-
Scientific Reports Aug 2023The World Health Organization's R&D Blueprint list of priority diseases for 2022 includes Lassa fever, signifying the need for research and development in emergency...
The World Health Organization's R&D Blueprint list of priority diseases for 2022 includes Lassa fever, signifying the need for research and development in emergency contexts. This disease is caused by the arenavirus Lassa virus (LASV). Being an enveloped virus, LASV should be susceptible to a variety of microbicidal actives, although empirical data to support this expectation are needed. We evaluated the virucidal efficacy of sodium hypochlorite, ethanol, a formulated dual quaternary ammonium compound, an accelerated hydrogen peroxide formulation, and a p-chloro-m-xylenol formulation, per ASTM E1052-20, against LASV engineered to express green fluorescent protein (GFP). A 10-μL volume of virus in tripartite soil (bovine serum albumin, tryptone, and mucin) was combined with 50 μL of disinfectant in suspension for 0.5, 1, 5, or 10 min at 20-25 °C. Neutralized test mixtures were quantified by GFP expression to determine log reduction. Remaining material was passaged on Vero cells to confirm absence of residual infectious virus. Input virus titers of 6.6-8.0 log per assay were completely inactivated by each disinfectant within 1-5 min contact time. The rapid and substantial inactivation of LASV suggests the utility of these microbicides for mitigating spread of infectious virus during Lassa fever outbreaks.
Topics: Animals; Chlorocebus aethiops; Humans; Lassa virus; Lassa Fever; Vero Cells; Anti-Infective Agents; Disinfectants; Green Fluorescent Proteins
PubMed: 37563252
DOI: 10.1038/s41598-023-38954-5 -
Emerging Microbes & Infections Dec 2024Lassa virus (LASV) is a World Health Organization (WHO) priority pathogen that causes high morbidity and mortality. Recently, we showed that a combination of three...
Lassa virus (LASV) is a World Health Organization (WHO) priority pathogen that causes high morbidity and mortality. Recently, we showed that a combination of three broadly neutralizing human monoclonal antibodies known as Arevirumab-3 (8.9F, 12.1F, 37.2D) based on the lineage IV Josiah strain protected 100% of cynomolgus macaques against heterologous challenge with lineage II and III strains of LASV when therapy was initiated beginning at day 8 after challenge. LASV strains from Benin and Togo represent a new lineage VII that are more genetically diverse from lineage IV than strains from lineages II and III. Here, we tested the ability of Arevirumab-3 to protect macaques against a LASV lineage VII Togo isolate when treatment was administered beginning 8 days after exposure. Unexpectedly, only 40% of treated animals survived challenge. In a subsequent study we showed that Arevirumab-3 protected 100% of macaques from lethal challenge when treatment was initiated 7 days after LASV Togo exposure. Based on our transcriptomics data, successful Arevirumab-3 treatment correlated with diminished neutrophil signatures and the predicted development of T cell responses. As the antiviral activity of Arevirumab-3 against LASV Togo was equivalent to lineage II and III strains, the reduced protection in macaques against Togo likely reflects the faster disease course of LASV Togo in macaques than other strains. This data causes concern regarding the ability of heterologous vaccines and treatments to provide cross protection against lineage VII LASV isolates.
Topics: Humans; Animals; Lassa virus; Lassa Fever; Virulence; Macaca fascicularis; Antibodies, Monoclonal
PubMed: 38164768
DOI: 10.1080/22221751.2023.2301061 -
PLoS Pathogens Jul 2023Many enveloped viruses enter host cells by fusing with acidic endosomes. The fusion activity of multiple viral envelope glycoproteins does not generally affect viral...
Many enveloped viruses enter host cells by fusing with acidic endosomes. The fusion activity of multiple viral envelope glycoproteins does not generally affect viral membrane permeability. However, fusion induced by the Lassa virus (LASV) glycoprotein complex (GPc) is always preceded by an increase in viral membrane permeability and the ensuing acidification of the virion interior. Here, systematic investigation of this LASV fusion phenotype using single pseudovirus tracking in live cells reveals that the change in membrane barrier function is associated with the fusogenic conformational reorganization of GPc. We show that a small-molecule fusion inhibitor or mutations that impair viral fusion by interfering with GPc refolding into the post-fusion structure prevent the increase in membrane permeability. We find that the increase in virion membrane permeability occurs early during endosomal maturation and is facilitated by virus-cell contact. This increase is observed using diverse arenavirus glycoproteins, whether presented on lentivirus-based pseudoviruses or arenavirus-like particles, and in multiple different cell types. Collectively, these results suggest that conformational changes in GPc triggered by low pH and cell factor binding are responsible for virion membrane permeabilization and acidification of the virion core prior to fusion. We propose that this viroporin-like activity may augment viral fusion and/or post-fusion steps of infection, including ribonucleoprotein release into the cytoplasm.
