EXPLOITING Anaplasma marginale GENOME

MORETTA ROSALIA; RUYBAL PAULA; PETRIGH ROMINA; WILKOWSKY SILVINA; FARBER MARISA

San Francisco, EE.UU

Congreso; International Congress of Bacteriology and Applied Microbiology; 2005

Background: The obligate intraerythrocytic bacterium Anaplasma marginale (Rickettsiales: Anaplasmataceae) is the most prevalent tick-borne livestock pathogen worldwide and is a severe constraint to animal health and production in tropic and subtropical regions of the world. Whole-genome sequencing of bacteria together with in silico analysis and genomic approaches are powerful tools for prediction of genes that take part in microbial pathogenesis. The aim of this study was the identification of epidemiological valuable markers and coding genes for putative virulence factors or immunogens using the A. marginale genome sequence.Methods: The selected methods were: PhoA fusion system for identifying exported proteins; PCR-based subtractive hybridization for detecting differential genes between A. marginale and A. centrale (low virulence vaccine strain); Bioinformatics analysis; Minisatellites PCR products sequence analysis.Results: We studied eight gene products so far: five were identified using the PhoA fusion system, two were selected from the differential subtraction library and one was identified by bioinformatics analysis. Among the selected genes, four are being evaluated to determine their antigenic potential and one of them is being characterized to elucidate its role as a virulence determinant. In addition, we found two polymorphic tandem repeats of 11 and 15 nucleotides (minisatellites) located in non-coding regions of the genome and five new mps1á genotype marker variations from Argentinean isolates. Minisatellites polymorphisms analysis showed 11pb repeat as a more polymorphic marker than 15pb repeat with variations within each isolate studied.Conclusions: This studies demonstrated the utility of Pho-A fusion system as a tool for proteins topology studies. The results obtained from the PCR-based subtractive hybridization strategy led us to consider A. centrale as a good model for comparative genomics studies in order to identify genes involved in pathogenic mechanisms. Moreover, minisatellites are being validated as a diagnostic and epidemiological tool and comparative genomics studies would allow us to elucidate a possible functional role of variable minisatellites within non-coding sequences in reduced genome organisms such as A. marginale.