Immunodeficient albino animals (BALB/c) that have been infected by Mycobacterium leprae form a T-cell immune response with predominant involvement of Th1 and Th17 cells with significant induction of IL-2 and IL-17, creating advantages for the development of intracellular bacterial pathogens. BALB/c nude mice are characterized by the suppression of the adaptive immune response, being used preferentially in the reproduction of leprosy. The gene discussed is IL17A; the disease is leprosy.