The Generation of the Human mAb RabD4 Specific to the Rabies Virus Glycoprotein and Characterization Thereof

We generated a novel human neutralizing human mAb RabD4 against rabies virus glycoprotein using in vitro stimulation of human peripheral B cells produced by immunized donor. The human mAb RabD4 showed a high antigen-binding activity and virus-neutralizing activity in the FAVN test with the CVS-11 rabies virus.

Recombinant Monoclonal Antibodies for Rabies Post-exposure Prophylaxis

Rabies virus is a prototypical neurotropic virus that causes one of the most dangerous zoonotic diseases in humans. Humanized or fully human monoclonal antibodies (mAb) that neutralize rabies virus would be the basis for powerful post-exposure prophylaxis of rabies in humans, having several significant benefits in comparison with human or equine rabies polyclonal immunoglobulins. The most advanced antibodies should broadly neutralize natural rabies virus isolates, bind with conserved antigenic determinants of the rabies virus glycoprotein, and show high neutralizing potency in assays in vivo. The antibodies should recognize nonoverlapping epitopes if they are used in combination. This review focuses on basic requirements for anti-rabies therapeutic antibodies. The urgency in the search for novel rabies post-exposure prophylaxis and methods of development of anti-rabies human mAb cocktail are discussed. The rabies virus structure and pathways of its penetration into the nervous system are also briefly described.

Links of gut microbiota composition with alcohol dependence syndrome and alcoholic liver disease

BACKGROUND

Alcohol abuse has deleterious effects on human health by disrupting the functions of many organs and systems. Gut microbiota has been implicated in the pathogenesis of alcohol-related liver diseases, with its composition manifesting expressed dysbiosis in patients suffering from alcoholic dependence. Due to its inherent plasticity, gut microbiota is an important target for prevention and treatment of these diseases. Identification of the impact of alcohol abuse with associated psychiatric symptoms on the gut community structure is confounded by the liver dysfunction. In order to differentiate the effects of these two factors, we conducted a comparative "shotgun" metagenomic survey of 99 patients with the alcohol dependence syndrome represented by two cohorts-with and without liver cirrhosis. The taxonomic and functional composition of the gut microbiota was subjected to a multifactor analysis including comparison with the external control group.

RESULTS

Alcoholic dependence and liver cirrhosis were associated with profound shifts in gut community structures and metabolic potential across the patients. The specific effects on species-level community composition were remarkably different between cohorts with and without liver cirrhosis. In both cases, the commensal microbiota was found to be depleted. Alcoholic dependence was inversely associated with the levels of butyrate-producing species from the Clostridiales order, while the cirrhosis-with multiple members of the Bacteroidales order. The opportunist pathogens linked to alcoholic dependence included pro-inflammatory Enterobacteriaceae, while the hallmarks of cirrhosis included an increase of oral microbes in the gut and more frequent occurrence of abnormal community structures. Interestingly, each of the two factors was associated with the expressed enrichment in many Bifidobacterium and Lactobacillus-but the exact set of the species was different between alcoholic dependence and liver cirrhosis. At the level of functional potential, the patients showed different patterns of increase in functions related to alcohol metabolism and virulence factors, as well as pathways related to inflammation.

CONCLUSIONS

Multiple shifts in the community structure and metabolic potential suggest strong negative influence of alcohol dependence and associated liver dysfunction on gut microbiota. The identified differences in patterns of impact between these two factors are important for planning of personalized treatment and prevention of these pathologies via microbiota modulation. Particularly, the expansion of Bifidobacterium and Lactobacillus suggests that probiotic interventions for patients with alcohol-related disorders using representatives of the same taxa should be considered with caution. Taxonomic and functional analysis shows an increased propensity of the gut microbiota to synthesis of the toxic acetaldehyde, suggesting higher risk of colorectal cancer and other pathologies in alcoholics.

[Influence of cultivation conditions on the proteomic profile of Mycobacterium tuberculosis H37RV]

Comparative proteomic profiling of M. tuberculosis H37Rv strains cultured on two different nutrient media, Levenstein-Jensen and Middlebrook 7H11, was performed using a label-free LC-MS/MS approach. It was shown that results obtained from two media possessed high convergence. The only difference was observed in the representation of fumarate reductase FrdB, its abundance was higher in the mycobacterial cells cultured on Levenstein-Jensen medium. The correlation analysis of biological repeats revealed the high convergence of the results obtained from Middlebrook 7H11 medium. Thus, we can conclude that the use of the Middlebrook 7H11 medium is most appropriate in the scientific laboratory.

