Vaccine trials against canine leishmaniasis

Zoonotic visceral leishmaniasis (ZVL) is a fatal disease caused by the sandfly-borne intracellular protozoan parasite Leishmania infantum, and vaccine development in the reservoir host (the domestic dog) is a current research priority. The aims of this study were (1) to conduct safety and immunogenicity trials of two candidate vaccines in dogs, and (2) to compare and demonstrate the utility of immunological and molecular tools for measurement of vaccine efficacy in naturally exposed dogs. DNA/ modified vaccinia virus Ankara (MVA) prime/boost canine vaccines expressing the Leishmania proteins TRYP and LACK were safe, and elicited a type-1 cytokine response, in vivo delayed-type hypersensitivity and IgG2 class responses, consistent with superior protective immunogenicity of TRYP over LACK. However, inconsistent associations were found between progressive disease in infected dogs and IgG class levels, prompting caution in use of the latter as a proxy for protective immunogenicity. Specific serological responses in vaccinated dogs did not cross-react with an unrelated diagnostic antigen rK39, and responses to crude parasite antigen (CLA) were minimal, enabling serological detection of infection incidence in vaccinated dogs. Particularly in early stage infection, CLA ELISA was more sensitive than rK39 ELISA and an rK39-based rapid diagnostic test, though rK39 serology was sensitive for diagnosis of symptomatic clinical cases. A commercially available PCR kit incorporating a rapid oligochromatographic detection step was tested for the first time in dogs, and proved highly sensitive for detection of ZVL infection in bone marrow, comparable to existing nested PCR methods. Molecular methods were investigated as proxy measures to replace labour-intensive xenodiagnosis for detection of the infectiousness of dogs to biting sand flies. Conventional and real-time PCR of tissues from naturally infected dogs were sensitive tests to identify infectiousness, but showed low to moderate specificity. Recommendations are made to improve the application of molecular methods as proxy measures of infectiousness and hence vaccine efficacy

Vaccine trials against canine leishmaniasis

Zoonotic visceral leishmaniasis (ZVL) is a fatal disease caused by the sandfly-borne intracellular protozoan parasite Leishmania infantum, and vaccine development in the reservoir host (the domestic dog) is a current research priority. The aims of this study were (1) to conduct safety and immunogenicity trials of two candidate vaccines in dogs, and (2) to compare and demonstrate the utility of immunological and molecular tools for measurement of vaccine efficacy in naturally exposed dogs. DNA/ modified vaccinia virus Ankara (MVA) prime/boost canine vaccines expressing the Leishmania proteins TRYP and LACK were safe, and elicited a type-1 cytokine response, in vivo delayed-type hypersensitivity and IgG2 class responses, consistent with superior protective immunogenicity of TRYP over LACK. However, inconsistent associations were found between progressive disease in infected dogs and IgG class levels, prompting caution in use of the latter as a proxy for protective immunogenicity. Specific serological responses in vaccinated dogs did not cross-react with an unrelated diagnostic antigen rK39, and responses to crude parasite antigen (CLA) were minimal, enabling serological detection of infection incidence in vaccinated dogs. Particularly in early stage infection, CLA ELISA was more sensitive than rK39 ELISA and an rK39-based rapid diagnostic test, though rK39 serology was sensitive for diagnosis of symptomatic clinical cases. A commercially available PCR kit incorporating a rapid oligochromatographic detection step was tested for the first time in dogs, and proved highly sensitive for detection of ZVL infection in bone marrow, comparable to existing nested PCR methods. Molecular methods were investigated as proxy measures to replace labour-intensive xenodiagnosis for detection of the infectiousness of dogs to biting sand flies. Conventional and real-time PCR of tissues from naturally infected dogs were sensitive tests to identify infectiousness, but showed low to moderate specificity. Recommendations are made to improve the application of molecular methods as proxy measures of infectiousness and hence vaccine efficacy.EThOS - Electronic Theses Online ServiceBiotechnology and Biological Sciences Research Council (Great Britain) (BBSRC)Pfizer Animal HealthGBUnited Kingdo

A prime/boost DNA/Modified vaccinia virus Ankara vaccine expressing recombinant Leishmania DNA encoding TRYP is safe and immunogenic in outbred dogs, the reservoir of zoonotic visceral leishmaniasis

