scholarly journals Hemolysin Co-regulated Family Proteins Hcp1 and Hcp2 Contribute to Edwardsiella ictaluri Pathogenesis

2021 ◽  
Vol 8 ◽  
Author(s):  
Safak Kalindamar ◽  
Hossam Abdelhamed ◽  
Adef O. Kordon ◽  
Lesya M. Pinchuk ◽  
Attila Karsi
Keyword(s):  
Clinical Signs ◽  
Peritoneal Macrophages ◽  
Edwardsiella Ictaluri ◽  
Economic Losses ◽  
Type Vi Secretion System ◽  
Secretion Systems ◽  
Gram Negative ◽  
Ovary Cells ◽  
Bacterial Secretion

Edwardsiella ictaluri is a Gram-negative facultative intracellular pathogen causing enteric septicemia of catfish (ESC), a devastating disease resulting in significant economic losses in the U.S. catfish industry. Bacterial secretion systems are involved in many bacteria's virulence, and Type VI Secretion System (T6SS) is a critical apparatus utilized by several pathogenic Gram-negative bacteria. E. ictaluri strain 93–146 genome has a complete T6SS operon with 16 genes, but the roles of these genes are still not explored. In this research, we aimed to understand the roles of two hemolysin co-regulated family proteins, Hcp1 (EvpC) and Hcp2. To achieve this goal, single and double E. ictaluri mutants (EiΔevpC, EiΔhcp2, and EiΔevpCΔhcp2) were generated and characterized. Catfish peritoneal macrophages were able to kill EiΔhcp2 better than EiΔevpC, EiΔevpCΔhcp2, and E. ictaluri wild-type (EiWT). The attachment of EiΔhcp2 and EiΔevpCΔhcp2 to ovary cells significantly decreased compared to EiWT whereas the cell invasion rates of these mutants were the same as that of EiWT. Mutants exposed to normal catfish serum in vitro showed serum resistance. The fish challenges demonstrated that EiΔevpC and EiΔevpCΔhcp2 were attenuated completely and provided excellent protection against EiWT infection in catfish fingerlings. Interestingly, EiΔhcp2 caused higher mortality than that of EiWT in catfish fingerlings, and severe clinical signs were observed. Although fry were more susceptible to vaccination with EiΔevpC and EiΔevpCΔhcp2, their attenuation and protection were significantly higher compared to EiWT and sham groups, respectively. Taken together, our data indicated that evpC (hcp1) is involved in E. ictaluri virulence in catfish while hcp2 is involved in adhesion to epithelial cells and survival inside catfish macrophages.

scholarly journals Modelling Bovine Granuloma Formation In Vitro upon Infection with Mycobacterium Avium Subspecies Paratuberculosis

2019 ◽  
Vol 6 (4) ◽  
pp. 80 ◽  
Author(s):  
J. Hunter Rice ◽  
Margaret M. McDaniel ◽  
Alyson Holland ◽  
Shigetoshi Eda
Keyword(s):  
Mycobacterium Avium ◽  
Mycobacterium Avium Subspecies Paratuberculosis ◽  
Clinical Signs ◽  
Host Cells ◽  
Economic Losses ◽  
Multiple Parameters ◽  
Cell Mediated Immune Response ◽  
A Cell ◽  
Vitro Model

Mycobacterium avium subspecies paratuberculosis (Map) causes chronic granulomatous disease in cattle and ruminant livestock, causing substantial economic losses. Current vaccines delay clinical signs but cannot train the immune system to fully eradicate latent Map. During latency, Map uses host defenses, cage-like macrophage clusters called granuloma, as incubators for months or years. We used an in vitro model to investigate the early coordination of macrophages into granuloma upon Map infection over ten days. We found that at multiplicities of infection (MOI; Map:macrophages) of 1:2 and below, the macrophages readily form clusters and evolve pro-inflammatory cytokines in keeping with a cell-mediated immune response. At higher MOIs, viability of host macrophages is negatively impacted. At 1:4 MOI, we quantified viable Map in our model and confirmed that intracellular Map reproduced over the first five days of infection. Host cells expressed Type 1-specific cytokines, and Map-infected macrophages displayed reduced motility compared to Map-exposed, uninfected macrophages, suggesting an important role for uninfected macrophages in the early aggregative response. Reported is the first in vitro JD granuloma model capturing Map and macrophage viability, size distribution of resulting clusters, motility of monocyte-derived macrophages, and cytokine response during clustering, allowing quantitative analysis of multiple parameters of the Map-specific granulomatous response.

