To enrich recombinant chlamydiae, we first derived a rifampin-resistant variant, termed MoPn_RifR from wild-type C. muridarum strain Nigg II (traditionally referred as strain mouse pneumonitis, MoPn), and an LBM415-resistant MCR variant, termed MCR_LBMR (Table 2). Here, NR3C2 is linked to pneumonitis.