The discrepancy between flow cytometry results (> 90% of cells positive to Annexin V 72 h post chlamydial infection; Fig 4) and the data obtained through MTS assay (40–50% of mortality; Fig 1) led us to evaluate also apoptotic/necrotic changes early after chlamydial infection (i.e. 24 hours) and to assess the effect of Z-VAD on the positivity for Annexin V 72 h post-infection. Here, ANXA5 is linked to chlamydia trachomatis infectious disease.