FREQUENT OCCURRENCE OF GENETIC REASSORTMENT BETWEEN INFLUENZA-C VIRUS-STRAINS IN NATURE

Previous studies of the haemagglutinin-esterase (HE) genes of various influenza C isolates suggested the existence of three distinct virus l ineages (C/Yamagata/26/81-, C/Aichi/1/81- and C/Mississippi/80-related lineages) in Japan in the 1980s. Here we analysed the genetic propert ies of three strains (C/Yamagata/5/92, C/Miyagi/3/93 and C/Miyagi/4/93 ) isolated in Yamagata and Sendai Cities, Japan, in 1992/1993, Compari son of total or partial nucleotide sequences of the seven RNA segments of C/Yamagata/5/92 with those of 11 previous isolates suggested that the 1992 strain is a reassortant which inherited HE, P3, NP and M gene s from a C/Mississippi/80-like virus and PB2, PB1 and NS genes from a C/pig/Beijing/115/81-like virus, Furthermore, it became evident that a t least two (C/England/83 and C/Yamagata/9/88) of the 11 reference str ains are also reassortants.