scholarly journals Atomic Structure of the Trichomonas vaginalis Double-Stranded RNA Virus 2

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Alexander Stevens ◽  
Katherine Muratore ◽  
Yanxiang Cui ◽  
Patricia J. Johnson ◽  
Z. Hong Zhou
Keyword(s):  
Trichomonas Vaginalis ◽  
Atomic Model ◽  
Causative Pathogen ◽  
Structural Comparison ◽  
Double Stranded Rna ◽  
Content Type ◽  
Sexually Transmitted ◽  
Shell Protein ◽  
Capsid Shell ◽  
Dsrna Viruses

ABSTRACT Trichomonas vaginalis, the causative pathogen for the most common nonviral sexually transmitted infection worldwide, is itself frequently infected with one or more of the four types of small double-stranded RNA (dsRNA) Trichomonas vaginalis viruses (TVV1 to 4, genus Trichomonasvirus, family Totiviridae). Each TVV encloses a nonsegmented genome within a single-layered capsid and replicates entirely intracellularly, like many dsRNA viruses, and unlike those in the Reoviridae family. Here, we have determined the structure of TVV2 by cryo-electron microscopy (cryoEM) at 3.6 Å resolution and derived an atomic model of its capsid. TVV2 has an icosahedral, T = 2*, capsid comprised of 60 copies of the icosahedral asymmetric unit (a dimer of the two capsid shell protein [CSP] conformers, CSP-A and CSP-B), typical of icosahedral dsRNA virus capsids. However, unlike the robust CSP-interlocking interactions such as the use of auxiliary “clamping” proteins among Reoviridae, only lateral CSP interactions are observed in TVV2, consistent with an assembly strategy optimized for TVVs’ intracellular-only replication cycles within their protozoan host. The atomic model reveals both a mostly negatively charged capsid interior, which is conducive to movement of the loosely packed genome, and channels at the 5-fold vertices, which we suggest as routes of mRNA release during transcription. Structural comparison of TVV2 to the Saccharomyces cerevisiae L-A virus reveals a conserved helix-rich fold within the CSP and putative guanylyltransferase domain along the capsid exterior, suggesting conserved mRNA maintenance strategies among Totiviridae. This first atomic structure of a TVV provides a framework to guide future biochemical investigations into the interplay between Trichomonas vaginalis and its viruses. IMPORTANCE Trichomonas vaginalis viruses (TVVs) are double-stranded RNA (dsRNA) viruses that cohabitate in Trichomonas vaginalis, the causative pathogen of trichomoniasis, the most common nonviral sexually transmitted disease worldwide. Featuring an unsegmented dsRNA genome encoding a single capsid shell protein (CSP), TVVs contrast with multisegmented dsRNA viruses, such as the diarrhea-causing rotavirus, whose larger genome is split into 10 dsRNA segments encoding 5 unique capsid proteins. To determine how TVVs incorporate the requisite functionalities for viral replication into their limited proteome, we derived the atomic model of TVV2, a first for TVVs. Our results reveal the intersubunit interactions driving CSP association for capsid assembly and the properties that govern organization and maintenance of the viral genome. Structural comparison between TVV2 capsids and those of distantly related dsRNA viruses indicates conserved strategies of nascent RNA release and a putative viral guanylyltransferase domain implicated in the cytoplasmic maintenance of viral messenger and genomic RNA.

scholarly journals Structure of a Protozoan Virus from the Human Genitourinary Parasite Trichomonas vaginalis

mBio ◽  
2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Kristin N. Parent ◽  
Yuko Takagi ◽  
Giovanni Cardone ◽  
Norman H. Olson ◽  
Maria Ericsson ◽  
...  
Keyword(s):  
Viral Genome ◽  
Trichomonas Vaginalis ◽  
Transmitted Disease ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Ribosomal Frameshifting ◽  
Double Stranded Rna ◽  
Content Type ◽  
Sexually Transmitted ◽  
Dsrna Viruses

