TFF2 and infection: These results suggested that PR8 infection inhibited the IMR to Sp. To determine the mortality rate of coinfected animals, after PBS inoculation or Sp infection, the mice were challenged with a high dose of Sp following PR8 infection (PBS-PR8-Sp or Sp-PR8-Sp) or PBS inoculation (PBS-PBS-Sp or Sp-PBS-Sp).