Moreover, LmexCen−/− vaccinated hamsters showed downregulation of disease promoting Th2 type of response as indicated by reduced IL-10 and IL-4 cytokine expression and higher IFN-γ response resulting in higher IFN-γ/IL-10 and IFN-γ/IL-4 ratios, the key biomarkers of protection compared to virulent LmexWT infection. This evidence concerns the gene IL4 and infection.