Cytopathic effect inhibition assay

One of the most popular bioassay for interferons is termed the cytopathic effect inhibition assay . This assay is based upon the ability of many interferons to render animal cells resistant to viral attack. It entails incubation of the interferon preparation with cells sensitive to destruction by a specific virus. That virus is then subsequently added, and the percentage of cells that survive thereafter is proportional to the levels of interferon present in the assay sample. Viable cells can assimilate certain dyes, such as neutral red. Addition of the dye followed by spectrophotometric quantitation of the amount of dye assimilated can thus be used to quantitate percentage cell survival. This type of assay can be scaled down to run in a single well of a microtitre plate. This facilitates automated assay of large numbers of samples with relative ease. 

Table 1. Antiherpesviral activity of 5-sub-stituted arabinosyluracil and deoxy-uridine analogues assayed by the cytopathic effect inhibition and their anti-HEL cell growth activity...

Researchers at SRMLSC recently developed a HTS that allowed the identification of potential inhibitors of the severe acute respiratory syndrome coronavirus (SARS CoV) from large compound libraries [34], The luminescent-based assay, which measured the inhibition of SARS CoV-induced cytopathic effects (CPE) in Vero E6 cells, was validated with two different diversity sets of compounds against the SARS CoV. The hit rate for both libraries was approximately 0.01%. 

The literature on antiviral screening for HHV-6 and HHV-7 is sparse and has been reviewed elsewhere (1,3-5). Cell systems for viral propagation have included primary human peripheral blood and cord blood lymphocytes (CBL), and T-cell lines. Methods for monitoring viral replication have included examining infected cultures for cytopathic effect, immunofluorescence analysis, quantitation of viral DNA, and focus-forming assays. Phosphonoformic acid (foscarnet), phosphonoacetic acid, and ganciclovir inhibit HHV-6 and HHV-7... 

Rhinacanthin E and rhinacanthin F isolated from the aerial parts of the plant Rhinacanthus nasutus (Acanthaceae) showed significant antiviral activity against influenza virus type A but no effect on HSV-2. The EC50 obtained in a hemadsorption-inhibition assay were 1.7 and < 0.94 pg/mL, and in a viral cytopathic effect assay were 7.4 and 3.1 pg/mL, respectively [168],... 

Cellular level models usually exploit the virus s ability to infect and replicate in specific cell lines in cell culture systems. The ceU culture system provides a rapid method to grow viruses at higher titres to test the antiviral activity of compounds/extracts. It is based on the observation that virus infection and multiplication results in cytopathic effect (CPE) due to either release of virus or induction of apoptosis as a result of host immune responses. Inhibition of CPE in presence of test compound could be due to inhibition of virus replication. The assay results combined with molecular level assay results will guide the later study in animal models. 

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