Non-virulent Strains Research Articles

Differentiation in pyroptosis induction by Burkholderia pseudomallei and Burkholderia thailandensis in primary human monocytes, a possible cause of sepsis in acute melioidosis patients.

Melioidosis caused by Burkholderia pseudomallei is an infectious disease with a high mortality rate. In acute melioidosis, sepsis is a major cause of death among patients. Once the bacterium enters the bloodstream, immune system dysregulation ensues, leading to cytokine storms. In contrast to B. pseudomallei, a closely related but non-virulent strain B. thailandensis has rarely been reported to cause cytokine storms or death in patients. However, the mechanisms in which the virulent B. pseudomallei causes sepsis are not fully elucidated. It is well-documented that monocytes play an essential role in cytokine production in the bloodstream. The present study, therefore, determined whether there is a difference in the innate immune response to B. pseudomallei and B. thailandensis during infection of primary human monocytes and THP-1 monocytic cells by investigating pyroptosis, an inflammatory death pathway known to play a pivotal role in sepsis. Our results showed that although both bacterial species exhibited a similar ability to invade human monocytes, only B. pseudomallei can significantly increase the release of cytosolic enzyme lactate dehydrogenase (LDH) as well as the increases in caspase-1 and gasdermin D activations in both cell types. The results were consistent with the significant increase in IL-1β and IL-18 production, key cytokines involved in pyroptosis. Interestingly, there was no significant difference in other cytokine secretion, such as IL-1RA, IL-10, IL-12p70, IL-15, IL-8, and IL-23 in cells infected by both bacterial species. Furthermore, we also demonstrated that ROS production played a crucial role in controlling pyroptosis activation during B. pseudomallei infection in primary human monocytes. These findings suggested that pyroptosis induced by B. pseudomallei in the human monocytes may contribute to the pathogenesis of sepsis in acute melioidosis patients.

Metabolomic profiling of virulent and non-virulent Beauveria bassiana strains: insights into the pathogenicity of Tetranychus truncatus.

In this study, the pathogenicity of local Beauveria bassiana strains was elucidated using molecular and metabolomics methodologies. Molecular verification of the B. bassiana-specific chitinase gene was achieved via phylogenetic analysis of the Bbchit1 region. Subsequent metabolomic analyses employing UPLC-Q-TOF-MS revealed a different number of non-volatile metabolite profiles among the six B. bassiana strains. Bb6 produced the most non-volatile compounds (17) out of a total of 18, followed by Bb15 (16) and Bb12 (15). Similarly, Bb5, Bb8, and Bb21, three non-virulent B. bassiana strains, produced 13, 14, and 14 metabolites, respectively. But unique secondary metabolites like bassianolide and beauvericin, pivotal for virulence and mite management, were exclusively found in the virulent strains (Bb6, Bb12, and Bb15) of B. bassiana. The distinctive non-volatile metabolomic profiles of these strains underscore their pathogenicity against Tetranychus truncatus, suggesting their promise in bio-control applications.

The effector-triggered immunity landscape of tomato against Pseudomonas syringae

Tomato (Solanum lycopersicum) is one of the world’s most important food crops, and as such, its production needs to be protected from infectious diseases that can significantly reduce yield and quality. Here, we survey the effector-triggered immunity (ETI) landscape of tomato against the bacterial pathogen Pseudomonas syringae. We perform comprehensive ETI screens in five cultivated tomato varieties and two wild relatives, as well as an immunodiversity screen on a collection of 149 tomato varieties that includes both wild and cultivated varieties. The screens reveal a tomato ETI landscape that is more limited than what was previously found in the model plant Arabidopsis thaliana. We also demonstrate that ETI eliciting effectors can protect tomato against P. syringae infection when the effector is delivered by a non-virulent strain either prior to or simultaneously with a virulent strain. Overall, our findings provide a snapshot of the ETI landscape of tomatoes and demonstrate that ETI can be used as a biocontrol treatment to protect crop plants.

Probable Role of Type IV Pili of Aeromonas hydrophila in Human Pathogenicity.

