Barriers to the Uptake of Tickborne Disease Prevention Measures: Connecticut, Maryland 2016-2017.

CONTEXT: Public health programs promote numerous tickborne disease (TBD) prevention measures. However, measures are not frequently or consistently performed. OBJECTIVE: Describe barriers to consistent use of 4 commonly promoted TBD prevention measures. DESIGN: We conducted an online survey (n = 1883) evaluating behaviors regarding TBD prevention measures including conducting tick checks, applying insect repellents, showering/bathing, and applying chemical or natural pesticides to residential yards. Respondents could select reasons for never, rarely, or sometimes performing these measures. Descriptive analysis and logistic regression modeling evaluated associations between the 3 most cited barriers for each measure and select demographic variables. SETTING: The survey was administered to residents in high Lyme disease incidence counties of Connecticut and Maryland, 2016-2017. RESULTS: For tick checks (n = 800), the most cited barriers were forgetting (63%), not spending time in tick habitat (28%), and too much trouble (11%). For applying insect repellents (n = 1303), the most cited barriers were forgetting (38%), personal safety concerns (24%), and too much trouble (19%). For showering/bathing 2 hours after outdoor activity in tick habitat (n = 1080), the most cited barriers were being unaware of the prevention measure (51%), too much trouble (18%), and forgetting (18%). For applying chemical pesticides to yards (n = 1320), the most cited barriers were having environmental (45%), pet safety (31%), and personal safety concerns (28%). Lastly, for applying natural pesticides to yards (n = 1357), the most cited barriers were being unaware of natural pesticides (31%), having cost concerns (23%), and not being concerned about ticks on property (16%). CONCLUSIONS: Forgetting, too much trouble, unawareness, and safety concerns were primary barriers to using several TBD prevention measures. Education regarding effectiveness, safety, and timing may increase uptake of certain measures. These challenges can be difficult to address, highlighting the need for passive TBD prevention measures, such as a Lyme disease vaccine.

Association Between Prolonged Shedding of Zika Virus in Human Semen and Male Reproductive Tract Inflammation.

Zika virus (ZIKV) is a mosquito-borne flavivirus that causes congenital defects. Sexual transmission of ZIKV was confirmed in a recent epidemic; however, mechanisms behind ZIKV infection and persistence in the male reproductive tract (MRT) are unknown. Previously, we found that approximately 33% of men with symptomatic ZIKV infections shed ZIKV RNA in semen, and some men shed ZIKV RNA for >3 months. Here, we evaluated the semen of 49 ZIKV-infected men to identify immune factors correlating with long-term ZIKV shedding in semen and ZIKV-infected cell types in semen. We found that prolonged ZIKV RNA shedding in semen was associated with MRT inflammation, indicated by higher leukocyte counts and inflammatory cytokine concentrations in semen of long-term versus short-term shedders. In addition, we found ZIKV RNA in seminal leukocytes and epithelial cells. This study of human semen from ZIKV-infected men provides critical insights into the effects of ZIKV on MRT health.

Effects of Tick-Control Interventions on Tick Abundance, Human Encounters with Ticks, and Incidence of Tickborne Diseases in Residential Neighborhoods, New York, USA.

Tickborne diseases (TBDs) such as Lyme disease result in ≈500,000 diagnoses annually in the United States. Various methods can reduce the abundance of ticks at small spatial scales, but whether these methods lower incidence of TBDs is poorly understood. We conducted a randomized, replicated, fully crossed, placebo-controlled, masked experiment to test whether 2 environmentally safe interventions, the Tick Control System (TCS) and Met52 fungal spray, used separately or together, affected risk for and incidence of TBDs in humans and pets in 24 residential neighborhoods. All participating properties in a neighborhood received the same treatment. TCS was associated with fewer questing ticks and fewer ticks feeding on rodents. The interventions did not result in a significant difference in incidence of human TBDs but did significantly reduce incidence in pets. Our study is consistent with previous evidence suggesting that reducing tick abundance in residential areas might not reduce incidence of TBDs in humans.

Economic Burden of Reported Lyme Disease in High-Incidence Areas, United States, 2014-2016.

