Rapid purification of avian influenza virus for use in enzyme-linked immunosorbent assay.

A rapid and easy purification method was developed to obtain avian influenza antigen for use in immunochemical assays. This was achieved by rapid concentration of virus from infective allantoic fluid, using 8% (w/v) polyethylene glycol 8000, and later, by purification on gel-permeation chromatography through controlled-pore glass beads. Rabbit anti-turkey globulins were made specific for turkey globulins, using affinity chromatography, conjugated to horseradish peroxidase and used in enzyme-linked immunosorbent assay. A significant increase in specificity and sensitivity of the enzyme-linked immunosorbent assay was observed when purified antigen was used in place of a crude antigen preparation. This purified antigen eliminated the false-positives obtained as a result of the turkeys being previously vaccinated with egg-grown virus vaccines (Newcastle disease virus). The details of the technique and the importance of antigen preparation are discussed.