such protection has been ascribed to the fact that administration of SGE-2 plus FAs permits the recognition of certain salivary components that under natural conditions are not immunogenic. The present findings confirm this hypothesis since in mice, which are unable to recognize the above components, the SGE-2-FAs do not induce any protection. We rule out the possibility that the cause of this could lie in the absence of prostaglandin E2 in the SGE-2 (vs saliva) since it is not present in either fluid. Neither could it be due to a change in antibody isotype since those induced by parasites bites and by the SGE-2-FAs are the same (IgG2a > IgG1 > IgG2b; not IgG3, IgM, IgE). No IgG2a were seen when the SGE-2 were administered alone or with alum or ricin. It is therefore suggested that first responses would be Th1 and the second ones Th2, although no IgE is seen in the latter responses either. The parasites do not require complement to feed; by contrast, they block its activation and skin cellular infiltrates, such as those elicited by IL-8, MCP-1 and C5a, do not affect them, regardless of the presence or not of antitick antibodies.

Alum Compounds↗
PubMed2000

Characterization of an alpha-macroglobulin-like glycoprotein isolated from the plasma of the soft tick Ornithodoros moubata.

We report the identification of the first representative of the alpha-2-macroglobulin family identified in terrestrial invertebrates. An abundant acidic glycoprotein was isolated from the plasma of the soft tick Ornithodoros moubata. Its molecular mass is about 420 kDa in the native state, whereas in SDS/PAGE it migrates as one band of 190 kDa under nonreducing conditions and a band of 92 kDa when reduced. Chemical deglycosylation reveals that it is composed of two different subunits, designated A and B. The N-terminal amino-acid sequence of subunit A is similar to the N-terminus of invertebrate alpha-2-macroglobulin. Sequence analysis of several internal peptides confirms that the tick protein belongs to the alpha-2-macroglobulin family, and the protein is therefore referred to as tick alpha-macroglobulin (TAM). Functional analyses strengthen this assignment. TAM inhibits trypsin and thermolysin cleavage of the high-molecular-weight substrate azocoll in a manner similar to that of bovine alpha-2-macroglobulin. This effect is abolished by pre-treatment of TAM with methylamine. In the presence of TAM, trypsin is protected against active-site inhibition by soybean trypsin inhibitor. We cloned and sequenced a PCR product containing sequences from both subunits and spanning the N-terminus of subunit B and the putative 'bait region' (a segment of alpha-2-macroglobulin which serves as target for various proteases). This indicates that the two subunits are generated from a precursor polypeptide by post-translational processing.

Amino Acid Sequence↗
PubMed1989

Susceptibility of Ornithodoros parkeri (Cooley) (Acari: Argasidae) and Dermanyssus gallinae (DeGeer) (Acari: Dermanyssidae) to ivermectin.

Ivermectin was injected into hosts and evaluated for effectiveness against the argasid tick Ornithodoros parkeri (Cooley) and the chicken mite Dermanyssus gallinae (DeGeer). O. parkeri second stage nymphs (N2s) showed a marked increase in mortality when fed on mice injected intraperitoneally with ivermectin at a dose between 0.1 and 0.2 mg/kg host body weight. For adult O. parkeri and D. gallinae, 0.4 and 0.5 mg, respectively, per kilogram of host body weight were necessary for an increase in mortality over controls. These latter findings are comparable to those reported for other tick species but differ from those reported for the northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago). Further testing narrowed the effective dose range for O. parkeri adults to between 0.425 and 0.450 mg/kg host body weight. The time interval (4, 8, and 24 h) between ivermectin injection of the host and tick feeding had only a slight influence on the overall effectiveness of the drug. In O. parkeri, doses of 0.0125 to 0.1000 mg/kg body weight did not affect fecundity, hatchability, gross morphology of the reproductive system and synganglion, or histology of the reproductive system. Contrary to reports of irreversibility of effects of ivermectin on gamma aminobutyric acid-mediated neurotransmission, many ivermectin-paralyzed ticks recovered partial mobility over time.

