Temperature-Sensitive Mutants of Influenza A Virus. XII. Safety, Antigenicity, Transmissibility, and Efficacy of Influenza A/Udorn/72-ts-l[E] Recombinant Viruses in Human Adults

Abstract

The presence of the temperature-sensitive (ts) lesions of complementation-recombination groups I and 5 in the Hong Kong/68-ts-I[A] virus was confirmed by genetic analysis of ts recombinants of the Hong Kongj68-ts-1 [A] virus and a Udorn / 72 wildtype virus. Three classes of Udorn/72-ts recombinants were found. One class possessed both ts genes of the Hong Kong/68-ts-I[A] parent, a second class possessed the ts lesion characteristic of group I, and a third class possessed the ts lesion of group 5. The Hong Kongj68-ts-1 [AJ parent and the Udorn/72-ts recombinants exhibited a lO,OOO-fold or greater restriction of replication in the lungs of hamsters than did the homologous wild-type virus. All isolates from the lungs and nasal turbinates of recipients of two of the four Udorn/72-ts-I[AJ recombinants contained only ts virus. These two properties, restricted replication and genetic stability after replication in vivo, suggest that the Udorn/72-ts-I[AJ recombinants should be considered for evaluation as vaccines for use in humans.