Resumo

The control of human viruses is of high interest in human and animal health. Despite the frequent appearance of drug resistant viruses, the development of new antiviral agents is needed to support medicine. Several works have demonstrated the presence of bioactive peptides and their potential use as therapeutic agents in insect hemolymph. However, relatively little data are available on molecules from insects with antiviral activities. So, the objective of this study, is to identify the potential antiviral of a protein isolated from hemolymph of larvae of Lepidoptera: Megalopygidae. The effect of hemolymph on virus growth was measured on confluent monolayers of infected cells with measles and influenza (H1N1) (enveloped virus). Picornavirus, a non enveloped virus, also was used. Citotoxicity and genotoxicity were evaluated and no adverse effects were observed in culture after hemolymph addition (up to 5%). The antiviral protein responsible for this activity was isolated and purified by gel filtration chromatography using a gel filtration column system (Superdex 75) and further fractionated using a Resource-Q ion exchange column system. Experiments with the purified protein led to a 32-fold reduction in influenza virus production, 64-fold reduction in measles virus production and a 256-fold reduction in picornavirus production. The viral replication was also studied by staining with antibodies and visualized in confocal microscopy. The replication of these viruses was compared between treated and untreated infected cells. Heating and freezing seem to have no influence over its antiviral activity. Also, the protein does not display virucidal activity and does not act on receptors on the cell membrane. The observations suggest an intracellular mechanism of action and that the protein may act as a constitutive agent that affects the innate antiviral immune response. Supported by: FAPESP 2010/52434-6 and 2011/50095-2