ABSTRACTThe flagellated protozoanTrichomonas vaginalisis an obligate human genitourinary parasite and the most frequent cause of sexually transmitted disease worldwide. Most clinical isolates ofT. vaginalisare persistently infected with one or more double-stranded RNA (dsRNA) viruses from the genusTrichomonasvirus, familyTotiviridae, which appear to influence not only protozoan biology but also human disease. Here we describe the three-dimensional structure ofTrichomonas vaginalisvirus 1 (TVV1) virions, as determined by electron cryomicroscopy and icosahedral image reconstruction. The structure reveals aT= 1 capsid comprising 120 subunits, 60 in each of two nonequivalent positions, designated A and B, as previously observed for fungalTotiviridaefamily members. The putative protomer is identified as an asymmetric AB dimer consistent with either decamer or tetramer assembly intermediates. The capsid surface is notable for raised plateaus around the icosahedral 5-fold axes, with canyons connecting the 2- and 3-fold axes. Capsid-spanning channels at the 5-fold axes are unusually wide and may facilitate release of the viral genome, promoting dsRNA-dependent immunoinflammatory responses, as recently shown upon the exposure of human cervicovaginal epithelial cells to either TVV-infectedT. vaginalisor purified TVV1 virions. Despite extensive sequence divergence, conservative features of the capsid reveal a helix-rich fold probably derived from an ancestor shared with fungalTotiviridaefamily members. Also notable are mass spectrometry results assessing the virion proteins as a complement to structure determination, which suggest that translation of the TVV1 RNA-dependent RNA polymerase in fusion with its capsid protein involves −2, and not +1, ribosomal frameshifting, an uncommonly found mechanism to date.IMPORTANCETrichomonas vaginaliscauses ~250 million new cases of sexually transmitted disease each year worldwide and is associated with serious complications, including premature birth and increased transmission of other pathogens, including HIV. It is an extracellular parasite that, in turn, commonly hosts infections with double-stranded RNA (dsRNA) viruses, trichomonasviruses, which appear to exacerbate disease through signaling of immunoinflammatory responses by human epithelial cells. Here we report the first three-dimensional structure of a trichomonasvirus, which is also the first such structure of any protozoan dsRNA virus; show that it has unusually wide channels at the capsid vertices, with potential for releasing the viral genome and promoting dsRNA-dependent responses by human cells; and provide evidence that it uses −2 ribosomal frameshifting, an uncommon mechanism, to translate its RNA polymerase in fusion with its capsid protein. These findings provide both mechanistic and translational insights concerning the role of trichomonasviruses in aggravating disease attributable toT. vaginalis.

scholarly journals Three-Dimensional Structure of a Protozoal Double-Stranded RNA Virus That Infects the Enteric Pathogen Giardia lamblia

2014 ◽  
Vol 89 (2) ◽  
pp. 1182-1194 ◽  
Author(s):  
Mandy E. W. Janssen ◽  
Yuko Takagi ◽  
Kristin N. Parent ◽  
Giovanni Cardone ◽  
Max L. Nibert ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Giardia Lamblia ◽  
Trichomonas Vaginalis ◽  
Enteric Pathogen ◽  
Dsrna Virus ◽  
Cell Entry ◽  
Electron Cryomicroscopy ◽  
Double Stranded Rna ◽  
Content Type ◽  
Dsrna Viruses

