Chlamydiae 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 1 Chlamydiae
O Biological Features Structure and chemical composition ◆ Developmental cycle ◆ Staining properties ◆ Antigens ◆ Growth and metabolism Characteristics of host-parasite relationship ◆ Classification 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 2 Biological Features Structure and chemical composition Developmental cycle Staining properties Antigens Growth and metabolism Characteristics of host-parasite relationship Classification
O Structure and chemical composition a nonreplicating, fectious particle called the elementary E.B. body(eB) . an intracytoplasmic form called the reticulate body(RB 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 3 Structure and chemical composition a nonreplicating, infectious particle called the elementary body (EB) an intracytoplasmic form called the reticulate body (RB)
O Structure and chemical composition (Foto: Prof. Eiko Petersen, Universitat Freiburg/Brsg) To be seen each cell are two nclusions with elementary bodies (Giemsa stain) 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 4 Structure and chemical composition
O Structure and chemical composition The elementary body, which is covered by a rigid cell wall, contains a DNA genome with a molecular weight of 66 X 107(about 600 genes, one-quarter of the genetic information present in the DNA of Escherichia coli) A cryptic DNA plasmid(7, 498 base pairs) is also found. It contains an open reading frame for a gene involved in DNA replication the elementary body contains an RNA polymerase responsible for the transcription of the DNA genome after entry into the host cell cytoplasm and the initiation of the growth cycle Ribosomes and ribosomal subunits are present in the elementary bodies Throughout the developmental cycle, the DNA genome, proteins, and ribosomes are retained in the membrane-bound reticulate body 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 5 Structure and chemical composition The elementary body, which is covered by a rigid cell wall, contains a DNA genome with a molecular weight of 66 X 107 (about 600 genes, one-quarter of the genetic information present in the DNA of Escherichia coli). A cryptic DNA plasmid (7,498 base pairs) is also found. It contains an open reading frame for a gene involved in DNA replication. the elementary body contains an RNA polymerase responsible for the transcription of the DNA genome after entry into the host cell cytoplasm and the initiation of the growth cycle. Ribosomes and ribosomal subunits are present in the elementary bodies. Throughout the developmental cycle, the DNA genome, proteins, and ribosomes are retained in the membrane-bound reticulate body
O Developmental cycle EBs attach to the microvilli of susceptive cells. Penetration into the host cell via endocytosis or pinocytosis and forming phagosomes Fusion of lysomes with the EB-containing phagosome are inhibited EBs reorganize into the meta bolically active rbs .RBs synthesize their own DNA, RNA and protein but lack the necessary metabolic pathways to produce high-energy phosphate compounds ● Energy parasites .RBs replicate by binary fission and inclusion forms. . RBs begin reorganizinginto EBS. Cell ruptures and releasesthe infective ebs The developmental cycle takes 24-48 hours 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 6 Developmental cycle EBs attach to the microvilli of susceptive cells. Penetration into the host cell via endocytosis or pinocytosis and forming phagosomes Fusion of lysomes with the EB-containing phagosome are inhibited EBs reorganize into the metabolically active RBs. RBs synthesize their own DNA, RNA and protein but lack the necessary metabolic pathways to produce high-energy phosphate compounds. Energy parasites. RBs replicate by binary fission and inclusion forms. RBs begin reorganizing into EBs. Cell ruptures and releasesthe infective Ebs. The developmental cycle takes 24～48 hours
O Developmental cycle Infectious Form Rep Nucleus lost Cel 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 7 Developmental cycle
O Staining properties EBs stain purple with Giemsa stain-in contrast to the blue of host cell cytoplasm RBs stain blue with Giemsa stain The Gram reaction of chlamydiae is negative or variable and is not useful in identification o Inclusions stain brightly by immunofluorescence, with group specifIc, species-speciTIC, or serovar-specifIC antibodies 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 8 Staining properties EBs stain purple with Giemsa stain—in contrast to the blue of host cell cytoplasm. RBs stain blue with Giemsa stain. The Gram reaction of chlamydiae is negative or variable and is not useful in identification. Inclusions stain brightly by immunofluorescence ,with groupspecific,species-specific, or serovar-specific antibodies
O Antigens Group(fenus)-specific antigens heat-stable LPS as an immunodominant component Antibody to these antigens can be detected by CF and immunofluorescence Species-specific or serovar-specific antigens Antigens are mainly outer membrane proteinS(MOMP) Specific antigens can best be detected by immunofluorescence, particularly using monoclonal antibodies 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 9 Antigens Group(fenus)-specific antigens: – heat-stable LPS as an immunodominant component. – Antibody to these antigens can be detected by CF and immunofluorescence Species-specific or serovar-specific antigens – Antigens are mainly outer membrane proteins(MOMP). – Specific antigens can best be detected by immunofluorescence,particularly using monoclonal antibodies
Growth and metabolism Unable to synthesize ATP and depend on the host cell for energy requirements Grow in cultures of a variety of eukaryotic cell lines McCoy cells are used to isolate chlamydiae C pneumoniae grows better in HL or Hep-2 cells All types of chlamydiae proliferate in embryonated eggs, particularly in the yolk sac The replication of chlamydiae can be inhibited by many antibacterial drugs Cell wall inhibitors(penicillins)result in the production of morphologically defective forms but are not effective in clinical diseases hibitors of protein synthesis(tetracyclines, erythromycins)are effective in most clinical infections C trachomatis strains synthesize folates and are susceptible to inhibition by sulfonamides 2021/2/21 microbiology 8-year course
2021/2/21 microbiology 8-year course 10 Growth and metabolism Unable to synthesize ATP and depend on the host cell for energy requirements. Grow in cultures of a variety of eukaryotic cell lines – McCoy cells are used to isolate chlamydiae – C pneumoniae grows better in HL or Hep-2 cells. – All types of chlamydiae proliferate in embryonated eggs,particularly in the yolk sac. The replication of chlamydiae can be inhibited by many antibacterial drugs. – Cell wall inhibitors (penicillins) result in the production of morphologically defective forms but are not effective in clinical diseases. – Inhibitors of protein synthesis (tetracyclines,erythromycins)are effective in most clinical infections. – C trachomatis strains synthesize folates and are susceptible to inhibition by sulfonamides