The Experts below are selected from a list of 16797 Experts worldwide ranked by ideXlab platform
Albert Mulenga - One of the best experts on this subject based on the ideXlab platform.
-
target validation of highly conserved amblyomma americanum tick Saliva serine protease inhibitor 19
Ticks and Tick-borne Diseases, 2016Co-Authors: Tae Kwon Kim, Zeljko Radulovic, Albert MulengaAbstract:Amblyomma americanum tick serine protease inhibitor (serpin, AAS) 19, is a highly conserved Protein that is characterized by its functional domain being 100% conserved across tick species. We also reported that AAS19 was an immunogenic tick Saliva Protein with anti-haemostatic functions and an inhibitor of trypsin-like proteases including five of the eight serine protease factors in the blood clotting cascade. In this study the goal was to validate the importance of AAS19 in A. americanum tick physiology, assess immunogenicity and investigate tick vaccine efficacy of yeast-expressed recombinant (r) AAS19. We confirm that AAS19 is important to A. americanum fitness and blood meal feeding. AAS19 mRNA disruption by RNAi silencing caused ticks to obtain blood meals that were 50% smaller than controls, and treated ticks being morphologically deformed with 100% of the deformed ticks dying in incubation. We show that rAAS19 is highly immunogenic in that two 500 μg inoculations mixed with TiterMax Gold adjuvant provoked antibody titers of more than 1:320,000 that specifically reacted with native AAS19 in unfed and partially fed tick tissue. Since AAS19 is injected into animals during tick feeding, we challenge infested immunized rabbits twice to test if tick infestations of immunized rabbits could act as booster. While in the first infestation significantly smaller tick blood meals were observed on one of the two immunized rabbits, smaller blood meals were observed on both rabbits, but 60% of ticks that engorged on immunized rabbits in the second infestation failed to lay eggs. It is notable that ticks fed faster on immunized animals despite obtaining smaller blood meals. We conclude that rAAS19 is a potential component of cocktail tick vaccine.
-
dual silencing of long and short amblyomma americanum acidic chitinase forms weakens the tick cement cone stability
The Journal of Experimental Biology, 2014Co-Authors: Tae Kwon Kim, Janet Curran, Albert MulengaAbstract:This study demonstrates that Amblyomma americanum (Aam) constitutively and ubiquitously expresses the long (L) and short (S) putative acidic chitinases (Ach) that are distinguished by a 210 base pair (bp) deletion in AamAch-S. Full-length AamAch-L and AamAch-S cDNA are 1959 and 1718 bp long, containing 1332 and 1104 bp open reading frames that code for 443 and 367 amino acid residues Proteins with the former predicted to be extracellular and the latter intracellular. Both AamAch-L and AamAch-S mRNA are expressed in multiple organs as revealed by qualitative RT-PCR analysis. Furthermore, quantitative reverse transcription polymerase chain reaction analysis revealed that AamAch-L mRNA was downregulated in the mid-gut, but was unchanged in the Salivary gland and in other organs in response to feeding. Of significant interest, AamAch-L and/or AamAch-S functions are probably associated with formation and/or maintenance of stability of A. americanum tick cement cone. Dual RNA interference silencing of AamAch-L and/or AamAch-S mRNA caused ticks to loosely attach onto host skin as suggested by bleeding around tick mouthparts and ticks detaching off host skin with a light touch. AamAch-L may apparently encode an inactive chitinase as indicated by Pichia pastoris-expressed recombinant AamAch-L failing to hydrolyse chitinase substrates. Unpublished related work in our laboratory, and published work by others that found AamAch-L in tick Saliva, suggest that native AamAch-L is a non-specific immunoglobulin binding tick Saliva Protein in that rAamAch-L non-specifically bound rabbit, bovine and chicken non-immune sera. We discuss findings in this study with reference to advancing knowledge on tick feeding physiology.
