摘要：Influenza A and influenza B viruses were adapted to growth at 25°C. When given to volunteer subjects, the viruses were attenuated but remained infective and antigenic. The minimum immunizing dose of an egg-adapted virus appeared to be 105.0 EID50. Cloning by plaque selection at 25°C gave seed cultures of relatively low infectivity titres. These titres were increased when necessary by passage at 33°C. No reversion to virulence was observed. Viruses attenuated in the United Kingdom and the USA were compared in volunteer trials with vaccine strains that had already been used in the USSR for mass immunization. Results were broadly similar. Currently available methods of attenuation and work with temperature-sensitive mutants are reviewed. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (759K), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . 593 594 595 596 597 598
