TLR4 and infection: Nasal administration of a TLR4 agonist prior to, but not after, pulmonary infection with F. novicida could confer protection [29], while intraperitoneal administration of a TLR4 agonist could confer some level of protection when given 48 h before pulmonary infection with type A F. tularensis[51]; however, this effect is diminished when the TLR4 agonist was given only at the time of infection.