-
a blood meal induced ixodes scapularis tick Saliva serpin inhibits trypsin and thrombin and interferes with platelet aggregation and blood clotting
International Journal for Parasitology, 2014Co-Authors: A M G Ibelli, Tae Kwon Kim, Creston Hill, Lauren Lewis, Mariam Bakshi, Stephanie Miller, Lindsay M Porter, Albert MulengaAbstract:Abstract Ixodes scapularis is a medically important tick species that transmits causative agents of important human tick-borne diseases including borreliosis, anaplasmosis and babesiosis. An understanding of how this tick feeds is needed prior to the development of novel methods to protect the human population against tick-borne disease infections. This study characterizes a blood meal-induced I. scapularis (Ixsc) tick Saliva serine protease inhibitor (serpin (S)), in-house referred to as IxscS-1E1. The hypothesis that ticks use serpins to evade the host’s defense response to tick feeding is based on the assumption that tick serpins inhibit functions of protease mediators of the host’s anti-tick defense response. Thus, it is significant that consistent with hallmark characteristics of inhibitory serpins, Pichia pastoris-expressed recombinant IxscS-1E1 (rIxscS-1E1) can trap thrombin and trypsin in SDS- and heat-stable complexes, and reduce the activity of the two proteases in a dose-responsive manner. Additionally, rIxscS-1E1 also inhibited, but did not apparently form detectable complexes with, cathepsin G and factor Xa. Our data also show that rIxscS-1E1 may not inhibit chymotrypsin, kallikrein, chymase, plasmin, elastase and papain even at a much higher rIxscS-1E1 concentration. Native IxscS-1E1 potentially plays a role(s) in facilitating I. scapularis tick evasion of the host’s hemostatic defense as revealed by the ability of rIxscS-1E1 to inhibit adenosine diphosphate- and thrombin-activated platelet aggregation, and delay activated partial prothrombin time and thrombin time plasma clotting in a dose-responsive manner. We conclude that native IxscS-1E1 is part of the tick Saliva Protein complex that mediates its anti-hemostatic, and potentially inflammatory, functions by inhibiting the actions of thrombin, trypsin and other yet unknown trypsin-like proteases at the tick–host interface.
-
deorphanization and target validation of cross tick species conserved novel amblyomma americanum tick Saliva Protein
International Journal for Parasitology, 2013Co-Authors: Albert Mulenga, Tae Kwon Kim, A M G IbelliAbstract:We previously identified a cross-tick species conserved tick feeding stimuli responsive Amblyomma americanum (Aam) AV422 gene. This study demonstrates that AamAV422 belongs to a novel group of arthropod Proteins that is characterized by 14 cysteine amino acid residues: C(23)-X7/9-C(33)-X23/24-C(58)-X8-C(67)-X7-C(75)-X23-C(99)-X15-C(115)-X10-C(126)-X24/25/33-C(150)C(151)-X7-C(159)-X8-C(168)-X23/24-C(192)-X9/10-C(202) predicted to form seven disulfide bonds. We show that AamAV422 Protein is a ubiquitously expressed Protein that is injected into the host within the first 24h of the tick attaching onto the host as revealed by Western blotting analyses of recombinant (r)AamAV422, tick Saliva and dissected tick organ Protein extracts using antibodies to 24 and 48 h tick Saliva Proteins. Native AamAV422 is apparently involved with mediating tick anti-hemostasis and anti-complement functions in that rAamAV422 delayed plasma clotting time in a dose responsive manner by up to ≈ 160 s, prevented platelet aggregation by up to ≈ 16% and caused ≈ 24% reduction in production of terminal complement complexes. Target validation analysis revealed that rAamAV422 is a potential candidate for a cocktail or multivalent tick vaccine preparation in that RNA interference (RNAi)-mediated silencing of AamAV422 mRNA caused a statistically significant (≈ 44%) reduction in tick engorgement weights, which is proxy for amounts of ingested blood. We speculate that AamAV422 is a potential target antigen for development of the highly desired universal tick vaccine in that consistent with high conservation among ticks, antibodies to 24h Ixodes scapularis tick Saliva Proteins specifically bound rAamAV422. We discuss data in this study in the context of advancing the biology of tick feeding physiology and discovery of potential target antigens for tick vaccine development.
Ian D. Fisk - One of the best experts on this subject based on the ideXlab platform.
