A Virus from Cases of Influenza-like Upper-respiratory Infection

Abstract

During the past few years at least two groups of investigators1, 2 have reported cases of upper-respiratory infection of unknown etiology, that resembled true “epidemic influenza” in clinical respects but which differed in that the convalescent serums failed to show any increase in capacity to neutralize standard strains of the influenza virus. Two similar cases of influenzalike infection occurred among the workers in this laboratory in February, 1940. The serums obtained from these cases 4 weeks after the infection and those obtained either at the time of or 3 weeks before the onset of illness were tested against the PR8 strain of the virus of epidemic influenza. Neither of the convalescent serums showed any detectable increase in capacity to neutralize the usual 1000 lethal doses of the virus; and neither of them fixed complement in tests against antigens prepared in the usual manner3 from mouse lung suspensions. This apparent lack of development of antibodies reactive against this standard strain of in...