Low-Temperature-Grown RS Virus in Adult Volunteers

A respiratory syncytial (RS) virus strain grown in bovine embryonic kidney tissue culture at 34 C or at 28 C infected the majority of inoculated adult volunteers. An acute mild upper-respiratory tract illness developed in most infected individuals. Subsequent cultivation of the virus strain in bovine embryonic kidney tissue culture at 26 C was associated with a decrease in infectivity for adult volunteers. The response of the infected volunteers suggested that the virus grown at 26 C had also lost virulence for adults. The results of the study were considered sufficiently encouraging to recommend a cautious stepwise evaluation of the RS virus grown at 26 C in progressively younger age groups.