Babesial vector tick defensin against Babesia sp. parasites.
(41/145)
Antimicrobial peptides are major components of host innate immunity, a well-conserved, evolutionarily ancient defensive mechanism. Infectious disease-bearing vector ticks are thought to possess specific defense molecules against the transmitted pathogens that have been acquired during their evolution. We found in the tick Haemaphysalis longicornis a novel parasiticidal peptide named longicin that may have evolved from a common ancestral peptide resembling spider and scorpion toxins. H. longicornis is the primary vector for Babesia sp. parasites in Japan. Longicin also displayed bactericidal and fungicidal properties that resemble those of defensin homologues from invertebrates and vertebrates. Longicin showed a remarkable ability to inhibit the proliferation of merozoites, an erythrocyte blood stage of equine Babesia equi, by killing the parasites. Longicin was localized at the surface of the Babesia sp. parasites, as demonstrated by confocal microscopic analysis. In an in vivo experiment, longicin induced significant reduction of parasitemia in animals infected with the zoonotic and murine B. microti. Moreover, RNA interference data demonstrated that endogenous longicin is able to directly kill the canine B. gibsoni, thus indicating that it may play a role in regulating the vectorial capacity in the vector tick H. longicornis. Theoretically, longicin may serve as a model for the development of chemotherapeutic compounds against tick-borne disease organisms. (+info)
The biogeography and population genetics of neotropical vector species.
(42/145)
Phylogenetic and population genetic data support the Pliocene or Pleistocene divergences of the co-distributed hematophagous insect vectors, the sand fly Lutzomyia longipalpis s.l., the mosquitoes Anopheles darlingi and A. albitarsis s.l., and the triatomines Rhodnius prolixus and R. robustus. We examined patterns of divergence and distribution in relation to three hypotheses of neotropical diversification: Miocene/Pliocene marine incursion, Pliocene/Pleistocene riverine barriers and Pleistocene refugia. Only R. prolixus has a pattern concordant with the refugia hypothesis, and R. robustus conforms to the marine incursion predictions. A. darlingi partially fits the refugia hypothesis. For L. longipalpis s.l. and A. albitarsis s.l., elements of both incursion and refugia hypotheses seem to fit, suggesting perhaps an interaction of factors determining their distribution patterns. (+info)
Bartonella species in blood of immunocompetent persons with animal and arthropod contact.
(43/145)
Using PCR in conjunction with pre-enrichment culture, we detected Bartonella henselae and B. vinsonii subspecies berkhoffii in the blood of 14 immunocompetent persons who had frequent animal contact and arthropod exposure. (+info)
Heterogeneity in the trypanosomosis incidence in Zebu cattle of different ages and sex on the plateau of eastern Zambia.
(44/145)
On the plateau of eastern Zambia, trypanosomosis is endemic. Glossina morsitans morsitans Westwood (Diptera: Glossinidae), the only tsetse species present, is almost entirely dependent on livestock as its source of food with cattle being the most preferred host. To determine if tsetse challenge is distributed equally over the various age categories and sexes within a cattle herd, a longitudinal study of trypanosomosis incidence was conducted during the rainy season. A total of 354 head of cattle consisting of 40% oxen, 30% cows, 15% young stock, 13% calves and 2% bulls were sampled for three consecutive months and their infection statuses determined using the PCR-RFLP technique as diagnostic method. Results indicated that there were significant differences (P<0.001) in the proportion of infected animals between the various categories. In oxen, the risk of infection was 5.6 times higher than in calves. Those results suggest heterogeneity in the challenge by tsetse flies and are in line with entomological observations on the feeding preference of tsetse on cattle. The implications of these results for the control of trypanosomosis in Eastern Province and other epidemiologically related areas are discussed. (+info)
Forecasting malaria incidence based on monthly case reports and environmental factors in Karuzi, Burundi, 1997-2003.
(45/145)
BACKGROUND: The objective of this work was to develop a model to predict malaria incidence in an area of unstable transmission by studying the association between environmental variables and disease dynamics. METHODS: The study was carried out in Karuzi, a province in the Burundi highlands, using time series of monthly notifications of malaria cases from local health facilities, data from rain and temperature records, and the normalized difference vegetation index (NDVI). Using autoregressive integrated moving average (ARIMA) methodology, a model showing the relation between monthly notifications of malaria cases and the environmental variables was developed. RESULTS: The best forecasting model (R2adj = 82%, p < 0.0001 and 93% forecasting accuracy in the range +/- 4 cases per 100 inhabitants) included the NDVI, mean maximum temperature, rainfall and number of malaria cases in the preceding month. CONCLUSION: This model is a simple and useful tool for producing reasonably reliable forecasts of the malaria incidence rate in the study area. (+info)
The crystal structure of D7r4, a salivary biogenic amine-binding protein from the malaria mosquito Anopheles gambiae.
(46/145)
The D7-related (D7r) proteins of the malaria vector Anopheles gambiae have been shown to bind the biogenic amines serotonin, norepinephrine, and histamine with high affinity. One member of the group (D7r1 or hamadarin) has also been shown to have an anticoagulant/antikinin activity. To understand the mechanistic details of its antihemostatic/anti-inflammatory effects, we have determined the crystal structure of one member of this group, D7r4, along with the structures of ligand complexes with serotonin, tryptamine, histamine, and norepinephrine. The D7 fold consists of an arrangement of eight alpha-helices stabilized by three disulfide bonds. The structure is similar to those of the arthropod odorant-binding proteins, a relationship that had been predicted based on sequence comparisons. Although odorant-binding proteins commonly have six alpha-helices, D7r4 has eight, resulting in significantly different positioning and structure of the ligand binding pocket. The pocket itself is lined by hydrophobic side chains along with polar and charged groups oriented to form hydrogen bonds with the aliphatic amino group and with groups on the aromatic portions of the ligands. These structures, along with accompanying mutagenesis studies, have allowed us to identify critical residues for biogenic amine binding and to predict which members of the large D7 protein family found in blood-feeding nematocerous Diptera will function as biogenic amine-binding proteins. (+info)
Experimental transmission of Anaplasma marginale by male Dermacentor reticulatus.
(47/145)
BACKGROUND: Bovine anaplasmosis has been reported in several European countries, but the vector competency of tick species for Anaplasma marginale from these localities has not been determined. Because of the wide distributional range of Dermacentor reticulatus within Europe and the major role of Dermacentor spp. as a vector of A. marginale in the United States, we tested the vector competency of D. reticulatus for A. marginale. RESULTS: Male D. reticulatus were allowed to feed for 7 days on a calf persistently infected with a Zaria isolate of A. marginale, after which they were removed and held off-host for 7 days. The ticks were then allowed to feed a second time for 7 days on a susceptible tick-naive calf. Infection of calf No. 4291 was detected 20 days post exposure (p.i.) and confirmed by msp4 PCR. Thirty percent of the dissected acquisition fed ticks was infected. In addition, A. marginale colonies were detected by light microscopy in the salivary glands of the acquisition fed ticks. Transmission of A. marginale to calf No. 9191 was confirmed by examination of Giemsa-stained blood smears and msp4 PCR. Ticks were dissected after transmission feeding and presence of A. marginale was confirmed in 18.5% of the dissected ticks. CONCLUSION: This study demonstrates that D. reticulatus males are competent vectors of A. marginale. Further studies are needed to confirm the vector competency of D. reticulatus for other A. marginale strains from geographic areas in Europe. (+info)
Genomic resources for invertebrate vectors of human pathogens, and the role of VectorBase.
(48/145)