IVA can localize to and encase the forespore in the absence of VM IVA can localize to and encase the forespore in the absence of VM. Fluorescence microscopy analyses of wild-type (WT) and ΔIVA sporulating cells (A) and wild-type and VM mutant sporulating cells (B) producing mCherry-IVA at 23 h post-sporulation induction. IVA can localize to and encase the forespore in the absence of VM. Fluorescence microscopy analyses of wild-type (WT) and ΔIVA sporulating cells (A) and wild-type and VM mutant sporulating cells (B) producing mCherry-IVA at 23 h post-sporulation induction. Differential interference contrast (DIC) microscopy was used to visualize forespores and free spores. The nucleoid was stained with Hoechst stain (blue), and mCherry-IVA fluorescence is shown in red. The merge of Hoechst stain and mCherry is also shown. Pink arrows highlight cells that have undergone asymmetric division but have not completed engulfment; these forespores stain with Hoechst stain (+), and mCherry-IVA localizes to the mother cell-forespore interface. Orange arrows highlight cells that appear to have completed engulfment but whose forespores retain the Hoechst dye (+). Yellow arrows mark forespores that are visible by DIC and no longer retain the Hoechst dye. Orange and yellow solid arrows indicate that mCherry-IVA fully encases the forespore, while dashed arrows indicate partial encasement of the forespore. Bars, 5 µm. John W. Ribis et al. mSphere 2017; doi:10.1128/mSphere.00315-17