900-1400 hemagglutinating particles/cell
||Horsfall, Reproduction of influenza viruses quantitative investigations with particle enumeration procedures on the dynamics of influenza A and B virus reproduction. J Exp Med. 1955 Oct 1 102(4):441-73. p.462 top paragraphPubMed ID13263486
||p.443 2nd paragraph:"The number of infective particles was computed from the 50 per cent infectivity end point on 0.5 log titration in the allantoic cavity of 10 day old chick embryos. The details of the procedure are described in a previous paper (8). Inoculated eggs were incubated at 35°C for at least 72 hours with Lee virus and for at least 48 hours with PR8 virus."
||p.462 top paragraph:"With inocula of about 0.2 particle or less per cell, Lee virus (influenza B) yielded between 900 and 1400 hemagglutinating
particles per cell. PR8 virus (influenza A), between 500 and 900. These values are similar to those reported recently from this laboratory (25) with chick embryo
lung cultures and the WS strain of influenza A virus."