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Trzebny A, Liberska J, Slodkowicz-Kowalska A, Dabert M. Metabarcoding reveals low prevalence of microsporidian infections in castor bean tick (Ixodes ricinus). Parasit Vectors 2022; 15:26. [PMID: 35033159 PMCID: PMC8760655 DOI: 10.1186/s13071-022-05150-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/03/2022] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Microsporidia is a large group of eukaryotic obligate intracellular spore-forming parasites, of which 17 species can cause microsporidiosis in humans. Most human-infecting microsporidians belong to the genera Enterocytozoon and Encephalitozoon. To date, only five microsporidian species, including Encephalitozoon-like, have been found in hard ticks (Ixodidae) using microscopic methods, but no sequence data are available for them. Furthermore, no widespread screening for microsporidian-infected ticks based on DNA analysis has been carried out to date. Thus, in this study, we applied a recently developed DNA metabarcoding method for efficient microsporidian DNA identification to assess the role of ticks as potential vectors of microsporidian species causing diseases in humans. METHODS In total, 1070 (493 juvenile and 577 adult) unfed host-seeking Ixodes ricinus ticks collected at urban parks in the city of Poznan, Poland, and 94 engorged tick females fed on dogs and cats were screened for microsporidian DNA. Microsporidians were detected by PCR amplification and sequencing of the hypervariable V5 region of 18S rRNA gene (18S profiling) using the microsporidian-specific primer set. Tick species were identified morphologically and confirmed by amplification and sequencing of the shortened fragment of cytochrome c oxidase subunit I gene (mini-COI). RESULTS All collected ticks were unambiguously assigned to I. ricinus. Potentially zoonotic Encephalitozoon intestinalis was identified in three fed ticks (3.2%) collected from three different dogs. In eight unfed host-seeking ticks (0.8%), including three males (1.1%), two females (0.7%) and three nymphs (0.7%), the new microsporidian sequence representing a species belonging to the genus Endoreticulatus was identified. CONCLUSIONS The lack of zoonotic microsporidians in host-seeking ticks suggests that I. ricinus is not involved in transmission of human-infecting microsporidians. Moreover, a very low occurrence of the other microsporidian species in both fed and host-seeking ticks implies that mechanisms exist to defend ticks against infection with these parasites.
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Affiliation(s)
- Artur Trzebny
- Molecular Biology Techniques Laboratory, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Justyna Liberska
- Molecular Biology Techniques Laboratory, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Anna Slodkowicz-Kowalska
- Department of Biology and Medical Parasitology, Faculty of Medicine I, University of Medical Sciences, Poznan, Poland
| | - Miroslawa Dabert
- Molecular Biology Techniques Laboratory, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
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Rapkin J, Jensen K, Archer CR, House CM, Sakaluk SK, Castillo ED, Hunt J. The Geometry of Nutrient Space-Based Life-History Trade-Offs: Sex-Specific Effects of Macronutrient Intake on the Trade-Off between Encapsulation Ability and Reproductive Effort in Decorated Crickets. Am Nat 2018; 191:452-474. [PMID: 29570407 DOI: 10.1086/696147] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Life-history theory assumes that traits compete for limited resources, resulting in trade-offs. The most commonly manipulated resource in empirical studies is the quantity or quality of diet. Recent studies using the geometric framework for nutrition, however, suggest that trade-offs are often regulated by the intake of specific nutrients, but a formal approach to identify and quantify the strength of such trade-offs is lacking. We posit that trade-offs occur whenever life-history traits are maximized in different regions of nutrient space, as evidenced by nonoverlapping 95% confidence regions of the global maximum for each trait and large angles (θ) between linear nutritional vectors and Euclidean distances (d) between global maxima. We then examined the effects of protein and carbohydrate intake on the trade-off between reproduction and aspects of immune function in male and female Gryllodes sigillatus. Female encapsulation ability and egg production increased with the intake of both nutrients, whereas male encapsulation ability increased with protein intake but calling effort increased with carbohydrate intake. The trade-offs between traits was therefore larger in males than in females, as demonstrated by significant negative correlations between the traits in males, nonoverlapping 95% confidence regions, and larger estimates of θ and d. Under dietary choice, the sexes had similar regulated intakes, but neither optimally regulated nutrient intake for maximal trait expression. We highlight the fact that greater consideration of specific nutrient intake is needed when examining nutrient space-based trade-offs.
