Induction of immune response in EPC cell and olive flounder and protective effect against viral haemorrhagic septicaemia virus (VHSV) by plant extracts.

Abstract

Antiviral agents isolated from roots of plant (Pinus Densiflora, Celosia cirstata, and Raphanus sativus) inhibited the in vitro and in vivo infectivity of the viral haemorrhagic septicaemia virus (VHSV). All of the plant extracts showed IC50 stand between 5mg/ml and 10mg/ml. Antiviral activity of plant product extracts performed that Epithelioma papulosum cyprini (EPC) cells treated for 72 hr at 10 ug/ml were inoculated with VHSV at MOI 0.1 by CPE (cytopathic effect). Through these results, we identified mixture of SR22 : Excipient among plant products with safe and effective antiviral agent. EPC cell pre-treated with Mixture before infection strongly reduced the viral infectivity. In addition, Mixture dramatically decreased VHSV titer in a time dependent manner when added to cell monolayers 72 hr post-treatment. It is suggested that antiviral activity of mixture of SR22 : excipient was able to inhibit VHSV replication. EPC cell treated antiviral agent showed the strongest expression of Mx gene at 4 day. In vivo, olive flounder administered antiviral agent indicated the strongest expression of TLR2 and TLR7 genes, otherwise no significant increase of Mx and ISG15 genes. After that, it was tested using mixture of SR22 : excipient was shown 40% survival rate. Therefore, we suggested that mixture of C. cristata and R. sativus can be used as a potential source of plant antivirals, also have significant abilities to increase resistance against different pathogens.