Antigenic and genetic characterization of three influenza C strains isolated in the kinki district of Japan in 1982–1983

Antigenic and genetic analyses of eight influenza C strains isolated in various areas of Japan during 1985–9

“…2 shows the oligonucleotide fingerprints of C/Nara/82, C/Nara/1/85, and C/Nara/2/85. The C/Nara/82 strain has been shown previously to possess the same antigenicity as the C/MS/80 strain [9,15], and the latter strain was observed here to be indistinguishable antigenically from the C/Nara/1/85 strain (Tables 1-3). It was unexpected, therefore, that the oligonucleotide pattern of C/Nara/ 1/85 was largely different from those of C/MS/80 and C/Nara/82; the patterns of the latter two isolates were very similar to each other, with a difference of only six oligonucleotide spots (Table 4).…”

“…To rule out the possibility that despite the identical antigenicity, there might be only a low degree of nucleotide sequence homology between the HE genes of C/Nara/1/85 and C/MS/80 or C/Nara/82. the sequence of the C/Nara/1/85 HE gene was determined and then compared with the previously determined sequences of the C/MS/80 and C/Nara/82 HE genes [12,15]. The results (Table 5) showed that the sequence of C/Nara/1/85 was highly homologous to those of C/MS/80 and C/Nara/82.…”

“…However, we found recently that all three strains (C/Kyoto/41/82, C/Nara/82, C/Hyogo/1/83) isolated in the Kinki district of Japan during the relatively short period from February 1982 to December 1983 were very similar to one another in both genetic and antigenic structure, although they were dissimilar to any of the strains isolated in Japan before 1982 [9,14]. Furthermore, it was later shown that the three Kinki isolates had a close relationship to the virus isolated in the United States in 1980 (C/Mississippi/1/80) and that they were distinguishable from previous isolates in serological tests with heterogeneous sera [15]. Based on these data, we supposed that influenza C virus closely related to C/Mississippi/1/80, newly introduced into Japan, spread rapidly to the Kinki district during 1982-3 because the virus had epidemiological advantages over the pre-existing viruses.…”

“…The MAb and immune sera. A total of 14 anti-HE MAb (11 to C/AA/50 and 3 to C/MS/80) prepared as described elsewhere [15,16] were used in this study. Competitive binding assays showed that antibodies against the HE of C/AA/50 are directed against six distinct antigenic sites which do not overlap: antibodies J14, Q5, J9, U4, and U9 to site A-1, antibody K16 to site A-2, antibodies Ut and U2 to site A-3.…”

“…Nucleotide sequencing. The HE gene of the C/Nara/1/85 strain was sequenced by the dideoxynucleotide-chain termination method [21] using purified viral RNA as template and synthetic oligonucleotide primers [15]. By using 17 primers described elsewhere [15], the HE gene sequence except for the first 63 nucleotides at the 5' terminal and 3' non-coding region (mRNA sense) could be determined.…”