CD69 and infection: In the LD model used here, the percentage of CD69+ and CD25+ Ag-specific T cells continues to increase up to 72 h p.i., while the MFI of both activation markers tends to peak at 48 h p.i. Similarly, 2PM data showed that Ag-specific T cells speeds recover by 72 h post LD infection as compared to 48 h p.i., while synapse-like behavior declined at this time point.