Genome analysis of E. coli isolated from Crohn's disease patients

BACKGROUND

Escherichia coli (E. coli) has been increasingly implicated in the pathogenesis of Crohn's disease (CD). The phylogeny of E. coli isolated from Crohn's disease patients (CDEC) was controversial, and while genotyping results suggested heterogeneity, the sequenced strains of E. coli from CD patients were closely related.

RESULTS

We performed the shotgun genome sequencing of 28 E. coli isolates from ten CD patients and compared genomes from these isolates with already published genomes of CD strains and other pathogenic and non-pathogenic strains. CDEC was shown to belong to A, B1, B2 and D phylogenetic groups. The plasmid and several operons from the reference CD-associated E. coli strain LF82 were demonstrated to be more often present in CDEC genomes belonging to different phylogenetic groups than in genomes of commensal strains. The operons include carbon-source induced invasion GimA island, prophage I, iron uptake operons I and II, capsular assembly pathogenetic island IV and propanediol and galactitol utilization operons.

CONCLUSIONS

Our findings suggest that CDEC are phylogenetically diverse. However, some strains isolated from independent sources possess highly similar chromosome or plasmids. Though no CD-specific genes or functional domains were present in all CD-associated strains, some genes and operons are more often found in the genomes of CDEC than in commensal E. coli. They are principally linked to gut colonization and utilization of propanediol and other sugar alcohols.

Data on gut metagenomes of the patients with Helicobacter pylori infection before and after the antibiotic therapy

Antibiotic therapy can lead to the disruption of gut microbiota community with possible negative outcomes for human health. One of the diseases for which the treatment scheme commonly included antibiotic intake is Helicobacter pylori infection. The changes in taxonomic and functional composition of microbiota in patients can be assessed using “shotgun” metagenomic sequencing. Ten stool samples were collected from 4 patients with Helicobacter pylori infection before and directly after the H. pylori eradication course. Additionally, for two of the subjects, the samples were collected 1 month after the end of the treatment. The samples were subject to “shotgun” (whole-genome) metagenomic sequencing using Illumina HiSeq platform. The reads are deposited in the ENA (project ID: PRJEB18265).

Data on gut metagenomes of the patients with alcoholic dependence syndrome and alcoholic liver cirrhosis

Alcoholism is associated with significant changes in gut microbiota composition. Metagenomic sequencing allows to assess the altered abundance levels of bacterial taxa and genes in a culture-independent way. We collected 99 stool samples from the patients with alcoholic dependence syndrome (n=72) and alcoholic liver cirrhosis (n=27). Each of the samples was surveyed using “shotgun” (whole-genome) sequencing on SOLiD platform. The reads are deposited in the ENA (project ID: PRJEB18041).

State of the Art of Chromosome 18-Centric HPP in 2016: Transcriptome and Proteome Profiling of Liver Tissue and HepG2 Cells

A gene-centric approach was applied for a large-scale study of expression products of a single chromosome. Transcriptome profiling of liver tissue and HepG2 cell line was independently performed using two RNA-Seq platforms (SOLiD and Illumina) and also by Droplet Digital PCR (ddPCR) and quantitative RT-PCR. Proteome profiling was performed using shotgun LC-MS/MS as well as selected reaction monitoring with stable isotope-labeled standards (SRM/SIS) for liver tissue and HepG2 cells. On the basis of SRM/SIS measurements, protein copy numbers were estimated for the Chromosome 18 (Chr 18) encoded proteins in the selected types of biological material. These values were compared with expression levels of corresponding mRNA. As a result, we obtained information about 158 and 142 transcripts for HepG2 cell line and liver tissue, respectively. SRM/SIS measurements and shotgun LC-MS/MS allowed us to detect 91 Chr 18-encoded proteins in total, while an intersection between the HepG2 cell line and liver tissue proteomes was ∼66%. In total, there were 16 proteins specifically observed in HepG2 cell line, while 15 proteins were found solely in the liver tissue. Comparison between proteome and transcriptome revealed a poor correlation (R² ≈ 0.1) between corresponding mRNA and protein expression levels. The SRM and shotgun data sets (obtained during 2015-2016) are available in PASSEL (PASS00697) and ProteomeExchange/PRIDE (PXD004407). All measurements were also uploaded into the in-house Chr 18 Knowledgebase at http://kb18.ru/protein/matrix/416126 .