scholarly journals The Type VI Secretion System Encoded in Salmonella Pathogenicity Island 19 Is Required for Salmonella enterica Serotype Gallinarum Survival within Infected Macrophages

2013 ◽  
Vol 81 (4) ◽  
pp. 1207-1220 ◽  
Author(s):  
Carlos J. Blondel ◽  
Juan C. Jiménez ◽  
Lorenzo E. Leiva ◽  
Sergio A. Álvarez ◽  
Bernardo I. Pinto ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Pathogenicity Island ◽  
Secretion System ◽  
Host Cells ◽  
Economic Losses ◽  
Type Vi Secretion System ◽  
Content Type ◽  
Type Vi Secretion ◽  
Core Components

ABSTRACTSalmonella entericaserotype Gallinarum is the causative agent of fowl typhoid, a disease characterized by high morbidity and mortality that causes major economic losses in poultry production. We have reported thatS. Gallinarum harbors a type VI secretion system (T6SS) encoded inSalmonellapathogenicity island 19 (SPI-19) that is required for efficient colonization of chicks. In the present study, we aimed to characterize the SPI-19 T6SS functionality and to investigate the mechanisms behind the phenotypes previously observedin vivo. Expression analyses revealed that SPI-19 T6SS core components are expressed and produced underin vitrobacterial growth conditions. However, secretion of the structural/secreted components Hcp1, Hcp2, and VgrG to the culture medium could not be determined, suggesting that additional signals are required for T6SS-dependent secretion of these proteins.In vitrobacterial competition assays failed to demonstrate a role for SPI-19 T6SS in interbacterial killing. In contrast, cell culture experiments with murine and avian macrophages (RAW264.7 and HD11, respectively) revealed production of a green fluorescent protein-tagged version of VgrG soon afterSalmonellauptake. Furthermore, infection of RAW264.7 and HD11 macrophages with deletion mutants of SPI-19 or strains with genes encoding specific T6SS core components (clpVandvgrG) revealed that SPI-19 T6SS contributes toS. Gallinarum survival within macrophages at 20 h postuptake. SPI-19 T6SS function was not linked toSalmonella-induced cytotoxicity or cell death of infected macrophages, as has been described for other T6SS. Our data indicate that SPI-19 T6SS corresponds to a novel tool used bySalmonellato survive within host cells.

scholarly journals A new family of Type VI secretion system-delivered effector proteins displays ion-selective pore-forming activity

2019 ◽  
Author(s):  
Giuseppina Mariano ◽  
Katharina Trunk ◽  
David J. Williams ◽  
Laura Monlezun ◽  
Henrik Strahl ◽  
...  
Keyword(s):  
Effector Proteins ◽  
Type Vi Secretion System ◽  
Secretion Systems ◽  
New Family ◽  
Type Vi Secretion ◽  
Outer Membrane Permeability ◽  
Polymicrobial Communities ◽  
Bacterial Effectors

AbstractType VI secretion systems (T6SSs) are nanomachines widely used by bacteria to compete with rivals. T6SSs deliver multiple toxic effector proteins directly into neighbouring cells and play key roles in shaping diverse polymicrobial communities. A number of families of T6SS-dependent anti-bacterial effectors have been characterised, however the mode of action of others remains unknown. Here we report that Ssp6, an anti-bacterial effector delivered by theSerratia marcescensT6SS, is an ion-selective pore-forming toxin.In vivo, Ssp6 inhibits growth by causing depolarisation of the inner membrane of intoxicated cells and also leads to increased outer membrane permeability, whilst reconstruction of Ssp6 activityin vitrodemonstrated that it forms cation-selective pores. A survey of bacterial genomes revealed that Ssp6-like effectors are widespread in Enterobacteriaceae and often linked with T6SS genes. We conclude that Ssp6 represents a new family of T6SS-delivered anti-bacterial effectors, further diversifying the portfolio of weapons available for deployment during inter-bacterial conflict.

