scholarly journals Blood Digestion by Trypsin-Like Serine Protease in the Lyme Disease Vector Tick, Ixodes Scapularis

2019 ◽  
Author(s):  
Jeremiah Reyes ◽  
Cuauhtemoc Ayala-Chavez ◽  
Andrew Nuss ◽  
Monika Gulia-Nuss
Keyword(s):  
Lyme Disease ◽  
Serine Protease ◽  
Blood Meal ◽  
Ixodes Scapularis ◽  
Life Stage ◽  
Blood Feeding ◽  
Eastern United States ◽  
Blood Digestion ◽  
Early Protein ◽  
Gut Ph

Ixodes scapularis is the major vector of Lyme disease in the eastern United States. This species undergoes a life cycle consisting of eggs and three active stages: larva, nymph, and adult. Each active life stage takes a blood meal either for developing and molting to the next stage (larvae and nymphs) or for oviposition (adult females). This protein rich blood meal is the only food taken by Ixodes ticks. Most studies on blood digestion in ticks have shown that the initial stages of blood digestion are carried out by cathepsin proteases within endosomes of acidic digestive cells. However, in other hematophagous arthropods, the serine protease trypsin plays an important role in early protein degradation. In this study, we determined transcript expression of I. scapularis cathepsins and serine proteases, some with previously characterized roles in blood digestion. Gut pH was also determined and a trypsin-benzoyl-D, L-arginine 4-nitoanilide assay was used to measure active trypsin levels during blood digestion. Our data suggest that trypsin levels increase significantly after blood feeding and peaked in larvae, nymphs, and adults at 3, 1, and 1 days post host detachment, respectively. In addition, alkaline gut pH (8.0) conditions after I. scapularis blood feeding were similar to those required for trypsin activity in other arthropods suggesting these enzymes have an important and previously overlooked role in I. scapularis blood digestion.

scholarly journals Blood Digestion by Trypsin-Like Serine Proteases in the Replete Lyme Disease Vector Tick, Ixodes scapularis

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 201
Author(s):  
Jeremiah Reyes ◽  
Cuauhtemoc Ayala-Chavez ◽  
Arvind Sharma ◽  
Michael Pham ◽  
Andrew B. Nuss ◽  
...  
Keyword(s):  
Lyme Disease ◽  
Blood Meal ◽  
Serine Proteases ◽  
Ixodes Scapularis ◽  
Life Stage ◽  
Blood Feeding ◽  
Eastern United States ◽  
Blood Digestion ◽  
Hemoglobin Degradation

Ixodes scapularis is the major vector of Lyme disease in the Eastern United States. Each active life stage (larva, nymph, and adult) takes a blood meal either for developing and molting to the next stage (larvae and nymphs) or for oviposition (adult females). This protein-rich blood meal is the only food taken by Ixodes ticks and therefore efficient blood digestion is critical for survival. Studies in partially engorged ticks have shown that the initial stages of digestion are carried out by cathepsin proteases within acidic digestive cells. In this study, we investigated the potential role of serine proteases in blood digestion in replete ticks. RNA interference was used for functional analysis and a trypsin-benzoyl-D, L-arginine 4-nitoanilide assay was used to measure active trypsin levels. Hemoglobinolytic activity was determined in vitro, with or without a serine protease inhibitor. Our data suggest that trypsin levels increase significantly after repletion. Knockdown of serine proteases negatively impacted blood feeding, survival, fecundity, levels of active trypsin in the midgut, and resulted in lower hemoglobin degradation. Incubation of midgut extract with a trypsin inhibitor resulted in 65% lower hemoglobin degradation. We provide evidence of the serine proteases as digestive enzymes in fully engorged, replete females. Understanding the digestive profile of trypsin during blood meal digestion in I. scapularis improves our understanding of the basic biology of ticks and may lead to new methods for tick control.

scholarly journals Blood Digestion by Trypsin-Like Serine Protease in the Replete Lyme Disease Vector Tick, Ixodes scapularis

2020 ◽  
Author(s):  
Jeremiah Reyes ◽  
Cuauhtemoc Ayala-Chavez ◽  
Michael Pham ◽  
Arvind Sharma ◽  
Andrew Nuss ◽  
...  
Keyword(s):  
Lyme Disease ◽  
Serine Protease ◽  
Blood Meal ◽  
Serine Proteases ◽  
Ixodes Scapularis ◽  
Life Stage ◽  
Blood Feeding ◽  
Blood Digestion ◽  
Hemoglobin Degradation

