Abstract
l. The growth of avian infectious bronchitis (IB) virus (IBV) in chicken kidneycell cultures was studied by the direct fluorescent antibody technique. The earliest visiblefluorescence was detected in a granularform in th cytoplasm 3 -4 hours after viral in-oculation. The fluorescence became diffuse gradually all over the cytoplasm, reaching amaximum at 12 hours.2. The occurrence of IBV antigen was studied on stamp-specimens prepared fromthe trachea of chickens inoculated with IBV. A detectable amount of fluorescence ap-peared 24 hours after virus inoculation. An almost constant level of fluorescence wasmaintained over an observation period of seven days. Fluorescence appeared in agranularform or diffusely in the cytoplasm.3. When a tracheal specimen from the normal chicken was stained with anti-IBfluorescent antibody, or when one from the IB-infected chicken was allowed to reactwith FITC-conjugated rnormal 7-globulin, no fluorescence was observed on the specimen.No fluorescence was detected from a tracheal specimen from the Newcastle-disease (ND)-infected chicken stained with anti-IB fluorescent antibody, though ND virus antigen wasobviously demonstrated with anti-ND virus fluorescent antibody. These findings indicatethat the fluorescence detected frorn the tracheal specimen from the IB-infected chickenstained with anti-[B fluorescent antibody reflects IBV-specific antigen.
