Plaque inhibition assay for drug susceptibility testing of influenza viruses

Abstract

The relative antiviral activities of four drugs against contemporary strains of influenza A and B viruses were determined in Madin-Darby canine kidney cell monolayers with a plaque inhibition assay. This assay proved to be a reliable, rapid method of determining 50% inhibitory concentrations that correlated well with clinically achievable drug levels and the results of clinical trials. Contemporary strains of influenza A viruses (subtypes HlNl, H3N2, HSW1N1) required amantadine hydrochloride and rimantadine hydrochloride 50% inhibitory concentrations in the range of 0.2 to 0.4 ,ug/rnl, whereas 50% inhibitory concentrations ranged from approximately 50 to 100 ,ug/ml against influenza B viruses. Ribavirin was approximately 10-fold less active than amantadine hydrochloride against influenza A viruses, and the ribavirin 50% inhibitory concentrations against both influenza A and B viruses ranged from 2.6 to 6.8 ,tg/ml. Inosiplex had no antiviral activity in this test system.

Isolation and characterization of the bioactive metabolites from the soil derived fungus Trichoderma viride

“…The assay was carried out according to the method of Hayden et al (1980) in a six-well plate where MDCKM cells (10 5 cells/ml) were cultivated for 24 h at 37°C. A/CHICKEN/QALUBIA/1/2006 (H5N1) virus was diluted to give 10 4 PFU/well and mixed with the concentration of the tested compounds; 1 µg/ml of L-1-(tosyl-amido-2-phenyl) ethyl chloromethyl ketone and incubated for 1 h at 37°C before being added to the cells.…”

Influenza neuraminidase operates via a nucleophilic mechanism and can be targeted by covalent inhibitors

“…The effectiveness of 2a,3ax-difluoro-N-acetylneuraminic acid against influenza plaque reduction was assessed with recombinant B/Lee/40 influenza virus based on a previously reported method 52 . MDCK cell monolayers were inoculated with virus (B40 PFU per well) and the plates were incubated for 1 h at 37°C.…”

Syncytium Formation and HIV-1 Replication Are Both Accentuated by Purified Influenza and Virus-associated Neuraminidase

“…Virus crude preparation of strain A/H3N2/England/427/88 was purified by a modified two-step centrifugation procedure as described previously (42). Flu virus was titrated by a standard plaque assay as described elsewhere (43). Partially purified flu preparation commonly achieved 10 7 PFU/ml.…”