Quantitative applications of fluorescent antibody technique to influenza-virus-infected cell cultures

Abstract

Tissue cultures of chick embryo cells, the FL strain of human amnion cells, and calf kidney cells, all infected with two strains of influenza virus (Asian and PR8) were studied by the fluorescent antibody technique. A quantitative method was used employing a differential count of fluorescent cells. The maximum yield of fluorescent cells was obtained with an adsorption period of 1 hour. The number of fluorescent cells could be halved by addition of antiserum 30 minutes after exposure to virus, whereas after 4 hours antiserum had no effect. The chick embryo cultures showed the highest proportion of fluorescent cells. Ninety per cent of these cells could be made to fluoresce with an EID 50: cell ratio of 20. Infective Asian influenza virus was released from infected calf kidney cells but not from infected chick and FL cells. Evidence is presented that this technique can be used for the rapid assay of viruses.