Previous studies demonstrated safety, immunogenicity and efficacy of DNA/modified vaccinia virus Ankara (MVA) prime/boost vaccines expressing tryparedoxin peroxidase (TRYP) and Leishmania homologue of the mammalian receptor for activated C kinase (LACK) against Leishmania major challenge in mice, which was consistent with results from TRYP protein/adjuvant combinations in non-human primates. This study aimed to conduct safety and immunogenicity trials of these DNA/MVA vaccines in dogs, the natural reservoir host of Leishmania infantum, followed-up for 4 months post-vaccination. In a cohort of 22 uninfected outbred dogs, blinded randomised administration of 1000 μg (high dose) or 100 μg (low dose) DNA prime (day 0) and 1 × 108 pfu MVA boost (day 28) was shown to be safe and showed no clinical side effects. High dose DNA/MVA vaccinated TRYP dogs produced statistically higher mean levels of the type-1 pro-inflammatory cytokine IFN-γ than controls in whole blood assays (WBA) stimulated with the recombinant vaccine antigen TRYP, up to the final sampling at day 126, and in the absence of challenge with Leishmania. TRYP vaccinated dogs also demonstrated significantly higher TRYP-specific total IgG and IgG2 subtype titres than in controls, and positive in vivo intradermal reactions at day 156 in the absence of natural infection, observed in 6/8 TRYP vaccinated dogs. No significant increases in IFN-γ in LACK-stimulated WBA, or in LACK-specific IgG levels, were detected in LACK vaccinated dogs compared to controls, and only 2/9 LACK vaccinated dogs demonstrated DTH responses at day 156. In all groups, IgG1 subclass responses and antigen-specific stimulation of IL-10 were similar to controls demonstrating an absence of Th2/Treg response, as expected in the absence of in vivo restimulation or natural/experimental challenge with Leishmania. These collective results indicate significant antigen-specific type-1 responses and in vivo memory phase cellular immune responses, consistent with superior potential for protective vaccine immunogenicity of DNA/MVA TRYP over LACK

Novel use of stir bar sorptive extraction (SBSE) as a tool for isolation of oviposition site attractants for gravid Culex quinquefasciatus

Mosquitoes such as Culex quinquefasciatus Say (Diptera: Culicidae) are important vectors of organisms that cause disease in humans. Research into the development of effective standardized odour baits for blood-fed females (oviposition attractants), to enable entomological monitoring of vector populations, is hampered by complex protocols for extraction of physiologically active volatile chemicals from natural breeding site water samples, which have produced inconsistent results. Air entrainment and solvent extraction are technically demanding methods and are impractical for use in resource poor environments where mosquito-borne disease is most prevalent. This study reports the first use of a simple, robust extraction technique, stir bar sorptive extraction (SBSE), to extract behaviourally active small lipophilic molecules (SLMs) present in water samples collected from Cx. quinquefasciatus breeding sites in Tanzania. Extracts from a pit latrine and from a cess pool breeding site attracted more gravid Cx. quinquefasciatus in pair choice bioassays than control extracts, and coupled gas chromatography-electroantennography (GC-EAG) allowed tentative identification of 15 electrophysiologically active chemicals, including the known oviposition attractant, skatole (3-methylindole). Here, we have demonstrated, using simple pair choice bioassays in controlled laboratory conditions, that SBSE is effective for the extraction of behaviourally and electrophysiologically active semiochemicals from mosquito breeding site waters. Further research is required to confirm that SBSE is an appropriate technique for use in field surveys in the search for oviposition cues for Cx. quinquefasciatus

Increasing incidence of zoonotic visceral leishmaniasis on Crete, Greece

To determine whether the incidence of canine leishmaniasis has increased on Crete, Greece, we fitted infection models to serodiagnostic records of 8,848 dog samples for 1990–2006. Models predicted that seroprevalence has increased 2.4% (95% confidence interval 1.61%–3.51%) per year and that incidence has increased 2.2- to 3.8-fold over this 17-year period

Concert recording 2019-03-09a

[Tracks 1-2]. Duo sonata / Gregory Wanamaker -- [Track 3]. Aulos - In memorium a Debussy / Ivana Loudova -- [Track 4]. Strange humors / John Mackey -- [Track 5]. Circus parade / Pierre Max Dubois -- [Track 6]. Parable XI for solo alto saxophone / Vincent Persichetti -- [Track 7]. Three preludes / George Gershwin arranged by Ryan Reynolds

Evaluation of rK39 rapid diagnostic tests for canine visceral leishmaniasis : longitudinal study and meta-analysis

