Giardia duodenalis: Biology and Pathogenesis

2021 ◽  
Author(s):  
Rodney D. Adam
Keyword(s):  
Giardia Duodenalis ◽  
Human Pathogen ◽  
Content Type ◽  
Reduced Genome ◽  
Molecular Approaches ◽  
Technological Advances ◽  
Eukaryotic Organism ◽  
The 1960S

Giardia duodenalis captured the attention of Leeuwenhoek in 1681 while he was examining his own diarrheal stool, but, ironically, it did not really gain attention as a human pathogen until the 1960s, when outbreaks were reported. Key technological advances, including in vitro cultivation, genomic and proteomic databases, and advances in microscopic and molecular approaches, have led to understand that this is a eukaryotic organism with a reduced genome rather than a truly premitochondriate eukaryote.

scholarly journals The Streptococcal Protease SpeB Antagonizes the Biofilms of the Human Pathogen Staphylococcus aureus USA300 through Cleavage of the Staphylococcal SdrC Protein

2020 ◽  
Vol 202 (11) ◽  
Author(s):  
Katelyn E. Carothers ◽  
Zhong Liang ◽  
Jeffrey Mayfield ◽  
Deborah L. Donahue ◽  
Mijoon Lee ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Proteolytic Activity ◽  
Streptococcus Pyogenes ◽  
Human Pathogen ◽  
Content Type ◽  
Functional Studies ◽  
Human Proteins ◽  
Group A ◽  
Biofilm Disruption

ABSTRACT Streptococcus pyogenes, or group A Streptococcus (GAS), is both a pathogen and an asymptomatic colonizer of human hosts and produces a large number of surface-expressed and secreted factors that contribute to a variety of infection outcomes. The GAS-secreted cysteine protease SpeB has been well studied for its effects on the human host; however, despite its broad proteolytic activity, studies on how this factor is utilized in polymicrobial environments are lacking. Here, we utilized various forms of SpeB protease to evaluate its antimicrobial and antibiofilm properties against the clinically important human colonizer Staphylococcus aureus, which occupies niches similar to those of GAS. For our investigation, we used a skin-tropic GAS strain, AP53CovS+, and its isogenic ΔspeB mutant to compare the production and activity of native SpeB protease. We also generated active and inactive forms of recombinant purified SpeB for functional studies. We demonstrate that SpeB exhibits potent biofilm disruption activity at multiple stages of S. aureus biofilm formation. We hypothesized that the surface-expressed adhesin SdrC in S. aureus was cleaved by SpeB, which contributed to the observed biofilm disruption. Indeed, we found that SpeB cleaved recombinant SdrC in vitro and in the context of the full S. aureus biofilm. Our results suggest an understudied role for the broadly proteolytic SpeB as an important factor for GAS colonization and competition with other microorganisms in its niche. IMPORTANCE Streptococcus pyogenes (GAS) causes a range of diseases in humans, ranging from mild to severe, and produces many virulence factors in order to be a successful pathogen. One factor produced by many GAS strains is the protease SpeB, which has been studied for its ability to cleave and degrade human proteins, an important factor in GAS pathogenesis. An understudied aspect of SpeB is the manner in which its broad proteolytic activity affects other microorganisms that co-occupy niches similar to that of GAS. The significance of the research reported herein is the demonstration that SpeB can degrade the biofilms of the human pathogen Staphylococcus aureus, which has important implications for how SpeB may be utilized by GAS to successfully compete in a polymicrobial environment.

scholarly journals Structure of Aichi Virus 1 and Its Empty Particle: Clues to Kobuvirus Genome Release Mechanism

2016 ◽  
Vol 90 (23) ◽  
pp. 10800-10810 ◽  
Author(s):  
Charles Sabin ◽  
Tibor Füzik ◽  
Karel Škubník ◽  
Lenka Pálková ◽  
A. Michael Lindberg ◽  
...  
Keyword(s):  
Aichi Virus ◽  
Release Mechanism ◽  
Human Pathogen ◽  
Content Type ◽  
X Ray ◽  
X Ray Crystallography ◽  
Antiviral Compounds ◽  
Cryo Electron Microscopy ◽  
Empty Capsid

