Análise morfológica do ciclo de multiplicação do Chikungunya vírus e avaliação do potencial antiviral do inibidor de MEK/ERK Trametinibe (Mekinist)

Abstract

The chikungunya virus (CHIKV) is an enveloped virus with an RNA positive strand genome, transmitted between sperm vertebrates and arthropod vectors such as Aedes aegypti and Aedes albopictus, comprising three genotypes. CHIKV enters cells through clathrin-dependent endocytosis, denuding the capsid and genome and immediately leading to the translation of the non-structural proteins that form the replication complex termed spherules. Throughout the infection it mounts cytopathic vacuoles, and in the final stage it is released via budding, acquiring the envelope through the plasma membrane. There are many gaps to be explored in the CHIKV life cycle, which can help to clarify events in the biology of the virus and support the development of new antiviral therapies. There are no specific drugs or vaccines for CHIKV, and there is a constant demand for the development of alternatives for the treatment of the disease. In this work, we used biological tests, animal models, characterization by electron, scanning, immunofluorescence and confocal microscopy. It was shown that treatment with Trametinib at a concentration of 40 μM reduced the viral titer by ~ 3-log, in addition to reducing the production of total viral particles analyzed by transmission electron microscopy (MET). However, in vivo, it was not possible to establish the immunocompetent infection model and in tests with A129 mice Trametinib unprotected animals of CHIKV lethality. In the characterization of the CHIKV life cycle, microscopic evidence was systematized in the references and classic components such as: penetration via clathrin-mediated endocytosis, production of the replication complex (spherules), production of cytopathic vacuoles and via budding can be verified. Interestingly, in addition to the classic findings, evidence also pointed to novel processes involved in the CHIKV multiplication cycle. We described penetration via macropinocytosis and macropinosis formation induced by single or multiple particles; particles enveloping through intracellular membranes without performing budding via plasma membrane; and we showed release via exocytosis and by protrusions of the plasma membrane, in which is suggestive of actin tail. These findings contribute to the understanding of some obscurities related to the CHIKV life cycle, helping the better comprehension of virus-host interactions and may also help in the search for novel antiviral targets.