Approximately 476,000 cases of Lyme disease are diagnosed in the United States annually, yet comprehensive economic evaluations are lacking. In a prospective study among reported cases in Lyme disease-endemic states, we estimated the total patient cost and total societal cost of the disease. In addition, we evaluated disease and demographic factors associated with total societal cost. Participants had a mean patient cost of ≈$1,200 (median $240) and a mean societal cost of ≈$2,000 (median $700). Patients with confirmed disseminated disease or probable disease had approximately double the societal cost of those with confirmed localized disease. The annual, aggregate cost of diagnosed Lyme disease could be $345-968 million (2016 US dollars) to US society. Our findings emphasize the importance of effective prevention and early diagnosis to reduce illness and associated costs. These results can be used in cost-effectiveness analyses of current and future prevention methods, such as a vaccine.

Understanding consumer and clinician perceptions of a potential Lyme disease vaccine.

Each year, over 450 000 Lyme disease diagnoses are estimated to occur in the United States, and current preventive measures have been insufficient to stem the rising incidence. An effective human Lyme disease vaccine could be a powerful intervention for population-level impact. In advance of new Lyme disease vaccines coming to market, this study explored barriers to acceptability and motivations for the uptake of a new Lyme disease vaccine. Researchers conducted 9 online focus groups among consumers who may potentially benefit from the vaccine and 30 in-depth interviews among clinician groups who may provide the vaccine. All participants were recruited from three US regions of high Lyme disease incidence. Researchers found that participants shared common motivators to either recommend (clinicians) or accept (consumers) a Lyme disease vaccine, largely driven by perceived benefits of the vaccine, the lack of current effective preventive measures and a greater peace of mind. The concern about the challenges associated with diagnosing and treating Lyme disease is a primary motivator for clinicians to recommend the vaccine, while the concern about getting Lyme disease is a primary motivator for consumers to desire the vaccine.

Liposomes with cyclodextrin channels and polyethyleneimine (PEI) improves cytoplasmic vaccine delivery and induces anti-cancer immune activity in mice.

Cancer vaccines have been developed as an additional method of treatment in the fight against cancer. However, an important barrier to an effective vaccine is the inefficient presentation of exogenous antigen by dendritic cells to cytotoxic CD8 T cells. In this study, DPPC liposomes were modified with channels and loaded with polyethyleneimine (PEI) and 5,6-dimethylxanthenone-4-acetic acid (DMXAA) to produce a vaccine carrier. The liposomes were designed to be pH responsive to facilitate delivery of antigens directly to the cytoplasm of antigen presenting cells, bypassing the cross-presentation pathway and improving cellular immune responses. The lysis of liposomes in acidic cell-free conditions was measured using a validated dynamic light scattering assay in order to gain an insight into the mechanism of PEI-mediated lysis. Dendritic cell stimulation and T cell proliferation was investigated in vitro and the potential of this formulation to stimulate a therapeutic anti-cancer immune response was examined in a murine melanoma model. The modified formulation stimulated T cell activation in vitro and induced a small but significant increase in survival in immunized mice. Overall, liposomes modified with PEI and channels successfully delivered antigen to the cytoplasm of dendritic cells, which subsequently led to the development of an appropriate immune response.

Willingness to Pay for Select Tick-Borne Disease Prevention Measures in Endemic Areas.

Tick-borne diseases (TBDs) are increasing despite prevention recommendations. We explored whether cost is a barrier to prevention use in Connecticut and Maryland, using a cross-sectional survey. Respondents were queried regarding their willingness to pay for chemical, natural, and rodent-targeted yard pesticide treatments and permethrin-treated clothing. We evaluated associations between demographics, TBD knowledge and attitudes, and willingness to pay for prevention methods. Most respondents would pay for yard treatments (85%); 95% preferring natural pesticide, and 82% would pay for permethrin-treated clothing. Most did not want to pay more than $99 for any of the yard treatments. Having a household income of $100 000 was associated with willingness to pay $100 or more for chemical, natural, or rodent-targeted treatments and $25 or more for permethrin self-treated and pretreated clothing. Yard treatments, especially natural pesticides, were acceptable for TBD prevention; however, current pricing may be cost-prohibitive. Permethrin-treated clothing may be an affordable and acceptable prevention method.