ABSTRACTGiardia lambliavirus (GLV) is a small, nonenveloped, nonsegmented double-stranded RNA (dsRNA) virus infectingGiardia lamblia, the most common protozoan pathogen of the human intestine and a major agent of waterborne diarrheal disease worldwide. GLV (genusGiardiavirus) is a member of familyTotiviridae, along with several other groups of protozoal or fungal viruses, includingLeishmaniaRNA viruses andTrichomonas vaginalisviruses. Interestingly, GLV is more closely related than otherTotiviridaemembers to a group of recently discovered metazoan viruses that includes penaeid shrimp infectious myonecrosis virus (IMNV). Moreover, GLV is the only known protozoal dsRNA virus that can transmit efficiently by extracellular means, also like IMNV. In this study, we used transmission electron cryomicroscopy and icosahedral image reconstruction to examine the GLV virion at an estimated resolution of 6.0 Å. Its outermost diameter is 485 Å, making it the largest totivirus capsid analyzed to date. Structural comparisons of GLV and other totiviruses highlighted a related “T=2” capsid organization and a conserved helix-rich fold in the capsid subunits. In agreement with its unique capacity as a protozoal dsRNA virus to survive and transmit through extracellular environments, GLV was found to be more thermoresistant thanTrichomonas vaginalisvirus 1, but no specific protein machinery to mediate cell entry, such as the fiber complexes in IMNV, could be localized. These and other structural and biochemical findings provide a basis for future work to dissect the cell entry mechanism of GLV into a “primitive” (early-branching) eukaryotic host and an important enteric pathogen of humans.IMPORTANCENumerous pathogenic bacteria, includingCorynebacterium diphtheriae,Salmonella enterica, andVibrio cholerae, are infected with lysogenic bacteriophages that contribute significantly to bacterial virulence. In line with this phenomenon, several pathogenic protozoa, includingGiardia lamblia,Leishmaniaspecies, andTrichomonas vaginalisare persistently infected with dsRNA viruses, and growing evidence indicates that at least some of these protozoal viruses can likewise enhance the pathogenicity of their hosts. Understanding of these protozoal viruses, however, lags far behind that of many bacteriophages. Here, we investigated the dsRNA virus that infects the widespread enteric parasiteGiardia lamblia. Using electron cryomicroscopy and icosahedral image reconstruction, we determined the virion structure of Giardia lamblia virus, obtaining new information relating to its assembly, stability, functions in cell entry and transcription, and similarities and differences with other dsRNA viruses. The results of our study set the stage for further mechanistic work on the roles of these viruses in protozoal virulence.

scholarly journals Novel Trichomonacidal Spermicides

2011 ◽  
Vol 55 (9) ◽  
pp. 4343-4351 ◽  
Author(s):  
Ashish Jain ◽  
Nand Lal ◽  
Lokesh Kumar ◽  
Vikas Verma ◽  
Rajeev Kumar ◽  
...  
Keyword(s):  
Hela Cells ◽  
Trichomonas Vaginalis ◽  
Human Sperm ◽  
Content Type ◽  
Sexually Transmitted ◽  
Vaginal Microflora ◽  
Anaerobic Energy ◽  
Resistant Strains ◽  
New Compounds

ABSTRACTMetronidazole, the U.S. Food and Drug Administration-approved drug against trichomoniasis, is nonspermicidal and thus cannot offer pregnancy protection when used vaginally. Furthermore, increasing resistance ofTrichomonas vaginalisto 5-nitro-imidazoles is a cause for serious concern. On the other hand, the vaginal spermicide nonoxynol-9 (N-9) does not protect against sexually transmitted diseases and HIV in clinical situations but may in fact increase their incidence due to its nonspecific, surfactant action. We therefore designed dually active, nonsurfactant molecules that were capable of killingTrichomonas vaginalis(both metronidazole-susceptible and -resistant strains) and irreversibly inactivating 100% human sperm at doses that were noncytotoxic to human cervical epithelial (HeLa) cells and vaginal microflora (lactobacilli)in vitro. Anaerobic energy metabolism, cell motility, and defense against reactive oxygen species, which are key to survival of both sperm andTrichomonasin the host after intravaginal inoculation, depend crucially on availability of free thiols. Consequently, molecules were designed with carbodithioic acid moiety as the major pharmacophore, and chemical variations were incorporated to provide high excess of reactive thiols for interacting with accessible thiols on sperm andTrichomonas. We report here thein vitroactivities, structure-activity relationships, and safety profiles of these spermicidal antitrichomonas agents, the most promising of which was more effective than N-9 (the OTC spermicide) in inactivating human sperm and more efficacious than metronidazole in killingTrichomonas vaginalis(including metronidazole-resistant strain). It also significantly reduced the available free thiols on human sperm and inhibited the cytoadherence ofTrichomonason HeLa cells. Experimentallyin vitro, the new compounds appeared to be safer than N-9 for vaginal use.

scholarly journals Mycoplasma genitalium Detection in Urogenital Specimens from Symptomatic and Asymptomatic Men and Women by Use of the cobas TV/MG Test

