INVESTIGADORES
SARNACKI Sebastian Hernan
congresos y reuniones científicas
Título:
A dam deletion mutant of Salmonella Enteritidis: studies on virulence and protection.
Autor/es:
M. NOTO LLANA, S. H. SARNACKI, M. N. GIACOMODONATO, M.C. CERQUETTI.
Lugar:
Rosario, Argentina.
Reunión:
Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2006
Institución organizadora:
Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.
Resumen:
<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> S. Typhimurium null dam mutants have been proposed as ideal vaccine strains. In contrast, S.Enteritidis mutants bearing a defective Dam protein are less protective and unable to agglutinate in the presence of antibodies against LPS O9 antigen. Here, we analyze the behaviour of SEDdam, a dam deletion mutant of S. Enteritidis. This mutant was constructed by PCR-based mutagenesis. Attenuation and protection studies were performed in BALB/c mice. Epithelial and macrophage cell lines were used for in vitro studies. Nitric oxide (NO) production was assessed using Griess reagent. We found that SEDdam mutant is moderately attenuated (LD50:107 cfu), induces significant delayed-type hypersensitivity and improves bacterial clearance from spleen of immunized mice (range: 44-200 vs. 4 x 105 - 2 x 108 cfu). However, its protective capacity is reduced (20% survival rate). In vitro SEDdam induces production of NO in macrophages but not in Hep2; concurrently, we found that it is unable to invade epithelial cells. In addition, SEDdam LPS presents high proportion of reduced length O antigen polysaccharide. This defect does not affect the mutant serum resistance. Our results suggest that deletion of dam gene in S. Enteritidis renders a modestly attenuated mutant with reduced protective capacity. Interestingly, we found that Dam protein is involved in the regulation of LPS synthesis.