BTLA and infection: The results showed that compared to PBS inoculated mice, relative expression levels of GITR, BTLA, TIM-3, and PD-1 mRNA were significantly decreased on day 3 or 7 after infection in KI or KO mice with CA07 infection but not in WT mice with CA07 infection, and their levels were significantly higher in WT mice than in KI or KO mice (Figures 5A–D).