[Metagenomic analysis of taxonomic and functional changes in gut microbiota of patients with alcoholic dependence syndrome]

Here we present the first metagenomic study of gut microbiota in patients with alcohol dependence syndrome (ADS) performed in the whole-genome ("shotgun") format. Taxonomic analysis highlighted changes in community "drivers" abundance previously associated with inflammatory processes (including increase in Ruminococcus gnavus and torques, as well as decrease in Faecalibacterium and Akkermansia). Microbiota of alcoholics manifested presence of specific opportunistic pathogens rarely detected in healthy control subjects of the world. Differential analysis of metabolic potential basing on changes in KEGG Orthology groups abundance revealed increase in pathways associated with response to oxidative stress. Analysis of two specific gene groups--alcohol metabolism and virulence factors--also showed increase in comparison with the control groups. We suggest that gut microbiota distinct in alcoholics by both taxonomic and functional composition plays role in modulating the effect of alcohol on host organism.

[ABILITY OF STAPHYLOCOCCUS OF VARIOUS STRAINS TO CREATE BIOFILMS AND THEIR EFFECT ON HUMAN BODY CELLS]

The urgency of the staphylococcus research is due to its ability to cause severe infections: softtissue infections, endocarditis, sepsis, toxic shock syndrome, and food poisoning. Coagulase-positive Staphylococcus aureus is the main infection agent of intrahospital infections. This agent has many factors of pathogenicity, which are well known. Among the coagulase-negative staphylococcus (CNS) strains, S. haemolyticus and S. epidermidis are clinically important, because they cause infections in patients with weak immune system. The mechanisms of the CNS pathogenicity are insufficiently understood. The goal of this work was to evaluate the potential pathogenicity of clinical strains of CNS from their capacity to create biofilms and the character of their interaction with human body cells by the example of the HT-29 cell culture. The research was carried out in laboratory strain S. aureus ATCC 29213 and clinical strains S. haemolyticus SH39, S. epidermidis SE36-1 isolated from the neonatal autopsy materials. The visual tests of biofilm formation by each strain and testing of the impact of the strains on the cell culture HT-29 was carried out in this work. The two species of CNS form biofilms at a higher rate than S. aureus. Upon incubation for 2 h of HT-29 cells with staphylococcus strains tested in this work, adhesion of bacteria on cell surface was observed. The adhesion was most pronounced in case of S. aureus ATCC 29213 and S. haemolyticus SH39. Upon 3 h of incubation with S. aureus ATCC 29213 and S. haemolyticus SH39, destruction of cell HT-29 monolayer was observed. The incubation for 24 h with the 3 strains tested in this work caused complete destruction of cell HT-29 monolayer. The maximal toxic effect on HT-29 cells was inherent in the strain S. haemolyticus SH39. The aggregate of the results obtained in this work indicates the presence of the pathogenicity factors in the strains S. haemolyticus SH39, which require additional research.

[MASS-SPECTROMETRY IN MICROBIOLOGICAL PRACTICE OF SCIENTIFIC CENTRE OF OBSTETRICS, GYNECOLOGY AND PERINATOLOGY]

AIM

Comparative evaluation of species identification of microorganisms by MALDI-TOF mass-spectrometry and automatic biochemical analyzer VITEK2 Compact 30.

MATERIALS AND METHODS

Species identification of 18,400 isolates of microorganisms (staphylococci, streptococci, enterococci, enterobacteria, nonfermenting gram-negative bacteria, lactobacilli, anaerobes, yeast fungi, neisseriae), isolated from vagina of pregnant and non-pregnant women and from newborns, was carried out. Identification of the isolated microorganisms was carried out by automatic bacteriologic analyzer VITEK2 Compact30 (BioMerieuX, France) and MALDI-TOF-MS analysis method on AutofleXIII (Bruker Daltonics, Germany) mass-spectrometer.