-
Analytical ultracentrifugation in Saliva research: Impact of green tea astringency and its significance on the in-vivo aroma release
Scientific Reports, 2018Co-Authors: Vlad Dinu, Chujiao Liu, Joseph Ali, Charfedinne Ayed, Gary G Adams, Pavel Gershkovich, Stephen E Harding, Ian D. FiskAbstract:Current Saliva testing methods rely on cutting edge yet expensive techniques for the detection and analysis of genetic material, Proteins and biomarkers for clinical use. However, these techniques are limited in scope and often cannot be used with complex food materials. We propose an efficient ex-vivo tool for evaluating biologically relevant interactions between food components and human Saliva using sedimentation velocity analytical ultracentrifugation (SV-AUC). We evaluated macromolecular content from “unstimulated” (US) and “stimulated” (SS) samples pooled from 5 healthy volunteers. Over 90% of total Saliva Protein consisted of α-amylase and mucin, and up to 10% was secretory immunoglobulin A (SIgA). It was shown that α-amylase concentration increased upon parafilm stimulation, which lead to a decrease in the viscosity of Saliva. Then, we used a simple food system (green tea) to evaluate changes in the Salivary Protein content caused by green tea polyphenols. It was found that aroma release from green tea is highly influenced by interactions between α-amylase and polyphenol epigallocatechin 3-gallate (EGCG). This interaction was found to increase the viscosity of the Salivary bulk, suggested to contribute to astringency, and increased the concentrations of β-ionone, benzaldehyde and isovaleraldehyde (P
-
analytical ultracentrifugation in Saliva research impact of green tea astringency and its significance on the in vivo aroma release
Scientific Reports, 2018Co-Authors: Vlad Dinu, Charfedinne Ayed, Gary G Adams, Pavel Gershkovich, Stephen E Harding, Ian D. FiskAbstract:Current Saliva testing methods rely on cutting edge yet expensive techniques for the detection and analysis of genetic material, Proteins and biomarkers for clinical use. However, these techniques are limited in scope and often cannot be used with complex food materials. We propose an efficient ex-vivo tool for evaluating biologically relevant interactions between food components and human Saliva using sedimentation velocity analytical ultracentrifugation (SV-AUC). We evaluated macromolecular content from “unstimulated” (US) and “stimulated” (SS) samples pooled from 5 healthy volunteers. Over 90% of total Saliva Protein consisted of α-amylase and mucin, and up to 10% was secretory immunoglobulin A (SIgA). It was shown that α-amylase concentration increased upon parafilm stimulation, which lead to a decrease in the viscosity of Saliva. Then, we used a simple food system (green tea) to evaluate changes in the Salivary Protein content caused by green tea polyphenols. It was found that aroma release from green tea is highly influenced by interactions between α-amylase and polyphenol epigallocatechin 3-gallate (EGCG). This interaction was found to increase the viscosity of the Salivary bulk, suggested to contribute to astringency, and increased the concentrations of β-ionone, benzaldehyde and isovaleraldehyde (P < 0.01), suggested to play a significant role in the characteristic flavour of green tea.
Tae Kwon Kim - One of the best experts on this subject based on the ideXlab platform.
-
target validation of highly conserved amblyomma americanum tick Saliva serine protease inhibitor 19
Ticks and Tick-borne Diseases, 2016Co-Authors: Tae Kwon Kim, Zeljko Radulovic, Albert MulengaAbstract:Amblyomma americanum tick serine protease inhibitor (serpin, AAS) 19, is a highly conserved Protein that is characterized by its functional domain being 100% conserved across tick species. We also reported that AAS19 was an immunogenic tick Saliva Protein with anti-haemostatic functions and an inhibitor of trypsin-like proteases including five of the eight serine protease factors in the blood clotting cascade. In this study the goal was to validate the importance of AAS19 in A. americanum tick physiology, assess immunogenicity and investigate tick vaccine efficacy of yeast-expressed recombinant (r) AAS19. We confirm that AAS19 is important to A. americanum fitness and blood meal feeding. AAS19 mRNA disruption by RNAi silencing caused ticks to obtain blood meals that were 50% smaller than controls, and treated ticks being morphologically deformed with 100% of the deformed ticks dying in incubation. We show that rAAS19 is highly immunogenic in that two 500 μg inoculations mixed with TiterMax Gold adjuvant provoked antibody titers of more than 1:320,000 that specifically reacted with native AAS19 in unfed and partially fed tick tissue. Since AAS19 is injected into animals during tick feeding, we challenge infested immunized rabbits twice to test if tick infestations of immunized rabbits could act as booster. While in the first infestation significantly smaller tick blood meals were observed on one of the two immunized rabbits, smaller blood meals were observed on both rabbits, but 60% of ticks that engorged on immunized rabbits in the second infestation failed to lay eggs. It is notable that ticks fed faster on immunized animals despite obtaining smaller blood meals. We conclude that rAAS19 is a potential component of cocktail tick vaccine.