scholarly journals A family of Type VI secretion system effector proteins that form ion-selective pores

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Giuseppina Mariano ◽  
Katharina Trunk ◽  
David J. Williams ◽  
Laura Monlezun ◽  
Henrik Strahl ◽  
...  
Keyword(s):  
Opportunistic Pathogen ◽  
Effector Proteins ◽  
Type Vi Secretion System ◽  
Secretion Systems ◽  
New Family ◽  
Type Vi Secretion ◽  
Genes Encoding ◽  
Outer Membrane Permeability ◽  
Bacterial Effectors

AbstractType VI secretion systems (T6SSs) are nanomachines widely used by bacteria to deliver toxic effector proteins directly into neighbouring cells. However, the modes of action of many effectors remain unknown. Here we report that Ssp6, an anti-bacterial effector delivered by a T6SS of the opportunistic pathogen Serratia marcescens, is a toxin that forms ion-selective pores. Ssp6 inhibits bacterial growth by causing depolarisation of the inner membrane in intoxicated cells, together with increased outer membrane permeability. Reconstruction of Ssp6 activity in vitro demonstrates that it forms cation-selective pores. A survey of bacterial genomes reveals that genes encoding Ssp6-like effectors are widespread in Enterobacteriaceae and often linked with T6SS genes. We conclude that Ssp6 and similar proteins represent a new family of T6SS-delivered anti-bacterial effectors.

scholarly journals Mycoplasma bovis in Spanish Cattle Herds: Two Groups of Multiresistant Isolates Predominate, with One Remaining Susceptible to Fluoroquinolones

Pathogens ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 545 ◽  
Author(s):  
Ana García-Galán ◽  
Laurent-Xavier Nouvel ◽  
Eric Baranowski ◽  
Ángel Gómez-Martín ◽  
Antonio Sánchez ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Inhibitory Concentration ◽  
Selective Pressure ◽  
Clinical Signs ◽  
Economic Losses ◽  
Mycoplasma Bovis ◽  
Cattle Herds ◽  
Detection Of Mutations ◽  
Antimicrobial Treatments

Mycoplasma bovis is an important bovine pathogen causing pneumonia, mastitis, and arthritis and is responsible for major economic losses worldwide. In the absence of an efficient vaccine, control of M. bovis infections mainly relies on antimicrobial treatments, but resistance is reported in an increasing number of countries. To address the situation in Spain, M. bovis was searched in 436 samples collected from beef and dairy cattle (2016–2019) and 28% were positive. Single-locus typing using polC sequences further revealed that two subtypes ST2 and ST3, circulate in Spain both in beef and dairy cattle, regardless of the regions or the clinical signs. Monitoring of ST2 and ST3 isolates minimum inhibitory concentration (MIC) to a panel of antimicrobials revealed one major difference when using fluoroquinolones (FQL): ST2 is more susceptible than ST3. Accordingly, whole-genome sequencing (WGS) further identified mutations in the gyrA and parC regions, encoding quinolone resistance-determining regions (QRDR) only in ST3 isolates. This situation shows the capacity of ST3 to accumulate mutations in QRDR and might reflect the selective pressure imposed by the extensive use of these antimicrobials. MIC values and detection of mutations by WGS also showed that most Spanish isolates are resistant to macrolides, lincosamides, and tetracyclines. Valnemulin was the only one effective, at least in vitro, against both STs.

scholarly journals Analysis of ATPases of putative secretion operons in the thermoacidophilic archaeon Sulfolobus solfataricus

Microbiology ◽  
2005 ◽  
Vol 151 (3) ◽  
pp. 763-773 ◽  
Author(s):  
Sonja-Verena Albers ◽  
Arnold J. M. Driessen
Keyword(s):  
Expression Patterns ◽  
Sulfolobus Solfataricus ◽  
Gene Clusters ◽  
Growth Conditions ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Gram Negative ◽  
Type Iv ◽  
Encoding Gene ◽  
Bacterial Secretion