Animals↗
PubMed1989

Distribution and pharmacokinetics of precocene-II in the tick Ornithodoros parkeri (Acari: Argasidae).

Injected [3H]precocene-II spread from the hemocoel of Ornithodoros parkeri (Cooley) ticks to gut, salivary glands, synganglion, ovary, and the remainder of the body (carcass). Analyses at 2, 24, and 48 h after injection of precocene revealed that radioactivity remained at low levels in the synganglia and ovaries of fed-mated and fed-virgin females. Radioactivity increased gradually during 48 h after injection in salivary glands of fed-mated and fed-virgin ticks. It also increased gradually in the gut of fed virgins but not in fed-mated females. The carcasses contained the majority of total radioactivity at 2, 24, and 48 h after injection. Most of the radioactivity was found in ether-soluble compounds and only minimal amounts in water-soluble metabolites. Analysis of tick excreta and washings indicate that female O. parkeri excrete injected precocene very slowly; only 6% of total radioactivity was recovered in these samples during the 48 h after injection. Thin-layer chromatographic analyses of ether extracts of salivary glands and carcasses from fed-mated ticks 24 h after injection showed that the majority of the injected [3H]precocene-II was present in unchanged form.

Animals↗
PubMed1989

Population structure and seasonal intra-burrow movement of Ornithodoros turicata (Acari: Argasidae) in gopher tortoise burrows.

Burrows of the gopher tortoise, Gopherus polyphemus Daudin, were sampled for Ornithodoros turicata (Dugès) infestation using carbon dioxide baits and vacuum extraction. Ticks were captured, marked, released, and recaptured, and population estimates were made using the Lincoln index. Estimated population ranged from 47 to 1,338 ticks per burrow. The tick population consisted predominantly of nymphs, with a significant increase in the larval population during the months of June and July. Adult sex ratio was slightly male-biased, but numbers of adults collected were consistently low. Ticks exhibited a low interburrow movement, but depth preferences fluctuated with season; more ticks occurred in the upper strata of the burrows during the hot, humid months.

African Swine Fever↗
PubMed1991

Field evaluation of carbon dioxide baits for sampling Ornithodoros turicata (Acari: Argasidae) in gopher tortoise burrows.

Field studies were conducted to assess the reliability of carbon dioxide baits in sampling Ornithodoros turicata Duges. Tick response to about 50 g of dry ice placed at various distances away from tick-infested burrows was monitored over a 2-h period. In addition, tick attraction to different flow rates of carbon dioxide was monitored. Tests were conducted over a 15-mo period, during which seasonal effects on O. turicata response to CO2 were assessed. The efficacy of the baits was evaluated at night and in daytime. Ticks responded to dry ice baits placed up to 8 m away from the burrows. There was no significant difference in the total number of ticks attracted in a 1-h period using 500 to 2,000 ml CO2/min. At night, ticks were attracted to CO2 bits throughout the year except in December and January. By contrast, ticks were attracted to CO2 baits during daytime only between May and mid-December.

Animals↗
PubMed1991

Laboratory biology of Ornithodoros (Alectorobius) puertoricensis (Acari: Argasidae).

The laboratory biology of Ornithodoros (Alectorobius) puertoricensis Fox was studied over a 2-yr period. Approximately 100-150 ticks were reared individually at each of four temperatures: 22, 27, 33, and 40 degrees C and 90-95% RH. The mean egg incubation periods at those temperatures were 20.3, 11.1, 7.3, and 6.1 d, respectively. The average larval feeding period was 5.8 +/- 1.5 d for 15,875 larvae that fed on guinea pigs. The development times for first to fourth nymphal instars were as follows: 11.7, 48.5, 75.1, and 92.1 d, respectively, at 22 degrees C; 5.8, 18.8, 38.0, and 36.0 d, respectively, at 27 degrees C; 4.2, 10.5, 14.9, and 38.1 d, respectively, at 33 degrees C; and 5.8, 10.7, 21.2, and 35.3 d, respectively, at 40 degrees C. Males usually eclosed after three or four molts, and females usually eclosed after four or five molts. Approximately 10% of all nymphs required more than one blood meal per instar at least once during development. Twenty pairs of adults were held at each of three temperatures (22, 27, and 33 degrees C) for a year to study reproductive behavior. The number of gonotrophic cycles per female per year was 6.9, 9.8, and 10.8 at 22, 27, and 33 degrees C, respectively. The mean duration of the gonotrophic cycle was 42.3 d at 22 degrees C, 25.5 d at 27 degrees C, and 20.5 d at 33 degrees C. Mean egg production per female per gonotrophic cycle was 151 at 22 degrees C, 117 at 27 degrees C, and 130 at 33 degrees C and was not affected by temperature. O. puertoricensis did not exhibit autogeny or parthenogenesis. Hyperparasitism was observed in immatures and adults.

