[Immunofluorescence with the PI-3 virus--study of various working conditions for the detection of viral infection using immunofluorescence on various types of cell cultures].

We used the fluorescence method for the investigation of the sensitivity of several kinds of cell cultures to the infection with the parainfluenza virus 3 (PI-3). Cultures from calf kidneys were the most sensitive while we did not determine any differences between primary cultures and cultures of the first and second subpassages and/or freshly cultivated or incubated cultures over seven days at a temperature of 37 degrees C. Equal values of infection titres like on the cultures of calf kidneys were determined by immunofluorescence also on the kidney cells of lambs though the presence of the infection was not accompanied by cytopathic changes. Infection of pig kidney cells appeared only after the inoculation of 10(3) TKID50 and higher doses of the virus, the infection having a very slow course of development without detectable cytopathic changes. Fluorescent findings were identical in different tissues. Antibodies present in the culture medium stopped the spreading of the infection by neutralizing the virus released from the cells, however, not the primary infection. The increase in the content of antibodies in the medium led - by inhibiting the intercellular virus - to the slowing down of the growth of primary fluorescent lesions.