Topics: Arenavirus; Viroporin Proteins; Glycoproteins; Viral Envelope Proteins; Lassa virus; Virus Internalization
PubMed: 37494374
DOI: 10.1371/journal.ppat.1011217 -
Virology Journal Dec 2023Lymphocytic choriomeningitis virus (LCMV) is a human pathogen naturally present in wild rodents. In addition, LCMV is routinely used in immunology research as a model of...
BACKGROUND
Lymphocytic choriomeningitis virus (LCMV) is a human pathogen naturally present in wild rodents. In addition, LCMV is routinely used in immunology research as a model of viral infection in mice. The Armstrong common laboratory strain and the Clone-13 variant induce acute and chronic infections in mice, respectively. The frequent use of this virus in laboratory settings is associated with a risk of human infection for laboratory personnel. In contrast to LCMV Clone-13, few human laboratory infections with LCMV Armstrong have been reported, leading to a poor understanding of symptoms related to infection with this specific LCMV strain.
CASE PRESENTATION
A researcher accidentally infected herself percutaneously with LCMV Armstrong. Symptoms including headaches, dizziness, eye pain and nausea appeared seven days post-exposure and lasted ten days. LCMV-IgM antibodies were detected at 28 days post-infection and IgG seroconversion was observed later. Complete recovery was confirmed three months post exposure.
CONCLUSIONS
Research involving live viruses comes with the risk of infection for research personnel. This case is the first reported accidental human infection with LCMV Armstrong. The symptoms differed from reported infections with LCMV Clone-13, by the absence of fever and vomiting, and presence of leg numbness. This report will therefore help clinicians and public health authorities to recognize the symptoms associated with LCMV Armstrong infections and to offer appropriate counselling to individuals who accidentally expose themselves.
Topics: Animals; Humans; Mice; Antibodies, Viral; Immunoglobulin M; Lymphocytic Choriomeningitis; Lymphocytic choriomeningitis virus; Mice, Inbred C57BL; Rodentia; Female
PubMed: 38087355
DOI: 10.1186/s12985-023-02258-x -
Journal of the American Chemical Society Dec 2023Lassa virus is a negative-strand RNA virus with only four structural proteins that causes periodic outbreaks in West Africa. The nucleoprotein (NP) encapsidates the...
Lassa virus is a negative-strand RNA virus with only four structural proteins that causes periodic outbreaks in West Africa. The nucleoprotein (NP) encapsidates the viral genome, forming ribonucleoprotein complexes (RNPs) together with the viral RNA and the L protein. RNPs must be continuously restructured during viral genome replication and transcription. The Z protein is important for membrane recruitment of RNPs, viral particle assembly, and budding and has also been shown to interact with the L protein. However, the interaction of NP, viral RNA, and Z is poorly understood. Here, we characterize the interactions between Lassa virus NP, Z, and RNA using structural mass spectrometry. We identify the presence of RNA as the driver for the disassembly of ring-like NP trimers, a storage form, into monomers to subsequently form higher order RNA-bound NP assemblies. We locate the interaction site of Z and NP and demonstrate that while NP binds Z independently of the presence of RNA, this interaction is pH-dependent. These data improve our understanding of RNP assembly, recruitment, and release in Lassa virus.
Topics: Lassa virus; Ribonucleoproteins; Nucleoproteins; Virus Assembly; RNA, Viral
PubMed: 38104324
DOI: 10.1021/jacs.3c07325 -
Frontiers in Immunology 2024Macrophage function is determined by microenvironment and origin. Brain and retinal microglia are both derived from yolk sac progenitors, yet their microenvironments...
INTRODUCTION
Macrophage function is determined by microenvironment and origin. Brain and retinal microglia are both derived from yolk sac progenitors, yet their microenvironments differ. Utilizing single-cell RNA sequencing (scRNA-seq) data from mice, we tested the hypothesis that retinal and brain microglia exhibit distinct transcriptional profiles due to their unique microenvironments.