Animals↗
PubMed1991

Stimulation of vitellogenesis by pyrethroids in mated and virgin female adults, male adults, and fourth instar females of Ornithodoros moubata (Acari: Argasidae).

The effects of several pyrethroids on vitellogenesis, i.e., vitellogenin (Vg) synthesis and ovarian development in unfed mated female adults of Ornithodoros moubata were investigated. Survival of ticks treated with pyrethrin, resmethrin, and etophenprox was very low. Ticks treated with cypermethrin (CyM), fenvalerate (Fev), and flucythrinate (Flu) survived even when high concentrations were used. Vg titer in the hemolymph of unfed mated females was the same level on day 5 and about three times higher on day 10 after treatment with CyM, Fev, and Flu, as that of engorged adult females. CyM was the most effective in inducing vitellogenesis and was further evaluated in unfed virgin females, males, and fourth instars. CyM was shown to stimulate vitellogenesis in unfed virgin females adults. Oviposition did not occur but ovaries were well developed. CyM also was shown to stimulate Vg in the hemolymph of unfed and fed adult males; however, the Vg levels were very low compared to that of engorged adult females. Extremely high concentrations of Vg were observed in the hemolymph of female nymphs (fourth instar), particularly engorged nymphs, treated with CyM (10 micrograms). No ovarian development was observed in these nymphs. Vg stimulated by CyM was shown to be immunologically and electrophoretically the same as that of normal engorged females.

Animals↗
PubMed1991

Artificial feeding of Ornithodoros concanensis (Acari: Argasidae) nymphs on bovine blood and morphological changes in erythrocytes undergoing hemolysis in the tick midgut.

The morphology of bovine erythrocytes undergoing hemolysis in the midgut of the argasid tick Ornithodoros concanensis Cooley & Kohls was examined after feeding nymphal ticks artificially on parafilm and latex membranes. Percentage of successful feeding was significantly higher on parafilm (63%) than on latex (43%) membrane. However, there was no difference in the amount of blood taken per tick. Scanning electron microscopy was used to follow the morphological changes of red blood cells in the tick gut during an 80-h postfeeding period. Erythrocytes converted from normal discocytes to spiculated cells (echinocyte stage III) within 20 h. During the development of spicules (echinocytosis), erythrocytes lost membrane surface area by the release of microvesicles. At 30 h after feeding, the first spherocytes appeared and after 80 h, only smooth spheres of different sizes were present. Reasons for the observed modifications in red blood cell morphology are discussed.

Animals↗
PubMed1991

Effects of juvenile hormone and its analogs on vitellogenin synthesis and ovarian development in Ornithodoros moubata (Acari: Argasidae).

