Genetic and phenotypic analysis of Vibrio cholerae non-O1, non-O139 isolated from German and Austrian patients.

Vibrio cholerae belonging to the non-O1, non-O139 serogroups are present in the coastal waters of Germany and in some German and Austrian lakes. These bacteria can cause gastroenteritis and extraintestinal infections, and are transmitted through contaminated food and water. However, non-O1, non-O139 V. cholerae infections are rare in Germany. We studied 18 strains from German and Austrian patients with diarrhea or local infections for their virulence-associated genotype and phenotype to assess their potential for infectivity in anticipation of possible climatic changes that could enhance the transmission of these pathogens. The strains were examined for the presence of genes encoding cholera toxin and toxin-coregulated pilus (TCP), as well as other virulence-associated factors or markers, including hemolysins, repeats-in-toxin (RTX) toxins, Vibrio seventh pandemic islands VSP-1 and VSP-2, and the type III secretion system (TTSS). Phenotypic assays for hemolysin activity, serum resistance, and biofilm formation were also performed. A dendrogram generated by incorporating the results of these analyses revealed genetic differences of the strains correlating with their clinical origin. Non-O1, non-O139 strains from diarrheal patients possessed the TTSS and/or the multifunctional autoprocessing repeats-in-toxin (MARTX) toxin, which were not found in the strains from ear or wound infections. Routine matrix-assisted laser desorption/ionization (MALDI-TOF) mass spectrometry (MS) analysis of all strains provided reliable identification of the species but failed to differentiate between strains or clusters. The results of this study indicate the need for continued surveillance of V. cholerae non-O1, non-O139 in Germany, in view of the predicted increase in the prevalence of Vibrio spp. due to the rise in surface water temperatures.

Novel regulatory SNPs in the promoter region of the TNFRSF18 gene in a Gabonese population

Parasites are accountable for driving diversity within immune gene families. We identified and investigated regulatory single nucleotide polymorphisms (SNPs) in the promoter regions of the tumor necrosis factor receptor superfamily member 18 (TNFRSF18) gene by direct sequencing in a group of male Gabonese individuals exposed to a wide array of parasitic diseases such as malaria, filariasis and schistosomiasis. Two new promoter variants were identified in 40 individuals. Both novel variants were heterozygous and were linked to SNP #rs3753344 (C/T), which has been described. One of the SNP variants (ss2080581728) was close to the general transcription factor site, the TATA box. We further validated these new promoter variants for their allelic gene expression using transient transfection assays. One new promoter variant with two base changes (C/T - ss2080581728/rs3753344) displayed an altered expression of the marker gene. Both novel variants remained less active at the non-induced state in comparison to the major allele. The allele frequencies observed in this study were consistent with data for other African populations. The detection and analysis of these human immune gene polymorphisms contribute to a better understanding of the interaction between host-parasite and expression of Treg activity.

Novel regulatory SNPs in the promoter region of the TNFRSF18 gene in a Gabonese population.

Parasites are accountable for driving diversity within immune gene families. We identified and investigated regulatory single nucleotide polymorphisms (SNPs) in the promoter regions of the tumor necrosis factor receptor superfamily member 18 (TNFRSF18) gene by direct sequencing in a group of male Gabonese individuals exposed to a wide array of parasitic diseases such as malaria, filariasis and schistosomiasis. Two new promoter variants were identified in 40 individuals. Both novel variants were heterozygous and were linked to SNP #rs3753344 (C/T), which has been described. One of the SNP variants (ss2080581728) was close to the general transcription factor site, the TATA box. We further validated these new promoter variants for their allelic gene expression using transient transfection assays. One new promoter variant with two base changes (C/T - ss2080581728/rs3753344) displayed an altered expression of the marker gene. Both novel variants remained less active at the non-induced state in comparison to the major allele. The allele frequencies observed in this study were consistent with data for other African populations. The detection and analysis of these human immune gene polymorphisms contribute to a better understanding of the interaction between host-parasite and expression of Treg activity.