| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1353-1 | ||||
Resumo:Human Respiratory Syncytial Virus (hRSV) is of medical importance because it causes acute respiratory infections mainly in children down to five years old. The infection affects the airways, being more severe when it reaches the lower respiratory tract, causing bronchiolitis, pneumonia, and bronchopneumonia. The estimation that one out of every 50 deaths in children younger than 5 years is attributable to RSV, the impact of this virus on global child health is very high. In addition, RSV infection in early life is associated with long-term respiratory dysfunction and it is estimated that of the 101,400 global deaths secondary to RSV in 2019, 97% occurred in low- and middle-income countries. According to PAHO/WHO (Pan American Health Organization/World Health Organization) in Brazil hRSV remains at high levels, with an increase in the number of weekly cases in children, mainly under 2 years old, from April 2023. So far, treatment is based on the use of Ribavirin and the monoclonal antibody Palivizumab, which are high-cost alternatives that can generate serious side effects. Therefore, hRSV infection needs safe and more efficient treatment alternatives. Products of natural origin, such as essential oils, extracted from plant organs, such as leaves, barks, roots and flowers, have shown antiviral potential against SARS-CoV, Influenzas and other viruses. Thus, essential oils may be effective in combating hRSV infection. The aim of this work was to investigate the virucidal potential and protective effect of essential oil 1 on HEp-2 cell cultures infected with hRSV. HEp-2 cells were adhered in 96-well plates. Upon reaching 80% confluence, the cytotoxicity (CC50) was determined by MTT adding different concentrations of the essential oil (0.64%, 0.32%, 0.16%, 0.08%, 0.04%, 0.02% and 0.01%) in the media, by 48 hours, at 37°C and 5% CO2. The antiviral activity was performed by bathing the virus sample (MOI 0.01, 0.05, 0.1, and 0.5) for 30 minutes at concentrations below that determined by the CC50 and, after inoculating, the fresh media was increased with the same concentrations of virus batting, than was incubated in a CO2 incubator for 5 days, at 37 °C. After this period, the cells were fixed and stained. Plaque forming units (PFU) were counted and compared untreated cells. Characterization of the CC50 of essential oil demonstrated 50% of cell viability in 0.2%. In the plaque formatting assay, the oil showed promising effects under MOI 0.05, inhibiting 68.6% the infection’s progress in 0.1% concentration, preventing plaque formation when compared to the viral control. High concentrations of essential oils were cytotoxic to HEp-2 cells, but at low concentrations, the essential oil inhibited the formation of syncytia. These results suggest that the molecules might block the interaction site on a cell receptor for the F or G proteins of RSV, preventing the virus from fusing with the host cell membrane, or interact with the M, M2-1/2, P, N or L proteins involved in viral replication and assembly, delaying the infection process and the formation of new infectious virus particles. The tested essential oil demonstrated promising effects against RSV infection and might be explored for future therapies and applications on human health. Palavras-chave: Essential oils, hRSV, antiviral, cell culture, inhibitors Agência de fomento:FAPESP, CNPq, FINEP, LINAX essentials oils | |||||