Zika Virus Shedding in Semen of Symptomatic Infected Men.

BACKGROUND: Zika virus (ZIKV) is an emerging mosquito-borne flavivirus that has been linked to adverse birth outcomes. Previous reports have shown that person-to-person transmission can occur by means of sexual contact. METHODS: We conducted a prospective study involving men with symptomatic ZIKV infection to determine the frequency and duration of ZIKV shedding in semen and urine and to identify risk factors for prolonged shedding in these fluids. Specimens were obtained twice per month for 6 months after illness onset and were tested by real-time reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay for ZIKV RNA and by Vero cell culture and plaque assay for infectious ZIKV. RESULTS: A total of 1327 semen samples from 184 men and 1038 urine samples from 183 men were obtained 14 to 304 days after illness onset. ZIKV RNA was detected in the urine of 7 men (4%) and in the semen of 60 (33%), including in semen samples from 22 of 36 men (61%) who were tested within 30 days after illness onset. ZIKV RNA shedding in semen decreased substantially during the 3 months after illness onset but continued for 281 days in 1 man (1%). Factors that were independently associated with prolonged RNA shedding included older age, less frequent ejaculation, and the presence of certain symptoms at the time of initial illness. Infectious ZIKV was isolated from 3 of 78 semen samples with detectable ZIKV RNA, all obtained within 30 days after illness onset and all with at least 7.0 log10 ZIKV RNA copies per milliliter of semen. CONCLUSIONS: ZIKV RNA was commonly present in the semen of men with symptomatic ZIKV infection and persisted in some men for more than 6 months. In contrast, shedding of infectious ZIKV appeared to be much less common and was limited to the first few weeks after illness onset. (Funded by the Centers for Disease Control and Prevention.).

Hydrogen Sulfide-Responsive Bicontinuous Nanospheres.

Block copolymers (BCPs) that can self-assemble into particles and be triggered by disease-specific molecules such as hydrogen sulfide (H2S) have the potential to impact on drug delivery, decreasing off-target toxicities while increasing drug efficacy. However, the incorporation of H2S-responsive aryl azides into BCPs for self-assembly has been limited by heat, light, and radical sensitivities. In this study, a robust activator regenerated by the electron-transfer atom-transfer radical polymerization reaction was used to synthesize aryl-azide-containing BCPs under ambient conditions. Conditions controlling self-assembly of the BCPs into 150-200 nm particles and the physicochemical properties of the particles were investigated. The use of nanoprecipitation with tetrahydrofuran to promote self-assembly of the BCPs resulted in vesicle structures, while dimethylformamide or dimethylsulfoxide resulted in polymeric bicontinuous nanospheres (BCNs). Triggering of the BCPs and particles (vesicles or BCNs) via exposure to H2S revealed that unsubstituted aryl azides were readily reduced (by HS-), resulting in particle disruption or cross-linking. The relative polar nature of the particle bilayers containing unsubstituted aryl azides and the open structure of the BCNs did however limit encapsulation of small hydrophilic and hydrophobic payloads. Incorporation of a benzylamide substituent onto the aryl azide group increased the hydrophobicity of the particles and encapsulation of hydrophilic cargo but reduced sensitivity to H2S, likely due to the reduced penetration of HS- into the bilayer.

EGFR-targeted prodrug activation using bioorthogonal alkene-azide click-and-release chemistry.

Epidermal growth factor receptor (EGFR) is overexpressed in many cancers and therefore serves as an excellent target for prodrug activation. Functionalised trans-cyclooctenes (TCO) were conjugated to an EGFR antibody (cetuximab), providing a reagent for pre-targeting and localisation of the bioorthogonal reagent. The TCOs react with a 4-azidobenzyl carbamate doxorubicin prodrug via a [3 + 2]-cycloaddition and subsequent self-immolation leads to release of doxorubicin (click-and-release). In vitro cell-based assays demonstrated proof-of-concept, that cetuximab conjugated to highly strained TCO (AB-d-TCO) could bind to the EGFR in a melanoma cell line, and selectively activate the doxorubicin prodrug. In a non-EGFR expressing melanoma cell line, no significant prodrug activation was observed. In vivo experiments using this combination of AB-d-TCO and the azido-doxorubicin prodrug in a murine melanoma model revealed no significant anti-tumour activity or increased survival, suggesting there was insufficient prodrug activation and drug release at the tumour site.