Gram-negative bacteria use a wide variety of complex mechanisms to secrete proteins across their membranes or to assemble secreted proteins into surface structures. As most archaea only possess a cytoplasmic membrane surrounded by a membrane-anchored S-layer, the organization of such complexes might be significantly different from that in Gram-negative bacteria. Five proteins of Sulfolobus solfataricus, SSO0120, SSO0572, SSO2316, SSO2387 and SSO2680, which are homologous to secretion ATPases of bacterial type II, type IV secretion systems and the type IV pili assembly machinery, were identified. The operon structures of these putative secretion systems encoding gene clusters and the expression patterns of the ATPases under different growth conditions were determined, and it was established that all five putative ATPases do show a divalent cation-dependent ATPase activity at high temperature. These results show that the archaeal secretion systems are related to the bacterial secretion systems and might be powered in a similar way.

scholarly journals The Cluster 1 Type VI Secretion System Is a Major Virulence Determinant inBurkholderia pseudomallei

2011 ◽  
Vol 79 (4) ◽  
pp. 1512-1525 ◽  
Author(s):  
Mary N. Burtnick ◽  
Paul J. Brett ◽  
Sarah V. Harding ◽  
Sarah A. Ngugi ◽  
Wilson J. Ribot ◽  
...  
Keyword(s):  
Growth Defect ◽  
Raw 264.7 ◽  
Type Vi Secretion System ◽  
Secretion Systems ◽  
Lethal Challenge ◽  
Hamster Model ◽  
Raw 264.7 Macrophages ◽  
Link Type ◽  
Type Vi Secretion

ABSTRACTTheBurkholderia pseudomalleiK96243genome encodes six type VI secretion systems (T6SSs), but little is known about the role of these systems in the biology ofB. pseudomallei. In this study, we purified recombinant Hcp proteins from each T6SS and tested them as vaccine candidates in the BALB/c mouse model of melioidosis. Recombinant Hcp2 protected 80% of mice against a lethal challenge withK96243, while recombinant Hcp1, Hcp3, and Hcp6 protected 50% of mice against challenge. Hcp6 was the only Hcp constitutively produced byB. pseudomallei in vitro; however, it was not exported to the extracellular milieu. Hcp1, on the other hand, was produced and exportedin vitrowhen the VirAG two-component regulatory system was overexpressed intrans. We also constructed sixhcpdeletion mutants (Δhcp1throughΔhcp6) and tested them for virulence in the Syrian hamster model of infection. The 50% lethal doses (LD50s) for theΔhcp2throughΔhcp6mutants were indistinguishable fromK96243(<10 bacteria), but the LD50for theΔhcp1mutant was >103bacteria. Thehcp1deletion mutant also exhibited a growth defect in RAW 264.7 macrophages and was unable to form multinucleated giant cells in this cell line. UnlikeK96243, theΔhcp1mutant was only weakly cytotoxic to RAW 264.7 macrophages 18 h after infection. The results suggest that the cluster 1 T6SS is essential for virulence and plays an important role in the intracellular lifestyle ofB. pseudomallei.

scholarly journals I267L Is Neither the Virulence- Nor the Replication-Related Gene of African Swine Fever Virus and Its Deletant Is an Ideal Fluorescent-Tagged Virulence Strain

Viruses ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 53
Author(s):  
Yanyan Zhang ◽  
Junnan Ke ◽  
Jingyuan Zhang ◽  
Huixian Yue ◽  
Teng Chen ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
African Swine Fever Virus ◽  
Clinical Signs ◽  
Case Fatality ◽  
African Swine Fever ◽  
Fever Virus ◽  
Economic Losses ◽  
Effective Vaccine ◽  
Domestic Pigs

African swine fever virus (ASFV) is the causative agent of African swine fever (ASF) which reaches up to 100% case fatality in domestic pigs and wild boar and causes significant economic losses in the swine industry. Lack of knowledge of the function of ASFV genes is a serious impediment to the development of the safe and effective vaccine. Herein, I267L was identified as a relative conserved gene and an early expressed gene. A recombinant virus (SY18ΔI267L) with I267L gene deletion was produced by replacing I267L of the virulent ASFV SY18 with enhanced green fluorescent protein (EGFP) cassette. The replication kinetics of SY18ΔI267L is similar to that of the parental isolate in vitro. Moreover, the doses of 102.0 TCID50 (n = 5) and 105.0 TCID50 (n = 5) SY18ΔI267L caused virulent phenotype, severe clinical signs, viremia, high viral load, and mortality in domestic pigs inoculated intramuscularly as the virulent parental virus strain. Therefore, the deletion of I267L does not affect the replication or the virulence of ASFV. Utilizing the fluorescent-tagged virulence deletant can be easy to gain a visual result in related research such as the inactivation effect of some drugs, disinfectants, extracts, etc. on ASFV.