METHODS
Eyes and brains from 2-4 month wildtype mice were combined (20 eyes; 3 brains) to yield one biologically diverse sample per organ. Each tissue was digested into single cell suspensions, enriched for immune cells, and sorted for scRNA-seq. Analysis was performed in Seurat v3 including clustering, integration, and differential expression. Multi-parameter flow cytometry was used for validation of scRNA-seq results. Lymphocytic choriomeningitis virus (LCMV) Clone 13, which produces a systemic, chronic, and neurotropic infection, was used to validate scRNA-seq and flow cytometry results .
RESULTS
Cluster analysis of integrated gene expression data from eye and brain identified 6 microglial clusters. Differential expression analysis revealed that eye microglia were enriched for more pro-inflammatory processes including antigen processing via MHC class I (14.0-fold, and ) and positive regulation of T-cell immunity (8.4-fold) compared to brain microglia. Multi-parameter flow cytometry confirmed that retinal microglia expressed 3.2-fold greater H2-Db and 263.3-fold more H2-Kb than brain microglia. On Day 13 and 29 after LCMV infection, CD8 T-cell density was greater in the retina than the brain.
DISCUSSION
Our data demonstrate that the microenvironment of retina and brain differs, resulting in microglia-specific gene expression changes. Specifically, retinal microglia express greater MHC class I by scRNA-seq and multi-parameter flow cytometry, resulting in a possibly enhanced capability to stimulate CD8 T-cell inflammation during LCMV infection. These results may explain tissue-specific differences between retina and brain during systemic viral infections and CD8 T-cell driven autoimmune disease.
Topics: Animals; Microglia; Mice; Retina; Brain; Mice, Inbred C57BL; Lymphocytic choriomeningitis virus; Histocompatibility Antigens Class I; T-Lymphocytes; Inflammation; Lymphocytic Choriomeningitis; Single-Cell Analysis; CD8-Positive T-Lymphocytes; Transcriptome
PubMed: 38799448
DOI: 10.3389/fimmu.2024.1399989 -
Viruses Jan 2024Metagenomic analysis of and mosquitoes from diverse geographical regions of India revealed the presence of several insect viruses of human interest. Most abundant...
Metagenomic analysis of and mosquitoes from diverse geographical regions of India revealed the presence of several insect viruses of human interest. Most abundant reads found in mosquitoes were of Phasi Charoen-like virus (PCLV), granulovirus (CfGV), Cell fusing agent virus (CFAV), and Wenzhou sobemo-like virus 4 (WSLV4), whereas WSLV4 and CfGV constituted the highest percentage of reads in viromes. Other reads that were of low percentage included Hubei mosquito virus 2 (HMV2), Porcine astrovirus 4 (PAstV4), and Wild Boar astrovirus (WBAstV). PCLV and CFAV, which were found to be abundant in . viromes were absent in viromes. Among the viromes analyzed, sampled from Pune showed the highest percentage (79.82%) of viral reads, while . mosquitoes sampled from Dibrugarh showed the lowest percentage (3.47%). Shamonda orthobunyavirus (SHAV), African swine fever virus (ASFV), Aroa virus (AROAV), and Ilheus virus (ILHV), having the potential to infect vertebrates, including humans, were also detected in both mosquito species, albeit with low read numbers. Reads of gemykibivirus, avian retrovirus, bacteriophages, herpesviruses, and viruses infecting protozoans, algae, etc., were also detected in the mosquitoes. A high percentage of reads in the mosquito samples belonged to unclassified viruses and warrant further investigation. The data generated in the present work may not only lead to studies to explain the influence of these viruses on the replication and transmission of viruses of clinical importance but also to find applications as biocontrol agents against pathogenic viruses.
Topics: Animals; Swine; Humans; Aedes; African Swine Fever Virus; Virome; India; Bacteriophages; Arenaviridae; Granulovirus
PubMed: 38257809
DOI: 10.3390/v16010109 -
Euro Surveillance : Bulletin Europeen... Oct 2023BackgroundRodent-borne viruses such as orthohantaviruses and arenaviruses cause considerable disease burden with regional and temporal differences in incidence and...