Tuning activation and self-immolative properties of the bioorthogonal alkene-azide click-and-release strategy.

We report on a series of 4-azidobenzyloxy-substituted self-immolative linkers which undergo [3 + 2]-cycloaddition (click reaction) with functionalized trans-cyclooctenes (TCOs) at second-order rate constants in the range of 0.017 to 4.9 M-1 s-1. The choice of 4-azidobenzyloxy-substituted linker and the TCO play a critical role in the rate of all click-and-release steps, which includes the [3 + 2]-cycloaddition and subsequent degradation pathway of the triazoline to an aniline that undergoes 1,6- or 1,8-self-immolation of the phenol. We demonstrate that reacting a 4-azido-2,3,5,6-tetrafluorobenzyloxy-linker with a highly strained TCO (d-TCO) gives, to the best of our knowledge, the fastest TCO-strained alkene-azide click reaction to date (4.9 M-1 s-1), but with one caveat; release of phenol via 1,6-self-immolation is extremely slow. A methyl substituent attached to the benzyl carbon of this analogue maintains the rapid click-reaction rate, but has the added benefit of enabling the release of the phenol within hours. In an aqueous solvent at reagent concentrations in the micromolar range a maximium release was observed after 48 hours; ≈65 and ≈78% of phenol released depending on the TCO used. The new suite of linkers and their combination with TCOs of varying structure add to the toolbox of bioorthogonal click-and-release reactions.

Chemical Tools for Studying Lipid-Binding Class A G Protein-Coupled Receptors.

Cannabinoid, free fatty acid, lysophosphatidic acid, sphingosine 1-phosphate, prostanoid, leukotriene, bile acid, and platelet-activating factor receptor families are class A G protein-coupled receptors with endogenous lipid ligands. Pharmacological tools are crucial for studying these receptors and addressing the many unanswered questions surrounding expression of these receptors in normal and diseased tissues. An inherent challenge for developing tools for these lipid receptors is balancing the often lipophilic requirements of the receptor-binding pharmacophore with favorable physicochemical properties to optimize highly specific binding. In this study, we review the radioligands, fluorescent ligands, covalent ligands, and antibodies that have been used to study these lipid-binding receptors. For each tool type, the characteristics and design rationale along with in vitro and in vivo applications are detailed.

Poloxamer 407-chitosan grafted thermoresponsive hydrogels achieve synchronous and sustained release of antigen and adjuvant from single-shot vaccines.

Sustained-release vaccine delivery systems may enhance the immunogenicity of subunit vaccines and reduce the need for multiple vaccinations. The aim of this study was to develop a thermoresponsive hydrogel using poloxamer 407-chitosan (CP) grafted copolymer as a delivery system for single-shot sustained-release vaccines. The CP copolymer was synthesized using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide chemistry. The CP copolymer was a free flowing solution at ambient temperature and transformed rapidly into a gel at body temperature. The hydrogels were loaded with vaccine antigen and adjuvants or the vaccine components were encapsulated in poly (lactic-co-glycolic acid) nanoparticles in order to ensure synchronous release. The CP hydrogels were stable for up to 18 days in vitro. Release of both nanoparticles and the individual components was complete, with release of the individual components being modulated by incorporation into nanoparticles. In vivo, a single dose of CP hydrogel vaccine induced strong, long lasting, cellular and humoral responses that could protect against the development of tumors in a murine melanoma model.

Mechanistic Evaluation of Bioorthogonal Decaging with trans-Cyclooctene: The Effect of Fluorine Substituents on Aryl Azide Reactivity and Decaging from the 1,2,3-Triazoline.

