TABLE 5.
In vitro antiviral screening assaysa
| Determination of viral infectivity under two conditions: I. In cultured cells during virus multiplication in the presence of a single compound (A-S) or a mixture of compounds, e.g., plant extracts (A-M). II. After extracellular incubation with a single compound (V-S) or a mixture of compounds (V-M). |
|---|
| Plaque inhibition assay (only for viruses which form plaques in suitable cell systems) |
| Titer determination of a limited number of viruses in the presence of a nontoxic dose of the test substance |
| Applicability: A-S |
| Plaque reduction assay (only for viruses which form plaques in suitable cell systems) |
| Titer determination of residual virus infectivity after extracellular action of test substance(s) (see reference for comments on cytotoxicity) |
| Applicability: V-S, V-M |
| Inhibition of virus-induced cytopathic effect (for viruses that induce cytopathic effect but do not readily form plaques in cell cultures) |
| Determination of virus-induced cytopathic effect in cell monolayers cultured in liquid medium, infected with a limited dose of virus, and treated with a nontoxic dose of the test substance(s) |
| Applicability: A-S, A-M |
| Virus yield reduction assay |
| Determination of the virus yield in tissues cultures infected with a given amount of virus and treated with a nontoxic dose of the test substance(s) |
| Virus titer determination carried out after virus multiplication by the plaque test or the 50% tissue culture infective dose end-point test |
| Applicability: A-S, A-M |
| End-point titer determination technique |
| Determination of virus titer reduction in the presence of twofold dilutions of test compound(s) |
| This method especially designed for the antiviral screening of crude extracts (238) |
| Applicability: A-S, A-M |
| Assays based on measurement of specialized functions and viral products (for viruses that do not induce cytopathic effects or form plaques in cell cultures) |
| Determination of virus specific parameters, e.g., hemagglutination and hemadsorption tests (myxoviruses), inhibition of cell transformation (Epstein-Barr virus), immunological tests detecting antiviral antigens in cell cultures (Epstein-Barr virus, HIV, HSV, cytomegalovirus) |
| Applicability: A-S, A-M, V-S, V-M |
| Reduction or inhibition of the synthesis of virus specific polypeptides in infected cell cultures, e.g., viral nucleic acids, determination of the uptake of radioactive isotope-labelled precursors or viral genome copy numbers |
| Applicability: A-S, A-M, V-S, V-M |
a
Reprinted from reference 238 with permission of the publisher.