RESULTS

Comparative identification of 2005 isolates of microorganisms was carried out. Sequencing of ribosomal RNA was used as a reference method. Authenticity of species identification my MALDI-TOF-MS analysis method was: for staphylococci (95.8%), enterococci (97.5%), enterobacteria (98.4%), nonfermenting gram-negative bacteria (93.6%), β-hemolytiC staphylococci (93.8%), lactobacilli (92.8%), yeast fungi (99.9%).

CONCLUSION

Introduction of MALDI-TOF-MS analysis technology into practical work of microbiological laboratories exceeds previously used methods of microbiological testing in terms of speed; cost and authenticity of identification of a wide spectrum of microorganisms.

The mystery of the fourth clone: comparative genomic analysis of four non-typeable Streptococcus pneumoniae strains with different susceptibilities to optochin

Optochin-resistant pneumococci can be rarely caught in clinical microbiology laboratories because of the routine identification of all such strains as viridans group non-pneumococci. We were lucky to find four non-typeable Streptococcus pneumoniae clones demonstrating the different susceptibilities to optochin: one of them (Spn_13856) was resistant to optochin, while the other three (Spn_1719, Spn_27, and Spn_2298) were susceptible. Whole genome nucleotide sequences of these strains were compared to reveal the differences between the optochin-resistant and optochin-susceptible strains. Two adjacent genes coding maltose O-acetyltransferase and uridine phosphorylase which were presented in the genomes of all optochin-susceptible strains and missed in the optochin-resistant strain were revealed. Non-synonymous substitutions in 14 protein-coding genes were discovered, including the Ala49Ser mutation in the C-subunit of the F0 part of the ATP synthase rotor usually associated with pneumococcal optochin resistance. Modeling of a process of optochin interaction with the F0 part of the ATP synthase rotor indicates that the complex of optochin with "domain C" composed by wild-type C-subunits is more stable than the same complex composed of Ala49Ser mutant C-subunits.

[Species Diversity of Bifidobacteria in the Intestinal Microbiota Studied Using MALDI-TOF Mass-Spectrometry]

BACKGROUND

The members of genus Bifidobacterium represent a significant part of intestinal microbiota in adults and predominate in infants. Species repertoire of the intestinal bifidobacteria is known to be subjected to major changes with age; however, many details of this process are still to be elucidated.

OBJECTIVE

Our aim was to study the diversity of intestinal bifidobacteria and changes of their qualitative and quantitative composition characteristics during the process of growing up using MALDI-TOF mass-spectrometric analysis ofpure bacterial cultures.

METHODS

A cross-sectional study of bifidobacteria in the intestinal microbiota was performed in 93 healthy people of the ages from 1 month to 57 years. Strains were identified using Microflex LT MALDI-TOF MS, the confirmation was performed by 16S rRNA gene fragment sequencing.

RESULTS

93% of isolated bifidobacterial strains were successfully identified using MALDI-TOF mass-spectrometry. At least two of the strains from each species were additionally identified by 16S rRNA gene fragment sequencing, in all of the cases the results were the same. It was shown that the total concentration of bifidobacteria decreases with age (p<0.001) as well as the frequency of isolation of Bifidobacterium bifidum (p=0.020) and Bifidobacterium breve (p<0.001), and the frequency of isolation of Bifidobacterium adolescentis, increases (p<0.001), representing the continuous process of transformation of microbiota.

CONCLUSION

The method of MALDI-TOF mass spectrometry demonstrated the ability to perform rapid and reliable identification of bifidobacteria that allowed the study of changes in the quantitative and qualitative characteristics of human microbiota in the process of growing up.

RNA-Seq gene expression profiling of HepG2 cells: the influence of experimental factors and comparison with liver tissue

Background

Human hepatoma HepG2 cells are used as an in vitro model of the human liver. High-throughput transcriptomic sequencing is an advanced approach for assessing the functional state of a tissue or cell type. However, the influence of experimental factors, such as the sample preparation method and inter-laboratory variation, on the transcriptomic profile has not been evaluated.