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Affiliation(s)
- Alison M. Triggs
- School of Biological and Chemical Sciences, Queen Mary; University of London; Mile End Road London E14NS UK
| | - Robert J. Knell
- School of Biological and Chemical Sciences, Queen Mary; University of London; Mile End Road London E14NS UK
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Triggs A, Knell RJ. Interactions between environmental variables determine immunity in the Indian meal moth Plodia interpunctella. J Anim Ecol 2011; 81:386-94. [PMID: 21999965 DOI: 10.1111/j.1365-2656.2011.01920.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. Animals raised in good environmental conditions are expected to have more resources to invest in immunity than those raised in poor conditions. Variation in immune activity and parasite resistance in response to changes in environmental temperature, population density and food quality have been shown in many invertebrate species. 2. Almost all studies to date have examined the effects of individual variables in isolation. The aim of this study was to address whether environmental factors interact to produce synergistic effects on phenoloxidase (PO) activity and haemocyte count, both indicators of immune system activity. Temperature, food quality and density were varied in a fully factorial design for a total of eight treatment combinations. 3. Strong interactions between the three environmental variables led to the magnitude and in some cases the direction of the effect of most variables changing as the other environmental factors were altered. Overall, food quality had the most important and consistent influence, larvae raised on a good-quality diet having substantially higher PO activity in every case and substantially higher haemocyte counts in all treatments except unheated/low density. 4. When food quality was good, the larvae showed 'density-dependent prophylaxis': raising their investment in immunity when population density is high. When food quality was poor and the temperature low, however, those larvae raised at high densities invested less in immunity. 5. Increased temperature is often thought to lead to increased immune reactivity in ectotherms, but we found that the effect of temperature was strongly dependent on the values of other environmental variables. PO activity increased with temperature when larvae were raised on good food or when density was high, but when food was poor and density low, a higher temperature led to reduced PO activity. A higher temperature led to higher haemocyte counts when density was high and food quality was poor, but in all other cases, the effect of increased temperature was either close to zero or somewhat negative. 6. Although PO activity and haemocyte count were weakly correlated across the whole data set, there were a number of treatments where the two measures responded in different ways to environmental change. Overall, effect sizes for PO activity were substantially higher than those for haemocyte count, indicating that the different components of the immune system vary in their sensitivity to environmental change. 7. Predictions of the effect of environmental or population change on immunity and disease dynamics based on laboratory experiments that only investigate the effects of single variable are likely to be inaccurate or even entirely wrong.
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Affiliation(s)
- Alison Triggs
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
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Cotter SC, Beveridge M, Simmons LW. Male morph predicts investment in larval immune function in the dung beetle, Onthophagus taurus. Behav Ecol 2007. [DOI: 10.1093/beheco/arm137] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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6
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SCHWARZENBACH GA, WARD PI. Phenoloxidase activity and pathogen resistance in yellow dung flies Scathophaga stercoraria. J Evol Biol 2007; 20:2192-9. [DOI: 10.1111/j.1420-9101.2007.01430.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ham PJ, Albuquerque C, Smithies B, Chalk R, Klager S, Hagen H. Antibacterial peptides in insect vectors of tropical parasitic disease. CIBA FOUNDATION SYMPOSIUM 2007; 186:140-51; discussion 151-9. [PMID: 7768149 DOI: 10.1002/9780470514658.ch9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The induction and characterization of immune peptides in two groups of medically important insects, the mosquitoes and blackflies, is currently an important research area. Mosquitoes transmit a variety of viral and parasitic diseases including yellow fever, dengue, malaria and lymphatic filariasis. Simuliid black flies are vectors of river blindness. The diseases are together responsible for death and morbidity in millions of people each year. The relationship between inducible peptides and bacterial and parasitic infections in these insects is proving to be a complex one. The identification of an insect defensin (4 kDa) in Aedes aegypti, the yellow fever mosquito, has proved to be the first peptide characterized in a vector of human disease. This inducible molecule appears in the haemolymph in response to bacterial and to a lesser extent filarial infection. The characterization of inducible blackfly peptides has revealed potent inducible anti-Gram-positive as well as anti-Gram-negative activity. In addition, non-self recognition molecules such as phenoloxidase may play a part in differentiating one species of eukaryotic pathogen from another of the same genus. The interactions between the peptides and these other proteins are likely to be important in the establishment of a successful immune response against a parasitic pathogen, particularly as we now know these peptides to have anti-eukaryotic activity (against a range of parasite species). As well as being of fundamental interest in our understanding of host-parasite relationships, the indication that antibacterial peptides are toxic to parasitic organisms has implications for their possible use in the disease vector control strategies of the future. It may also mean that a revision in our understanding of their mode of action, loose as it is, has to take place.
