TABLE 1.

rPIV3-2CT and rPIV3-2TM are not ts in LLC-MK2 cells, but inclusion of the cp45 mutations confers a nearly authentic cp45 ts phenotype^a

Virus	Titer at 32°C (log10 TCID50)	Change in titer (log10) compared to that at 32°Cb
		35°C	36°C	37°C	38°C	39°C	40°C
rPIV3/JS	7.9	0.3	0.1	0.1	(0.3)	(0.4)	0.4
PIV3cp45c	7.8	0.5	0.3	1.3	3.4	6.8	6.9
PIV1/Wash64c	8.5	1.5	1.1	1.4	0.6	0.5	0.9
rPIV3-1d	8.0	0.8	0.5	0.6	0.9	1.1	2.6
rPIV3-1cp45e	8.0	0.5	0.4	3.4	4.8	6.6	≥7.5
PIV2/V9412c	7.8	0.3	(0.1)	0.0	(0.4)	(0.4)	0.0
rPIV3-2CT	6.9	0.3	0.3	0.6	(0.1)	0.6	0.4
rPIV3-2TM	8.3	0.3	(0.1)	0.3	0.6	1.0	2.1
rPIV3-2CTcp45	8.0	0.8	(0.4)	2.0	4.3	≥7.5	≥7.5
rPIV3-2TMcp45	8.0	0.3	0.6	2.4	5.4	≥7.5	≥7.5

^aData presented are means of two experiments except values for 35°C, which are from one experiment. 

^bNumbers not in parentheses represent titer decrease; numbers in parentheses represent titer increase. Underlined values represent the lowest temperature at which there was a 100-fold reduction of virus titer compared to the titer at the permissive temperature (32°C). This restrictive temperature is referred to as the shutoff temperature. 

^cBiologically derived virus. 

^drPIV3 in which the F and HN ORFs were replaced by those of PIV1 (43). 

^eDerivative containing the 12 cp45 mutations which lie outside of F and HN (37).