Rapid detection of influenza was a key focus for method development for many years. Traditional viral culture methods require special transport mediums, appropriate cell culture lines, and staff well versed in the manipulation of these cultures. Although the introduction of shell vial cultures and monoclonal fluorescent staining provided some improvement, delayed availability of results did not always meet the clinical need.
Direct fluorescent antibody (DFA) staining of specimen smears can provide more immediately available results; however, the availability of trained staff to interpret these smears is an obstacle for many laboratories. Antigen detection kits employing enzyme immunoassay (EIA) or immunochromatographic membrane principles did provide easily performed alternatives that fit well in most laboratory settings and provided more immediate results. Despite the fact that published studies demonstrated less than desirable sensitivity, these assays had found a niche and remained in place, even as molecular methods began to target these viruses.
