IFNG and infection: During the early stage of infection the strongest responses were in the TBLN (mean 474 SFC/106 cells at 7 DPI), whereas from 14 to 21 DPI the highest number of IFNγ-secreting cells was detected in the lung, with SFC continuing to expand in this tissue (mean 368 SFC/106 cells at 14 DPI and 972/106 cells SFC at 21 DPI).