2020 ◽  
Vol 58 (6) ◽  
Author(s):  
Barbara Van Der Pol ◽  
Ken B. Waites ◽  
Li Xiao ◽  
Stephanie N. Taylor ◽  
Arundhati Rao ◽  
...  
Keyword(s):  
United States ◽  
Trichomonas Vaginalis ◽  
Mycoplasma Genitalium ◽  
The United States ◽  
Clinical Samples ◽  
Men And Women ◽  
Content Type ◽  
Sexually Transmitted ◽  
Asymptomatic Individuals ◽  
Asymptomatic Men

ABSTRACT Mycoplasma genitalium (MG) infections are a growing concern within the field of sexually transmitted infections. However, diagnostic assays for M. genitalium have been limited in the United States. As most infections are asymptomatic, individuals can unknowingly pass the infection on, and the prevalence is likely to be underestimated. Diagnosis of M. genitalium infection is recommended using a nucleic acid test. This multicenter study assessed the performance of the cobas Trichomonas vaginalis (TV)/MG assay (cobas) for the detection of M. genitalium, using 22,150 urogenital specimens from both symptomatic and asymptomatic men and women collected at geographically diverse sites across the United States. The performance was compared to a reference standard of three laboratory-developed tests (LDTs). The specificity of the cobas assay for M. genitalium ranged from 96.0% to 99.8% across symptomatic and asymptomatic men and women. The sensitivities in female vaginal swabs and urine samples were 96.6% (95% confidence interval [CI], 88.5 to 99.1%) and 86.4% (95% CI, 75.5 to 93.0%), respectively. The sensitivities in male urine and meatal swab samples were 100% (95% CI, 94.0 to 100%) and 85.0% (95% CI, 73.9 to 91.9%), respectively. This study demonstrated that the cobas assay was highly sensitive and specific in all relevant clinical samples for the detection of M. genitalium.

scholarly journals Expansion of Comprehensive Screening of Male Sexually Transmitted Infection Clinic Attendees with Mycoplasma genitalium and Trichomonas vaginalis Molecular Assessment: a Retrospective Analysis

2016 ◽  
Vol 55 (1) ◽  
pp. 321-325 ◽  
Author(s):  
Erik Munson ◽  
David Wenten ◽  
Sheila Jhansale ◽  
Mary Kay Schuknecht ◽  
Nicki Pantuso ◽  
...  
Keyword(s):  
Sexually Transmitted Infection ◽  
Trichomonas Vaginalis ◽  
Screening Program ◽  
Mycoplasma Genitalium ◽  
Transmitted Infection ◽  
Additional Specimen ◽  
Content Type ◽  
Sexually Transmitted ◽  
High Prevalence ◽  
Infection Clinic

ABSTRACTOf 1,493 encounters of males at a sexually transmitted infection (STI) clinic in a community with a high prevalence of STI,Chlamydia trachomatiswas detected in 8.7% andNeisseria gonorrhoeaewas detected in 6.6%. AdditionalTrichomonas vaginalisandMycoplasma genitaliumscreening found 17.4% and 23.9% of the encounters, respectively, to be positive for STI. STI agents were detected in 13.7% of urine specimens; addition of pharyngeal and rectal collections to the analysis resulted in detection of STI agents in 19.0% and 23.9% of encounters, respectively. A total of 101 (23.8%) encounters of identified STI involved sole detection ofM. genitalium. Expansion of the STI analyte panel (includingM. genitalium) and additional specimen source sampling within a comprehensive STI screening program increase identification of male STI carriers.

scholarly journals A Novel Trichomonas vaginalis Surface Protein Modulates Parasite Attachment via Protein:Host Cell Proteoglycan Interaction

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Brenda M. Molgora ◽  
Anand Kumar Rai ◽  
Michael J. Sweredoski ◽  
Annie Moradian ◽  
Sonja Hess ◽  
...  
Keyword(s):  
Host Cell ◽  
Trichomonas Vaginalis ◽  
Surface Protein ◽  
Host Cells ◽  
Parasite Line ◽  
Cell Adherence ◽  
Common Component ◽  
Content Type ◽  
Sexually Transmitted ◽  
Significant Difference