Results

The whole-transcriptome sequencing of HepG2 cells was performed using the SOLiD platform and validated using droplet digital PCR. The gene expression profile was compared to the results obtained with the same sequencing method in another laboratory and using another sample preparation method. We also compared the transcriptomic profile HepG2 cells with that of liver tissue. Comparison of the gene expression profiles between the HepG2 cell line and liver tissue revealed the highest variation, followed by HepG2 cells submitted to two different sample preparation protocols. The lowest variation was observed between HepG2 cells prepared by two different laboratories using the same protocol. The enrichment analysis of the genes that were differentially expressed between HepG2 cells and liver tissue mainly revealed the cancer-associated gene signature of HepG2 cells and the activation of the response to chemical stimuli in the liver tissue. The HepG2 transcriptome obtained with the SOLiD platform was highly correlated with the published transcriptome obtained with the Illumina and Helicos platforms, with moderate correspondence to microarrays.

Conclusions

In the present study, we assessed the influence of experimental factors on the HepG2 transcriptome and identified differences in gene expression between the HepG2 cell line and liver cells. These findings will facilitate robust experimental design in the fields of pharmacology and toxicology. Our results were supported by a comparative analysis with previous HepG2 gene expression studies.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-1108) contains supplementary material, which is available to authorized users.

Emergence of carbapenemase-producing Gram-negative bacteria in Saint Petersburg, Russia

The emergence and spread of carbapenemase-producing Gram-negative bacteria represents a serious public health concern. Here we show that of 477 Gram-negative isolates collected from 18 hospitals between November 2011 and February 2013 in Saint Petersburg (Russia), minimum inhibitory concentrations (MICs) were greater than the European Committee on Antimicrobial Susceptibility Testing (EUCAST) epidemiological cut-off value of at least one carbapenem antibiotic in 101 isolates (21.2%). The bla(NDM-1) gene was detected by PCR in 17 Klebsiella pneumoniae and 1 Acinetobacter nosocomialis isolate. Multilocus sequence typing (MLST) revealed that all NDM-1-producing K. pneumoniae isolates belonged to sequence type 340 (ST340) and harboured genes encoding additional β-lactamases; presence of the bla(CTX-M-1-like) gene correlated with aztreonam resistance, whilst its absence correlated with susceptibility. The epidemiological situation in Saint Petersburg can be assessed as regional spread of NDM-1-producers. The bla(KPC-2) gene was detected in two K. pneumoniae isolates (ST258 and ST273) and one Enterobacter cloacae isolate. Two E. cloacae isolates harboured the bla(VIM-4) gene, and one K. pneumoniae (ST395) isolate harboured the bla(OXA-48) gene. In NDM-1-producers, MICs of biapenem were the lowest compared with those of other carbapenems. Most isolates were susceptible to tigecycline and polymyxin, except for one K. pneumoniae isolate that was found to be polymyxin-resistant and one E. cloacae isolate that was tigecycline-resistant. Only one patient with a urinary tract infection caused by KPC-2-producing K. pneumoniae had a history of travel abroad (Southeast Asia). Thus, there is an actual threat of the emergence of an alarming endemic situation with NDM-1-producers in Saint Petersburg.

Spoligotyping of Mycobacterium tuberculosis complex isolates using hydrogel oligonucleotide microarrays

Mycobacterium tuberculosis remains a leading cause of morbidity and mortality worldwide. This circumstance underscores the relevance of population studies of tuberculosis for transmission dynamics control. In this study, we describe a conversion of the spoligotyping of M.tuberculosis complex isolates on a platform of custom designed hydrogel microarrays (biochips). An algorithm of automated data processing and interpretation of hybridization results using online database was proposed. In total, the 445 samples were tested. Initially, 97 samples representing multiple species of M.tuberculosis complex and nontuberculous mycobacteria were used for protocol optimization and cut-off settings. The developed assay was further evaluated on the out-group of the 348 mycobacterial samples. Results showed high concordance with the conventional membrane-based spoligotyping method. Diagnostic sensitivity and diagnostic specificity of the spoligo-biochip assay were 99.1% and 100%, respectively. The analytical sensitivity was determined to be 500 genomic equivalents of mycobacterial DNA. The high sensitivity and specificity, ease of operation procedures, and the automatic processing of measured data make the developed assay a useful tool for the rapid and accurate genotyping of M. tuberculosis.

