“…Indeed, in the experiments of Hill and Garren (5) on fowl typhoid, protein has been advanced as a susceptibility factor. Ruebner and Bramhall (6) reported that low protein intake lowered resistance of mice to mouse hepatitis virus. Sprunt and Flanigan (7) have advanced the most complicated hypothesis of all, and believe that protein deficiency is cyclic in its effects on resistance to viral disease, leading first to susceptibility, then to resistance, and thence to susceptibility again.…”