AmpliTaq and AmpliTaq Gold DNA Polymerase - Applied Biosystems

The flagellum protein flagellin of Listeria monocytogenes is encoded by the flaA gene.Immediately downstream of flaA, two genes, cheY and cheA, encoding products with homology tochemotaxis proteins of other bacteria, are located. In this study we constructed deletion mutantswith mutations in flaA. cheY, and cheA to elucidate their role in the biology of infection with L.monocytogenes. The {Delta}cheY, {Delta}cheA, and double-mutant {Delta}cheYA mutants, butnot {Delta}flaA mutant, were motile in liquid media. However, the {Delta}cheA mutant hadimpaired swarming and the {Delta}cheY and {Delta}cheYA mutants were unable to swarm on softagar plates, suggesting that cheY and cheA genes encode proteins involved in chemotaxis. The{Delta}flaA, {Delta}cheY, {Delta}cheA, and {Delta}cheYA mutants (grown at 24{degrees}C)showed reduced association with and invasion of Caco-2 cells compared to the wild-type strain.However, spleens from intragastrically infected BALB/c and C57BL/6 mice showed larger andsimilar numbers of the {Delta}flaA and {Delta}cheYA mutants, respectively, compared to the wildtypecontrols. Such a discrepancy could be explained by the fact that tumor necrosis factorreceptor p55 deficient mice showed dramatically exacerbated susceptibility to the wild-type butunchanged or only slightly increased levels of the {Delta}flaA or {Delta}cheYA mutant. Insummary, we show that listerial flaA. cheY, and cheA gene products facilitate the initial contactwith epithelial cells and contribute to effective invasion but that flaA could also be involved in thetriggering of immune responses.Feldmesser, M., A. Mednick, et al. (2002). "Antibody-Mediated Protection in Murine Cryptococcusneoformans Infection Is Associated with Pleotrophic Effects on Cytokine and LeukocyteResponses." Infect. Immun. 70(3): 1571-1580.http://iai.asm.org/cgi/content/abstract/70/3/1571Cryptococcus neoformans, an encapsulated yeast, is a common cause of life-threateningmeningoencephalitis in immunosuppressed patients. We previously observed that administrationof a monoclonal antibody (MAb) to the capsular polysaccharide to mice with pulmonary infectionprolonged survival and enhanced granulomatous inflammation without reducing lung CFU. Tounderstand the mechanism of MAb action, we studied leukocyte recruitment and cytokine profilesin lungs of A/JCr mice. B lymphocytes were the predominant cell type in lung infiltrates,comprising 15 to 30% of the leukocytes. Despite alterations in histological appearance,fluorescence-activated cell sorter analysis revealed no significant difference in total numbers oflung leukocytes in MAb-treated mice and controls. Differences in the immune response to C.neoformans between MAb-treated mice and controls included (i) an increase in the percentage ofgranulocytes among lung leukocytes on day 14, (ii) higher macrophage surface expression ofCD86 on day 28, (iii) larger amounts of IL-10 in lung homogenates at day 7, (iv) a trend towardsmaller amounts of gamma interferon mRNA and protein on day 7, and (v) a smaller increase inthe levels of interleukin-4 mRNA and protein on day 7. Hence, the immune responses to C.neoformans infection in the presence and absence of specific antibody were qualitatively similar,and antibody administration was associated with several subtle quantitative differences inimmune response parameters that could translate into enhanced survival. MAb may functionpartly by down-regulating the inflammatory response and reducing host damage. Our findingsdemonstrate unexpected complexity in the interaction between specific MAb and othercomponents of the host immune response.Garandeau, C., H. Reglier-Poupet, et al. (2002). "The Sortase SrtA of Listeria monocytogenes Is Involvedin Processing of Internalin and in Virulence." Infect. Immun. 70(3): 1382-1390.http://iai.asm.org/cgi/content/abstract/70/3/1382Listeria monocytogenes is an intracellular gram-positive human pathogen that invades eucaryotic