Mosquito borne pathogens are transmitted to humans via saliva during blood feeding. Mosquito saliva is a complex concoction of many secretory factors that modulate the feeding foci to enhance pathogen
infection and establishment. Multiple
salivary proteins/factors have been identified/characterized that enhance pathogen
infection. Here, we describe, for the first time, the identification of exogenous
microRNAs from mosquito saliva.
MicroRNAs are short, 18-24
nucleotide, non-coding RNAs that regulate gene expression, and are generally intracellular. However, circulating
miRNAs have been described from serum and saliva of humans. Exogenous
miRNAs have not been reported from hematophagous arthropod saliva. We sought to identify
miRNAs in the mosquito saliva and their role in Chikungunya virus (CHIKV)
infection. Next generation sequencing was utilized to identify 103 exogenous
miRNAs in mosquito saliva of which 31
miRNAs were previously unidentified and were designated novel. Several
miRNAs that we have identified are expressed only in the CHIKV infected mosquitoes. Five of the saliva
miRNAs were tested for their potential to regulated CHIKV
infection, and our results demonstrate their functional role in the transmission and establishment of
infection during blood feeding on the host.