Bioorthogonal prodrug activation/decaging strategies need to be selective, rapid and release the drug from the masking group upon activation. The rates of the 1,3-dipolar cycloaddition between a trans-cyclooctene (TCO) and a series of fluorine-substituted azido-PABC self-immolative spacers caging two model drugs, and subsequent release from the 1,2,3-triazoline are reported. As the number of fluorine substituents on the PABC linker increases from one to four, the rate of cycloaddition increases by almost one order of magnitude. Using a combination of fluorescence, 1H/19F NMR, and computational experiments, we have been able to determine how substituents on the PABC ring can influence the degradation rates and also the product distribution of the 1,2,3-triazoline. We have also been able to determine how these substituents influence the rate of imine hydrolysis and 1,6-self-immolation decaging rates of the generated anilines. The NMR and computational studies demonstrate that fluorine substituents on the aromatic ring lower the transition state energy required for converting the triazoline to the imine or aziridine intermediates via extrusion of diatomic nitrogen, and that in the case of a tetrafluoro substituted aromatic ring, it is the imine hydrolysis and 1,6-self-immolation that is rate-limiting. This knowledge further enhances the understanding of factors which influence the stability of triazolines, and enables potential applications of fluorinated aromatics, in particular, perfluorinated aromatics, in synthetic chemistry and sustained-release drug delivery systems.

Characterization and evaluation of stabilized particulate formulations as therapeutic oral vaccines for allergy.

Allergic conditions affect more than a quarter of the population in developed countries, but currently available treatments focus more on symptom relief than treating the underlying atopic condition. α-Galactosylceramide (α-GalCer) is a potent immunomodulating compound that has been shown to have a regulatory effect when delivered systemically in nanoparticles. Parenteral delivery is not preferred for chronic conditions, such as allergy, and therefore, the aim of this study was to determine whether a regulatory response could be induced through oral administration in a model of atopy through incorporation of α-GalCer into stable particulate formulations (cationic liposomes, polymerized liposomes and poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs)). The formulations showed only minor changes in particle size, polydispersity index and retention of the model antigen ovalbumin (OVA) during incubation in simulated gastrointestinal (GI) conditions. Oral delivery of α-GalCer in cationic liposomes could induce immunostimulating effects systemically, as seen through increases in serum IgG antibody levels, whereas delivery of α-GalCer in polymerized liposomes and PLGA NPs induced local cytokine changes in the mesenteric lymph nodes (MLNs). The generated responses did not exhibit tolerogenic traits which could be useful for immunoregulation, but the responses generated varied between formulations and suggests that further characterization and optimization could lead to the desired immune response.

Further assessment of the protozoal contribution to the nutrition of the ruminant animal.

The flow of protozoa from the reticulo-rumen is lower than expected, due to ability of protozoa to prevent washout through sequestration on feed particles and the rumen epithelium. In order to estimate the distribution of protozoa within the reticulo-rumen and passage to the omasum, Czerkawski (1987) developed a model containing pools for the rumen liquid phase, rumen solid phase, and the omasum. This model was used to estimate loss of protozoa in the omasum as well as the amount of protozoal protein available to the animal in the lower gut. A number of assumptions were incorporated into the model, some of which appear unsupported by current research. This paper represents an update, revision, and re-evaluation of Czerkawski's model, where the assumptions that all protozoa in the 'attached' phase are in solid digesta, and that protozoa only leave the rumen in the liquid, have been relaxed. Therefore, the revised model allows for sequestration of protozoa on the rumen epithelium and protozoal passage with particulate outflow. Using experimental observations with inputs within biological limits, the revised model and Czerkawski's original model were verified. The effect of diet on the model was then assessed using inputs from a 100% forage diet and a 35-65% concentrate diet. The extent of sequestration was also varied from complete sequestration, to partial sequestration, and no sequestration. A sensitivity analysis was conducted through a linear regression of perturbed mean inputs versus outputs. The results from the revised model indicate that within the reticulo-rumen, the concentrate diet has a greater fractional flow rate of protozoa from the liquid to solid phase, but a lesser fractional flow rate back to the liquid phase, compared to the forage diet. As well, the concentrate diet has a slower net growth rate of protozoa in the attached phase, compared to the forage diet. In the omasum, the forage diet has a less negative net growth rate, compared to the concentrate diet. The forage diet was also associated with smaller loss of protozoa from the omasum. There are limited data from the omasum to be incorporated into the revised model, especially for quantity of protozoa in the omasum. Further research on quantification of protozoa in the omasum could strengthen the predictions made by the model. Despite this, the revised model found a loss of protozoa in the omasum similar to that suggested by Czerkawski's original model 65-73% versus 66%. The revised model results indicate that efforts to increase protozoal flow to the duodenum should focus on reduced sequestration and increased outflow rate from the rumen, although more research is needed to quantify protozoa in the omasum, and to investigate the role of sequestration onto the wall of the reticulo-rumen.