Genome-wide Mycobacterium tuberculosis variation (GMTV) database: a new tool for integrating sequence variations and epidemiology

Background

Tuberculosis (TB) poses a worldwide threat due to advancing multidrug-resistant strains and deadly co-infections with Human immunodeficiency virus. Today large amounts of Mycobacterium tuberculosis whole genome sequencing data are being assessed broadly and yet there exists no comprehensive online resource that connects M. tuberculosis genome variants with geographic origin, with drug resistance or with clinical outcome.

Description

Here we describe a broadly inclusive unifying Genome-wide Mycobacterium tuberculosis Variation (GMTV) database, (http://mtb.dobzhanskycenter.org) that catalogues genome variations of M. tuberculosis strains collected across Russia. GMTV contains a broad spectrum of data derived from different sources and related to M. tuberculosis molecular biology, epidemiology, TB clinical outcome, year and place of isolation, drug resistance profiles and displays the variants across the genome using a dedicated genome browser. GMTV database, which includes 1084 genomes and over 69,000 SNP or Indel variants, can be queried about M. tuberculosis genome variation and putative associations with drug resistance, geographical origin, and clinical stages and outcomes.

Conclusions

Implementation of GMTV tracks the pattern of changes of M. tuberculosis strains in different geographical areas, facilitates disease gene discoveries associated with drug resistance or different clinical sequelae, and automates comparative genomic analyses among M. tuberculosis strains.

Unusual large-scale chromosomal rearrangements in Mycobacterium tuberculosis Beijing B0/W148 cluster isolates

The Mycobacterium tuberculosis (MTB) Beijing family isolates are geographically widespread, and there are examples of Beijing isolates that are hypervirulent and associated with drug resistance. One-fourth of Beijing genotype isolates found in Russia belong to the B0/W148 group. The aim of the present study was to investigate features of these endemic strains on a genomic level. Four Russian clinical isolates of this group were sequenced, and the data obtained was compared with published sequences of various MTB strain genomes, including genome of strain W-148 of the same B0/W148 group. The comparison of the W-148 and H37Rv genomes revealed two independent inversions of large segments of the chromosome. The same inversions were found in one of the studied strains after deep sequencing using both the fragment and mate-paired libraries. Additionally, inversions were confirmed by RFLP hybridization analysis. The discovered rearrangements were verified by PCR in all four newly sequenced strains in the study and in four additional strains of the same Beijing B0/W148 group. The other 32 MTB strains from different phylogenetic lineages were tested and revealed no inversions. We suggest that the initial largest inversion changed the orientation of the three megabase (Mb) segment of the chromosome, and the second one occurred in the previously inverted region and partly restored the orientation of the 2.1 Mb inner segment of the region. This is another remarkable example of genomic rearrangements in the MTB in addition to the recently published of large-scale duplications. The described cases suggest that large-scale genomic rearrangements in the currently circulating MTB isolates may occur more frequently than previously considered, and we hope that further studies will help to determine the exact mechanism of such events.

Chromosome 18 transcriptoproteome of liver tissue and HepG2 cells and targeted proteome mapping in depleted plasma: update 2013

We report the results obtained in 2012-2013 by the Russian Consortium for the Chromosome-centric Human Proteome Project (C-HPP). The main scope of this work was the transcriptome profiling of genes on human chromosome 18 (Chr 18), as well as their encoded proteome, from three types of biomaterials: liver tissue, the hepatocellular carcinoma-derived cell line HepG2, and blood plasma. The transcriptome profiling for liver tissue was independently performed using two RNaseq platforms (SOLiD and Illumina) and also by droplet digital PCR (ddPCR) and quantitative RT-PCR. The proteome profiling of Chr 18 was accomplished by quantitatively measuring protein copy numbers in the three types of biomaterial (the lowest protein concentration measured was 10(-13) M) using selected reaction monitoring (SRM). In total, protein copy numbers were estimated for 228 master proteins, including quantitative data on 164 proteins in plasma, 171 in the HepG2 cell line, and 186 in liver tissue. Most proteins were present in plasma at 10(8) copies/μL, while the median abundance was 10(4) and 10(5) protein copies per cell in HepG2 cells and liver tissue, respectively. In summary, for liver tissue and HepG2 cells a "transcriptoproteome" was produced that reflects the relationship between transcript and protein copy numbers of the genes on Chr 18. The quantitative data acquired by RNaseq, PCR, and SRM were uploaded into the "Update_2013" data set of our knowledgebase (www.kb18.ru) and investigated for linear correlations.

