Malaria, sleeping sickness and so on lead to the death of millions of people in the world. African countries are particularly strongly hit. The expansion of Dengue fever and the recent epidemics of Chikungunya and West Nile disease illustrate the trend.
The pathogens responsible for these diseases can be viruses, bacteria or protozoans which are passed on to humans by an arthropod vector, most often a dipteran insect. This becomes infected when it feeds, taking blood from an infected vertebrate host. The pathogenic agent finds conditions to reproduce and proliferate in the vector’s body. In most cases, the parasite moves back into the vector’s salivary glands in order to be transmitted to the human host when the insect bites again to take another blood meal. Morbidity among infected people is therefore associated with the degree of exposure of the subject to insect vector bites.
The vector saliva, which is adapted for blood feeds, plays a prime role in the transmission of the associated diseases. It contains numerous proteins, including immunogenic ones that can modulate or induce a human immune response. Working for the EpiVect programme initiated in 2003 (1), scientists from IRD research unit UR 024 studied this still little known response with the aim of identifying in the arthropod vector saliva the immunogenic proteins responsible. They called on immunological techniques to evaluate qualitatively and quantitatively, in the serum sampled from human populations living in transmission areas, the presence of antibodies targeting specifically these proteins contained in an extract of total saliva of the culprit vector.
This approach, based on the studies of malaria transmission by mosquitoes of the genus Anopheles and human African trypanosomiasis (sleeping sickness) by Glossinia species or tsetse flies, revealed that the antibody response can represent a good indicator of the degree of exposure of humans to bites, which could in the long term allow improved assessment of the risk of transmission of these diseases in a given region.
In Senegal the rate of antisalivary antibodies against Anopheles in young children (under 5 years), the population most exposed to the risk of malaria, appeared to be proportional to the actual degree of exposure, which had been assessed beforehand by standard entomological capture techniques. All the children involved in the study showed a higher level during the period of most intense transmission, in September. The antibody rate proved also to be associated with the risk of occurrence of a malarial attack in the following three months. These antisalivary antibodies consequently seem to be indicators of the risk of malaria in endemic areas, that could be used to improve strategies of prevention and care of young patients in the context of seasonal transmission of the disease.
The objective of the work conducted on human African trypanosomiasis was to analyse the antibody response to identify exactly, in total saliva extract of Glossinia flies, the immunogenic proteins responsible for synthesis of these specific antibodies (2). The different saliva proteins of four Glossinia species, uninfected, vectors or non-vectors, were separated then put into contact with the serum of individual subjects, infected or uninfected, exposed to bites. Comparison of salivary protein immunogenic profiles obtained showed that they differ depending on the infection status of the subjects (exposed uninfected/infected) and the vector or non-vector status of the Glossinia. Hence, immunogenic proteins specific for two Glossinia species investigated (a 42 kDa protein in G. fuscipes fuscipes, and 50, 55, 65 and 72 kDa proteins in G. morsitans morsitans) could be used to assess specifically the degree of exposure to bites of each of these species.
Starting from immunogenic salivary proteins, simple and effective prevention tools (immuno-tests) can be devised to assess the exposure of human subjects, or be used in endemic areas to evaluate the efficacy of existing vector control strategies, such as the use of impregnated mosquito nets. Analysis of the host-vector relationship, up to now dealt with mainly from the angle of allergic responses to bites or in the search for veterinary vaccines, constitutes now an important research path for new surveillance and prevention strategies.
Marie Guillaume | EurekAlert!
To proliferate or not to proliferate
21.03.2019 | Max-Planck-Institut für molekulare Zellbiologie und Genetik
Discovery of a Primordial Metabolism in Microbes
21.03.2019 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.
The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum
For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
21.03.2019 | Life Sciences
21.03.2019 | Physics and Astronomy
21.03.2019 | HANNOVER MESSE