Sex pili as immunogens

Groups of chickens were vaccinated intravenously with live cultures of Escherichia coli K12 possessing transfer factors F, I, A2 or no transfer factor (Tra-minus) and their immunity challenged by injecting them intravenously with an F-plus strain of Salmonella heidelberg or an F-plus or I-plus strain of Salmonella typhimurium. Compared with the Tra-minus strain, vaccination with the F-plus, but not the I-plus or A2-plus, K12 strain significantly reduced the mortality rate caused by the F-plus salmonella strains; vaccination with the I-plus or A2-plus, but not the F-plus, K12 strain significantly reduced the mortality rate caused by the I-plus salmonella strain.