Which of the following is not true regarding Chlamydia?
Ans. (b) Elementary body is metabolically active Reproductive Cycle of Chlamydiae Elementary body (EB) Stable spherical form, metabolically inactive - Extracellular phase Infectious form 200 - 300 nm diameter Rigid trilaminar cell wall Electron dense nucleoid (contains DNA) DNA = RNA Attach to surface of susceptible epithelial cell near base of microvilli by adhesins (e.g. major outer membrane protein); receptors (heparin sulfate like proteoglycans in case of C. trachomatis) | Engulfment of EB into host cell either by endocytosis into clathrin-coated pits or pinocytosis into non-coated pits. Lysosomal fusion is inhibited by unknown mechanism, so EB form of chlamydiae is protected under membrane bound environment. | Reorganisation of EB by spheroplast-like transformation/loss of cross-linking of EB membrane proteins. Reticulate body (Initial body form) - Pleomorphic stage Intracellular form Growing and replicative form 500-1000 nm size No electron dense nucleoid RNA > DNA Within membrane bound vacoule RB divides by binary fission repeatedly to form EB. |Cytoplasmic inclusion bodies form (EB filled vacoule) |This EB liberate from host cell to infect new cells.
Has biphasic life
Elementary body is metabolically active
Reticulate body undergoes binary fission
Once it invades into cell it abates phagolysosomal fusion