scholarly journals Interplay between Yersinia pestis and its flea vector in lipoate metabolism

2021 ◽  
Author(s):  
Typhanie Bouvenot ◽  
Amélie Dewitte ◽  
Nadia Bennaceur ◽  
Elizabeth Pradel ◽  
François Pierre ◽  
...  
Keyword(s):  
Yersinia Pestis ◽  
Transmission Rate ◽  
Metabolic Enzymes ◽  
Level Of Detail ◽  
Time And Space ◽  
Temporal Factors ◽  
Vector Borne

AbstractTo thrive, vector-borne pathogens must survive in the vector’s gut. How these pathogens successfully exploit this environment in time and space has not been extensively characterized. Using Yersinia pestis (the plague bacillus) and its flea vector, we developed a bioluminescence-based approach and employed it to investigate the mechanisms of pathogenesis at an unprecedented level of detail. Remarkably, lipoylation of metabolic enzymes, via the biosynthesis and salvage of lipoate, increases the Y. pestis transmission rate by fleas. Interestingly, the salvage pathway’s lipoate/octanoate ligase LplA enhances the first step in lipoate biosynthesis during foregut colonization but not during midgut colonization. Lastly, Y. pestis primarily uses lipoate provided by digestive proteolysis (presumably as lipoyl peptides) rather than free lipoate in blood, which is quickly depleted by the vector. Thus, spatial and temporal factors dictate the bacterium’s lipoylation strategies during an infection, and replenishment of lipoate by digestive proteolysis in the vector might constitute an Achilles’ heel that is exploited by pathogens.

Simulation and prediction of dengue outbreaks based on an SIR model with a time-dependent transmission rate including meteorological data. An example for Colombo and Jakarta

2021 ◽  
pp. 2150073
Author(s):  
Peter Heidrich ◽  
Thomas Götz
Keyword(s):  
Transmission Rate ◽  
Meteorological Data ◽  
Weather Conditions ◽  
Time Dependent ◽  
Data Sets ◽  
Vector Borne Diseases ◽  
Dengue Outbreaks ◽  
Vector Borne ◽  
Text Model ◽  
Periodic Transmission

Vector-borne diseases can usually be examined with a vector–host model like the [Formula: see text] model. This, however, depends on parameters that contain detailed information about the mosquito population that we usually do not know. For this reason, in this article, we reduce the [Formula: see text] model to an [Formula: see text] model with a time-dependent and periodic transmission rate [Formula: see text]. Since the living conditions of the mosquitos depend on the local weather conditions, meteorological data sets flow into the model in order to achieve a more realistic behavior. The developed [Formula: see text] model is adapted to existing data sets of hospitalized dengue cases in Jakarta (Indonesia) and Colombo (Sri Lanka) using numerical optimization based on Pontryagin’s maximum principle. A previous data analysis shows that the results of this parameter fit are within a realistic range and thus allow further investigations. Based on this, various simulations are carried out and the prediction quality of the model is examined.

scholarly journals Disrupting the Transmission of a Vector-Borne Plant Pathogen

2011 ◽  
Vol 78 (3) ◽  
pp. 638-643 ◽  
Author(s):  
Nabil Killiny ◽  
Arash Rashed ◽  
Rodrigo P. P. Almeida
Keyword(s):  
Cell Attachment ◽  
Transmission Rate ◽  
Disease Spread ◽  
Content Type ◽  
Vector Borne Diseases ◽  
Whole Cells ◽  
Complex Biological Process ◽  
Bacterial Transmission ◽  
Vector Borne ◽  
Cuticular Surface

ABSTRACTApproaches to control vector-borne diseases rarely focus on the interface between vector and microbial pathogen, but strategies aimed at disrupting the interactions required for transmission may lead to reductions in disease spread. We tested if the vector transmission of the plant-pathogenic bacteriumXylella fastidiosawas affected by three groups of molecules: lectins, carbohydrates, and antibodies. Although not comprehensively characterized, it is known thatX. fastidiosaadhesins bind to carbohydrates, and that these interactions are important for initial cell attachment to vectors, which is required for bacterial transmission from host to host. Lectins with affinity to substrates expected to occur on the cuticular surface of vectors colonized byX. fastidiosa, such as wheat germ agglutinin, resulted in statistically significant reductions in transmission rate, as did carbohydrates withN-acetylglucosamine residues. Presumably, lectins bound to receptors on the vector required for cell adhesion/colonization, while carbohydrate-saturated adhesins onX. fastidiosa's cell surface. Furthermore, antibodies againstX. fastidiosawhole cells, gum, and afimbrial adhesins also resulted in transmission blockage. However, no treatment resulted in the complete abolishment of transmission, suggesting that this is a complex biological process. This work illustrates the potential to block the transmission of vector-borne pathogens without directly affecting either organism.

