Because it has been shown that increasing the dose of virus inoculation can overcome the defect in latency establishment of a virus containing a stop mutation in the latency-associated M2 gene [44], we increased the dose of virus 100-fold to 1 × 105 PFU and examined infection of lung B cells by limiting-dilution PCR analysis of FACS-sorted CD19+ cells (B cells). Here, CD19 is linked to infection.