-
dual silencing of long and short amblyomma americanum acidic chitinase forms weakens the tick cement cone stability
The Journal of Experimental Biology, 2014Co-Authors: Tae Kwon Kim, Janet Curran, Albert MulengaAbstract:This study demonstrates that Amblyomma americanum (Aam) constitutively and ubiquitously expresses the long (L) and short (S) putative acidic chitinases (Ach) that are distinguished by a 210 base pair (bp) deletion in AamAch-S. Full-length AamAch-L and AamAch-S cDNA are 1959 and 1718 bp long, containing 1332 and 1104 bp open reading frames that code for 443 and 367 amino acid residues Proteins with the former predicted to be extracellular and the latter intracellular. Both AamAch-L and AamAch-S mRNA are expressed in multiple organs as revealed by qualitative RT-PCR analysis. Furthermore, quantitative reverse transcription polymerase chain reaction analysis revealed that AamAch-L mRNA was downregulated in the mid-gut, but was unchanged in the Salivary gland and in other organs in response to feeding. Of significant interest, AamAch-L and/or AamAch-S functions are probably associated with formation and/or maintenance of stability of A. americanum tick cement cone. Dual RNA interference silencing of AamAch-L and/or AamAch-S mRNA caused ticks to loosely attach onto host skin as suggested by bleeding around tick mouthparts and ticks detaching off host skin with a light touch. AamAch-L may apparently encode an inactive chitinase as indicated by Pichia pastoris-expressed recombinant AamAch-L failing to hydrolyse chitinase substrates. Unpublished related work in our laboratory, and published work by others that found AamAch-L in tick Saliva, suggest that native AamAch-L is a non-specific immunoglobulin binding tick Saliva Protein in that rAamAch-L non-specifically bound rabbit, bovine and chicken non-immune sera. We discuss findings in this study with reference to advancing knowledge on tick feeding physiology.
-
a blood meal induced ixodes scapularis tick Saliva serpin inhibits trypsin and thrombin and interferes with platelet aggregation and blood clotting
International Journal for Parasitology, 2014Co-Authors: A M G Ibelli, Tae Kwon Kim, Creston Hill, Lauren Lewis, Mariam Bakshi, Stephanie Miller, Lindsay M Porter, Albert MulengaAbstract:Abstract Ixodes scapularis is a medically important tick species that transmits causative agents of important human tick-borne diseases including borreliosis, anaplasmosis and babesiosis. An understanding of how this tick feeds is needed prior to the development of novel methods to protect the human population against tick-borne disease infections. This study characterizes a blood meal-induced I. scapularis (Ixsc) tick Saliva serine protease inhibitor (serpin (S)), in-house referred to as IxscS-1E1. The hypothesis that ticks use serpins to evade the host’s defense response to tick feeding is based on the assumption that tick serpins inhibit functions of protease mediators of the host’s anti-tick defense response. Thus, it is significant that consistent with hallmark characteristics of inhibitory serpins, Pichia pastoris-expressed recombinant IxscS-1E1 (rIxscS-1E1) can trap thrombin and trypsin in SDS- and heat-stable complexes, and reduce the activity of the two proteases in a dose-responsive manner. Additionally, rIxscS-1E1 also inhibited, but did not apparently form detectable complexes with, cathepsin G and factor Xa. Our data also show that rIxscS-1E1 may not inhibit chymotrypsin, kallikrein, chymase, plasmin, elastase and papain even at a much higher rIxscS-1E1 concentration. Native IxscS-1E1 potentially plays a role(s) in facilitating I. scapularis tick evasion of the host’s hemostatic defense as revealed by the ability of rIxscS-1E1 to inhibit adenosine diphosphate- and thrombin-activated platelet aggregation, and delay activated partial prothrombin time and thrombin time plasma clotting in a dose-responsive manner. We conclude that native IxscS-1E1 is part of the tick Saliva Protein complex that mediates its anti-hemostatic, and potentially inflammatory, functions by inhibiting the actions of thrombin, trypsin and other yet unknown trypsin-like proteases at the tick–host interface.