ABSTRACTAichi virus 1(AiV-1) is a human pathogen from theKobuvirusgenus of thePicornaviridaefamily. Worldwide, 80 to 95% of adults have antibodies against the virus. AiV-1 infections are associated with nausea, gastroenteritis, and fever. Unlike most picornaviruses, kobuvirus capsids are composed of only three types of subunits: VP0, VP1, and VP3. We present here the structure of the AiV-1 virion determined to a resolution of 2.1 Å using X-ray crystallography. The surface loop puff of VP0 and knob of VP3 in AiV-1 are shorter than those in other picornaviruses. Instead, the 42-residue BC loop of VP0 forms the most prominent surface feature of the AiV-1 virion. We determined the structure of AiV-1 empty particle to a resolution of 4.2 Å using cryo-electron microscopy. The empty capsids are expanded relative to the native virus. The N-terminal arms of capsid proteins VP0, which mediate contacts between the pentamers of capsid protein protomers in the native AiV-1 virion, are disordered in the empty capsid. Nevertheless, the empty particles are stable, at leastin vitro, and do not contain pores that might serve as channels for genome release. Therefore, extensive and probably reversible local reorganization of AiV-1 capsid is required for its genome release.IMPORTANCEAichi virus 1 (AiV-1) is a human pathogen that can cause diarrhea, abdominal pain, nausea, vomiting, and fever. AiV-1 is identified in environmental screening studies with higher frequency and greater abundance than other human enteric viruses. Accordingly, 80 to 95% of adults worldwide have suffered from AiV-1 infections. We determined the structure of the AiV-1 virion. Based on the structure, we show that antiviral compounds that were developed against related enteroviruses are unlikely to be effective against AiV-1. The surface of the AiV-1 virion has a unique topology distinct from other related viruses from thePicornaviridaefamily. We also determined that AiV-1 capsids form compact shells even after genome release. Therefore, AiV-1 genome release requires large localized and probably reversible reorganization of the capsid.

scholarly journals Parameters Affecting Continuous In Vitro Culture of Treponema pallidum Strains

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Diane G. Edmondson ◽  
Bridget D. DeLay ◽  
Lindsay E. Kowis ◽  
Steven J. Norris
Keyword(s):  
Culture System ◽  
Treponema Pallidum ◽  
Basal Medium ◽  
Human Pathogen ◽  
Low Oxygen ◽  
Term Survival ◽  
Content Type ◽  
Long Term Culture

ABSTRACT The bacterium that causes syphilis, Treponema pallidum subsp. pallidum, has now been cultured in vitro continuously for periods exceeding 3 years using a system consisting of coculture with Sf1Ep rabbit epithelial cells in TpCM-2 medium and a low-oxygen environment. In addition, long-term culture of several other syphilis isolates (SS14, Mexico A, UW231B, and UW249B) and the T. pallidum subsp. endemicum Bosnia A strain has been achieved. During in vitro passage, T. pallidum subsp. pallidum exhibited a typical bacterial growth curve with logarithmic and stationary phases. Sf1Ep cells are required for sustained growth and motility; however, high initial Sf1Ep cell numbers resulted in reduced multiplication and survival. Use of Eagle’s minimal essential medium as the basal medium was not effective in sustaining growth of T. pallidum subsp. pallidum beyond the first passage, whereas CMRL 1066 or M199 supported long-term culture, confirming that additional nutrients present in these more complex basal media are required for long-term culture. T. pallidum subsp. pallidum growth was dependent upon the presence of fetal bovine serum, with 20% (vol/vol) being the optimal concentration. Omission of reactive oxygen species scavengers dithiothreitol, d-mannitol, or l-histidine did not dramatically affect survival or growth. Additionally, T. pallidum subsp. pallidum can be successfully cultured in a Brewer jar instead of a specialized low-oxygen incubator. Phosphomycin or amphotericin B can be added to the medium to aid in the prevention of bacterial or fungal contamination, respectively. These results help define the parameters of the T. pallidum subsp. pallidum culture system that are required for sustained, long-term survival and multiplication. IMPORTANCE Syphilis is caused by the bacterium Treponema pallidum subsp. pallidum. Until recently, this pathogen could only be maintained through infection of rabbits or other animals, making study of this important human pathogen challenging and costly. T. pallidum subsp. pallidum has now been successfully cultured for over 3 years in a tissue culture system using a medium called TpCM-2. Here, we further define the growth requirements of this important human pathogen, promoting a better understanding of the biology of this fastidious organism.