Aeromonas hydrophila is a widely recognized broad-spectrum pathogen that primarily targets the gastrointestinal tract. Type IV pili (T4P) are proteinaceous nano-machines located on the bacterial cell surface, playing a crucial role in host colonization and infection. Regrettably, the T4P systems of A. hydrophila remain largely underexplored. A. hydrophila genomes with complete genome assembly and annotation reports up to 31 March 2023, were obtained from the NCBI Genome database or KEGG genome database, followed by a global search for T4P secretion system genes. Protein sequences of these manually curetted genes were used as secondary quarry for Synteny analysis. Protein-protein interaction analysis was performed by string analysis and in silico study of genomic islands. We identified 27 orthologs of type IV pili (T4P) nano-machine components in A. hydrophila. These orthologs are primarily distributed across three operons: pilABCD, pilMNOPQ, and pilVWXY. While the first two operons are commonly found in all experimental genomes, the presence of the pilVWXY operon, coding for 11 orthologs, is reported here for the first time in A. hydrophila. Notably, the complete pilVWXY operon is absent in nonvirulent strains. A genomic islands study between a nonvirulent and hypervirulent strain also confirms absence of most of the genes coded by pilVWXY in nonvirulent strain. Interestingly, among the 51 experimental genomes analyzed, the pilVWXY operon was completely absent in 10 strains, most of which are categorized as nonvirulent; Conclusions: The distribution of two major type IV pili (T4P) nano-machines, PilABCDMNOPQ and PilVWXY, is reported here for the first time in A. hydrophila. Additionally, this study suggests a potential role for the PilVWXY nano-machine in establishing human disease.

Comparative Genome Analysis of Two Streptococcus suis Serotype 8 Strains Identifies Two New Virulence-Associated Genes.

Streptococcus suis is an important zoonotic pathogen that can cause meningitis and septicemia in swine and humans. Among numerous pathogenic serotypes, S. suis serotype 8 has distinctive characteristics such as a high detection rate and causing multi-host infection. There is no complete genome of serotype 8 strains so far. In this study, the complete genome of two S. suis serotype 8 strains, virulent strain 2018WUSS151 and non-virulent strain WUSS030, were sequenced. Comparative genomic analysis showed that the homology of the two genomes reaches 99.68%, and the main difference is the distinctive prophages. There are 83 genes unique to virulent strain 2018WUSS151, including three putative virulence-associated genes (PVGs). Two PVGs, padR and marR, are passenger genes in ISSsu2 family transposons that are able to form circular DNA intermediates during transposition, indicating the possibility of horizontal transmission among S. suis strains. The deletion mutant of PVGs marR or atpase attenuated the virulence of serotype 2 virulent SC070731 in a mouse infection model, confirming their role in S. suis virulence. These findings contribute to clarifying the genomic characterization of S. suis serotype 8 and S. suis pathogenesis.

Insights into Newcastle disease: Isolation and propagation of non-virulent strain for antigen production

Insights into Newcastle disease: Isolation and propagation of non-virulent strain for antigen production

Opportunistic Bacteria of Grapevine Crown Galls Are Equipped with the Genomic Repertoire for Opine Utilization.

Young grapevines (Vitis vinifera) suffer and eventually can die from the crown gall disease caused by the plant pathogen Allorhizobium vitis (Rhizobiaceae). Virulent members of A. vitis harbor a tumor-inducing plasmid and induce formation of crown galls due to the oncogenes encoded on the transfer DNA. The expression of oncogenes in transformed host cells induces unregulated cell proliferation and metabolic and physiological changes. The crown gall produces opines uncommon to plants, which provide an important nutrient source for A. vitis harboring opine catabolism enzymes. Crown galls host a distinct bacterial community, and the mechanisms establishing a crown gall-specific bacterial community are currently unknown. Thus, we were interested in whether genes homologous to those of the tumor-inducing plasmid coexist in the genomes of the microbial species coexisting in crown galls. We isolated 8 bacterial strains from grapevine crown galls, sequenced their genomes, and tested their virulence and opine utilization ability in bioassays. In addition, the 8 genome sequences were compared with 34 published bacterial genomes, including closely related plant-associated bacteria not from crown galls. Homologous genes for virulence and opine anabolism were only present in the virulent Rhizobiaceae. In contrast, homologs of the opine catabolism genes were present in all strains including the nonvirulent members of the Rhizobiaceae and non-Rhizobiaceae. Gene neighborhood and sequence identity of the opine degradation cluster of virulent and nonvirulent strains together with the results of the opine utilization assay support the important role of opine utilization for cocolonization in crown galls, thereby shaping the crown gall community.