ABSTRACT Trichomonas vaginalis is a highly prevalent, sexually transmitted parasite which adheres to mucosal epithelial cells to colonize the human urogenital tract. Despite adherence being crucial for this extracellular parasite to thrive within the host, relatively little is known about the mechanisms or key molecules involved in this process. Here, we have identified and characterized a T. vaginalis hypothetical protein, TVAG_157210 (TvAD1), as a surface protein that plays an integral role in parasite adherence to the host. Quantitative proteomics revealed TvAD1 to be ∼4-fold more abundant in parasites selected for increased adherence (MA parasites) than the isogenic parental (P) parasite line. De novo modeling suggested that TvAD1 binds N-acetylglucosamine (GlcNAc), a sugar comprising host glycosaminoglycans (GAGs). Adherence assays utilizing GAG-deficient cell lines determined that host GAGs, primarily heparan sulfate (HS), mediate adherence of MA parasites to host cells. TvAD1 knockout (KO) parasites, generated using CRISPR-Cas9, were found to be significantly reduced in host cell adherence, a phenotype that is rescued by overexpression of TvAD1 in KO parasites. In contrast, there was no significant difference in parasite adherence to GAG-deficient lines by KO parasites compared with wild-type, which is contrary to that observed for KO parasites overexpressing TvAD1. Isothermal titration calorimetric (ITC) analysis showed that TvAD1 binds to HS, indicating that TvAD1 mediates host cell adherence via HS interaction. In addition to characterizing the role of TvAD1 in parasite adherence, these studies reveal a role for host GAG molecules in T. vaginalis adherence. IMPORTANCE The ability of the sexually transmitted parasite Trichomonas vaginalis to adhere to its human host is critical for establishing and maintaining an infection. Yet how parasites adhere to host cells is poorly understood. In this study, we employed a novel adherence selection method to identify proteins involved in parasite adherence to the host. This method led to the identification of a protein, with no previously known function, that is more abundant in parasites with increased capacity to bind host cells. Bioinformatic modeling and biochemical analyses revealed that this protein binds a common component on the host cell surface proteoglycans. Subsequent creation of parasites that lack this protein directly demonstrated that the protein mediates parasite adherence via an interaction with host cell proteoglycans. These findings both demonstrate a role for this protein in T. vaginalis adherence to the host and shed light on host cell molecules that participate in parasite colonization.

scholarly journals In situ structures of RNA-dependent RNA polymerase inside bluetongue virus before and after uncoating

2019 ◽  
Vol 116 (33) ◽  
pp. 16535-16540 ◽  
Author(s):  
Yao He ◽  
Sakar Shivakoti ◽  
Ke Ding ◽  
Yanxiang Cui ◽  
Polly Roy ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Viral Entry ◽  
Bluetongue Virus ◽  
Rational Drug Design ◽  
Fold Axis ◽  
Rna Dependent Rna Polymerase ◽  
Shell Protein ◽  
Capsid Shell ◽  
Dsrna Viruses

Bluetongue virus (BTV), a major threat to livestock, is a multilayered, nonturreted member of the Reoviridae, a family of segmented dsRNA viruses characterized by endogenous RNA transcription through an RNA-dependent RNA polymerase (RdRp). To date, the structure of BTV RdRp has been unknown, limiting our mechanistic understanding of BTV transcription and hindering rational drug design effort targeting this essential enzyme. Here, we report the in situ structures of BTV RdRp VP1 in both the triple-layered virion and double-layered core, as determined by cryo-electron microscopy (cryoEM) and subparticle reconstruction. BTV RdRp has 2 unique motifs not found in other viral RdRps: a fingernail, attached to the conserved fingers subdomain, and a bundle of 3 helices: 1 from the palm subdomain and 2 from the N-terminal domain. BTV RdRp VP1 is anchored to the inner surface of the capsid shell via 5 asymmetrically arranged N termini of the inner capsid shell protein VP3A around the 5-fold axis. The structural changes of RdRp VP1 and associated capsid shell proteins between BTV virions and cores suggest that the detachment of the outer capsid proteins VP2 and VP5 during viral entry induces both global movements of the inner capsid shell and local conformational changes of the N-terminal latch helix (residues 34 to 51) of 1 inner capsid shell protein VP3A, priming RdRp VP1 within the capsid for transcription. Understanding this mechanism in BTV also provides general insights into RdRp activation and regulation during viral entry of other multilayered, nonturreted dsRNA viruses.

