The man, the plant, and the insect: shooting host specificity determinants in Serratia marcescens pangenome

IntroductionSerratia marcescens is most commonly known as an opportunistic pathogen causing nosocomial infections. It, however, was shown to infect a wide range of hosts apart from vertebrates such as insects or plants as well, being either pathogenic or growth-promoting for the latter. Despite being extensively studied in terms of virulence mechanisms during human infections, there has been little evidence of which factors determine S. marcescens host specificity. On that account, we analyzed S. marcescens pangenome to reveal possible specificity factors.MethodsWe selected 73 high-quality genome assemblies of complete level and reconstructed the respective pangenome and reference phylogeny based on core genes alignment. To find an optimal pipeline, we tested current pangenomic tools and obtained several phylogenetic inferences. The pangenome was rich in its accessory component and was considered open according to the Heaps’ law. We then applied the pangenome-wide associating method (pan-GWAS) and predicted positively associated gene clusters attributed to three host groups, namely, humans, insects, and plants.ResultsAccording to the results, significant factors relating to human infections included transcriptional regulators, lipoproteins, ABC transporters, and membrane proteins. Host preference toward insects, in its turn, was associated with diverse enzymes, such as hydrolases, isochorismatase, and N-acetyltransferase with the latter possibly exerting a neurotoxic effect. Finally, plant infection may be conducted through type VI secretion systems and modulation of plant cell wall synthesis. Interestingly, factors associated with plants also included putative growth-promoting proteins like enzymes performing xenobiotic degradation and releasing ammonium irons. We also identified overrepresented functional annotations within the sets of specificity factors and found that their functional characteristics fell into separate clusters, thus, implying that host adaptation is represented by diverse functional pathways. Finally, we found that mobile genetic elements bore specificity determinants. In particular, prophages were mainly associated with factors related to humans, while genetic islands-with insects and plants, respectively.DiscussionIn summary, functional enrichments coupled with pangenomic inferences allowed us to hypothesize that the respective host preference is carried out through distinct molecular mechanisms of virulence. To the best of our knowledge, the presented research is the first to identify specific genomic features of S. marcescens assemblies isolated from different hosts at the pangenomic level

Development of the Multiplex Real-Time PCR for Marburg, Ebola, and Lassa Viruses Identification

Presented are the data on the development and approbation of the method of Marburg, Ebola, and Lassa viruses identification based on real-time multiplex PCR with hybridization-fluorescent detection. This method is meant for the differential diagnostics of hemorrhagic fevers caused by these viruses. Displayed are the results of determination of multiplex PCR analytical sensitivity and specific activity

Development of DNA-Biochip for Identification of Influenza A Virus Subtypes

Developed was the DNA-biochip to identify subtypes of influenza A virus, pathogenic for humans. Microchip was capable of detecting H1, H3, H5-subtypes of hemagglutinin (including H1-subtype of pandemic A/H1N1(2009) influenza virus ) and neuraminidase subtypes N1,N2 of influenza virus. This microchip was successfully tested on the strains of A/H5N1 highly pathogenic avian influenza virus, A/H1N1(2009) pandemic influenza virus, A/H1N1 and A/H3N2 seasonal influenza viruses

Dissemination of Influenza A/H5N1 Virus after Intranasal Inoculation of Chickens

Studied was dissemination of avian influenza virus (AIV) in the organism of chickens after intranasal challenge with 10-100 LD50. The primary organ of accumulation of AIV A/H5N1 (A/Chicken/Kurgan/05/2005strain) is the respiratory tract (nasal mucosa), where the virus is registered in 18 hours after challenge. The accumulation of pathogen is observed in many organs and serum of chicken in 30-32 hours after challenge. The animals die in 54 hours, the concentration of virus reaches critical value in all studied samples. The highest AIV loads (7 lg of chicken embryo infective dose - EID50/g or ml) are registered in lungs, blood serum and kidneys of chicken. The results of AIV loads measuring using titration and real time RT-PCR show high degree of correlation (r=0.89)

Anti-Helicobacter pylori activity and immunostimulatory effect of extracts from Byrsonima crassa Nied. (Malpighiaceae)

<p>Abstract</p> <p>Background</p> <p>Several <it>in vitro </it>studies have looked at the effect of medicinal plant extracts against <it>Helicobacter pylori </it>(<it>H. pylori</it>). Regardless of the popular use of <it>Byrsonima crassa </it>(<it>B. crassa</it>) as antiemetic, diuretic, febrifuge, to treat diarrhea, gastritis and ulcers, there is no data on its effects against <it>H. pylori</it>. In this study, we evaluated the anti-<it>H. pylori </it>of <it>B. crassa </it>leaves extracts and its effects on reactive oxygen/nitrogen intermediates induction by murine peritoneal macrophages.</p> <p>Methods</p> <p>The minimal inhibitory concentration (MIC) was determined by broth microdilution method and the production of hydrogen peroxide (H₂O₂) and nitric oxide (NO) by the horseradish peroxidase-dependent oxidation of phenol red and Griess reaction, respectively.</p> <p>Results</p> <p>The methanolic (MeOH) and chloroformic (CHCl₃) extracts inhibit, <it>in vitro</it>, the growth of <it>H. pylori </it>with MIC value of 1024 μg/ml. The MeOH extract induced the production H₂O₂and NO, but CHCl₃extract only NO.</p> <p>Conclusion</p> <p>Based in our results, <it>B. crassa </it>can be considered a source of compounds with anti-<it>H. pylori </it>activity, but its use should be done with caution in treatment of the gastritis and peptic ulcers, since the reactive oxygen/nitrogen intermediates are involved in the pathogenesis of gastric mucosal injury induced by ulcerogenic agents and <it>H. pylori </it>infections.</p