scholarly journals Lyme Disease and Pregnancy

1995 ◽  
Vol 3 (6) ◽  
pp. 256-261 ◽  
Author(s):  
James M. Alexander ◽  
Susan M. Cox
Keyword(s):  
Lyme Disease ◽  
Clinical Course ◽  
Transmission Rate ◽  
Pregnant Patient ◽  
The United States ◽  
Prompt Treatment ◽  
Clinical Presentations ◽  
Vector Borne ◽  
Harmful Effects ◽  
In Pregnancy

Lyme disease is the most commonly transmitted vector-borne disease in the United States, with many regions of the country at risk. Like other spirochete-borne infections, Lyme disease progresses in stages, making diagnosis in the early stages of the illness and prompt treatment important for cure. An early diagnosis is made difficult by the less-than-ideal serologic tests and the varied clinical presentations of the disease. Although Lyme disease has been reported in pregnancy, the transmission rate to the fetus and potential harmful effects are largely unknown. This review discusses the diagnosis, clinical course, and treatment of Lyme disease with an emphasis on the pregnant patient.

Droughts may increase susceptibility of prairie dogs to fleas: incongruity with hypothesized mechanisms of plague cycles in rodents

2016 ◽  
Vol 97 (4) ◽  
pp. 1044-1053 ◽  
Author(s):  
David A. Eads ◽  
Dean E. Biggins ◽  
Dustin H. Long ◽  
Kenneth L. Gage ◽  
Michael F. Antolin
Keyword(s):  
New Mexico ◽  
Yersinia Pestis ◽  
Cynomys Ludovicianus ◽  
Prairie Dogs ◽  
Supplemental Food ◽  
Disease Rates ◽  
Dry Conditions ◽  
Vector Borne ◽  
Term Data

Abstract Plague is a reemerging, rodent-associated zoonosis caused by the flea-borne bacterium Yersinia pestis. As a vector-borne disease, rates of plague transmission may increase when fleas are abundant. Fleas are highly susceptible to desiccation under hot-dry conditions; we posited that their densities decline during droughts. We evaluated this hypothesis with black-tailed prairie dogs (Cynomys ludovicianus) in New Mexico, June–August 2010–2012. Precipitation was relatively plentiful during 2010 and 2012 but scarce during 2011, the driest spring–summer on record for the northeastern grasslands of New Mexico. Unexpectedly, fleas were 200% more abundant in 2011 than in 2010 and 2012. Prairie dogs were in 27% better condition during 2010 and 2012, and they devoted 287% more time to grooming in 2012 than in 2011. During 2012, prairie dogs provided with supplemental food and water were in 23% better condition and carried 40% fewer fleas. Collectively, these results suggest that during dry years, prairie dogs are limited by food and water, and they exhibit weakened defenses against fleas. Long-term data are needed to evaluate the generality of whether droughts increase flea densities and how changes in flea abundance during sequences of dry and wet years might affect plague cycles in mammalian hosts.

scholarly journals Fractional Dynamics of Vector-Borne Infection with Sexual Transmission Rate and Vaccination

Mathematics ◽  
2021 ◽  
Vol 9 (23) ◽  
pp. 3118
Author(s):  
Shah Hussain ◽  
Elissa Nadia Madi ◽  
Naveed Iqbal ◽  
Thongchai Botmart ◽  
Yeliz Karaca ◽  
...  
Keyword(s):  
Public Health ◽  
Zika Virus ◽  
Fixed Point Theory ◽  
Transmission Rate ◽  
Research Work ◽  
Population Increase ◽  
Fractional Dynamics ◽  
Fractional Operators ◽  
Vector Borne ◽  
The Impact

New fractional operators have the aim of attracting nonlocal problems that display fractal behaviour; and thus fractional derivatives have applications in long-term relation description along with micro-scaled and macro-scaled phenomena. Formulated by fractional operators, the formulation of a dynamical system is used in applications for the description of systems with long-range interactions. Vector-borne illnesses are one of the world’s most serious public health issues with a large economic impact on the nations that are impacted. Population increase, urbanization, globalization, and a lack of public health infrastructure have all had a role in the introduction and reemergence of vector-borne illnesses during the last four decades. The control of these infections are important to lessen the economic burden of vector-borne diseases in infected regions. In this research work, we formulate the transmission process of Zika virus with the impact of sexual incidence rate and vaccination in terms of mathematics. We presented the fundamental theory of fractional operators Caputo–Fabrizio (CF) and Atangana–Baleanu (AB) for the analysis of the proposed system. We examine our system of Zika infection and determined the endemic indicator through a next-generation matrix technique. The uniqueness and existence of the solution has been investigated through fixed point theory. Accordingly, a numerical method has been introduced to investigate the dynamical nature of the system and make a comparison of the outcomes of the operators. The impact of different input factors has been conceptualized through dynamical behaviour of the system. We observed that lowering the index of memory, the fractional system provides accurate results about the recommended Zika dynamics and dramatically reduces infected people. It has been proved that high efficacy of a vaccine can lower the level of infection. Moreover, the impact of other parameters on the system of Zika virus infection are highlighted through numerical results.