-
deorphanization and target validation of cross tick species conserved novel amblyomma americanum tick Saliva Protein
International Journal for Parasitology, 2013Co-Authors: Albert Mulenga, Tae Kwon Kim, A M G IbelliAbstract:We previously identified a cross-tick species conserved tick feeding stimuli responsive Amblyomma americanum (Aam) AV422 gene. This study demonstrates that AamAV422 belongs to a novel group of arthropod Proteins that is characterized by 14 cysteine amino acid residues: C(23)-X7/9-C(33)-X23/24-C(58)-X8-C(67)-X7-C(75)-X23-C(99)-X15-C(115)-X10-C(126)-X24/25/33-C(150)C(151)-X7-C(159)-X8-C(168)-X23/24-C(192)-X9/10-C(202) predicted to form seven disulfide bonds. We show that AamAV422 Protein is a ubiquitously expressed Protein that is injected into the host within the first 24h of the tick attaching onto the host as revealed by Western blotting analyses of recombinant (r)AamAV422, tick Saliva and dissected tick organ Protein extracts using antibodies to 24 and 48 h tick Saliva Proteins. Native AamAV422 is apparently involved with mediating tick anti-hemostasis and anti-complement functions in that rAamAV422 delayed plasma clotting time in a dose responsive manner by up to ≈ 160 s, prevented platelet aggregation by up to ≈ 16% and caused ≈ 24% reduction in production of terminal complement complexes. Target validation analysis revealed that rAamAV422 is a potential candidate for a cocktail or multivalent tick vaccine preparation in that RNA interference (RNAi)-mediated silencing of AamAV422 mRNA caused a statistically significant (≈ 44%) reduction in tick engorgement weights, which is proxy for amounts of ingested blood. We speculate that AamAV422 is a potential target antigen for development of the highly desired universal tick vaccine in that consistent with high conservation among ticks, antibodies to 24h Ixodes scapularis tick Saliva Proteins specifically bound rAamAV422. We discuss data in this study in the context of advancing the biology of tick feeding physiology and discovery of potential target antigens for tick vaccine development.
Gary G Adams - One of the best experts on this subject based on the ideXlab platform.
-
Analytical ultracentrifugation in Saliva research: Impact of green tea astringency and its significance on the in-vivo aroma release
Scientific Reports, 2018Co-Authors: Vlad Dinu, Chujiao Liu, Joseph Ali, Charfedinne Ayed, Gary G Adams, Pavel Gershkovich, Stephen E Harding, Ian D. FiskAbstract:Current Saliva testing methods rely on cutting edge yet expensive techniques for the detection and analysis of genetic material, Proteins and biomarkers for clinical use. However, these techniques are limited in scope and often cannot be used with complex food materials. We propose an efficient ex-vivo tool for evaluating biologically relevant interactions between food components and human Saliva using sedimentation velocity analytical ultracentrifugation (SV-AUC). We evaluated macromolecular content from “unstimulated” (US) and “stimulated” (SS) samples pooled from 5 healthy volunteers. Over 90% of total Saliva Protein consisted of α-amylase and mucin, and up to 10% was secretory immunoglobulin A (SIgA). It was shown that α-amylase concentration increased upon parafilm stimulation, which lead to a decrease in the viscosity of Saliva. Then, we used a simple food system (green tea) to evaluate changes in the Salivary Protein content caused by green tea polyphenols. It was found that aroma release from green tea is highly influenced by interactions between α-amylase and polyphenol epigallocatechin 3-gallate (EGCG). This interaction was found to increase the viscosity of the Salivary bulk, suggested to contribute to astringency, and increased the concentrations of β-ionone, benzaldehyde and isovaleraldehyde (P
-
analytical ultracentrifugation in Saliva research impact of green tea astringency and its significance on the in vivo aroma release
Scientific Reports, 2018Co-Authors: Vlad Dinu, Charfedinne Ayed, Gary G Adams, Pavel Gershkovich, Stephen E Harding, Ian D. FiskAbstract:Current Saliva testing methods rely on cutting edge yet expensive techniques for the detection and analysis of genetic material, Proteins and biomarkers for clinical use. However, these techniques are limited in scope and often cannot be used with complex food materials. We propose an efficient ex-vivo tool for evaluating biologically relevant interactions between food components and human Saliva using sedimentation velocity analytical ultracentrifugation (SV-AUC). We evaluated macromolecular content from “unstimulated” (US) and “stimulated” (SS) samples pooled from 5 healthy volunteers. Over 90% of total Saliva Protein consisted of α-amylase and mucin, and up to 10% was secretory immunoglobulin A (SIgA). It was shown that α-amylase concentration increased upon parafilm stimulation, which lead to a decrease in the viscosity of Saliva. Then, we used a simple food system (green tea) to evaluate changes in the Salivary Protein content caused by green tea polyphenols. It was found that aroma release from green tea is highly influenced by interactions between α-amylase and polyphenol epigallocatechin 3-gallate (EGCG). This interaction was found to increase the viscosity of the Salivary bulk, suggested to contribute to astringency, and increased the concentrations of β-ionone, benzaldehyde and isovaleraldehyde (P < 0.01), suggested to play a significant role in the characteristic flavour of green tea.
