Indirect immunoperoxidase assay

Indirect immunoperoxidase assay (IPA) is a laboratory technique used to detect and titrate viruses that do not cause measurable cytopathic effects and cannot be measured by classical plaque assays.

[1] Susceptible cells are inoculated with serial logarithmic dilutions of samples in a 96-well plate.

After viral growth, viral detection by IPA yields the infectious virus titer, expressed as tissue culture infectious dose (TCID50).

This represents the dilution of a virus-containing sample at which half of a series of laboratory wells contain replicating viruses.

This technique is a reliable method for the titration of human coronaviruses (HCoV) in biological samples (cells, tissues, or fluids).