scholarly journals The virulence–transmission trade-off in vector-borne plant viruses: a review of (non-)existing studies

2010 ◽  
Vol 365 (1548) ◽  
pp. 1907-1918 ◽  
Author(s):  
R. Froissart ◽  
J. Doumayrou ◽  
F. Vuillaume ◽  
S. Alizon ◽  
Y. Michalakis
Keyword(s):  
Transmission Rate ◽  
Host Density ◽  
Theoretical Models ◽  
Plant Viruses ◽  
Trade Off ◽  
Virulence Evolution ◽  
Natural Isolates ◽  
Vector Borne ◽  
The Cost ◽  
Viral Accumulation

The adaptive hypothesis invoked to explain why parasites harm their hosts is known as the trade-off hypothesis, which states that increased parasite transmission comes at the cost of shorter infection duration. This correlation arises because both transmission and disease-induced mortality (i.e. virulence) are increasing functions of parasite within-host density. There is, however, a glaring lack of empirical data to support this hypothesis. Here, we review empirical investigations reporting to what extent within-host viral accumulation determines the transmission rate and the virulence of vector-borne plant viruses. Studies suggest that the correlation between within-plant viral accumulation and transmission rate of natural isolates is positive. Unfortunately, results on the correlation between viral accumulation and virulence are very scarce. We found only very few appropriate studies testing such a correlation, themselves limited by the fact that they use symptoms as a proxy for virulence and are based on very few viral genotypes. Overall, the available evidence does not allow us to confirm or refute the existence of a transmission–virulence trade-off for vector-borne plant viruses. We discuss the type of data that should be collected and how theoretical models can help us refine testable predictions of virulence evolution.

One Million Direct Magnification Microscopy

1971 ◽  
Vol 29 ◽  
pp. 166-167
Author(s):  
J. A. Hugo ◽  
V. A. Phillips
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Illumination Level ◽  
Level Of Detail ◽  
Photographic Emulsion ◽  
Low Contrast ◽  
Fluorescent Screen ◽  
Resolution Electron ◽  
Lattice Images ◽  
Electron Microscopes

A continuing problem in high resolution electron microscopy is that the level of detail visible to the microscopist while he is taking a picture is inferior to that obtainable by the microscope, readily readable on a photographic emulsion and visible in an enlargement made from the plate. Line resolutions, of 2Å or better are now achievable with top of the line 100kv microscopes. Taking the resolution of the human eye as 0.2mm, this indicates a need for a direct viewing magnification of at least one million. However, 0.2mm refers to optimum viewing conditions in daylight or the equivalent, and certainly does not apply to a (colored) image of low contrast and illumination level viewed on a fluorescent screen through a glass window by the dark-adapted eye. Experience indicates that an additional factor of 5 to 10 magnification is needed in order to view lattice images with line spacings of 2 to 4Å. Fortunately this is provided by the normal viewing telescope supplied with most electron microscopes.

Interfacing of a TEM/STEM System to a Computer

1981 ◽  
Vol 39 ◽  
pp. 250-251
Author(s):  
P. Hagemann
Keyword(s):  
Image Analysis ◽  
Transmission Rate ◽  
Analytical Electron Microscopy ◽  
Signal Beam ◽  
Automated Image Analysis ◽  
Beam Deflection ◽  
External Control ◽  
Computer Input ◽  
Instrument Control ◽  
Data Acquisition And Processing

The use of computers in the analytical electron microscopy today shows three different trends (1) automated image analysis with dedicated computer systems, (2) instrument control by microprocessors and (3) data acquisition and processing e.g. X-ray or EEL Spectroscopy.While image analysis in the T.E.M. usually needs a television chain to get a sequential transmission suitable as computer input, the STEM system already has this necessary facility. For the EM400T-STEM system therefore an interface was developed, that allows external control of the beam deflection in TEM as well as the control of the STEM probe and video signal/beam brightness on the STEM screen.The interface sends and receives analogue signals so that the transmission rate is determined by the convertors in the actual computer periphery.

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