Microbiology 7 - Chlamydia Order - Chlamydiales Family - Chlamydiaceae Genus - Chlamydia C. trachomatis OR Chlamydophila C. pneumoniae C. psittaci C. abortus C. felis C. caviae C. pecorum Red ones infect Chlamydia - Characteristics - Obligate Has to stay inside the cell - Intracellular bacteria - Doesn't have a lot of peptidoglycan - Very small o Can't be filtered through a 0.45um filter - Contain both DNA and RNA - Possess ribosomes - Make their own proteins, nucleic acids and lipids - Possess inner and outer membranes - Bi-phasic life cycle o Two different version Extracellular form EB - Elementary body RB - Reticulate Body Small Larger 0.ff-0.3um ffum No metabolism Metabolically ACTIVE Highly resistant Non-replicating Spore-like Life Cycle Intracellular form Sensitive Replicating Fragile - Starts with the cell and external elementary body - Attach to surface - Will be phagocytised It's in a protective environment - Converts to reticulate body - Start to divide by binary fission - Some of those bodies, convert back to elementary bodies - The inclusion now contains EBs and RBs Becomes intermediate bodies whilst it is reverting back to EBS
- Later on, release of the bodies by the cell popping In half an hour, all bodies are phagocytosed Developmental cycle of C.trachomatis elementary body (EB) epithelial cell nucleus 0.5 0 inclusion 1-8 48-72 hours 12-24 40 30 24-30 reticulate body (RB) @ Y. Pannekoek Growth Cycle - Organisms go into the phagosome o Intracellular membranes get involved in that i.e. golgi - Phagosome fuse to make one large INCLUSION - Incredibly prevalent - Good at surviving - With hardly any genes o 600 genes - It nicks things off the cell o They are energy parasites Endotoxin (LOS) - Lipooligosaccharides - Poor endotoxin activity o Lipid A o Core - OMPs o OMPff/MOMP · 40kDa trimer; porin function · Unique to each species · Abs to variable segments (VSff-4) can neutralize infectivity · Defines serological variants o OMP2 · 60kDa Cysteine-rich protein · Cysteine carry sulphur - helps make disulphide bonds · Structural stability in EB o POMPs (polymorphic OMPs) · Multiple shaped · 90kDa EB surface protein . One step ahaead of the immune system o Inc proteins
· RB specific . Fusion of inclusion membranes " Helps slightly with immune evasion Classification: Serovar - serological variant Defined because they get different antibody responses to them Biovar - biological variants We have two in chlamydia o Trachoma o LGV - Within those groups we have different serovars O Trachoma - ff5 o LGV - 4 - Biological features: o Trachea - non. Invasive o LGV - can cause systemic effects Infection: - Poorly understood o Microfilament-dependent phagocytosis o Receptor-mediated endocytosis - No definitive receptor on cells o Something to do with GAG: heparan sulphate (Loads of sugars) - No definitive bacterial adhesion o GAG: MOMP - Not all chlamydia use the same mechanism - They inhibit that lysosome-phagosome fusion - Limited target cell range - Epithelial cells of mucous membranes o