CHARACTERIZATION OF PUTATIVE DEFECTIVE INTERFERING (DI) A WSN RNAS ISOLATED FROM THE LUNGS OF MICE PROTECTED FROM AN OTHERWISE LETHAL RESPIRATORY-INFECTION WITH INFLUENZA-VIRUS A/WSN (H1N1) - A SUBSET OF THE INOCULUM DI RNAS/

Defective interfering (DI) influenza virus A/WSN (H1N1) grown in embry onated eggs protected adult mice from a lethal respiratory infection w ith A/WSN virus. Eighteen bands of putative DI RNA, ranging in size fr om about 230 to 1020 nt, were identified in this preparation by revers e transcription and polymerase chain reaction using a segment-specific 3' primer and a segment-universal 5' primer. Every Virion RNA segment was represented by one to four bands of putative DI RNA. However, onl y five bands of putative DI RNA could be isolated, using the same cond itions, from lungs of WSN-infected mice protected from death by co-ino culation with egg-grown DI WSN. These five bands originated from PB1, PB2, PA, and M Virion RNAs and were all about 350-450 nt in length. Fo ur putative pi RNAs originating from PBI, PB2, and PA virion RNAs were sequenced, and three were identical (including deletion junctions and base substitutions) to putative pi RNAs from the inoculum. These data suggest that the mouse lung was highly selective for a subset of inoc ulum DI RNAs and that one or more of these DI RNAs was responsible for protection in vivo. All putative DI RNAs had a single internal deleti on. (C) 1995 Academic Press, Inc.