Fosfolipase A2 isolada da serpente Crotalus durissus terrificus inibe o vírus chikungunya in vitro

Abstract

Chikungunya virus (CHIKV) is the etiologic agent of Chikungunya fever, a globally spreading mosquito-borne disease. To date, there is no approved antiviral treatment or vaccine against CHIKV, being mandatory the development of new therapeutic strategies. In this context, proteins isolated from snake venoms have demonstrated antiviral activity against several virus, including arbovirus which are relevant the public health system. The phospholipase A2CB (PLA2CB), a protein isolated from the venom of Crotalus durissus terrificus, demonstrated to possess anti-inflammatory, antiparasitic, antibacterial, and antiviral activities. In this study, we investigated the multiple effects of PLA2CB on the CHIKV replicative cycle in vitro. The antiviral activity of PLA2CB was assessed using CHIKV-nanoluciferase, a viral construct inserted of a reporter gene (-nanoluc), to infect baby hamster kidney cells (BHK-21) cells and evaluate cell viability (MTT assay) and infectivity rates (luminescence levels). The results demonstrated that PLA2CB possess a strong antiviral activity judged by the selective index of 128 (ratio of cytotoxicity to antiviral activity). We identified that the treatment with PLA2CB protected the cells against CHIKV infection in 84% and strongly impaired virus entry to the host cells by a virucidal effect of over 99%, or by reducing adsorption and uncoating in 98 and 95 %, respectively. Moreover, PLA2CB presented a modest yet significant activity inhibiting 64 % of post-entry stages of CHIKV replicative cycle. Molecular docking calculations were performed and results suggested binding interactions between PLA2CB and CHIKV glycoprotein, mainly with E1 through hydrophobic interactions. In addition, infrared spectroscopy spectral analysis indicated interactions of PLA2CB and CHIKV glycoproteins, corroborating with data from in silico analyzes. Our data demonstrated the multiple antiviral effects of PLA2CB on the CHIKV replicative cycle, and suggest the interactions of PLA2CB with CHIKV glycoproteins as a mode of action of this compound on blocking virus entry to the host cells.