Mutation in ribosomal protein S5 leads to spectinomycin resistance in Neisseria gonorrhoeae

Spectinomycin remains a useful reserve option for therapy of gonorrhea. The emergence of multidrug-resistant Neisseria gonorrhoeae strains with decreased susceptibility to cefixime and to ceftriaxone makes it the only medicine still effective for treatment of gonorrhea infection in analogous cases. However, adoption of spectinomycin as a routinely used drug of choice was soon followed by reports of spectinomycin resistance. The main molecular mechanism of spectinomycin resistance in N. gonorrhoeae was C1192T substitution in 16S rRNA genes. Here we reported a Thr-24→Pro mutation in ribosomal protein S5 (RPS5) found in spectinomycin resistant clinical N. gonorrhoeae strain, which carried no changes in 16S rRNA. In a series of experiments, the transfer of rpsE gene allele encoding the mutant RPS5 to the recipient N. gonorrhoeae strains was analyzed. The relatively high rate of transformation [ca. 10⁻⁵ colony-forming units (CFUs)] indicates the possibility of spread of spectinonycin resistance within gonococcal population due to the horizontal gene transfer (HGT).

Comparative genomic analysis of Mycobacterium tuberculosis drug resistant strains from Russia

Tuberculosis caused by multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis (MTB) strains is a growing problem in many countries. The availability of the complete nucleotide sequences of several MTB genomes allows to use the comparative genomics as a tool to study the relationships of strains and differences in their evolutionary history including acquisition of drug-resistance. In our work, we sequenced three genomes of Russian MTB strains of different phenotypes--drug susceptible, MDR and XDR. Of them, MDR and XDR strains were collected in Tomsk (Siberia, Russia) during the local TB outbreak in 1998-1999 and belonged to rare KQ and KY families in accordance with IS6110 typing, which are considered endemic for Russia. Based on phylogenetic analysis, our isolates belonged to different genetic families, Beijing, Ural and LAM, which made the direct comparison of their genomes impossible. For this reason we performed their comparison in the broader context of all M. tuberculosis genomes available in GenBank. The list of unique individual non-synonymous SNPs for each sequenced isolate was formed by comparison with all SNPs detected within the same phylogenetic group. For further functional analysis, all proteins with unique SNPs were ascribed to 20 different functional classes based on Clusters of Orthologous Groups (COG). We have confirmed drug resistant status of our isolates that harbored almost all known drug-resistance associated mutations. Unique SNPs of an XDR isolate CTRI-4(XDR), belonging to a Beijing family were compared in more detail with SNPs of additional 14 Russian XDR strains of the same family. Only type specific mutations in genes of repair, replication and recombination system (COG category L) were found common within this group. Probably the other unique SNPs discovered in CTRI-4(XDR) may have an important role in adaptation of this microorganism to its surrounding and in escape from antituberculosis drugs treatment.

Chromosome 18 transcriptome profiling and targeted proteome mapping in depleted plasma, liver tissue and HepG2 cells

The final goal of the Russian part of the Chromosome-centric Human Proteome Project (C-HPP) was established as the analysis of the chromosome 18 (Chr 18) protein complement in plasma, liver tissue and HepG2 cells with the sensitivity of 10(-18) M. Using SRM, we have recently targeted 277 Chr 18 proteins in plasma, liver, and HepG2 cells. On the basis of the results of the survey, the SRM assays were drafted for 250 proteins: 41 proteins were found only in the liver tissue, 82 proteins were specifically detected in depleted plasma, and 127 proteins were mapped in both samples. The targeted analysis of HepG2 cells was carried out for 49 proteins; 41 of them were successfully registered using ordinary SRM and 5 additional proteins were registered using a combination of irreversible binding of proteins on CN-Br Sepharose 4B with SRM. Transcriptome profiling of HepG2 cells performed by RNAseq and RT-PCR has shown a significant correlation (r = 0.78) for 42 gene transcripts. A pilot affinity-based interactome analysis was performed for cytochrome b5 using analytical and preparative optical biosensor fishing followed by MS analysis of the fished proteins. All of the data on the proteome complement of the Chr 18 have been integrated into our gene-centric knowledgebase ( www.kb18.ru ).

