Table 2.

Fraction of EBV-infected memory cells expressing EBNA1(Q-K), LMP1, and LMP2

Tonsil	1	2*	3*
Frequency of infected cells per 105 memory cells	10	2	20
No. of infected cells required to detect LMP1	1	≤2	≤2
No. of infected cells required to detect LMP2	≤5	≤2	≤2
No. of infected cells required to detect EBNA1(Q-K)	≤5	≤2	2–20
No. of infected cells required to detect EBNA2†	>100	>40	>200

 The number of infected cells required to detect the latent genes was estimated from the minimum number of cells required to detect a signal in titrations of the type shown in Fig. 2 for tonsil 2. The estimated number of infected cells for each cell number tested in an RT-PCR reaction was derived from the frequencies measured with the limiting dilution DNA PCR method. 

^*Tonsils 2 and 3 are from Table 1 and are numbers 2 and 4, respectively, in Fig. 1. 

^†EBNA2 was never detected in any samples.