Ixodes scapularis is the major vector of Lyme disease in the eastern United States. Each active life stage (larva, nymph, and adult) takes a blood meal either for developing and molting to the next stage (larvae and nymphs) or for oviposition (adult females). This protein-rich blood meal is the only food taken by Ixodes ticks and therefore blood digestion is very important for tick survival. Most studies on blood digestion in ticks have shown that the initial stages of digestion are carried out by cathepsin proteases within acidic digestive cells. However, most of these studies have focused on partially engorged ticks. In other hematophagous arthropods, the serine proteases play an important role in blood protein degradation. In this study, we determined transcript expression of four I. scapularis serine proteases with previously characterized roles in blood digestion. RNA interference was used for functional analysis and a trypsin-benzoyl-D, L-arginine 4-nitoanilide assay was used to measure active trypsin levels. An in vitro hemoglobinolytic assay was performed with or without serine protease inhibitor. Our data suggest that trypsin levels increase significantly after blood feeding and peaked in larvae, nymphs, and adults at 3, 1, and 1 day post host detachment, respectively. The knockdown of three previously identified serine proteases by RNAi negatively impacted blood intake, survival, fecundity, levels of active trypsin in the gut and resulted in lower hemoglobin degradation in vitro. A trypsin inhibitor, PMSF, blocked the action of trypsin in the gut extract resulting in 65% lower hemoglobin degradation. We provide evidence of the serine proteases as digestive enzymes in fully engorged, replete females. Our data also demonstrated that in addition to blood digestion, these serine proteases might have a role in blood feeding success in I. scapularis.

scholarly journals Assessing the blood-host plasticity and dispersal rate of the malaria vector Anopheles coluzzii

2018 ◽  
Author(s):  
James Orsborne ◽  
Luis Furuya-Kanamori ◽  
Claire L. Jeffries ◽  
Mojca Kristan ◽  
Abdul Rahim Mohammed ◽  
...  
Keyword(s):  
Blood Meal ◽  
Disease Transmission ◽  
Blood Feeding ◽  
Host Choice ◽  
Anopheles Coluzzii ◽  
Dispersal Rate ◽  
Blood Digestion ◽  
Novel Method ◽  
Blood Meal Digestion ◽  
Blood Meals

AbstractDifficulties with observing the dispersal of insect vectors in the field have hampered understanding of several aspects of their behaviour linked to disease transmission. Here, a novel method based on detection of blood-meal sources is introduced to inform two critical and understudied mosquito behaviours: plasticity in the malaria vector’s blood-host choice and vector dispersal. Strategically located collections of Anopheles coluzzii from a malaria-endemic village of southern Ghana showed statistically significant variation in host species composition of mosquito blood-meals. Trialling a new sampling approach gave the first estimates for the remarkably local spatial scale across which host choice is plastic. Using quantitative PCR, the blood-meal digestion was then quantified for field-caught mosquitoes and calibrated according to timed blood digestion in colony mosquitoes. We demonstrate how this new ‘molecular Sella score’ approach can be used to estimate the dispersal rate of blood-feeding vectors caught in the field.

scholarly journals Immature Ixodes scapularis (Acari: Ixodidae) Collected From Peromyscus leucopus (Rodentia: Cricetidae) and Peromyscus maniculatus (Rodentia: Cricetidae) Nests in Northern Wisconsin

2019 ◽  
Vol 57 (1) ◽  
pp. 304-307 ◽  
Author(s):  
Ryan T Larson ◽  
Xia Lee ◽  
Tela Zembsch ◽  
Gebbiena M Bron ◽  
Susan M Paskewitz
Keyword(s):  
United States ◽  
Lyme Disease ◽  
Forest Floor ◽  
Ixodes Scapularis ◽  
Dermacentor Variabilis ◽  
Immature Stages ◽  
Eastern United States ◽  
Blacklegged Tick ◽  
Disease Vector ◽  
Blood Meals

Abstract The blacklegged tick, Ixodes scapularis Say, is the primary Lyme disease vector in the eastern United States. Both immature stages of I. scapularis take blood meals from mice belonging to the genus Peromyscus. Mice are active during the night and spend the majority of diel periods in nests. Thus, immature I. scapularis have a greater opportunity to drop from Peromyscus hosts while in nests compared with the forest floor. Here, we collected 11 Peromyscus nests during a 3-mo period during which the immature I. scapularis are known to be active. We then examined nesting materials for the presence of I. scapularis. Immature I. scapularis were detected in 64% of Peromyscus nests examined. Additionally, 55% of the nests contained at least one Dermacentor variabilis Say larva. Eighty-seven percent of all larval ticks found within nests were blood-fed. Because Peromyscus spp. are highly competent reservoirs of numerous tick-borne pathogens, the ticks that detach in their nests may be important for the maintenance of tick-borne diseases. However, further studies are needed to determine the fate of the I. scapularis that detach in Peromyscus nests.