Multiple-locus variable number tandem repeat analysis of Neisseria gonorrhoeae isolates in Russia

In the present study, a multiple-locus variable number tandem repeat analysis (MLVA) was used to assess the molecular epidemiology of Neisseria gonorrhoeae clinical isolates originating from different regions of Russia. MLVA, based on seven loci, was performed on 218 isolates that were previously tested for susceptibility to penicillin, tetracycline and ciprofloxacin and for the presence of certain genetic determinants of drug resistance. In total, 83 MLVA types were identified, indicating that MLVA is a highly discriminatory technique with a Hunter-Gaston discriminatory index of 0.963 (95% CI, 0.950-0.977). MLVA type 16 was shown to be the most prevalent type and is undoubtedly associated with a multidrug resistant phenotype. The spread of MLVA type 16 from Moscow to Irkutsk suggests that this type has a highly successful transmission rate. Hierarchical cluster analysis of the MLVA profiles classified 208 isolates (95%) into six large groups (containing more than 10 isolates). Clusters differed in geographical characteristics and susceptibility profiles. MLVA cluster A comprised in total 34 isolates and was unambiguously associated with multidrug resistance. Most isolates in cluster A carried mutations in penA, ponA, rpsJ, mtrR, gyrA, and parC genes. MLVA cluster D was associated with resistance to penicillin and with mutations in ponA and rpsJ genes and the presence of plasmid-borne bla(TEM-1) gene. MLVA clusters B, C and E were associated with susceptibility to ciprofloxacin and had a lack of mutations in ponA, rpsJ, gyrA, and parC genes. We conclude that MLVA will be a useful tool for N. gonorrhoeae epidemiological studies.

First detection of VIM-4 metallo-β-lactamase-producing Escherichia coli in Russia

An Escherichia coli isolate co-producing VIM-4 metallo-β-lactamase and CTX-M-15 extended spectrum β-lactamase was recovered from the urine of a patient with head trauma in Moscow, Russia. The bla(VIM-4) and bla(CTX-M-15) genes were carried, respectively, by transmissible plasmids of IncW and IncI1 groups. The nucleotide sequence of the VIM-4-encoding integron was nearly identical to that of In416, which represent a large group of structurally related integrons previously found in Enterobacteriaceae all around the Mediterranean basin. This is the first report of a metallo-β-lactamase-producing E. coli in Russia.

Application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the study of Helicobacter pylori

The characteristics of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry based investigation of extremely variable bacteria such as Helicobacter pylori were studied. H. pylori possesses a very high natural variability. Accurate tools for species identification and epidemiological characterization could help the scientific community to better understand the transmission pathways and virulence mechanisms of these bacteria. Seventeen clinical as well as two laboratory strains of H. pylori were analyzed by the MALDI Biotyper method for rapid species identification. Mass spectra collected were found containing 7-13 significant peaks per sample, and only six protein signals were identical for more than half of the strains. Four of them could be assigned to ribosomal proteins RL32, RL33, RL34, and RL36. The reproducible peak with m/z 6948 was identified as a histidine-rich metal-binding polypeptide by tandem mass spectrometry (MS/MS). In spite of the evident protein heterogeneity of H. pylori the mass spectra collected for a particular strain under several cultivations were highly reproducible. Moreover, all clinical strains were perfectly identified as H. pylori species through comparative analysis using the MALDI Biotyper software (Bruker Daltonics, Germany) by pattern matching against a database containing mass spectra from different microbial strains (n = 3287) including H. pylori 26695 and J99. The results of this study allow the conclusion that the MALDI-TOF direct bacterial profiling is suited for H. pylori identification and could be supported by mass spectra fragmentation of the observed polypeptide if necessary.