TABLE 1.

Slopes of the regression coefficients for H2N3 virus stocks incubated at 37°C and 55°C

Virusa	Slope (±SE) for incubation at:
	37°C (log10 PFU/h)b		55°C (log10 PFU/min)
	Egg grown	MDCK grown	Linearc	Stabled	Sensitived
A/Mallard/Alberta/77/1977 (P2E1)	−0.031 ± 0.003*	−0.031 ± 0.002*	−0.031 ± 0.004	−0.005 ± 0.003	−0.078 ± 0.005
A/Mallard/Alberta/376/1985 (P1E1)	−0.038 ± 0.001†	−0.041 ± 0.001†	−0.053 ± 0.004	−0.027 ± 0.002	−0.093 ± 0.003
A/Mallard/Alberta/353/1988 (P2E1)	−0.028 ± 0.002*	−0.029 ± 0.002*	−0.047 ± 0.003	−0.029 ± 0.005	−0.072 ± 0.009
A/Mallard/Alberta/201/1996 (P2E1)	−0.026 ± 0.002*	−0.025 ± 0.002*	−0.042 ± 0.002	−0.032 ± 0.002	−0.075 ± 0.006
A/Mallard/Alberta/205/1998 (P2E1)	−0.039 ± 0.002†	−0.031 ± 0.002*	−0.036 ± 0.006	−0.010 ± 0.004	−0.120 ± 0.007
A/Mallard/Alberta/226/1998 (E4)	−0.039 ± 0.002†	−0.028 ± 0.001*	−0.047 ± 0.006	−0.016 ± 0.005	−0.115 ± 0.010
A/Mallard/Alberta/79/2003 (E2)	−0.026 ± 0.002*	−0.036 ± 0.002†	−0.032 ± 0.006	−0.003 ± 0.004	−0.125 ± 0.008

^aThe passage history of the stock viruses is included in parentheses (P, unknown passage; E, embryonated chicken egg).

^bRegression analysis suggested two groups for the various slope coefficients; values within a column with the same symbol (* or †) are not significantly different.

^cLinear fit of the data was not appropriate, but the slopes are included for comparison to the 37°C data.

^dSegmented regression produced a fit for 2 lines; the shallow slope is the stable fraction of the population, and the steep slope is the sensitive fraction.