Expression ofNocardia brasiliensissuperoxide dismutase during the early infection of murine peritoneal macrophages

Abstract

Nocardia brasiliensis is the main agent of actinomycetoma in Mexico, but little is known about its virulence and molecular pathogenic pathways. These facultative intracellular bacteria are able to survive and divide within the host phagocytic cells, in part by neutralizing the reactive oxygen intermediates. Superoxide dismutase (SOD) participates in the intracellular survival of several bacterial species and, in particular, constitutes one of Nocardia asteroides virulence factors. To clarify SOD participation in the N. brasiliensis early infective process, we report its isolation and the consequent comparison of its transcript level. A 630 bp polymerase chain reaction fragment that included most of the coding sequence of N. brasiliensis sodA was cloned. A competitive assay was developed, allowing comparison of bacterial sod expression in exponential culture and 1 h after infecting peritoneal macrophages from BALB/c mice. At that time, there were viable bacteria in the macrophages. The intracellular bacteria presented a clear decrease in their sod transcript amount, although their 16S rRNA (used as an internal control) and hsp levels were maintained or slightly increased, respectively. These results indicate that sodA transcription is not maintained within the SOS bacterial response induced by phagosomal conditions. Further kinetics will be necessary to precisely define sod transcriptional regulation during N. brasiliensis intra-macrophage growth.

Bacterial diseases in marine bivalves

“…The importance of superoxide dismutase (SOD) and catalase were demonstrated as important pathology determinants for N. asteroides (Beaman and Beaman, 1994). SOD was also identified from N. brasiliensis (Revol et al, 2006). Whole genome sequence analysis of N. brasiliensis revealed orthologs for virulence factors, especially genes involved in synthesis of bioactive compounds and in the synthesis and catabolism of lipids (Vera-Cabera et al, 2013) An association of the ability to inhibit phagosome-lysosome fusion and virulence has been well characterized in N. asteroides GUH-2 (Davis-Scibienski and Beaman, 1980 green, or concave with or without a greenish color; both pathogens may produce flat lesions that are green-yellow in color (Quayle, 1961;Elston et al, 1987;Farley et al, 1988;.…”

Retnla down-regulation and IL-13-rich environment correlate with inflammation severity in experimental actinomycetoma byNocardia brasiliensis

“…The humoral immune response is also activated, in which, apart from IgG antibodies, relatively high sustained levels of IgM antibodies seem important for partial protection in a complement‐independent way (Salinas‐Carmona & Perez‐Rivera, ; Gonzalez‐Suarez et al ., ). Cord factor, catalase, and superoxide dismutase have been identified as Nb's virulence factors (Salinas‐Carmona et al ., , ; Revol et al ., ; Trevino‐Villarreal et al ., ). Theorizing that some bacteria escape from the immune response by hiding in non‐hostile cells, we focused on the activation type of macrophages.…”

Complete Genome Sequence Analysis of Nocardia brasiliensis HUJEG-1 Reveals a Saprobic Lifestyle and the Genes Needed for Human Pathogenesis

“…There have been several experimentally described virulence factors of Nocardia, including catalase, superoxide dismutase, cell-wall lipids, and proteases, as well as some immunodominant antigens, using mainly N. cyriacigerogica GUH-2 (formerly N. asteroides ) and N. brasiliensis HUJEG-1 [21], [22], [23], [24], [25].…”