Amino acid substitutions in the neuraminidase protein of an H9N2 avian influenza virus affect its airborne transmission in chickens

Table 4 Neuraminidase activities of H9N2 AIV

virus	K _M (μM) ^a	V _max (fluorescence a.u/s) ^a	Relative V _max ^b	Elution time(h)
rSD01	54.16 ± 3.12	192.73 ± 6.54	1.00	1.5
r01/NASS	49.167 ± 3.34	118.83 ± 1.43*	0.62	3.5
r01/NAHB	52.43 ± 6.68	123.83 ± 3.40*	0.64	2
r01/NA381	53.84 ± 2.53	92.25 ± 1.69*	0.48	4

^aThe enzyme kinetics data was fit to the Michaelis-Menten equation by nonlinear regression to determine the Michaelis constant (K _M) and maximum velocity (Vmax) of substrate conversion. Results are given as the mean ± standard deviation from three duplicate samples. ^bRelative Vmax: homologous of recombinant virus to SD01. *P < 0.05 compared with SD01.

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