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 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 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.

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 Temporal Changes in Outer Surface Proteins A and C of the Lyme Disease-Associated Spirochete, Borrelia burgdorferi, during the Chain of Infection in Ticks and Mice

2000 ◽  
Vol 38 (1) ◽  
pp. 382-388 ◽  
Author(s):  
Tom G. Schwan ◽  
Joseph Piesman
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Outer Surface ◽  
Ixodes Scapularis ◽  
Protein A ◽  
Surface Protein ◽  
Surface Proteins ◽  
In Vitro Cultivation ◽  
Outer Surface Protein A

ABSTRACT The Lyme disease-associated spirochete, Borrelia burgdorferi, is maintained in enzootic cycles involvingIxodes ticks and small mammals. Previous studies demonstrated that B. burgdorferi expresses outer surface protein A (OspA) but not OspC when residing in the midgut of unfed ticks. However, after ticks feed on blood, some spirochetes stop making OspA and express OspC. Our current work examined the timing and frequency of OspA and OspC expression by B. burgdorferi in infected Ixodes scapularis nymphs as they fed on uninfected mice and in uninfected I. scapularis larvae and nymphs as they first acquired spirochetes from infected mice. Smears of midguts from previously infected ticks were prepared at 12- or 24-h intervals following attachment through repletion at 96 h, and spirochetes were stained for immunofluorescence for detection of antibodies to OspA and OspC. As shown previously, prior to feeding spirochetes in nymphs expressed OspA but not OspC. During nymphal feeding, however, the proportion of spirochetes expressing OspA decreased, while spirochetes expressing OspC became detectable. In fact, spirochetes rapidly began to express OspC, with the greatest proportion of spirochetes having this protein at 48 h of attachment and then with the proportion decreasing significantly by the time that the ticks had completed feeding. In vitro cultivation of the spirochete at different temperatures showed OspC to be most abundant when the spirochetes were grown at 37°C. Yet, the synthesis of this protein waned with continuous passage at this temperature. Immunofluorescence staining of spirochetes in smears of midguts from larvae and nymphs still attached or having completed feeding on infected mice demonstrated that OspA but not OspC was produced by these spirochetes recently acquired from mice. Therefore, the temporal synthesis of OspC by spirochetes only in feeding ticks that were infected prior to the blood meal suggests that this surface protein is involved in transmission from tick to mammal but not from mammal to tick.

scholarly journals Passage through Ixodes scapularis Ticks Enhances the Virulence of a Weakly Pathogenic Isolate of Borrelia burgdorferi

2009 ◽  
Vol 78 (1) ◽  
pp. 138-144 ◽  
Author(s):  
Sarojini Adusumilli ◽  
Carmen J. Booth ◽  
Juan Anguita ◽  
Erol Fikrig
Keyword(s):  
United States ◽  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Ixodes Scapularis ◽  
The United States ◽  
Sensu Stricto ◽  
Array Analysis ◽  
C3h Mice ◽  
Attenuated Isolate

ABSTRACT Lyme disease is the most common tick-borne illness in the United States. In this paper we explore the contribution of Ixodes scapularis ticks to the pathogenicity of Borrelia burgdorferi in mice. Previously we demonstrated that an isolate of B. burgdorferi sensu stricto (designated N40), passaged 75 times in vitro (N40-75), was infectious but was no longer able to cause arthritis and carditis in C3H mice. We now show that N40-75 spirochetes can readily colonize I. scapularis and multiply during tick engorgement. Remarkably, tick-transmitted N40-75 spirochetes cause disease in mice. N40-75 spirochetes isolated from these animals also retained their pathogenicity when subsequently administered to mice via syringe inoculation. Array analysis revealed that several genes associated with virulence, including bba25, bba65, bba66, bbj09, and bbk32, had higher expression levels in the tick-passaged N40-75 spirochete. These data suggest that transmission of a high-passage attenuated isolate of B. burgdorferi by the arthropod vector results in the generation of spirochetes that have enhanced pathogenesis in mice.

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.

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