Phylogeography of Francisella tularensis: global expansion of a highly fit clone.

Francisella tularensis contains several highly pathogenic subspecies, including Francisella tularensis subsp. holarctica, whose distribution is circumpolar in the northern hemisphere. The phylogeography of these subspecies and their subclades was examined using whole-genome single nucleotide polymorphism (SNP) analysis, high-density microarray SNP genotyping, and real-time-PCR-based canonical SNP (canSNP) assays. Almost 30,000 SNPs were identified among 13 whole genomes for phylogenetic analysis. We selected 1,655 SNPs to genotype 95 isolates on a high-density microarray platform. Finally, 23 clade- and subclade-specific canSNPs were identified and used to genotype 496 isolates to establish global geographic genetic patterns. We confirm previous findings concerning the four subspecies and two Francisella tularensis subsp. tularensis subpopulations and identify additional structure within these groups. We identify 11 subclades within F. tularensis subsp. holarctica, including a new, genetically distinct subclade that appears intermediate between Japanese F. tularensis subsp. holarctica isolates and the common F. tularensis subsp. holarctica isolates associated with the radiation event (the B radiation) wherein this subspecies spread throughout the northern hemisphere. Phylogenetic analyses suggest a North American origin for this B-radiation clade and multiple dispersal events between North America and Eurasia. These findings indicate a complex transmission history for F. tularensis subsp. holarctica.

Developmental validation of a single-tube amplification of the 13 CODIS STR loci, D2S1338, D19S433, and amelogenin: the AmpFlSTR Identifiler PCR Amplification Kit.

Analysis of length polymorphism at short tandem repeat (STR) loci utilizing the polymerase chain reaction (PCR) process has proven to be an ideal assay for human identification purposes. The short length of STR loci coupled with the amplification of target sequence through PCR allows for a robust, sensitive, and specific assay for highly polymorphic markers. A multiplex containing fifteen STR loci plus the gender-determining locus Amelogenin was developed to provide a single amplification/detection of all CODIS (Combined DNA Index System) STR loci (CSF1PO, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, FGA, TH01, TPOX, and vWA) as well as two internationally-accepted STRs (D2S1338 and D19S433). By incorporating five-dye fragment analysis technology and non-nucleotide linkers, previously optimized AmpFlSTR kit primer sequences have been maintained. This kit has been developed in accordance with the standards of the forensic community as defined by the DNA Advisory Board. Validation studies were performed to include developmental validation, and the results support the use of the AmpFlSTR Identifiler PCR Amplification Kit for human identity and parentage testing.

Development of the AmpFISTR SEfiler PCR amplification kit: a new multiplex containing the highly discriminating ACTBP2 (SE33) locus.

The AmpFISTR SEfiler kit co-amplifies 11 short tandem repeat loci including SE33 in a single multiplex. After establishing the optimum in primer titration studies, the primer concentrations of all loci in the multiplex were chosen such that the heterozygote peak height ratios of each of the loci were balanced. The combined primer set was then tested to determine the robustness of the multiplex under various conditions. Different MgCl(2) concentrations were evaluated to establish the optimum concentration for the multiplex. The amplification of the various loci in the multiplex was tested at several annealing temperatures (55-63 degrees C). Additionally, DNA from primates, non-primates and microorganisms were amplified to investigate the specificity of the kit. The stability of the AmpFISTR SEfiler kit was determined by addition of hematin, to simulate inhibition, and the use of degraded DNA. Population studies revealed a probability of identity of 6.47x10(-15) for African Americans and 7.46x10(-14) for US Caucasians. To assess the ability of the multiplex to analyze forensic samples, testing on blood, oral swabs and mixtures was performed. Based on the various studies, it was determined that the AmpFISTR SEfiler PCR amplification kit can be used to successfully analyze a variety of forensic, databasing and paternity samples.