Aminopeptidase secreted by Chromobacterium sp. Panama inhibits dengue virus infection by degrading the E protein

Abstract

Dengue virus (DENV) is the most prevalent and burdensome arbovirus transmitted by Aedes mosquitoes, against which there is only a limited licensed vaccine and no approved drug treatment. A Chromobacterium species, C. sp. Panama, isolated from the midgut of A. aegypti is able to inhibit DENV replication within the mosquito and in vitro. Here we show that C. sp. Panama mediates its anti-DENV activity through secreted factors that are proteinous in nature. The inhibitory effect occurs prior to virus attachment to cells, and is attributed to a factor that destabilizes the virion by promoting the degradation of the viral envelope protein. Bioassay-guided fractionation, coupled with mass spectrometry, allowed for the identification of a C. sp. Panama-secreted neutral protease and an aminopeptidase that are co-expressed and appear to act synergistically to degrade the viral envelope (E) protein and thus prevent viral attachment and subsequent infection of cells. This is the first study characterizing the anti-DENV activity of a common soil and mosquito-associated bacterium, thereby contributing towards understanding how such bacteria may limit disease transmission, and providing new tools for dengue prevention and therapeutics.

Aedes spp. and Their Microbiota: A Review

“…The Gram-negative Chromobacterium inhibits growth of other bacteria in the midgut, displays entomopathogenic activity on larvae and adults, and was suggested to exert in vitro and in vivo anti-pathogen activity through stable secondary metabolites. While romidepsin appeared to be the most likely Chromobacterium -produced metabolite responsible for antiplasmodial activity (Saraiva et al, 2018b), the anti-DENV activity is mediated by an aminopeptidase interfering with DENV-2 attachment by promoting the degradation of the Flavivirus E protein (Saraiva et al, 2018a). These effects on mosquitoes, together with its culturability, make Chromobacterium an ideal candidate to be integrated in strategies for controlling both mosquito populations and pathogen transmission.…”

“…aegypti , it negatively impacts mosquito vector competence to dengue viruses (Saridaki and Bourtzis, 2010; Mohanty et al, 2016; O’Neill, 2018). Additional strategies aim at identifying natural symbionts of mosquitoes and either alter them genetically to express anti-pathogen effectors or disrupt their natural symbiosis with the insect host (Coutinho-Abreu et al, 2010; Ramirez et al, 2014; Kean et al, 2015; Saraiva et al, 2018a, b).…”

Thermal stress responses of Sodalis glossinidius, an indigenous bacterial symbiont of hematophagous tsetse flies

“…While these theories have never been experimentally proven, they are correlatively validated by the fact that Sodalis density positively correlates with trypanosome infection prevalence (16, 19, 63). Finally, symbiotic bacteria from the genera Kosakonia and Chromobacterium , which are found naturally in the midgut of Anopheles gambiae and Aedes aegypti mosquitoes, produce and secrete reactive oxygen intermediates (64), histone deacetylases (65) and aminopeptidases (66) that exert direct anti- Plasmodium and anti-dengue activity.…”

The Challenges of Microbial Control of Mosquito-Borne Diseases Due to the Gut Microbiome

“…This bacterium can prevent dengue virus and Plasmodium falciparum infection in lab-reared A. aegypti and A. gambiae , respectively, by rapidly colonizing the mosquito gut, prompting expression of host immune factors, and maintaining an effective level of host innate immunity ( Ramirez et al, 2014 ). Csp_P also secretes an aminopeptidase that degrades the envelope protein of dengue virus that is required for attachment to host cells ( Saraiva et al, 2018a ) and romidepsin, a histone deacetylase inhibitor, that suppresses Plasmodium development in A. gambiae mosquitoes ( Saraiva et al, 2018b ). The entomopathogenic activity of Csp_P seems to be independent of the presence of a gut bacterial community, as rapid mortality is seen in lab-reared A. aegypti and A. gambiae with both aseptic and bacteria inhabited guts ( Ramirez et al, 2014 ).…”