scholarly journals The Copper-Responsive RicR Regulon Contributes to Mycobacterium tuberculosis Virulence

mBio ◽  
2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Xiaoshan Shi ◽  
Richard A. Festa ◽  
Thomas R. Ioerger ◽  
Susan Butler-Wu ◽  
James C. Sacchettini ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Microbial Growth ◽  
Human Pathogen ◽  
Content Type ◽  
Cu Toxicity ◽  
Cu Homeostasis ◽  
Cu Resistance ◽  
Life On Earth

ABSTRACTAs with most life on Earth, the transition metal copper (Cu) is essential for the viability of the human pathogenMycobacterium tuberculosis. However, infected hosts can also use Cu to control microbial growth. Several Cu-responsive pathways are present inM. tuberculosis, including the regulated in copper repressor (RicR) regulon, which is unique to pathogenic mycobacteria. In this work, we describe the contribution of each RicR-regulated gene to Cu resistancein vitroand to virulence in animals. We found that the deletion or disruption of individual RicR-regulated genes had no impact on virulence in mice, although several mutants had Cu hypersensitivity. In contrast, a mutant unable to activate the RicR regulon was not only highly susceptible to Cu but also attenuated in mice. Thus, these data suggest that several genes of the RicR regulon are required simultaneously to combat Cu toxicityin vivoor that this regulon is also important for resistance against Cu-independent mechanisms of host defense.IMPORTANCEMycobacterium tuberculosisis the causative agent of tuberculosis, killing millions of people every year. Therefore, understanding the biology ofM. tuberculosisis crucial for the development of new therapies to treat this devastating disease. Our studies reveal that although host-supplied Cu can suppress bacterial growth,M. tuberculosishas a unique pathway, the RicR regulon, to defend against Cu toxicity. These findings suggest that Cu homeostasis pathways in both the host and the pathogen could be exploited for the treatment of tuberculosis.

scholarly journals Pneumococcal 6-Phospho-β-Glucosidase (BglA3) Is Involved in Virulence and Nutrient Metabolism

2015 ◽  
Vol 84 (1) ◽  
pp. 286-292 ◽  
Author(s):  
Vanessa Sofia Terra ◽  
Xiangyun Zhi ◽  
Hasan F. Kahya ◽  
Peter W. Andrew ◽  
Hasan Yesilkaya
Keyword(s):  
Hyaluronic Acid ◽  
Streptococcus Pneumoniae ◽  
Cell Membrane ◽  
Human Pathogen ◽  
Wild Type ◽  
Abiotic Surface ◽  
Nutrient Metabolism ◽  
Content Type ◽  
A Cell

For the generation of energy, the important human pathogenStreptococcus pneumoniaerelies on host-derived sugars, including β-glucoside analogs. The catabolism of these nutrients involves the action of 6-phospho-β-glucosidase to convert them into usable monosaccharaides. In this study, we characterized a 6-phospho-β-glucosidase (BglA3) encoded by SPD_0247. We found that this enzyme has a cell membrane localization and is active only against a phosphorylated substrate. A mutated pneumococcal ΔSPD0247 strain had reduced 6-phospho-glucosidase activity and was attenuated in growth on cellobiose and hyaluronic acid compared to the growth of wild-type D39. ΔSPD0247-infected mice survived significantly longer than the wild-type-infected cohort, and the colony counts of the mutant were lower than those of the wild type in the lungs. The expression of SPD_0247 inS. pneumoniaeharvested from infected tissues was significantly increased relative to its expressionin vitroon glucose. Additionally, ΔSPD0247 is severely impaired in its attachment to an abiotic surface. These results indicate the importance of β-glucoside metabolism in pneumococcal survival and virulence.

scholarly journals Novel 4-Aminoquinoline Analogs Highly Active against the Blood and Sexual Stages of PlasmodiumIn VivoandIn Vitro

2012 ◽  
Vol 56 (9) ◽  
pp. 4685-4692 ◽  
Author(s):  
Fabián E. Sáenz ◽  
Tina Mutka ◽  
Kenneth Udenze ◽  
Ayoade M. J. Oduola ◽  
Dennis E. Kyle
Keyword(s):  
Plasmodium Berghei ◽  
Multidrug Resistant ◽  
New Drugs ◽  
Content Type ◽  
Highly Active ◽  
Resistant Strains ◽  
Sexual Stages ◽  
The 1960S

