B.K. virus haemagglutinin.

Among the widely applied buffered media, the HSAG (hepes-salt-albumin-gelatin) medium at pH 5.75--6.25 was found to be the most favourable for B.K. virus haemagglutinin titration. The optimum temperature was at 4 degrees C. The haemagglutinin was not affected by temperatures up to 37 degrees C, pHs between 5.5 and 9.5, and NaCl concentrations between 0.063 M and 2.56 M. When incubated at 56 degrees C, the haemagglutinin shows a time and pH dependent decline in titre. No significant time dependent titre fall occurred at 56 degrees C if NaCl molarity was varied between 1.31 and 2.56.