TABLE 3.

ITD of typed poliovirus isolates^a

Serotype(s)	No. of plaquesb		Total no. of isolatesc
	37°C	40°C	37°C	40°C
S1	98	3	117	3
S2	77	45	92	48
S3	72	22	95	25
NS	2d	2d	2	2
S1 + S2	1	0
S1 + S3	9	0
S2 + S3	5	3
S1 + S2 + S3	9	0

^aIncludes the additional serotyped isolates from plaques containing more than one serotype. Polioviruses from viral stocks were prepared from L20B plaques amplified at 37°C or after selection at 40°C for 5 days and reamplified at 37°C. The cell medium for all lines was Dulbecco modified Eagle medium containing 10% fetal bovine serum, penicillin (160 U/ml), streptomycin (0.32 g/ml), and mycostatin (20 U/ml).

^bThe total number of nonvaccine isolates/total number analyzed was 2/306 at 37°C and 2/78 at 40°C.

^cTotal number of isolates from both plaque categories characterized by ITD as either Sabin 1 (S1), Sabin 2 (S2), Sabin 3 (S3), or non-Sabin like (NS).

^dBoth characterized as wild type 1 polioviruses by sequencing, dot blot hybridization, and microneutralization with monoclonal and polyclonal anti-Sabin antibodies.