ABSTRACTNew drugs to treat malaria must act rapidly and be highly potent against asexual blood stages, well tolerated, and affordable to residents of regions of endemicity. This was the case with chloroquine (CQ), a 4-aminoquinoline drug used for the prevention and treatment of malaria. However, since the 1960s,Plasmodium falciparumresistance to this drug has spread globally, and more recently, emerging resistance to CQ byPlasmodium vivaxthreatens the health of 70 to 320 million people annually. Despite the emergence of CQ resistance, synthetic quinoline derivatives remain validated leads for new drug discovery, especially if they are effective against CQ-resistant strains of malaria. In this study, we investigated the activities of two novel 4-aminoquinoline derivatives, TDR 58845,N1-(7-chloro-quinolin-4-yl)-2-methyl-propane-1,2-diamine, and TDR 58846,N1-(7-chloro-quinolin-4-yl)-2,N2,N2-trimethylpropane-1,2-diamine and found them to be active againstP. falciparumin vitroandPlasmodium bergheiin vivo. TheP. falciparumclones and isolates tested were susceptible to TDR 58845 and TDR 58846 (50% inhibitory concentrations [IC50s] ranging from 5.52 to 89.8 nM), including the CQ-resistant reference clone W2 and two multidrug-resistant parasites recently isolated from Thailand and Cambodia. Moreover, these 4-aminoquinolines were active against early and lateP. falciparumgametocyte stages and cured BALB/c mice infected withP. berghei. TDR 58845 and TDR 58846 at 40 mg/kg were sufficient to cure mice, and total doses of 480 mg/kg of body weight were well tolerated. Our findings suggest these novel 4-aminoquinolines should be considered for development as potent antimalarials that can be used in combination to treat multidrug-resistantP. falciparumandP. vivax.

scholarly journals Evolution of Antibiotic Tolerance Shapes Resistance Development in Chronic Pseudomonas aeruginosa Infections

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Isabella Santi ◽  
Pablo Manfredi ◽  
Enea Maffei ◽  
Adrian Egli ◽  
Urs Jenal
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Prolonged Exposure ◽  
Drug Tolerance ◽  
Antibiotic Tolerance ◽  
Human Pathogen ◽  
Chronic Infections ◽  
Resistance Development ◽  
Content Type

ABSTRACT The widespread use of antibiotics promotes the evolution and dissemination of resistance and tolerance mechanisms. To assess the relevance of tolerance and its implications for resistance development, we used in vitro evolution and analyzed the inpatient microevolution of Pseudomonas aeruginosa, an important human pathogen causing acute and chronic infections. We show that the development of tolerance precedes and promotes the acquisition of resistance in vitro, and we present evidence that similar processes shape antibiotic exposure in human patients. Our data suggest that during chronic infections, P. aeruginosa first acquires moderate drug tolerance before following distinct evolutionary trajectories that lead to high-level multidrug tolerance or to antibiotic resistance. Our studies propose that the development of antibiotic tolerance predisposes bacteria for the acquisition of resistance at early stages of infection and that both mechanisms independently promote bacterial survival during antibiotic treatment at later stages of chronic infections. IMPORTANCE Over the past decades, pan-resistant strains of major bacterial pathogens have emerged and have rendered clinically available antibiotics ineffective, putting at risk many of the major achievements of modern medicine, including surgery, cancer therapy, and organ transplantation. A thorough understanding of processes leading to the development of antibiotic resistance in human patients is thus urgently needed. We show that drug tolerance, the ability of bacteria to survive prolonged exposure to bactericidal antibiotics, rapidly evolves in the opportunistic human pathogen Pseudomonas aeruginosa upon recurrent exposures to antibiotics. Our studies show that tolerance protects P. aeruginosa against different classes of antibiotics and that it generally precedes and promotes resistance development. The rapid evolution of tolerance during treatment regimens may thus act as a strong driving force to accelerate antibiotic resistance development. To successfully counter resistance, diagnostic measures and novel treatment strategies will need to incorporate the important role of antibiotic tolerance.

scholarly journals Genetic Engineering Activates Biosynthesis of Aromatic Fumaric Acid Amides in the Human Pathogen Aspergillus fumigatus

2014 ◽  
Vol 81 (5) ◽  
pp. 1594-1600 ◽  
Author(s):  
Daniel Kalb ◽  
Thorsten Heinekamp ◽  
Gerald Lackner ◽  
Daniel H. Scharf ◽  
Hans-Martin Dahse ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Fumaric Acid ◽  
Transcriptional Activation ◽  
High Resolution Mass Spectrometry ◽  
Genetically Engineered ◽  
Adenylation Domain ◽  
Human Pathogen ◽  
Content Type ◽  
Peptide Synthetase