<i>Helicobacter pylori</i> Persistence in Patients with Peptic Ulcer Disease and Chronic Gastritis in the Treatment with Antibiotics and Acid-Suppressive Agents

Background. Chronic gastritides still have no division into forms according to the data of the genotyping of Helicobacter pylori isolates. Monitoring the results of anti-Helicobacter pylori therapy cannot be limited to eradication, by taking into account the data on Helicobacter pylori detection in healthy individuals. Is increased acid production associated with the presence of virulent or nonvirulent strains?Objective. To search for the predominance of cagA or any allelic combination of vacA in the isolates from patients with mild and severe chronic gastritis and from those with peptic ulcer disease. To track the time course of changes in the disappearance and repeated gastric colonization with different Helicobacter pylori strains in patients with peptic ulcer disease immediately after anti-Helicobacter pylori therapy and 1.5–2 months later. To confirm or refute the fact that the increased acid production is associated with the presence of virulent Helicobacter pylori strains rather than with the persistence of nonvirulent strains.Methods. The Helicobacter pylori isolates from the gastric biopsy specimens taken from patients with chronic gastritis and peptic ulcer disease were genotyped for cagA and allelic combinations of vacA. The strains from patients who had received anti-Helicobacter pylori therapy were genotyped using the variable number tandem repeat (VNTR) method. Patients with an exacerbation of peptic ulcer disease and those wth an exacerbation of chronic pancreatitis with concomitant gastritis were compared from the level of acid production and from the belonging of Helicobacter pylori to virulent strains.Results. Patients with mild chronic gastritis were observed to have an abundance of nonvirulent allelic combination of vacAs2m2, which differed significantly from its frequency in both the patients with severe chronic gastritis and those with peptic ulcer disease. In the latter patients, the differences between the background bacteriological pattern and the pattern observed after 1.5–2 months had a high degree of significance; in these follow-up periods, in contrast to the control immediately after therapy, the number of eradications increased and the number of cagA-containing strains decreased due to the change of strains. Acid production was significantly higher in the patients with peptic ulcer disease than in those with chronic pancreatits and concomitant gastritis; the former patients show a statistically significant predominance of virulent strains; the latter patients had nonvirulent strains (at the same rate of Helicobacter pylori detection).Conclusion. Filling the blank spots in the study of helicobacteriosis remains relevant due to the progress of genetic methods in bacteriology and to the introduction of novel approaches to assessing the results of anti-Helicobacter pylori therapy.

Vaccinia virus induces endoplasmic reticulum stress and activates unfolded protein responses through the ATF6α transcription factor

BackgroundCell responses to different stress inducers are efficient mechanisms that prevent and fight the accumulation of harmful macromolecules in the cells and also reinforce the defenses of the host against pathogens. Vaccinia virus (VACV) is an enveloped, DNA virus, belonging to the Poxviridae family. Members of this family have evolved numerous strategies to manipulate host responses to stress controlling cell survival and enhancing their replicative success. In this study, we investigated the activation of the response signaling to malformed proteins (UPR) by the VACV virulent strain—Western Reserve (WR)—or the non-virulent strain—Modified Vaccinia Ankara (MVA).MethodsThrough RT-PCR RFLP and qPCR assays, we detected negative regulation of XBP1 mRNA processing in VACV-infected cells. On the other hand, through assays of reporter genes for the ATF6 component, we observed its translocation to the nucleus of infected cells and a robust increase in its transcriptional activity, which seems to be important for virus replication. WR strain single-cycle viral multiplication curves in ATF6α-knockout MEFs showed reduced viral yield.ResultsWe observed that VACV WR and MVA strains modulate the UPR pathway, triggering the expression of endoplasmic reticulum chaperones through ATF6α signaling while preventing IRE1α-XBP1 activation.ConclusionsThe ATF6α sensor is robustly activated during infection while the IRE1α-XBP1 branch is down-regulated.

Ex vivo infection model for Francisella using human lung tissue.

