INTERSPECIES TRANSMISSION OF INFLUENZA-C VIRUS BETWEEN HUMANS AND PIGS

The antigenic and genetic characteristics of the 18 human strains of i nfluenza C virus isolated in Yamagata and Sendai Cities, Japan between January 1991 and February 1993 were investigated. Antigenic analysis with monoclonal antibodies to the hemagglutinin-esterase glycoprotein showed that the isolates could be divided into three distinct groups c losely related to C/Yamagata/26/8l, C/Aichi/1/81 and C/Mississippi/80, respectively. T1-oligonucleotide fingerprinting of total vRNA reveale d that the six isolates belonging to the C/Yamagata/26/81 virus group had the genomes greatly similar to one another but considerably differ ent from those of the 1988/1990 isolates (except C/Yamagata/10/89) of the same antigenic group. Comparison of total or partial nucleotide se quences of the seven RNA. segments of the three strains (C/Miyagi/3/91 , C/Miyagi/9/91 and C/Miyagi/2/92) representative of the 1991/1993 str ains of the C/Yamagata/26/81 virus group with those of the previous in fluenza C isolates obtained from humans and pigs during 1980/1989 show ed that the 1991/1993 strains, like C/Yamagata/10/89, are more closely related to viruses isolated from pigs in Beijing, China in 1981/1982 than to any of the isolates from humans. This observation suggests str ongly that interspecies transmission of influenza C virus between huma ns and pigs has occurred in nature, although it is not known whether t he virus has been transmitted from pigs to humans or from humans to pi gs. (C) 1997 Elsevier Science B.V.