ABSTRACTTheAspergillus fumigatusnonribosomal peptide synthetase FtpA is among the few of this species whose natural product has remained unknown. Both FtpA adenylation domains were characterizedin vitro. Fumaric acid was identified as preferred substrate of the first and bothl-tyrosine andl-phenylalanine as preferred substrates of the second adenylation domain. Genetically engineeredA. fumigatusstrains expressed eitherftpAor the regulator geneftpR, encoded in the same cluster of genes, under the control of the doxycycline-inducible tetracycline-induced transcriptional activation (tet-on) cassette. These strains produced fumaryl-l-tyrosine and fumaryl-l-phenylalanine which were identified by liquid chromatography and high-resolution mass spectrometry. Modeling of the first adenylation domainin silicoprovided insight into the structural requirements to bind fumaric acid as peptide synthetase substrate. This work adds aromatic fumaric acid amides to the secondary metabolome of the important human pathogenA. fumigatuswhich was previously not known as a producer of these compounds.

scholarly journals Ethanol and Isopropanol in Concentrations Present in Hand Sanitizers Sharply Reduce Excystation of Giardia and Entamoeba and Eliminate Oral Infectivity of Giardia Cysts in Gerbils

2015 ◽  
Vol 59 (11) ◽  
pp. 6749-6754 ◽  
Author(s):  
Aparajita Chatterjee ◽  
Giulia Bandini ◽  
Edwin Motari ◽  
John Samuelson
Keyword(s):  
Giardia Duodenalis ◽  
Single Layer ◽  
Oral Route ◽  
Protozoan Parasites ◽  
Content Type ◽  
Hand Sanitizer ◽  
Amebic Dysentery ◽  
Entamoeba Invadens ◽  
Enteric Protozoan

ABSTRACTEnteric protozoan parasites, which are spread by the fecal-oral route, are important causes of diarrhea (Giardia duodenalis) and amebic dysentery (Entamoeba histolytica). Cyst walls ofGiardiaandEntamoebahave a single layer composed of fibrils of β-1,3-linked GalNAc and β-1,4-linked GlcNAc (chitin), respectively. The goal here was to determine whether hand sanitizers that contain ethanol or isopropanol as the active microbicide might reduce transmission of these parasites. We found that treatment with these alcohols with or without drying in a rotary evaporator (to model rapid evaporation of sanitizers on hands) kills 85 to 100% of cysts ofG. duodenalisand 90 to 100% of cysts ofEntamoeba invadens(a nonpathogenic model forE. histolytica), as shown by nuclear labeling with propidium iodide and failure to excystin vitro. Alcohols with or without drying collapsed the cyst walls ofGiardiabut did not collapse the cyst walls ofEntamoeba. To validate thein vitroresults, we showed that treatment with alcohols eliminated oral infection of gerbils by 1,000G. duodenaliscysts, while a commercial hand sanitizer (Purell) killedE. invadenscysts that were directly applied to the hands. These results suggest that expanded use of alcohol-based hand sanitizers might reduce the transmission ofGiardiaandEntamoeba.

scholarly journals Bimodular Peptide Synthetase SidE Produces Fumarylalanine in the Human Pathogen Aspergillus fumigatus

2013 ◽  
Vol 79 (21) ◽  
pp. 6670-6676 ◽  
Author(s):  
Wieland Steinchen ◽  
Gerald Lackner ◽  
Sabiha Yasmin ◽  
Markus Schrettl ◽  
Hans-Martin Dahse ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Lung Infection ◽  
Pharmaceutical Products ◽  
Immunomodulatory Activity ◽  
Human Pathogen ◽  
Content Type ◽  
Peptide Synthetase ◽  
Life Threatening ◽  
Culture Supernatants

ABSTRACTThe filamentous moldAspergillus fumigatuscauses invasive aspergillosis, a potentially life-threatening infectious disease, in humans. ThesidEgene encodes a bimodular peptide synthetase and was shown previously to be strongly upregulated during initiation of murine lung infection. In this study, we characterized the two adenylation domains of SidE with the ATP-[32P]pyrophosphate exchange assayin vitro, which identified fumarate andl-alanine, respectively, as the preferred substrates. Using full-lengthholo-SidE, fumarylalanine (FA) formation was observedin vitro. Furthermore, FA was identified inA. fumigatusculture supernatants under inducing conditions, unlesssidEwas genetically inactivated. As FA is structurally related to established pharmaceutical products exerting immunomodulatory activity, this work may contribute to our understanding of the virulence ofA. fumigatus.

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