Vlad Dinu - One of the best experts on this subject based on the ideXlab platform.
-
Analytical ultracentrifugation in Saliva research: Impact of green tea astringency and its significance on the in-vivo aroma release
Scientific Reports, 2018Co-Authors: Vlad Dinu, Chujiao Liu, Joseph Ali, Charfedinne Ayed, Gary G Adams, Pavel Gershkovich, Stephen E Harding, Ian D. FiskAbstract:Current Saliva testing methods rely on cutting edge yet expensive techniques for the detection and analysis of genetic material, Proteins and biomarkers for clinical use. However, these techniques are limited in scope and often cannot be used with complex food materials. We propose an efficient ex-vivo tool for evaluating biologically relevant interactions between food components and human Saliva using sedimentation velocity analytical ultracentrifugation (SV-AUC). We evaluated macromolecular content from “unstimulated” (US) and “stimulated” (SS) samples pooled from 5 healthy volunteers. Over 90% of total Saliva Protein consisted of α-amylase and mucin, and up to 10% was secretory immunoglobulin A (SIgA). It was shown that α-amylase concentration increased upon parafilm stimulation, which lead to a decrease in the viscosity of Saliva. Then, we used a simple food system (green tea) to evaluate changes in the Salivary Protein content caused by green tea polyphenols. It was found that aroma release from green tea is highly influenced by interactions between α-amylase and polyphenol epigallocatechin 3-gallate (EGCG). This interaction was found to increase the viscosity of the Salivary bulk, suggested to contribute to astringency, and increased the concentrations of β-ionone, benzaldehyde and isovaleraldehyde (P
-
analytical ultracentrifugation in Saliva research impact of green tea astringency and its significance on the in vivo aroma release
Scientific Reports, 2018Co-Authors: Vlad Dinu, Charfedinne Ayed, Gary G Adams, Pavel Gershkovich, Stephen E Harding, Ian D. FiskAbstract:Current Saliva testing methods rely on cutting edge yet expensive techniques for the detection and analysis of genetic material, Proteins and biomarkers for clinical use. However, these techniques are limited in scope and often cannot be used with complex food materials. We propose an efficient ex-vivo tool for evaluating biologically relevant interactions between food components and human Saliva using sedimentation velocity analytical ultracentrifugation (SV-AUC). We evaluated macromolecular content from “unstimulated” (US) and “stimulated” (SS) samples pooled from 5 healthy volunteers. Over 90% of total Saliva Protein consisted of α-amylase and mucin, and up to 10% was secretory immunoglobulin A (SIgA). It was shown that α-amylase concentration increased upon parafilm stimulation, which lead to a decrease in the viscosity of Saliva. Then, we used a simple food system (green tea) to evaluate changes in the Salivary Protein content caused by green tea polyphenols. It was found that aroma release from green tea is highly influenced by interactions between α-amylase and polyphenol epigallocatechin 3-gallate (EGCG). This interaction was found to increase the viscosity of the Salivary bulk, suggested to contribute to astringency, and increased the concentrations of β-ionone, benzaldehyde and isovaleraldehyde (P < 0.01), suggested to play a significant role in the characteristic flavour of green tea.