scholarly journals Novel Insights into the Molecular Events Linking to Cell Death Induced by Tetracycline in the Amitochondriate Protozoan Trichomonas vaginalis

2015 ◽  
Vol 59 (11) ◽  
pp. 6891-6903 ◽  
Author(s):  
Kuo-Yang Huang ◽  
Fu-Man Ku ◽  
Wei-Hung Cheng ◽  
Chi-Ching Lee ◽  
Po-Jung Huang ◽  
...  
Keyword(s):  
Cell Death ◽  
Trichomonas Vaginalis ◽  
Transmitted Disease ◽  
Chemotherapeutic Agents ◽  
Public Health Issue ◽  
Rna Seq ◽  
Content Type ◽  
Sexually Transmitted ◽  
Molecular Events

ABSTRACTTrichomonas vaginaliscolonizes the human urogenital tract and causes trichomoniasis, the most common nonviral sexually transmitted disease. Currently, 5-nitroimidazoles are the only recommended drugs for treating trichomoniasis. However, increased resistance of the parasite to 5-nitroimidazoles has emerged as a highly problematic public health issue. Hence, it is essential to identify alternative chemotherapeutic agents against refractory trichomoniasis. Tetracycline (TET) is a broad-spectrum antibiotic with activity against several protozoan parasites, but the mode of action of TET in parasites remains poorly understood. Thein vitroeffect of TET on the growth ofT. vaginaliswas examined, and the mode of cell death was verified by various apoptosis-related assays. Next-generation sequencing-based RNA sequencing (RNA-seq) was employed to elucidate the transcriptome ofT. vaginalisin response to TET. We show that TET has a cytotoxic effect on both metronidazole (MTZ)-sensitive and -resistantT. vaginalisisolates, inducing some features resembling apoptosis. RNA-seq data reveal that TET significantly alters the transcriptome via activation of specific pathways, such as aminoacyl-tRNA synthetases and carbohydrate metabolism. Functional analyses demonstrate that TET disrupts the hydrogenosomal membrane potential and antioxidant system, which concomitantly elicits a metabolic shift toward glycolysis, suggesting that the hydrogenosomal function is impaired and triggers cell death. Collectively, we providein vitroevidence that TET is a potential alternative therapeutic choice for treating MTZ-resistantT. vaginalis. The in-depth transcriptomic signatures inT. vaginalisupon TET treatment presented here will shed light on the signaling pathways linking to cell death in amitochondriate organisms.

Trichomonas vaginalis virus: a review of the literature

2019 ◽  
Vol 30 (5) ◽  
pp. 496-504 ◽  
Author(s):  
KJ Graves ◽  
AP Ghosh ◽  
PJ Kissinger ◽  
CA Muzny
Keyword(s):  
Systematic Review ◽  
Clinical Significance ◽  
Golgi Complex ◽  
Sexually Transmitted Infection ◽  
Trichomonas Vaginalis ◽  
Rna Virus ◽  
Review Of The Literature ◽  
Transmitted Infection ◽  
Double Stranded Rna ◽  
Sexually Transmitted

Trichomonas vaginalis (TV) is a parasitic protozoan responsible for the sexually transmitted infection trichomoniasis. Trichomonas vaginalis virus (TVV) is a nonsegmented, 4.5–5 kbp, double-stranded RNA virus, from the Totiviridae family, which inhabits TV. A capsid protein consisting of 120 subunits is covered in channels aiding in RNA release. TVV is closely associated with the Golgi complex and is transmitted vertically. TVV has four subspecies, TVV1, TVV2, TVV3, and TVV4. The clinical significance of TVV and its effect on the pathogenicity of TV is not well known. We performed a systematic review of the literature on TVV to better understand its clinical significance and its role in the pathogenesis of TV.

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