Navigation Links
The insect vector always bites twice

The reality of the threat from vector-borne diseases has been recognized and the problem is prompting research scientists to take a strong interest. Most of these infections, classified as emerging or re-emerging diseases, are linked to ecosystem changes, climatic variations or pressure from human activities. 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 appro ach, 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.


Source:Institut de Recherche Pour le Développement

Related biology news :

1. Researchers find how protein allows insects to detect and respond to pheromones
2. Experiments provide proof of how traveling in groups protects insects
3. Experiments provide proof of how traveling in groups protects insects
4. Why do insects stop breathing? To avoid damage from too much oxygen, say researchers
5. Influenza vaccine uses insect cells to speed development
6. Novel compounds show promise as safer, more potent insecticides
7. DDT-resistant insects have additional genetic advantage that helps resistance spread
8. Stolen gene allows insect virus to enter cells
9. K-State researchers study insects immune system
10. K-State researchers study gene regulation in insects
11. Gene needed for butterfly transformation also key for insects like grasshoppers

Post Your Comments:

(Date:10/29/2015)... , Oct. 29, 2015  Rubicon Genomics, Inc., ... U.S. distribution of its DNA library preparation products, ... Rubicon,s new ThruPLEX Plasma-seq kit. ThruPLEX Plasma-seq has ... preparation of NGS libraries for liquid biopsies--the analysis ... and prognostic applications in cancer and other conditions. ...
(Date:10/27/2015)... -- In the present market scenario, security is one ... verticals such as banking, healthcare, defense, electronic gadgets, and ... secure & simplified access control and growing rate of ... bank accounts, misuse of users, , and so on. ... and smartphones are expected to provide potential opportunities for ...
(Date:10/26/2015)... and LAS VEGAS , Oct. ... Labs , an innovator in modern authentication and a ... announced the launch of its latest version of the ... enabling organizations to use standards-based authentication that supports existing ... S3 Authentication Suite is ideal for organizations deploying customer-facing ...
Breaking Biology News(10 mins):
(Date:11/27/2015)... PA (PRWEB) , ... November 27, 2015 , ... ... Technical Program that includes over 2,000 technical presentations offered in symposia, oral ... chemistry and applied spectroscopy, covers a wide range of applications such as, but ...
(Date:11/26/2015)... MUMBAI , November 26, 2015 ... --> Accutest Research ... accredited Contract Research Organization (CRO), has ... Chase Cancer Center - Temple Health ... ,     (Photo: ) ...
(Date:11/25/2015)... , November 26, 2015 ... Global Biobanking Market 2016 - 2020 report analyzes ... maintaining integrity and quality in long-term samples, minimizing ... long-term cost-effectiveness. Automation minimizes manual errors such as ... technical efficiency. Further, it plays a vital role ...
(Date:11/25/2015)... -- 2 nouvelles études permettent d , ... entre les souches bactériennes retrouvées dans la plaque ... . Ces recherches  ouvrent une nouvelle voie ... efficace de l,un des problèmes de santé les ...    --> 2 nouvelles études permettent d ...
Breaking Biology Technology: