Abstract
As no critical and reliable reports on the isolation of influenza C virus have appeared so far in Japan for the past two decades, an isolation of influenza C virus from a sporadic case in Yamagata Prefecture was reported. The strain designated as C/Yamagata/64 was quite related to either C/1233/47 or C/JJ/50 as far as several biological characteristics are concerned. However, serologic test revealed the clear-cut antigenic difference among these three, reflecting the chronological sequence of their isolation. The receptor for influenza C was found to be quite different and independent from those for influenza A, B and mumps viruses.