scholarly journals The impact of type VI secretion system, bacteriocins and antibiotics on competition amongst Soft-RotEnterobacteriaceae: Regulation of carbapenem biosynthesis by iron and the transcriptional regulator Fur

2018 ◽  
Author(s):  
Divine Yutefar Shyntum ◽  
Ntombikayise Nkomo ◽  
Alessandro Rino Gricia ◽  
Ntwanano Luann Shigange ◽  
Daniel Bellieny-Rabelo ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Plant Pathogens ◽  
Soft Rot ◽  
Secretion System ◽  
Economic Losses ◽  
Computational Techniques ◽  
In Planta ◽  
Type Vi Secretion System ◽  
Type Vi Secretion

AbstractPlant microbial communities’ complexity provide a rich model for investigation on biochemical and regulatory strategies involved in interbacterial competition. Within these niches, the soft rotEnterobacteriaceae(SRE) comprise an emerging group of plant-pathogens inflicting soft rot/black-leg diseases and causing economic losses worldwide in a variety of crops. In this report, a range of molecular and computational techniques are utilized to survey the contribution of antimicrobial factors such as bacteriocins, carbapenem antibiotic and type VI secretion system (T6SS) in interbacterial competition among plant-pathogens/endophytes using an aggressive SRE as a case study (Pectobacterium carotovorumsubsp.brasiliensestrain PBR1692 –Pcb1692). A preliminary screening using next-generation sequencing of 16S rRNA comparatively analysing healthy and diseased potato tubers, followed byin vitrocompetition assays, corroborated the aggressiveness ofPcb1692 against several relevant taxa sharing this niche ranging from Proteobacteria toFirmicutes. The results showed growth inhibition of several Proteobacteria by Pcb1692 depends either on carbapenem or pyocin production. Whereas for targetedFirmicutes, only pyocin seems to play a role in growth inhibition byPcb1692. Further analyses elucidated that although T6SS confers no relevant advantage duringin vitrocompetition, a significant attenuation in competition by the mutant strain lacking a functional T6SS was observedin planta. Furthermore, production of carbapenem byPcb1692 was observably dependent on the presence of environmental iron and oxygen. Additionally, upon deletion offur, slyA andexpI regulators, carbapenem production ceased, implying a complex regulatory mechanism involving these three genes. Potential Fur binding sites found upstream ofslyA,carR andexpR inPectobacteriumgenomes harboring carbapenem-associated genes further suggests a conserved regulatory pattern in the genus, in which carbapenem might be modulated in response to iron through the control exerted by Fur over secondary regulators. Furthermore, we unveiled the striking role played by S-pyocin in growth inhibition within the SRE group.Authors SummaryFor many phytopathogenic bacteria, more is known about interactions within the host and virulence factors used for host colonisation while relatively less is known about microbe-microbe interactions and factors that shape niche colonisation. The soft rotEnterobacteriaceae(SRE) comprise an emerging group of phytopathogens causing soft rot/black-leg diseases in a variety of crops leading to huge economic losses worldwide. In this report, a range of molecular and computational techniques are utilized to survey the contribution of antimicrobial factors such as bacteriocins, carbapenem antibiotic and type VI secretion system (T6SS) in interbacterial competition among plant-pathogens/endophytes using an aggressive SRE as a case study (Pcb1692). Our results show thatPcb1692 inhibits growth of other SRE and several potato endophytes using either the type VI secretion, carbapenem or bacteriocins. Carbapenem plays a role in both inter and intrabacterial competitionin vitro, while thePcb1692T6SS plays a role in interbacterial competitionin planta(in potato tubers). We also demonstrate that carbapenem regulation requires the presence of environmental iron and oxygen in a complex network consisting ofPcb1692 Fur, SlyA, and ExpI. The presence of these gene homologs in several SREs suggests that they too can deploy similar antimicrobials to target other bacteria.

Sign in / Sign up

Export Citation Format

Share Document