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Affiliation(s)
- P J Ham
- Centre for Applied Entomology and Parasitology, Keele University, Staffordshire, UK
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Pomfret JC, Knell RJ. Immunity and the expression of a secondary sexual trait in a horned beetle. Behav Ecol 2006. [DOI: 10.1093/beheco/arj050] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Cotter SC, Kruuk LEB, Wilson K. Costs of resistance: genetic correlations and potential trade-offs in an insect immune system. J Evol Biol 2004; 17:421-9. [PMID: 15009275 DOI: 10.1046/j.1420-9101.2003.00655.x] [Citation(s) in RCA: 196] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Theory predicts that natural selection will erode additive genetic variation in fitness-related traits. However, numerous studies have found considerable heritable variation in traits related to immune function, which should be closely linked to fitness. This could be due to trade-offs maintaining variation in these traits. We used the Egyptian cotton leafworm, Spodoptera littoralis, as a model system to examine the quantitative genetics of insect immune function. We estimated the heritabilities of several different measures of innate immunity and the genetic correlations between these immune traits and a number of life history traits. Our results provide the first evidence for a potential genetic trade-off within the insect immune system, with antibacterial activity (lysozyme-like) exhibiting a significant negative genetic correlation with haemocyte density, which itself is positively genetically correlated with both haemolymph phenoloxidase activity and cuticular melanization. We speculate on a potential trade-off between defence against parasites and predators, mediated by larval colour, and its role in maintaining genetic variation in traits under natural selection.
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Affiliation(s)
- S C Cotter
- Institute of Biological Sciences, University of Stirling, Stirling, UK.
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Mucklow PT, Vizoso DB, Jensen KH, Refardt D, Ebert D. Variation in phenoloxidase activity and its relation to parasite resistance within and between populations of Daphnia magna. Proc Biol Sci 2004; 271:1175-83. [PMID: 15306368 PMCID: PMC1691701 DOI: 10.1098/rspb.2004.2707] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Estimates of phenoloxidase (PO) activity have been suggested as a useful indicator of immunocompetence in arthropods, with the idea that high PO activity would indicate high immunocompetence against parasites and pathogens. Here, we test for variation in PO activity among clones of the planktonic crustacean Daphnia magna and its covariation with susceptibility to infections from four different microparasite species (one bacterium and three microsporidia). Strong clonal variation in PO activity was found within and among populations of D. magna, with 45.6% of the total variation being explained by the clone effect. Quantitative measures of parasite success in infection correlated negatively with PO activity when tested across four host populations. However, these correlations disappeared when the data were corrected for population effects. We conclude that PO activity is not a useful measure of resistance to parasites or of immunocompetence within populations of D. magna. We further tested whether D. magna females that are wounded to induce PO activity are more resistant to infections with the bacterium Pasteuria ramosa than non-wounded controls. We found neither a difference in susceptibility nor a difference in disease progression between the induced group and the control group. These results do not question the function of the PO system in arthropod immune response, but rather suggest that immunocompetence cannot be assessed by considering PO activity alone. Immune response is likely to be a multifactorial trait with various host and parasite characteristics playing important roles in its expression.