Canine visceral leishmaniasis is a vector-borne disease caused by the intracellular parasite Leishmania infantum. It is an important veterinary disease, and dogs are also the main animal reservoir for human infection. The disease is widespread in the Mediterranean area, and parts of Asia and South and Central America, and is potentially fatal in both dogs and humans unless treated. Diagnosis of canine infections requires serological or molecular tests. Detection of infection in dogs is important prior to treatment, and in epidemiological studies and control programmes, and a sensitive and specific rapid diagnostic test would be very useful. Rapid diagnostic tests (RDTs) have been developed, but their diagnostic performance has been reported to be variable. We evaluated the sensitivity of a RDT based on serological detection of the rK39 antigen in a cohort of naturally infected Brazilian dogs. The sensitivity of the test to detect infection was relatively low, but increased with time since infection and the severity of infection. We then carried out a meta-analysis of published studies of rK39 RDTs, evaluating the sensitivity to detect disease and infection. The results suggest that rK39 RDTs may be useful in a veterinary clinical setting, but the sensitivity to detect infection is too low for operational control programmes

Concert recording 2017-11-05d

[Track 1]. Quatour pour Saxophones. Overture Brillante / Pierre Max Dubois -- [Track 2]. Arrivée de la Reine de Sabbat / G.F. Handel -- [Track 3]. Recitation book. Broken heart: Der du bist drei in Einigkeit / David Maslanka -- [Track 4]. Stemming+ / Nigel Wood -- [Track 5]. Capriol suite. Basse danse Pavane Tordion Bransles Pieds-en-l\u27air Mattachins / Peter Warlock arranged by R. Stevens -- [Track 6]. Carnival / Karen Street

Systematic Review of the Relationships Between Objectively Measured Physical Activity and Health Indicators in School-Aged Children and Youth

Moderate-to-vigorous physical activity (MVPA) is essential for disease prevention and health promotion. Emerging evidence suggests other intensities of physical activity (PA), including light-intensity activity (LPA), may also be important, but there has been no rigorous evaluation of the evidence. The purpose of this systematic review was to examine the relationships between objectively measured PA (total and all intensities) and health indicators in school-aged children and youth. Online databases were searched for peer-reviewed studies that met the a priori inclusion criteria: population (apparently healthy, aged 5–17 years), intervention/exposure/comparator (volumes, durations, frequencies, intensities, and patterns of objectively measured PA), and outcome (body composition, cardiometabolic biomarkers, physical fitness, behavioural conduct/pro-social behaviour, cognition/academic achievement, quality of life/well-being, harms, bone health, motor skill development, psychological distress, self-esteem). Heterogeneity among studies precluded meta-analyses; narrative synthesis was conducted. A total of 162 studies were included (204 171 participants from 31 countries). Overall, total PA was favourably associated with physical, psychological/social, and cognitive health indicators. Relationships were more consistent and robust for higher (e.g., MVPA) versus lower (e.g., LPA) intensity PA. All patterns of activity (sporadic, bouts, continuous) provided benefit. LPA was favourably associated with cardiometabolic biomarkers; data were scarce for other outcomes. These findings continue to support the importance of at least 60 min/day of MVPA for disease prevention and health promotion in children and youth, but also highlight the potential benefits of LPA and total PA. All intensities of PA should be considered in future work aimed at better elucidating the health benefits of PA in children and youth

Heterogeneities in leishmania infantum infection : using skin parasite burdens to identify highly infectious dogs

Background: The relationships between heterogeneities in host infection and infectiousness (transmission to arthropod vectors) can provide important insights for disease management. Here, we quantify heterogeneities in Leishmania infantum parasite numbers in reservoir and non-reservoir host populations, and relate this to their infectiousness during natural infection. Tissue parasite number was evaluated as a potential surrogate marker of host transmission potential. Methods: Parasite numbers were measured by qPCR in bone marrow and ear skin biopsies of 82 dogs and 34 crab-eating foxes collected during a longitudinal study in Amazon Brazil, for which previous data was available on infectiousness (by xenodiagnosis) and severity of infection. Results: Parasite numbers were highly aggregated both between samples and between individuals. In dogs, total parasite abundance and relative numbers in ear skin compared to bone marrow increased with the duration and severity of infection. Infectiousness to the sandfly vector was associated with high parasite numbers; parasite number in skin was the best predictor of being infectious. Crab-eating foxes, which typically present asymptomatic infection and are non-infectious, had parasite numbers comparable to those of non-infectious dogs. Conclusions: Skin parasite number provides an indirect marker of infectiousness, and could allow targeted control particularly of highly infectious dogs