AmpliTaq and AmpliTaq Gold DNA Polymerase - Applied Biosystems

700.http://iai.asm.org/cgi/content/abstract/72/2/691Type IV pili (Tfp) of gram-negative species share many characteristics, including a commonarchitecture and conserved biogenesis pathway. Much less is known about the regulation of Tfpexpression in response to changing environmental conditions. We investigated the diversity of Tfpregulatory systems by searching for the molecular basis of the reported variable expression of theTfp gene cluster of the pathogen Actinobacillus pleuropneumoniae. Despite the presence of anintact Tfp gene cluster consisting of four genes, apfABCD, no Tfp were formed under standardgrowth conditions. Sequence analysis of the predicted major subunit protein ApfA showed anatypical alanine residue at position -1 from the prepilin peptidase cleavage site in 42 strains. Thisalanine deviates from the consensus glycine at this position in Tfp from other species. Yet,cloning of the apfABCD genes under a constitutive promoter in A. pleuropneumoniae resulted inpilin and Tfp assembly. Tfp promoter-luxAB reporter gene fusions demonstrated that the Tfppromoter was intact but tightly regulated. Promoter activity varied with bacterial growth phase andwas detected only when bacteria were grown in chemically defined medium. Infectionexperiments with cultured epithelial cells demonstrated that Tfp promoter activity was upregulatedupon adherence of the pathogen to primary cultures of lung epithelial cells. Nonadherent bacteriain the culture supernatant exhibited virtually no promoter activity. A similar upregulation of Tfppromoter activity was observed in vivo during experimental infection of pigs. The host cellcontact-induced and in vivo-upregulated Tfp promoter activity in A. pleuropneumoniae adds anew dimension to the diversity of Tfp regulation.Sommer, F., H. Wilken, et al. (2004). "Systemic Th1 Immunization of Mice against Helicobacter pyloriInfection with CpG Oligodeoxynucleotides as Adjuvants Does Not Protect from Infection butEnhances Gastritis." Infect. Immun. 72(2): 1029-1035.http://iai.asm.org/cgi/content/abstract/72/2/1029Recent reports have suggested that oral vaccination of mice against Helicobacter pylori isdependent on a Th1-mediated immune response. However, oral vaccination in mice neitherinduces sterilizing immunity nor leads to complete protection from disease. Therefore, in thisstudy we investigated whether a systemic subcutaneous immunization against H. pylori by usingCpG oligodeoxynucleotides as a Th1 adjuvant could achieve protection in a mouse model of H.pylori infection. CpG oligodeoxynucleotides are known for their ability to induce nearly entirelyTh1-biased immune responses and may be approved for human use in future. Immunization ofmice with H. pylori lysate and CpG induced a strong local and systemic Th1 immune response.Despite this strong Th1 response, mice were not protected from infection with H. pylori yet had a10-fold reduction in the number of H. pylori in the gastric mucosa compared to nonimmunizedmice. Of note, reduction of the bacterial density in immunized mice was accompanied by asignificantly enhanced gastritis. Hence, systemic Th1 immunization of mice, even though beingable to reduce the bacterial load in the stomach, is associated with aggravated pathology.Giuliani, M. M., L. Santini, et al. (2005). "The Region Comprising Amino Acids 100 to 255 of Neisseriameningitidis Lipoprotein GNA 1870 Elicits Bactericidal Antibodies." Infect. Immun. 73(2): 1151-1160.http://iai.asm.org/cgi/content/abstract/73/2/1151GNA 1870 is a novel surface-exposed lipoprotein, identified by genome analysis of Neisseria