Either way, Type II IFN signaling makes up for lacking Type I IFN in both situations.
Mice lacking Type III IFN signaling were given the vaccine, and it didn’t seem that Type III IFN was needed for an adequate immune response because the mice dealt with the virus without a problem.
In mice lacking both Type I and Type III signaling, high viral loads that continued to increase.
Right panel: The additional loss of Type III IFN signaling in Type I IFN-deficient mice impairs the integrity of the blood-brain-barrier and alters immune cell function, which aggravates spongiosis and is ultimately lethal.
According to past research, Type III IFN signaling involves epithelial cells in the blood-brain barrier, which serves to protect the central nervous system from pathogens like yellow fever.
Without Type III IFN signaling, the integrity of the BBB faltered just enough to let the virus in.
With this finding in mind, researchers from the present study confirmed that the BBB was similarly weakened in mice lacking Type I and Type III IFN signaling after yellow fever vaccination.