Preliminary evaluation of the antiviral activity of Ageratina havanensis against dengue-2 virus using enzyme immunoassays

Abstract

Introduction: A preliminary evaluation is presented of the antiviral activity of Ageratina havanensis extracts (stem ethanolic, AH-T-EtOH; leaf butanolic, AH-H-ButOH; and leaf ethyl acetate, AH-H-AcEtO) using two enzyme immunoassays, cellular ELISA (C-ELISA) and immunoperoxidase technique.

Objective: Evaluate the antiviral activity of Ageratine havanensis extracts using two enzyme immunoassays.

Methods: C-ELISA and immunoperoxidase technique were standardized for use in the preliminary evaluation of the antiviral activity of three Ageratina havanensis extracts at different concentrations and addition times through detection of the expression of the E protein of dengue virus.

Results: C-ELISA achieved the following optimal parameters: Vero cell line, viral antigen in cell culture, protein E expression time 96 h, methanol-acetone fixation compound and 1% skimmed milk blocker. The smallest expression of protein E (greatest inhibition over viral replication) was achieved at addition of extract AH-T-EtOH at its highest concentration and 1 h before inoculating dengue-2 virus strain A15 (VDEN-2 A15). Extract AH-H-ButOH at concentrations of 125 µg/ml and 250 µg/ml presented a slight limitation in the expression of E 1 h after viral inoculation. Extract AH-H-AcEtO at the concentrations used did not show any difference when added before and after inoculation. The immunoperoxidase assay exhibited similar results for the extracts.

Conclusions: The greatest inhibition of viral replication was obtained with extract AH-H-ButOH at its highest concentration and at both addition times. The enzyme immunoassays applied are useful tools to evaluate Ageratine havanensis extracts with potential antiviral activity.