Study of the O-acetylesterase activity of five influenza C virus strains

Summary

Four influenza C virus strains, isolated in France in 1991, were used as a source for a kinetic study of the enzyme O-acetylesterase (EC 3.1.1.53) related to another strain, C/JHB/1/66, considered as the reference strain. Similarities, but also differences, in their haemagglutination titres were detected. Remarkable differences were found for enzyme activity and the K_m, V_max, and the V _max/K_m ratio between certain strains, as well as for their thermostability at 40 °C when methylumbelliferyl acetate was used as substrate. By contrast, their optimum pH, stability at different pH values, and stability at 4 °C over 14 days were very similar. The effect of some compounds on O-acetylesterase activity was studied. The peculiarities of these factors are discussed in relation to the functional variation of the virus.