Tularemia is mainly caused by Francisella tularensis (Ft) subsp. tularensis (Ftt) and Ft subsp. holarctica (Ftt) in humans and in more than 200 animal species including rabbits and hares. Human clinical manifestations depend on the route of infection and range from flu-like symptoms to severe pneumonia with a mortality rate up to 60% without treatment. So far, only 2D cell culture and animal models are used to study Francisella virulence, but the gained results are transferable to human infections only to a certain extent. In this study, we firstly established an ex vivo human lung tissue infection model using different Francisella strains: Ftt Life Vaccine Strain (LVS), Ftt LVS ΔiglC, Ftt human clinical isolate A-660 and a German environmental Francisella species strain W12-1067 (F-W12). Human lung tissue was used to determine the colony forming units and to detect infected cell types by using spectral immunofluorescence and electron microscopy. Chemokine and cytokine levels were measured in culture supernatants. Only LVS and A-660 were able to grow within the human lung explants, whereas LVS ΔiglC and F-W12 did not replicate. Using human lung tissue, we observed a greater increase of bacterial load per explant for patient isolate A-660 compared to LVS, whereas a similar replication of both strains was observed in cell culture models with human macrophages. Alveolar macrophages were mainly infected in human lung tissue, but Ftt was also sporadically detected within white blood cells. Although Ftt replicated within lung tissue, an overall low induction of pro-inflammatory cytokines and chemokines was observed. A-660-infected lung explants secreted slightly less of IL-1β, MCP-1, IP-10 and IL-6 compared to Ftt LVS-infected explants, suggesting a more repressed immune response for patient isolate A-660. When LVS and A-660 were used for simultaneous co-infections, only the ex vivo model reflected the less virulent phenotype of LVS, as it was outcompeted by A-660. We successfully implemented an ex vivo infection model using human lung tissue for Francisella. The model delivers considerable advantages and is able to discriminate virulent Francisella from less- or non-virulent strains and can be used to investigate the role of specific virulence factors.

Single-Cell Transcriptome Atlas of Newcastle Disease Virus in Chickens Both In Vitro and In Vivo.

Newcastle disease virus (NDV) is an avian paramyxovirus that causes major economic losses to the poultry industry around the world, with NDV pathogenicity varying due to strain virulence differences. However, the impacts of intracellular viral replication and the heterogeneity of host responses among cell types are unknown. Here, we investigated the heterogeneity of lung tissue cells in response to NDV infection in vivo and that of the chicken embryo fibroblast cell line DF-1 in response to NDV infection in vitro using single-cell RNA sequencing. We characterized the NDV target cell types in the chicken lung at the single-cell transcriptome level and classified cells into five known and two unknown cell types. The five known cell types are the targets of NDV in the lungs with virus RNA detected. Different paths of infection in the putative trajectories of NDV infection were distinguished between in vivo and in vitro, or between virulent Herts/33 strain and nonvirulent LaSota strain. Gene expression patterns and the interferon (IFN) response in different putative trajectories were demonstrated. IFN responses were elevated in vivo, especially in myeloid and endothelial cells. We distinguished the virus-infected and non-infected cells, and the Toll-like receptor signaling pathway was the main pathway after virus infection. Cell-cell communication analysis revealed the potential cell surface receptor-ligand of NDV. Our data provide a rich resource for understanding NDV pathogenesis and open the way to interventions specifically targeting infected cells. IMPORTANCE Newcastle disease virus (NDV) is an avian paramyxovirus that causes major economic losses to the poultry industry around the world, with NDV pathogenicity varying due to strain virulence differences. However, the impacts of intracellular viral replication and the heterogeneity of host responses among cell types are unknown. Here, we investigated the heterogeneity of lung tissue cells in response to NDV infection in vivo and that of the chicken embryo fibroblast cell line DF-1 in response to NDV infection in vitro using single-cell RNA sequencing. Our results open the way to interventions specifically targeting infected cells, suggest principles of virus-host interactions applicable to NDV and other similar pathogens, and highlight the potential for simultaneous single-cell measurements of both host and viral transcriptomes for delineating a comprehensive map of infection in vitro and in vivo. Therefore, this study can be a useful resource for the further investigation and understanding of NDV.

Development of a new multiplex quantitative PCR for the detection of Glaesserella parasuis, Mycoplasma hyorhinis, and Mycoplasma hyosynoviae.