Effects of juvenile hormones (JH) and JH analogs on the release of vitellogenin (Vg) into the hemolymph and ovarian development in unfed adult female ticks, Ornithodoros moubata (Murray), were investigated. Topical application of acetone solvent and injection of acetone or oils showed some increase in Vg titer in the hemolymph. Topical application of JH (JH I, JH II, JH III) and JH analogs (methoprene, S21149, S21150, and S31183) dissolved in acetone to unengorged adult females elevated Vg titer in the hemolymph but only to the same level as the acetone controls. These effects were independent of dose. Injection of JH (JH I, JH II, JH III) and methoprene dissolved in mineral oil also did not significantly increase the Vg titer in the hemolymph compared with the controls (mineral oil injection). Electrophoretic analysis of hemolymph from females 5 d after treatment topically or by injection with JH and JH analogs showed faint Vg bands which comigrated with Vg's (Vg-1 and Vg-2) of normal, engorged female hemolymph, but Vg bands were detected more clearly in the hemolymph samples that were collected greater than 2 wk after treatment. However, the same level of Vg also was detected in the hemolymph of females treated with acetone or mineral oil. Vg synthesis in females treated with JH and JH analogs was analyzed by in vivo labeling and fluorography, which showed that Vg synthesis was not induced by application of JH to unengorged females.

Animals↗
PubMed1991

Experimental transmission of African swine fever virus by the tick Ornithodoros (Alectorobius) puertoricensis (Acari: Argasidae).

The soft tick Ornithodoros puertoricensis Fox has been found on the Caribbean island of Hispaniola (Haiti and the Dominican Republic) where African swine fever (ASF) was endemic from 1978 to 1984. To evaluate the vector potential of O. puertoricensis for African swine fever virus (ASFV), second-instar nymphs were experimentally infected by feeding on a viremic pig that was infected with the Dominican Republic isolate (DR-II) of ASFV. Subsequent infection rates and mean virus titers for individually triturated ticks were: second-instar nymph (95.4%, 10(4.38 +/- 0.85)), third-instar nymph (48.9%, 10(4.59 +/- 0.61)), male (46.7%, 10(4.36 +/- 0.61)), and female (35.3%, 10(4.38 +/- 1.09)). Infected ticks transmitted ASFV to susceptible pigs by bite 23, 85, 126, 160, 182, and 239 d after the infective blood meal. These findings show that ASFV is passed transstadially among O. puertoricensis and that O. puertoricensis can be an efficient vector of African swine fever virus.

African Swine Fever↗
PubMed1992

Occurrence of Ornithodoros kelleyi (Acari: Argasidae) in Kentucky.

A new distribution record is established for the tick Ornithodoros kelleyi Cooley & Kohls for Kentucky. Collections of this tick were associated with bat roosting sites in attics of houses. Scanning electron microscopy was used as an aid in distinguishing various taxonomic characteristics and morphological structures of O. kelleyi.

Animals↗
PubMed1992

Ornithodoros (Alectorobius) capensis Neumann (Acari: Ixodoidea: Argasidae), a parasite of seabirds, established along the southeastern seacoast of the United States.

Ornithodoros (Alectorobius) capensis Neumann, an ectoparasite of seabirds found circumglobally in the tropics and subtropics, has become established along the southeastern seacoast of the United States. The tick has been found feeding primarily on brown pelicans, Pelecanus occidentalis, but also has been found on the laughing gull, Larus atricilla, and the American oystercatcher, Haematopus palliatus. We report here the presence of O. (A.) capensis from New Hanover and Brunswick counties (near the mouth of the Cape Fear River) in North Carolina, to the Charleston Harbor area of South Carolina and thence south to Cumberland Island (a barrier island) in Camden County, Georgia, just north of the Florida state line.

Animals↗
PubMed1992

Cellular responses of laboratory mice to feedings of Ornithodoros talaje (Acari: Argasidae) larvae.

Studies were carried out in which laboratory mice were subjected to sequential feedings by slow feeding Ornithodoros talaje (Guerín-Méneville) larvae to detect and characterize the host cellular response. After the first exposure, histological evidence showed a strong neutrophil infiltration at the site of attachment and feeding. By the third exposure, a marked shift to lymphocytes was noted in the mouse tissues using histological preparations of the feeding ticks. Lymphocyte proliferation tests also provided indirect evidence of a host lymphocyte response as a result of the three tick exposures and feedings.

Animals↗
PubMed1992

Experimental transmission of African swine fever virus by the soft tick Ornithodoros (Pavlovskyella) marocanus (Acari: Ixodoidea: Argasidae).

