Isolation of Three Strains of Type B Influenza Virus Incompletely Related to Lee

Abstract

An outbreak of influenza on the Univ. of Washington campus, involving an estimated minimum of 500 cases, yielded 3 strains of influenza virus, type B, by inoculation of throat washings to embryonated eggs. Paired serum specimens were obtained from 28 patients and were examined by the agglutination-inhibition technic. 22 patients showed a significant rise in titer against Lee virus, and 18 of these showed a significant rise against the newly isolated strains. The new viruses were not inhibited by high titer serum prepd. against Lee virus in roosters. The new strains did not appear to be as highly antigenic as Lee virus, but the failure of specific anti-Lee serum to inhibit agglutination by the new strains was interpreted as evidence that the new viruses were incompletely related to the standard type B virus.