Figure 2. Single cell RT-PCR following increasing inoculum doses.

BALB/c mice were treated i.n. with CFSE. 6 hours later, groups of mice (20 mice/group) were left uninfected (Naïve) or infected with the indicated dose of IAV. At 18 hours p.i., draining LN (20 mice/group) were pooled and migratory rDC (CFSE⁺CD11c⁺MHC II⁺) and LNDC (CFSE^negCD11c⁺MHC II⁺) were single-cell FACS sorted into 96 well plates and analyzed by single-cell RT-PCR for expression of viral NS-2 mRNA as described in Materials and Methods. (A) Data represent the frequency of NS-2 IAV mRNA⁺ cells/total cells analyzed. (B) cDNA from positive samples in (A) was again amplified by nested PCR for NS2. Indicated is the cycle at which the PCR reaction was stopped during the second nested PCR reaction (i.e. the amplification with the NS2C:NS3 primers).