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Affiliation(s)
- Patrick T Mucklow
- Institut für Zoologie, Universität Basel, Rheinsprung 9, 4051 Basel, Switzerland
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Cotter SC, Hails RS, Cory JS, Wilson K. Density-dependent prophylaxis and condition-dependent immune function in Lepidopteran larvae: a multivariate approach. J Anim Ecol 2004. [DOI: 10.1111/j.0021-8790.2004.00806.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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12
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Bain O, Babayan S. Behaviour of filariae: morphological and anatomical signatures of their life style within the arthropod and vertebrate hosts. FILARIA JOURNAL 2003; 2:16. [PMID: 14675490 PMCID: PMC305371 DOI: 10.1186/1475-2883-2-16] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2003] [Accepted: 12/15/2003] [Indexed: 11/17/2022]
Abstract
This paper attempts to pinpoint the most original morphological anatomical features of the biology of filariae per se and those which are or could be important for triggering regulatory processes in the arthropod vector and uncontrolled pathogenic processes in the vertebrate hosts. The following stages are considered: the motile egg or newly-hatched larva, the microfilaria, in the lymphatic or blood vessels of its vertebrate host; the larva, its migrations and its intrasyncitial development in the hematophagous arthropod subverted as vector; its transfer to the vertebrate host, migratory properties through the lymphatic system, maturation, mating and, finally, egg laying in the tissues they reach. This synthesis is based on parasite morphological features and their functional interpretation, histological features in the different niches the filariae reach, and on quantitative analyses of filarial development at its different phases, as well as on the rare and valuable observations of living parasites in situ. Data have been drawn from various species of Onchocercidae from amphibians, reptiles, birds and mammals. These comparative analyses have revealed the major constraints to which the filariae, including those parasitizing humans, have been subjected during their evolution from their ancestors, the oviparous and heteroxenic spirurids. Emphasis is placed on mechanical events: resistance of the microfilariae to the currents in the blood or lymph vessels, regulatory processes induced in the vector mesenteron by the movements of the ingested microfilariae, transient disruption by the microfilarial cephalic hook of the vectors' tissues and cell membranes during microfilarial translocation, attachment of males to females during mating by means of 'non-slip' systems, etc. Like other nematodes, filariae are equipped with sensory organs and a locomotor system, composed of the muscles and of the original osmoregulatory-excretory cell. Any change in one of these elements will result in the destruction of the filaria, at some stage of its development. In the vertebrate host, the intravascular stages will no longer be able to resist being carried passively towards the organs of destruction such as the lymph nodes or the lungs.
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Affiliation(s)
- Odile Bain
- Parasitologie comparée et Modèles expérimentaux, associé à l'INSERM, (U567), Muséum National d'Histoire Naturelle et Ecole Pratique des Hautes, Etudes, 61 rue Buffon, 75231 Paris cedex 05, France
| | - Simon Babayan
- Parasitologie comparée et Modèles expérimentaux, associé à l'INSERM, (U567), Muséum National d'Histoire Naturelle et Ecole Pratique des Hautes, Etudes, 61 rue Buffon, 75231 Paris cedex 05, France
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Wilson K, Knell R, Boots M, Koch-Osborne J. Group living and investment in immune defence: an interspecific analysis. J Anim Ecol 2003. [DOI: 10.1046/j.1365-2656.2003.00680.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Cotter SC, Wilson K. Heritability of immune function in the caterpillar Spodoptera littoralis. Heredity (Edinb) 2002; 88:229-34. [PMID: 11920128 DOI: 10.1038/sj.hdy.6800031] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2000] [Accepted: 11/07/2001] [Indexed: 11/08/2022] Open
Abstract
Phenoloxidase (PO) is believed to be a key mediator of immune function in insects and has been implicated both in non-self recognition and in resistance to a variety of parasites and pathogens, including baculoviruses and parasitoids. Using larvae of the Egyptian cotton leafworm, Spodoptera littoralis, we found that despite its apparent importance, haemolymph PO activity varied markedly between individuals, even amongst insects reared under apparently identical conditions. Sib-analysis methods were used to determine whether individuals varied genetically in their PO activity, and hence in one aspect of immune function. The heritability estimate of haemolymph PO activity was high (h(2) = 0.690 +/- 0.069), and PO activity in the haemolymph was strongly correlated with PO activity in both the cuticle and midgut; the sites of entry for most parasites and pathogens. Haemolymph PO activity was also strongly correlated with the degree to which a synthetic parasite (a small piece of nylon monofilament) was encapsulated and melanized (r = 0.622 +/- 0.142), suggesting that the encapsulation response is also heritable. The mechanism maintaining this genetic variation has yet to be elucidated.
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Affiliation(s)
- S C Cotter
- Institute of Biological Sciences, University of Stirling, Stirling FK9 4LA, UK.
