1st December 2016 Microbiology Obligate intracellular parasites: Chlamydia Must be in a cell to survive Now looking at Chlamydia in the phylogenetic tree Order: Chlamydiales Family: Chlamydiaceae Genus: Chlamydia Species: C. trachomatis - important human pathogen Order: Chlamydiales Family: Chlamydiaceae Genus: Chlamydophila - mostly pathogens of animals Species: - C. pneumoniae - human pathogen - C. psittaci - human pathogen - C. abortus - causes abortion in sheep - C. felis - C. caviae - C. pecorum LOS porin Chlamydia- characteristics outer · Obligate intracellular bacteria membrane o Virus can only replicate inside cells peptidoglycan . It is a bacterium and was considered a virus because of its obligation to be inside a cell plasma membrane Lack peptidoglycan (unusual for bacteria) Cannot be filtered by 0.45micrometer filter (large) Contain both DNA and RNA (viruses are one or the other) Possess ribosomes (viruses don't have this) Makes their own proteins, nucleic acids, and lipids · Possess inner and outer membranes It is a mix of what sounds like a virus and bacteria periplasmic space lipoprotein 0000000 Typical membrane structure - doesn't have peptidoglycan; it is not used for structure · Gram negative Unique bacterial life cycle Genome sequencing - very small with 600 genes (it is a parasite, uses the host cell to deliever everything it needs) · Very small genome Require host for · Energy
Microbiology · Energy parasites · Nutrients 1st December 2016 Bi-phasic life cycle Infecting form EB and the dividing form RB Fragile because it is replication The forms are well suited what it needs to do extracellular and intracellular Extracellular form EB - Elementary body RB - Reticulate Body Small Larger 0.1-0.3pm 1um No metabolism Metabolically ACTIVE Highly resistant Non-replicating Spore-like Intracellular form Sensitive Replicating Fragile Binary fission when it is intracellular - standard bacterium Chlamdia- life cycle - 1 EB Attachment 1. Susceptible cell 2. Ingestion 3. Reorganization into RB inside phagosome 4. Growth by binary fission-24 hours the vesicle - it isn't cytoplasmic - the membrane bag gets bigger and bigger and it will eventually convert back to the infectious form (EB) and comes out of the infected cell by lysis and they go on to infect other cells. It lives within Chlamdia- life cycle - 2 5. Reorganized into EBs 6. Inclusion contains EBs and RBs Release of chlamydial EB 7. Continued reorganization 8. Extrusion of mass of EBs by reverse endocytosis Developmental cycle of C.trachomatis epithelial cell elementary body (EB) nucleus 0.5 0 inclusion 1-8 48-72 hours 12-24 40 30 24-30 reticulate body (RB) @ Y. Pannekoek
1st December 2016 Microbiology Timing of life cycle The organism needs to condense it DNA for it replicate - 3hrs 9hrs the organisms are replicating 15hrs the inclusion body has got bigger - there is more membrane to allow for it to expand as the organism divides 40hrs there is elementary bodies - intermediate bodies, condense the DNA back down. Growth cycle Phagosome fuses with intracellular membranes - massive amounts of membrane to allow for