Mathematical descriptions of indeterminate growth.

Two models were derived in an effort to better describe the indeterminate nature of growth exhibited by ectotherms. The models are characterized by their non-sigmoidal shape and are based on three assumptions: quantity of growth machinery works at a rate dependent on feed intake; the relationship between growth rate and intake level follows the law of diminishing returns; and growth is irreversible. The Michaelis-Menten and Mitscherlich equations are used in their formulation. To investigate their potential, the models were fitted to six datasets, representing repeated measures of live body weights of two species: rainbow trout (Oncorhynchus mykiss) and Nile tilapia (Oreochromis niloticus). The models were evaluated on the basis of fitting behaviour, examination of residuals, along with measures of goodness-of-fit. Agreement between predicted and observed body weights, and flexibility to mimic growth patterns given varying species and culture conditions, affirm the ability of both models to describe indeterminate growth in fish.

Chitosan gel vaccine protects against tumour growth in an intracaecal mouse model of cancer by modulating systemic immune responses.

BACKGROUND: Vaccination generating a robust memory population of CD8+ T cells may provide protection against cancer. However, immune therapies for cancer are influenced by the local tumour immune microenvironment. An infiltrate of T cells into tumours of people with colorectal cancer has proven to be a significant indicator of good prognosis. METHODS: We used an intracaecal mouse model of cancer to determine whether a protective immune response against a mucosal gut tumour could be generated using a systemic intervention. We investigated the generation of murine memory CD8+ T cells using a sustained antigen release vaccine vehicle (chitosan gel; Gel + OVA) containing the model antigen ovalbumin, chitosan gel alone (Gel) or conventional dendritic cell vaccination (DC + OVA) using the same protein antigen. RESULTS: Following vaccination with Gel + OVA, CD8+ T cell memory populations specific for ovalbumin protein were detected. Only vaccination with Gel + OVA gave decreased tumour burden compared to unvaccinated or DC + OVA-vaccinated mice in the intracaecal cancer challenge model. CONCLUSION: These results indicate that subcutaneous vaccination with Gel + OVA generates a population of functional CD8+ memory T cells in lymphoid tissue able to protect against intracaecal tumour challenge. Vaccination with chitosan gel may be valuable in anti-cancer treatment at both peripheral and mucosal sites.

Is There an Optimal Formulation and Delivery Strategy for Subunit Vaccines?

Modern vaccine design has moved away from attenuated or inactivated whole-pathogen vaccines to more pure and defined subunit vaccines. However subunit antigens have poor bioavailability and stability and lack immunogenicity. To overcome these issues subunit vaccines have to be administered in a suitable delivery system in combination with immune stimulants. Many different delivery systems have been developed and investigated each having different modes of action, for example increasing delivery and/or sustaining delivery of antigen to immune cells. In addition a number of different routes of immunization are possible and these can play a crucial role in determining the fate of an immune response. In this review the different strategies for the delivery of prophylactic and therapeutic subunit vaccines along with the impact of these on the immune responses generated are discussed.

TickNET-A Collaborative Public Health Approach to Tickborne Disease Surveillance and Research.

TickNET, a public health network, was created in 2007 to foster greater collaboration between state health departments, academic centers, and the Centers for Disease Control and Prevention on surveillance and prevention of tickborne diseases. Research activities are conducted through the Emerging Infections Program and include laboratory surveys, high-quality prevention trials, and pathogen discovery.