TABLE 3-3.

Comparison of Quantitative and Quantal Infectivity Titrations

Virus dilutiona	Quantitative assay (plaque count)	Quantal assayb(cpe or death of host)
10–2	C, C, C, C, Cc	+ + + + +
10–3	50, 42, 54, 59, 45	+ + + + +
10–4	5, 7, 3, 6, 4	+ + – + +
10–5	0, 0, 1, 0, 1	– + – – –
10–6	0, 0, 0, 0, 0	– – – – –
Titer	105.4 PFU per ml	105.2 TCID50 per ml

^aInoculum: 0.2 ml.

^bEach symbol (+ or –) represents the result in one tissue culture tube or animal.

^cC, Confluent (uncountable).