This study investigated BCG masking dependency on the species of Mycobacterium through the immune response to the mycobacterial region of deletion 1 (RD-1) associated growth affecting proteins (GEP). To evaluate the effects of GEP, 8-week old female BALB/c mice were immunized with either the wild type Mycobacterium bovis (MBGEP) or the ATCC Mycobacterium avium subsp. avium (MAGEP) strain and then subjected to further exposure with Mycobacterium terrae or M. avium sub. avium. Mice immunized with MAGEP and those mice further exposed to M. avium subsp. avium had increased granulocytes (GRA) and monocytes to lymphocytes rate (MLR) compared to control mice. Immunization of mice with GEP induced an antibody response one month after primary immunization, as observed by cross-reactivity. Our findings suggest that MAGEP is related to a latent hypersensitivity reaction and an increased risk of mycobacterial infection susceptibility. According to the results of the present study, previous sensitization with NTM antigens results in varying immune reactions after contact with different NTM argued that masking phenomena may be dependent on the species of Mycobacterium.  Kulcsszavak: tuberculosis, BCG vaccine, mycobacterial proteins, region of deletion 1, mice immunization