Vector saliva controlled inflammatory response of the host may represent the Achilles heel during pathogen transmission

Abstract

Infection with vector-borne pathogens starts with the inoculation of these pathogens during blood feeding. In endemic regions, the population is regularly bitten by naive vectors, implicating a permanent stimulation of the immune system by the vector saliva itself (pre-immune context). Comparatively, the number of bites received by exposed individuals from non-infected vectors is much higher than the bites from infected ones. Therefore, vector saliva and the immunological response in the skin may play an important role, so far underestimated, in the establishment of anti-pathogen immunity in endemic areas. Hence, the parasite biology and the disease pathogenesis in "salivaprimed" and "saliva-unprimed" individuals must be different. This integrated view on how the pathogen evolves within the host together with vector salivary components, which are known to be endowed with a variety of pharmacological and immunological properties, must remain the focus of any investigational study dealing with vector-borne diseases. Considering this three-way partnership, the host skin (immune system), the pathogen, and the vector saliva, the approach that consists in the validation of vector saliva as a source of molecular entities with anti-disease vaccine potential has been recently a subject of active and fruitful investigation. As an example, the vaccination with maxadilan, a potent vasodilator peptide extracted from the saliva of the sand fly Lutzomyia longipalpis, was able to protect against infection with various leishmanial parasites. More interestingly, a universal mosquito saliva vaccine that may potentially protect against a range of mosquito-borne infections including malaria, dengue, Zika, chikungunya and yellow fever. In this review, we highlight the key role played by the immunobiology of vector saliva in shaping the outcome of vector-borne diseases and discuss the value of studying diseases in the light of intimate cross talk among the pathogen, the vector saliva, and the host immune mechanisms.

Identification, Baculoviral Expression, and Biochemical Characterization of a Novel Cholinesterase of Amblyomma americanum (Acari: Ixodidae)

“…Arthropod vector immunity is poorly understood, including the role that the arthropod immune system has on microbevector interactions and its effects on arthropod populations in nature [29]. Saliva-assisted transmission (SAT) of vector pathogens is an important but poorly understood mechanism in vector-borne disease [30][31][32]. Salivary ChE injected into host tissue during blood feeding of vector arthropods is hypothesized to alter the cholinergic balance and control of developing immune responses of the host in response to tissue damage and the presence of pathogens or foreign antigens [11].…”

Dengue: updates for dermatologists on the world's fastest‐growing vector‐borne disease

“…It remains to be seen if these vaccines will differ significantly in side effect profile. The importance of continued research with full genome vaccines has been emphasized, 11 and recent studies have identified possible vaccine targets in mosquito saliva that may influence infection rates 51 . Research on both is ongoing.…”

Identification of culturable fungi and bacteria in mosquito saliva and impact on arbovirus infection in vitro

“…Additionally, mosquito saliva contains molecules that could alert the immune system of the host which potentially may block viral transmission. Therefore, mosquito saliva components are being studied as promising candidates for vaccine development 25 . Mosquito saliva has recently also been shown to contain bacteria 26 .…”