title: [Isolation of spontaneous mutants from influenza A virus recombinants after several plaque passages in embryonic chicken cells].
abstract: Clones with larger plaques (2.5-4 mm in diameter) could be isolated after sequential passages of influenza virus recombinants A/Greifswald 6/74 X A/PR8/34 (H3N1) and A/Bangkok 1/79 X A/PR8/34 (H3N1 and H3N2) in chick embryo cells. In addition to the large plaques, very small ones (1-1.5 mm in diameter) could be regularly observed in a proportion of about 10% at subsequent passages of these variants. The clones exhibited a constant size of the plaques, and there were no large-plaque forming revertants. In most of the cases cultivation of these mutants in embryonated chicken eggs (ECE) did not lead to positive HA titers. PFU titers in the infected allantoic fluid were usually lower than 10(-5). One virus clone with large plaques (3.8 mm) lacked the capacity of multiplication in ECE. This appears to be a host-range mutant. Revertants occurred with a frequency of less than 1%; they could multiply normally in ECE.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D005814:Genes, Viral; D009980:Influenza A virus / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification; D009154:Mutation; D011995:Recombination, Genetic; D010948:Viral Plaque Assay
vernacular_title: Isolation von Spontanmutanten bei Influenzavirus A-Rekombinanten nach mehreren Plaquepassagen auf embryonalen Hühnerzellen.