We previously showed that in immunocompromised nu/nu mice, BCGΔBCG1419c was as safe as parental BCG, and that in a mouse model of progressive infection with M. tuberculosis H37Rv, compared to BCG, vaccination with BCGΔBCG1419c increased the levels of CD4+ and CD8+ T lymphocytes, and reduced 1-log10 bacterial burden in lungs after 24 weeks post-infection, with reduced pneumonia, indicating its potential as a preventive vaccine against chronic TB (Pedroza-Roldán et al., 2016). Here, CD4 is linked to infection.