scholarly journals Landscape determinants of density of blacklegged ticks, vectors of Lyme disease, at the northern edge of their distribution in Canada

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Benoit Talbot ◽  
Andreea Slatculescu ◽  
Charles R. Thickstun ◽  
Jules K. Koffi ◽  
Patrick A. Leighton ◽  
...  
Keyword(s):  
Lyme Disease ◽  
Ixodes Scapularis ◽  
Sensu Stricto ◽  
Forest Composition ◽  
Eastern United States ◽  
Tick Density ◽  
Blacklegged Tick ◽  
Forested Areas ◽  
Northern Edge ◽  
The Many

Abstract In eastern North America, including Canada, Lyme disease is caused by Borrelia burgdorferi sensu stricto and transmitted to humans by the blacklegged tick, Ixodes scapularis. The last decade has seen a growing incidence of Lyme disease in Canada, following the northward range expansion of I. scapularis tick populations from endemic areas in eastern United States. This may be attributable to movement of the many hosts that they parasitize, including songbirds, deer and small mammals. In this study, we wanted to test the effect of spatial, temporal and ecological variables, on blacklegged tick density and infection rates, near the northern limit of their distribution in Ontario and Quebec, Canada. We found an effect of both proportion of forested areas and distance to roads, on density of I. scapularis ticks and prevalence of infection by B. burgdorferi. We also found an effect of both sampling year and ordinal sampling data on prevalence of infection by B. burgdorferi. In six adjacent sites showing evidence of reproducing I. scapularis populations, we found that forest composition and structure influenced density of I. scapularis ticks. Our results suggest that blacklegged tick density and infection rate in Canada may be influenced by a variety of factors.

scholarly journals Decorin-Binding Protein A (DbpA) of Borrelia burgdorferi Is Not Protective When Immunized Mice Are Challenged via Tick Infestation and Correlates with the Lack of DbpA Expression by B. burgdorferi in Ticks

2000 ◽  
Vol 68 (8) ◽  
pp. 4759-4764 ◽  
Author(s):  
Kayla E. Hagman ◽  
Xiaofeng Yang ◽  
Stephen K. Wikel ◽  
George B. Schoeler ◽  
Melissa J. Caimano ◽  
...  
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Murine Model ◽  
Blood Meal ◽  
Tick Infestation ◽  
Ixodes Scapularis ◽  
Binding Protein ◽  
Protein A ◽  
Lyme Disease Vaccine

ABSTRACT Previous studies showed that decorin-binding protein A (DbpA) ofBorrelia burgdorferi was a protective immunogen in the murine model of Lyme borreliosis when mice were challenged (needle inoculated) intradermally with in vitro-cultivated spirochetes. In the present study, DbpA-immunized C3H/HeJ mice were not protected from infection when infested with Ixodes scapularis nymphs harboring virulent B. burgdorferi 297. This lack of protection correlated with the failure to detect DbpA on B. burgdorferi in ticks, suggesting that DbpA is not available as a target for bactericidal antibodies in serum when B. burgdorferi-infected ticks take their blood meal from an immunized host. The failure of DbpA immunization to protect tick-challenged mice contradicts the results of earlier needle inoculation vaccination experiments and suggests that DbpA may not be suitable as a Lyme disease vaccine.

Modeling the Sensitivity of Blacklegged Ticks (Ixodes scapularis) to Temperature and Land Cover in the Northeastern United States

2020 ◽  
Author(s):  
Jonathan M Winter ◽  
Trevor F Partridge ◽  
Dorothy Wallace ◽  
Jonathan W Chipman ◽  
Matthew P Ayres ◽  
...  
Keyword(s):  
United States ◽  
Lyme Disease ◽  
Land Cover ◽  
New Hampshire ◽  
Ixodes Scapularis ◽  
Compartment Model ◽  
The United States ◽  
Growth Stages ◽  
Eastern United States ◽  
Northeastern United States

