In order to verify the parasite-host relationship during infection with wild type and attenuated strain of C. pseudotuberculosis [30], used the Balb/c, C57Black / 6 (wild, knockout (KO) for nitric oxide (ON), KO-IFN-γ, KO-IL-10) and Swiss were used, and it was found that all are susceptible to CLA in different degrees, the mice of the Swiss strain were consider sensitive for CLA, similar results with the isogenic line Balb /c. The gene discussed is IL10; the disease is infection.