A total of 1,600 Ornithodoros (Pavlovskyella) marcocanus larvae were fed on a pig with a viremia of 10(7.4) HAd50/ml of African swine fever virus (ASFV). Infected larvae were sampled daily for 15 d, and nymphs were sampled at least once per instar until they became adults. Initial titers of 10(4.48) HAd50 per larva declined to 10(4.04) within 2 d. Larval titers reached a maximum of 10(6.0) HAd50 per larva 10 d after the infective blood meal. Nymphs of each instar were fed on a susceptible pig and in each case transmitted ASFV by bite. Virus titers for first to fourth instars ranged from 10(4.61) to 10(3.34) HAd50 per nymph. Transstadial survival occurred in subsequent first, second, third, and fourth instars with an 89% survival rate over 250 d. Approximately 30% of adult ticks that were infected as larvae remained infected and transmitted ASFV to susceptible pigs 588 d later. In addition, ASFV was recovered from the same adult ticks 655 d after the infective blood meal.

African Swine Fever↗
PubMed1992

African swine fever virus infection in the Iberian soft tick, Ornithodoros (Pavlovskyella) marocanus (Acari: Argasidae).

One thousand six hundred Ornithodoros (Pavlovskyella) marocanus Velu larvae were fed on a pig infected with African swine fever virus (titer: 10(7.4) HAd50/ml), and 1,600 larvae were fed on an uninfected pig. Ticks in each group were compared for mortality rates, mean time to death for ticks that died, mean time from feeding to either molting or eclosion, percentage of ticks that eclosed or molted, and the number of blood meals per nymph or instar. Cumulative virus-induced mortality for all immature stages (larvae to adult) of O. marocanus that had been fed as larvae on a pig infected with African swine fever was ca. 73% over a 390-d period. In contrast, less than 9% mortality was observed among ticks fed on uninfected pigs. Mean time to death for infected ticks was 15-87 d versus 10-17 d for uninfected ticks. Differences in the premolt period (number of days from blood meal to molt) between infected and control ticks were not observed. Mean premolt periods for larvae and first-, second-, third-, fourth-, and fifth-instar nymphs fed on pigs were 7, 9, 15, 11, 15, and 15 d, respectively. The majority of infected and all uninfected ticks required only one blood meal from pigs to molt. Mean weights for unfed second-, third-, and fourth-instar nymphs and males and females were 0.50, 0.67, 3.07, 3.63, and 5.91 mg, respectively.

African Swine Fever↗
PubMed1992

African swine fever virus infection in the soft tick, Ornithodoros (Alectorobius) puertoricensis (Acari: Argasidae).

In total, 1,186 second instar Ornithodoros (Alectorobius) puertoricensis Fox second instars were fed on a pig when it had a viremia of 10(5.2) hemadsorption units (HAd50/ml) and 420 second-instar O. puertoricensis were fed on an uninfected pig. Subsequent blood meals for ticks in both groups were from uninfected pigs. The effects of African swine fever virus (ASFV) infection on O. puertoricensis populations were evaluated for the following parameters: mortality; mean time to death; percentage molted per instar; percentage molted to male, female, or subsequent instar; effects on duration of premolt period; and the number of blood meals per instar. The cumulative virus-induced mortality rate for all immature stages (second to fifth instar) of O. puertoricensis that had been fed as second instars on a pig infected with ASFV was 43.2%. In contrast, 23.1% mortality was observed among ticks fed on uninfected pigs. The mortality rate among third instars that fed on the viremic pig was 55.3% versus 4.8% among nymphs fed on normal pigs. One-third to more than one-half of all third, fourth, and fifth instars required at least two blood meals to molt. Mean premolt periods for second, third, fourth, fifth, and sixth instars fed on uninfected pigs were approximately 12, 15, 32, 22, and 14 d, respectively. Mean weights for unfed second to fifth instars, males, and females were: 0.6, 1.0, 1.5, 1.7, 1.5, and 3.1 mg per tick, respectively.

African Swine Fever↗