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Cui L, Luckhart S, Rosenberg R. Molecular characterization of a prophenoloxidase cDNA from the malaria mosquito Anopheles stephensi. INSECT MOLECULAR BIOLOGY 2000; 9:127-137. [PMID: 10762420 DOI: 10.1046/j.1365-2583.2000.00169.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Some refractory anopheline mosquitoes are capable of killing Plasmodium, the causative agent of malaria, by melanotic encapsulation of invading ookinetes. Phenoloxidase (PO) appears to be involved in the formation of melanin and toxic metabolites in the surrounding capsule. A cDNA encoding Anopheles stephensi prophenoloxidase (Ans-proPO) was isolated from a cDNA library screened with an amplimer produced by reverse transcriptase polymerase chain reaction (RT-PCR) with degenerate primers designed against conserved proPO sequences. The 2.4-kb-long cDNA has a 2058 bp open reading frame encoding Ans-proPO of 686 amino acids. The deduced amino acid sequence shows significant homology to other insect proPO sequences especially at the two putative copper-binding domains. In A. stephensi, Ans-proPO expression was detected in larval, pupal and adult stages. The Ans-proPO mRNA was detected by RT-PCR and in situ hybridization in haemocytes, fat body and epidermis of adult female mosquitoes. A low level of expression was detected in the ovaries, whereas no expression was detected in the midguts. Semi-quantitative RT-PCR analysis of Ans-proPO mRNA showed that its expression was similar in adult female heads, thoraxes and abdomens. No change in the level of Ans-proPO expression was found in adult females after blood feeding, bacterial challenge or Plasmodium berghei infection. However, elevated PO activity was detected in P. berghei-infected mosquitoes, suggesting that in non-selected permissive mosquitoes PO may be involved in limiting parasite infection. Genomic Southern blot and immunoblots suggest the presence of more than one proPO gene in the A. stephensi genome, which is consistent with the findings in other Diptera and Lepidoptera species. The greatest similarity in sequence and expression profile between Ans-proPO and A. gambiae proPO6 suggests that they might be homologues. Our results demonstrate that Ans-proPO is constitutively expressed through different developmental stages and under different physiological conditions, implying that other factors in the proPO activation cascade regulate melanotic encapsulation.
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Affiliation(s)
- L Cui
- Department of Entomology, Walter Reed Army Institute of Research, Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA.
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Hagen HE, Kläger SL, Williams GT. Is apoptosis involved in mechanisms to eliminate Onchocerca ochengi during Simulium damnosum s.l. immune response? Trop Med Int Health 1998; 3:945-50. [PMID: 9892279 DOI: 10.1046/j.1365-3156.1998.00331.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Co-injection of the parasite Onchocerca ochengi and the caspase inhibitors z-VAD.fmk and boc-D.fmk into the natural vector Simulium damnosum s.l. led to significantly increased survival of the parasites. Subsequent in situ apoptosis detection assays demonstrated that in the case of boc-D.fmk the enhanced survival was due to a diminished apoptosis level of the microfilariae in vivo. Additional assays using O. ochengi microfilariae which were coinjected with serine protease inhibitors into S. damnosum s.l. revealed that certain serine protease inhibitors can reduce the level of apoptosis.
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Affiliation(s)
- H E Hagen
- Department of Biological Sciences, University of Keele, UK.
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Hagen HE, Kläger SL, McKerrow JH, Ham PJ. Simulium damnosum s.l.: isolation and identification of prophenoloxidase following an infection with Onchocerca spp. using targeted differential display. Exp Parasitol 1997; 86:213-8. [PMID: 9225772 DOI: 10.1006/expr.1997.4165] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Phenoloxidase (PO) is the key enzyme for melanin synthesis and plays an important role in the defense and recognition of pathogens in insects and other arthropods. We now report the upregulated transcription of the gene encoding the precursor of PO, prophenoloxidase, in Onchocerca-infected Simulium damnosum s.l., the main vector of human and bovine onchocerciasis in subsaharan Africa. Using homology-based generic primers in a polymerase chain reaction-based targeted differential display, the gene itself was identified and partially sequenced.
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Affiliation(s)
- H E Hagen
- Department of Biological Sciences, Keele University, Staffordshire, United Kingdom
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Abstract
Mosquitoes and blackflies have been the focus of recent efforts to elucidate factors influencing the susceptibility of vector insects to metazoan and protozoan parasites of medical significance. Vector species exhibit variation in cellular and humoral immune responses, as highlighted by studies of melanotic encapsulation and components of the phenoloxidase system. Significant progress has been made in the development of genetic maps based upon molecular markers, leading to the genetic analysis of loci influencing susceptibility. The identification of specific inducible antibacterial peptides, and the cloning of genes encoding immune effector proteins as well as potential regulatory factors, open the path to fruitful studies of vector insect innate immunity and its relationship to insect-parasite interactions.
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Affiliation(s)
- A Richman
- European Molecular Biology Laboratory, Heidelberg, Germany.
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