Glaesserella parasuis, Mycoplasma hyorhinis, and Mycoplasma hyosynoviae are important porcine pathogens responsible for polyserositis, polyarthritis, meningitis, pneumonia, and septicemia causing significant economic losses in the swine industry. A new multiplex quantitative polymerase chain reaction (qPCR) was designed on one hand for the detection of G. parasuis and the virulence marker vtaA to distinguish between highly virulent and non-virulent strains. On the other hand, fluorescent probes were established for the detection and identification of both M. hyorhinis and M. hyosynoviae targeting 16S ribosomal RNA genes. The development of the qPCR was based on reference strains of 15 known serovars of G. parasuis, as well as on the type strains M. hyorhinis ATCC 17981T and M. hyosynoviae NCTC 10167T . The new qPCR was further evaluated using 21 G. parasuis, 26 M. hyorhinis, and 3M. hyosynoviae field isolates. Moreover, a pilot study including different clinical specimens of 42 diseased pigs was performed. The specificity of the assay was 100% without cross-reactivity or detection of other bacterial swine pathogens. The sensitivity of the new qPCR was demonstrated to be between 11-180 genome equivalents (GE) of DNA for M. hyosynoviae and M. hyorhinis, and 140-1200 GE for G. parasuis and vtaA. The cut-off threshold cycle was found to be at 35. The developed sensitive and specific qPCR assay has the potential to become a useful molecular tool, which could be implemented in veterinary diagnostic laboratories for the detection and identification of G. parasuis, its virulence marker vtaA, M. hyorhinis, and M. hyosynoviae.

Screening of linear B-cell epitopes and its proinflammatory activities of Haemophilus parasuis outer membrane protein P2.

Haemophilus parasuis is a commensal organism of the upper respiratory tract of pigs, but virulent strains can cause Glässer's disease, resulting in significant economic losses to the swine industry. OmpP2 is an outer membrane protein of this organism that shows considerable heterogeneity between virulent and non-virulent strains, with classification into genotypes I and II. It also acts as a dominant antigen and is involved in the inflammatory response. In this study, 32 monoclonal antibodies (mAbs) against recombinant OmpP2 (rOmpP2) of different genotypes were tested for reactivity to a panel of OmpP2 peptides. Nine linear B cell epitopes were screened, including five common genotype epitopes (Pt1a, Pt7/Pt7a, Pt9a, Pt17, and Pt19/Pt19a) and two groups of genotype-specific epitopes (Pt5 and Pt5-II, Pt11/Pt11a, and Pt11a-II). In addition, we used positive sera from mice and pigs to screen for five linear B-cell epitopes (Pt4, Pt14, Pt15, Pt21, and Pt22). After porcine alveolar macrophages (PAMs) were stimulated with overlapping OmpP2 peptides, we found that the epitope peptides Pt1 and Pt9, and the loop peptide Pt20 which was adjacent epitopes could all significantly upregulated the mRNA expression levels of IL-1α, IL-1β, IL-6, IL-8, and TNF-α. Additionally, we identified epitope peptides Pt7, Pt11/Pt11a, Pt17, Pt19, and Pt21 and loop peptides Pt13 and Pt18 which adjacent epitopes could also upregulate the mRNA expression levels of most proinflammatory cytokines. This suggested that these peptides may be the virulence-related sites of the OmpP2 protein, with proinflammatory activity. Further study revealed differences in the mRNA expression levels of proinflammatory cytokines, including IL-1β and IL-6, between genotype-specific epitopes, which may be responsible for pathogenic differences between different genotype strains. Here, we profiled a linear B-cell epitope map of the OmpP2 protein and preliminarily analyzed the proinflammatory activities and effects of these epitopes on bacterial virulence, providing a reliable theoretical basis for establishing a method to distinguish strain pathogenicity and to screen candidate peptides for subunit vaccines.

The Identification of Streptococcus pasteurianus Obtained from Six Regions in China by Multiplex PCR Assay and the Characteristics of Pathogenicity and Antimicrobial Resistance of This Zoonotic Pathogen.

Streptococcus pasteurianus is a zoonotic pathogen causing meningitis and bacteremia in animals and humans. A lack of accurate and convenient detection methods hinders preventing and controlling diseases caused by S. pasteurianus. Additionally, there is limited knowledge about its pathogenicity and antimicrobial resistance characteristics, as there are only three complete genome sequences available. In this study, we established a multiplex PCR assay for the detection of S. pasteurianus, which was applied to six fecal samples from cattle with diarrhea and 285 samples from healthy pigs. Out of the samples tested, 24 were positive, including 5 from pig tonsils, 18 from pig hilar lymph nodes, and 1 from cattle feces. Two strains were isolated from positive samples, and their complete genomes were sequenced. The two strains were non-virulent in mice and multidrug-resistant by the antimicrobial susceptibility test. We first found the presence of genes tet(O/W/32/O) and lsa(E) in S. pasteurianus, leading to resistance to lincosamides and tetracyclines. The convenient and specific multiplex PCR assay provides essential technical support for epidemiological research, and the complete genome sequence of two non-virulent strains contributes to understanding this zoonotic bacterium's genomic characteristics and pathogenesis.

