Growth of Influenza Virus in the Chick Chorion

Hoyle1 found that, following inoculation of influenza virus into the allantoic cavity of fertile hens' eggs, complement-fixing ‘soluble’ antigen became detectable in suspensions of chorio-allantoic membranes before the virus itself. He suggested1,2 that the ‘soluble’ antigen was an intracellular form of the virus or a virus precursor. Henle and Henle3 and Fulton4, working on similar lines, concluded that ‘soluble’ antigen and virus antigens appeared together ; and Cairns5 has shown that Hoyle's interpretation of his own results is not necessarily correct, since there are differences in the sensitivity of the experimental methods in this particular situation.