Abstract The prevalence of Lyme disease and other tick-borne diseases is dramatically increasing across the United States. While the rapid rise in Lyme disease is clear, the causes of it are not. Modeling Ixodes scapularis Say (Acari: Ixodidae), the primary Lyme disease vector in the eastern United States, presents an opportunity to disentangle the drivers of increasing Lyme disease, including climate, land cover, and host populations. We improved upon a recently developed compartment model of ordinary differential equations that simulates I. scapularis growth, abundance, and infection with Borrelia burgdorferi (Spirochaetales: Spirochaetaceae) by adding land cover effects on host populations, refining the representation of growth stages, and evaluating output against observed data. We then applied this model to analyze the sensitivity of simulated I. scapularis dynamics across temperature and land cover in the northeastern United States. Specifically, we ran an ensemble of 232 simulations with temperature from Hanover, New Hampshire and Storrs, Connecticut, and land cover from Hanover and Cardigan in New Hampshire, and Windsor and Danielson in Connecticut. Consistent with observations, simulations of I. scapularis abundance are sensitive to temperature, with the warmer Storrs climate significantly increasing the number of questing I. scapularis at all growth stages. While there is some variation in modeled populations of I. scapularis infected with B. burgdorferi among land cover distributions, our analysis of I. scapularis response to land cover is limited by a lack of observations describing host populations, the proportion of hosts competent to serve as B. burgdorferi reservoirs, and I. scapularis abundance.

Do-It-Yourself Tick Control: Granular Gamma-Cyhalothrin Reduces Ixodes scapularis (Acari: Ixodidae) Nymphs in Residential Backyards

2020 ◽  
Author(s):  
Gebbiena M Bron ◽  
Xia Lee ◽  
Susan M Paskewitz
Keyword(s):  
United States ◽  
Lyme Disease ◽  
Ixodes Scapularis ◽  
Low Cost ◽  
The United States ◽  
Tick Control ◽  
Eastern United States ◽  
Individual Level ◽  
Nymphal Tick ◽  
Do It Yourself

Abstract Lyme disease is the most common vector-borne disease in the United States with hotspots in the Northeast and Midwest. Integrated vector control for mosquito-borne disease prevention is often organized at the community level, but tick control is primarily coordinated at the household and individual level. Management of the blacklegged tick, Ixodes scapularis (Say), the vector of the causative agent of Lyme disease in the Midwest and eastern United States in peridomestic environments may be critical as many tick encounters are reported to occur in the yard. Therefore, we assessed the effectiveness of a widely available and low-cost pesticide that targets common lawn pests and is labeled for use against ticks. In June 2019, we evaluated a granular form of gamma-cyhalothrin in a placebo-controlled residential backyard study (n = 90) in two communities in Wisconsin. The product applied by the research team reduced nymphal blacklegged ticks in plots established in the lawn part of the ecotone by 97% one week after application at both communities and by 89–97% three to four weeks postapplication. The proportion of homes with at least one nymphal tick postapplication was significantly lower at acaricide-treated homes and ranged from 4.2 to 29.2% compared with placebo homes where at least one nymphal tick was found at 50–81.5% of homes. These results support the efficacy of a low-cost do-it-yourself strategy for homeowners seeking to reduce blacklegged ticks in the yard.

scholarly journals Practical Guide to Trapping Peromyscus leucopus (Rodentia: Cricetidae) and Peromyscus maniculatus for Vector and Vector-Borne Pathogen Surveillance and Ecology

2020 ◽  
Vol 20 (6) ◽  
Author(s):  
Erika T Machtinger ◽  
Scott C Williams
Keyword(s):  
United States ◽  
Lyme Disease ◽  
Small Mammals ◽  
Ixodes Scapularis ◽  
The United States ◽  
Eastern United States ◽  
Ixodes Pacificus ◽  
Tick Borne Disease ◽  
Vector Borne ◽  
Pathogen Surveillance

Abstract Arthropods pests are most frequently associated with both plants and vertebrate animals. Ticks, in particular the blacklegged ticks Ixodes scapularis Say and Ixodes pacificus Cooley & Kohls (Acari: Ixodidae), are associated with wildlife hosts and are the primary vectors of Lyme disease, the most frequently reported vector-borne disease in the United States. Immature blacklegged ticks in the eastern United States frequently use small mammals from the genus Peromyscus as hosts. These mice are competent reservoirs for Borrelia burgdorferi, the causative agent of Lyme disease, as well as other tick-borne pathogens. To conduct surveillance on immature ticks and pathogen circulation in hosts, capture and handling of these small mammals is required. While protocols for rearing and pest surveillance on plants are common, there are very few protocols aimed at entomologists to conduct research on vertebrate–arthropod relationships. The goal of this manuscript is to provide a practical template for trapping Peromyscus spp. for vector and vector-borne pathogen surveillance and ecology for professionals that may not have a background in wildlife research. Important considerations are highlighted when targeting P. leucopus Rafinesque and P. maniculatus Wagner. Specifically, for tick and tick-borne disease-related projects, materials that may be required are suggested and references and other resources for researchers beginning a trapping study are provided.

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