Virulence assessment of four Glaesserella parasuis strains isolated in Liaoning province of China

Glaesserella parasuis (G. parasuis) is a part of the normal upper respiratory microbiota of healthy swine. In many studies, the serovars 1, 4, 5, and 12 of G. parasuis are considered to be highly virulent and its serovars 3, 6, 7, 9, and 11 are considered to be non-virulent. Until now, researchers have found that non-virulent strains of G. parasuis cause an increasing number of diseases. However, little is known concerning why non-virulent strains cause disease with the virulence changes. In present study, four G. parasuis strains were evaluated for their cytotoxicity property, which aims to compare their virulence. The results showed that highly virulent strains XX0306 and CY1201, as well as, non-virulent strains HLD0115 and YK1603 caused a series of pathological changes, increased lactate dehydrogenase (LDH) release, and decreased cell activity. In addition, compared to the control group, both highly and non-virulent strains showed similar trends, demonstrating that the method of classifying the virulence of G. parasuis based on its serovar is worth further deliberation. Hence, we investigated the adhesion capacity and invasion rate of G. parasuis, the results indicated that XX0306 and HLD0115 had the strongest adhesion and invasion ability, which contradicts the classification of the virulence of G. parasuis based on its serovar. The apoptosis degree induced by highly virulent strains was more intensive than non-virulent strains, as measured by annexin V and propidium iodide (PI) double staining. Through testing the expression of apoptosis-related genes Bcl-2 and Bax, we found highly virulent strains induced apoptosis by inhibiting the expression of Bcl-2.

Effects of Priming Rice Seeds with Decoyinine on Fitness Traits and Virus Transmission Ability of the Small Brown Planthopper, Laodelphax striatellus

Laodelphax striatellus is a notorious sap-feeding insect that also serves as a vector of rice stripe virus (RSV) and is responsible for a significant decline in rice yield. Pesticide application remains a crucial strategy for controlling insect pests. In recent years, the utilization of biopesticides has gained attention due to their eco-friendliness and suitability for controlling insect pests and pathogens in agriculture. The present study aimed Figureto evaluate the potential efficacy of a microbial pesticide, decoyinine (DCY), as a seed priming agent in rice against SBPH’s biology, feeding behavior, and RSV transmission ability in the laboratory. Here, we revealed that the body weight of females and males and honeydew extraction of RSV-virulent SBPH were (22.50%, 25.0%, and 23.25%, respectively) significantly lower than non-virulent SBPH. Meanwhile, the fecundity of RSV-virulent SBPH females was significantly higher (8.24%) than non-virulent SBPH. However, nymphal survival and RSV transmission (horizontal and vertical) were found to be non-significantly affected by DCY application. Furthermore, DCY-primed rice seedlings significantly prolonged the time period and frequency of the electrical penetration graph (EPG) feeding waveforms (np, N2, and N3), and also reduced the time period of the waveform (N4-b) for both RSV-virulent and non-virulent SBPH strains with reduced RSV inoculation. The recent study provides new insights for DCY application in rice against SBPH by reducing fecundity, body weight, and honeydew contents, which might contribute to modern integrated pest management.

Cooperative virulence via the collective action of secreted pathogen effectors.

Although virulence is typically attributed to single pathogenic strains, here we investigated whether effectors secreted by a population of non-virulent strains could function as public goods to enable the emergence of collective virulence. We disaggregated the 36 type III effectors of the phytopathogenic bacterium Pseudomonas syringae strain PtoDC3000 into a 'metaclone' of 36 coisogenic strains, each carrying a single effector in an effectorless background. Each coisogenic strain was individually unfit, but the metaclone was collectively as virulent as the wild-type strain on Arabidopsis thaliana, suggesting that effectors can drive the emergence of cooperation-based virulence through their public action. We show that independently evolved effector suits can equally drive this cooperative behaviour by transferring the effector alleles native to the strain PmaES4326 into the conspecific but divergent strain PtoDC3000. Finally, we transferred the disaggregated PtoDC3000 effector arsenal into Pseudomonas fluorescens and show that their cooperative action was sufficient to convert this rhizosphere-inhabiting beneficial bacterium into a phyllosphere pathogen. These results emphasize the importance of microbial community interactions and expand the ecological scale at which disease may be attributed.

