title: Genetics study and transmission electron microscopy of pili in susceptible and resistant clinical isolates of Mycobacterium tuberculosis.
abstract: OBJECTIVE
  To study genetic bases and morphology of pili in Mycobacterium tuberculosis (M. tuberculosis).
  
  
  METHODS
  PCR and sequencing were used to investigate two related pili, Mtp and Flp genes in clinical isolates of M. tuberculosis. The primers were designed and PCR program were set for whole genes amplification. PCR products of the two genes from all isolates were sequenced by an applied biosystems apparatus and the results were analysed by online software. In the other hands, harvested cells from fresh cultures of isolates were undergoing specific sample preparation for sectional and negative staining for transmission electron microscopy.
  
  
  RESULTS
  Electrophoresis revealed two specific bonds of 361 bp for Mtp and 150 bp for Flp genes and confirmed primer and PCR conditions designing. There were not any mutations in sequencing results of Mtp and Flp in comparison with reference sequence. Transmission electron microscopy examination revealed two distinct types of pili in the isolates as a bundle-forming pilus and rope-like pilus. From total investigated cells, 10% harbored pili in their structure.
  
  
  CONCLUSIONS
  Two genes of pili in all clinical isolates of M. tuberculosis were conserved and two morphological types of pili were detected. We proposed that by targeting pili proteins by a suitable inhibitor, it could affect the pathogenesis especially in resistant forms.
authors.affiliation: Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Hosseini
authors.affiliation: Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Abbas Ali Imani
authors.initials: AA
authors.lastname: Fooladi
authors.affiliation: Tuberculosis and Pediatric Infectious Resaerch Center, Arak University of Medical Sciences, Arak, Iran. Electronic address: mmatinam81@yahoo.com.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Arjomandzadegan
authors.affiliation: Tuberculosis and Pediatric Infectious Resaerch Center, Arak University of Medical Sciences, Arak, Iran.
authors.forename: Navid
authors.initials: N
authors.lastname: Emami
authors.affiliation: Tuberculosis and Pediatric Infectious Resaerch Center, Arak University of Medical Sciences, Arak, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Bornasi
keywords: Mycobacterium tuberculosis; Pili genes; Sequencing; Transmission electron microscopy