Consistent with the results of Vegfb knockdown by lentivirus, Vegfb or Flt1 knockout resulted in a weakened antigen-specific response on day 7 of prime infection, and the survival of antigen-specific T cells decreased, starting at the contraction phase after 21 days (Figure 3, J and K, and Supplemental Figure 5, M and N). The gene discussed is FLT1; the disease is infection.