Differential Effect of Extracellular Vesicles Derived from Plasmodium falciparum-Infected Red Blood Cells on Monocyte Polarization.

Malaria is a life-threatening tropical arthropod-borne disease caused by Plasmodium spp. Monocytes are the primary immune cells to eliminate malaria-infected red blood cells. Thus, the monocyte's functions are one of the crucial factors in controlling parasite growth. It is reasoned that the activation or modulation of monocyte function by parasite products might dictate the rate of disease progression. Extracellular vesicles (EVs), microvesicles, and exosomes, released from infected red blood cells, mediate intercellular communication and control the recipient cell function. This study aimed to investigate the physical characteristics of EVs derived from culture-adapted P. falciparum isolates (Pf-EVs) from different clinical malaria outcomes and their impact on monocyte polarization. The results showed that all P. falciparum strains released similar amounts of EVs with some variation in size characteristics. The effect of Pf-EV stimulation on M1/M2 monocyte polarization revealed a more pronounced effect on CD14+CD16+ intermediate monocytes than the CD14+CD16- classical monocytes with a marked induction of Pf-EVs from a severe malaria strain. However, no difference in the levels of microRNAs (miR), miR-451a, miR-486, and miR-92a among Pf-EVs derived from virulent and nonvirulent strains was found, suggesting that miR in Pf-EVs might not be a significant factor in driving M2-like monocyte polarization. Future studies on other biomolecules in Pf-EVs derived from the P. falciparum strain with high virulence that induce M2-like polarization are therefore recommended.

Biofilm-Mediated Heavy Metal Removal from Aqueous System by Multi-Metal-Resistant Bacterial Strain Bacillus sp. GH-s29.

Worldwide ever-augmenting urbanization, modernization, and industrialization have contributed to the release of pernicious compounds and a variety of pollutants into the environment. The pollutants discharged due to industrialization are of global concern. Industrial waste and effluent are comprised of hazardous organic and inorganic chemicals including heavy metals which pose a significant threat to the environment and may bring about numerous diseases or abnormalities in human beings. This brings on greater urgency for remediation of these polluted soil and water using sustainable approaches and mechanisms. In the present research, a multi-metal-resistant, gram-positive, non-virulent bacterial strain Bacillus sp. GH-s29 was isolated from contaminated groundwater of Bhojpur district, Bihar, India. The strain had the potential to develop a biofilm that was able to remediate different heavy metals [arsenic, cadmium, and chromium] from individual and multi-heavy metal solutions. Maximum removal for As (V), Cd (II), and Cr (VI) from individual-metal and the multi-metal solution was observed to be 73.65%, 57.37%, 61.62%, and 48.92%, 28.7%, and 35.46%, respectively. SEM-EDX analysis revealed the sequestration of multi-heavy metals by bacterial biofilm. Further characterization by FTIR analysis ensured that the presence of negatively charged functional groups on the biofilm-EPS such as hydroxyl, phosphate, sulfate, and carboxyl helps in binding to the positively charged metal ions. Thus, Bacillus sp. GH-s29 proved to be an effective and economical alternative for different heavy metal remediation from contaminated sites.

Rapid Detection of Lipopolysaccharide and Whole Cells of Francisella tularensis Based on Agglutination of Antibody-Coated Gold Nanoparticles and Colorimetric Registration.

The paper presents development and characterization of a new bioanalytical test system for rapid detection of lipopolysaccharide (LPS) and whole cells of Francisella tularensis, a causative agent of tularemia, in water samples. Gold nanoparticles (AuNPs) coated by the obtained anti-LPS monoclonal antibodies were used for the assay. Their contact with antigen in tested samples leads to aggregation with a shift of absorption spectra from red to blue. Photometric measurements at 530 nm indicated the analyte presence. Three preparations of AuNPs with different diameters were compared, and the AuNPs having average diameter of 34 nm were found to be optimal. The assay is implemented in 20 min and is characterized by detection limits equal to 40 ng/mL for LPS and 3 × 104 CFU/mL for whole cells of F. tularensis. Thus, the proposed simple one-step assay integrates sensitivity comparable with other immunoassay of microorganisms and rapidity. Selectivity of the assay for different strains of F. tularensis was tested and the possibility to choose its variants with the use of different antibodies to distinguish virulent and non-virulent strains or to detect both kinds of F. tularensis was found. The test system has been successfully implemented to reveal the analyte in natural and tap water samples without the loss of sensitivity.