title: Role of PPE18 protein in intracellular survival and pathogenicity of Mycobacterium tuberculosis in mice.
abstract: BACKGROUND
  Ever since its discovery the mycobacterial proline-proline-glutamic acid (PPE) family of proteins has generated a huge amount of interest. Understanding the role of these proteins in the pathogenesis of Mycobacterium tuberculosis (Mtb) is important. We have demonstrated earlier that the PPE18 protein of Mtb induces IL-10 production in macrophages with subsequent downregulation of pro-inflammatory cytokines like IL-12 and TNF-α and favors a T-helper (Th) 2-type of immune response.
  
  
  RESULTS
  Using a ppe18 genetic knock-out Mtb strain, we have now carried out infection studies in mice to understand the role of PPE18 in Mtb virulence. The studies reveal that lack of PPE18 leads to attenuation of Mtb in vivo. Mice infected with the ppe18 deleted strain have reduced infection burden in lung, liver and spleen and have better survival rates compared to mice infected with the wild-type Mtb strain.
  
  
  CONCLUSIONS
  Taken together our data suggest that PPE18 could be a crucial virulence factor for intracellular survival of Mtb.
authors.affiliation: Centre for DNA Fingerprinting and Diagnostics-CDFD, Nampally, Hyderabad, India.
authors.forename: Khalid Hussain
authors.initials: KH
authors.lastname: Bhat
authors.forename: Asma
authors.initials: A
authors.lastname: Ahmed
authors.forename: Santosh
authors.initials: S
authors.lastname: Kumar
authors.forename: Pawan
authors.initials: P
authors.lastname: Sharma
authors.forename: Sangita
authors.initials: S
authors.lastname: Mukhopadhyay
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D058491:Bacterial Load; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D005260:Female; D055786:Gene Knockout Techniques; D054884:Host-Pathogen Interactions; D008099:Liver / Q000382:microbiology / Q000473:pathology; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D050296:Microbial Viability; D009169:Mycobacterium tuberculosis / Q000378:metabolism / Q000472:pathogenicity / Q000502:physiology*; D013154:Spleen / Q000382:microbiology / Q000473:pathology; D014397:Tuberculosis, Pulmonary / Q000382:microbiology*; D014774:Virulence
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C544170:Rv1196 protein, Mycobacterium tuberculosis