BackgroundRodent-borne viruses such as orthohantaviruses and arenaviruses cause considerable disease burden with regional and temporal differences in incidence and clinical awareness. Therefore, it is important to regularly evaluate laboratory diagnostic capabilities, e.g. by external quality assessments (EQA).AimWe wished to evaluate the performance and diagnostic capability of European expert laboratories to detect orthohantaviruses and lymphocytic choriomeningitis virus (LCMV) and human antibody response towards orthohantaviruses.MethodsWe conducted an EQA in 2021; molecular panels consisted of 12 samples, including different orthohantaviruses (Seoul, Dobrava-Belgrade (DOBV), Puumala (PUUV) and Hantaan orthohantavirus), LCMV and negative controls. Serological panels consisted of six human serum samples reactive to PUUV, DOBV or negative to orthohantaviruses. The EQA was sent to 25 laboratories in 20 countries.ResultsThe accuracy of molecular detection of orthohantaviruses varied (50‒67%, average 62%) among 16 participating laboratories, while LCMV samples were successfully detected in all 11 participating laboratories (91-100%, average 96%). The accuracy of serological diagnosis of acute and past orthohantavirus infections was on average 95% among 20 participating laboratories and 82% in 19 laboratories, respectively. A variety of methods was used, with predominance of in-house assays for molecular tests, and commercial assays for serological ones.ConclusionSerology, the most common tool to diagnose acute orthohantavirus infections, had a high accuracy in this EQA. The molecular detection of orthohantaviruses needs improvement while LCMV detection (performed in fewer laboratories) had 95% accuracy. Further EQAs are recommended to be performed periodically to monitor improvements and challenges in the diagnostics of rodent-borne diseases.
Topics: Humans; Lymphocytic choriomeningitis virus; Orthohantavirus; Europe; Hantavirus Infections; Antibodies, Viral
PubMed: 37796441
DOI: 10.2807/1560-7917.ES.2023.28.40.2300054 -
Activation of protein kinase receptor (PKR) plays a pro-viral role in mammarenavirus-infected cells.Journal of Virology Mar 2024Many viruses, including mammarenaviruses, have evolved mechanisms to counteract different components of the host cell innate immunity, which is required to facilitate...
Many viruses, including mammarenaviruses, have evolved mechanisms to counteract different components of the host cell innate immunity, which is required to facilitate robust virus multiplication. The double-stranded RNA (dsRNA) sensor protein kinase receptor (PKR) pathway plays a critical role in the cell anti-viral response. Whether PKR can restrict the multiplication of the Old World mammarenavirus lymphocytic choriomeningitis virus (LCMV) and the mechanisms by which LCMV may counteract the anti-viral functions of PKR have not yet been investigated. Here we present evidence that LCMV infection results in very limited levels of PKR activation, but LCMV multiplication is enhanced in the absence of PKR. In contrast, infection with a recombinant LCMV with a mutation affecting the 3'-5' exonuclease (ExoN) activity of the viral nucleoprotein resulted in robust PKR activation in the absence of detectable levels of dsRNA, which was associated with severely restricted virus multiplication that was alleviated in the absence of PKR. However, pharmacological inhibition of PKR activation resulted in reduced levels of LCMV multiplication. These findings uncovered a complex role of the PKR pathway in LCMV-infected cells involving both pro- and anti-viral activities.IMPORTANCEAs with many other viruses, the prototypic Old World mammarenavirus LCMV can interfere with the host cell innate immune response to infection, which includes the dsRNA sensor PKR pathway. A detailed understanding of LCMV-PKR interactions can provide novel insights about mammarenavirus-host cell interactions and facilitate the development of effective anti-viral strategies against human pathogenic mammarenaviruses. In the present work, we present evidence that LCMV multiplication is enhanced in PKR-deficient cells, but pharmacological inhibition of PKR activation unexpectedly resulted in severely restricted propagation of LCMV. Likewise, we document a robust PKR activation in LCMV-infected cells in the absence of detectable levels of dsRNA. Our findings have revealed a complex role of the PKR pathway during LCMV infection and uncovered the activation of PKR as a druggable target for the development of anti-viral drugs against human pathogenic mammarenaviruses.
Topics: Humans; Arenaviridae; Cell Line; Protein Kinases; Host-Pathogen Interactions; Lymphocytic choriomeningitis virus; Carrier Proteins; Lymphocytic Choriomeningitis; Antiviral Agents; eIF-2 Kinase
PubMed: 38376197
DOI: 10.1128/jvi.01883-23 -
Proceedings of the National Academy of... Mar 2024Viral mimicry of host cell structures has been postulated to curtail the B cell receptor (BCR) repertoire against persisting viruses through tolerance mechanisms. This...
Viral mimicry of host cell structures has been postulated to curtail the B cell receptor (BCR) repertoire against persisting viruses through tolerance mechanisms. This concept awaits, however, experimental testing in a setting of natural virus-host relationship. We engineered mouse models expressing a monoclonal BCR specific for the envelope glycoprotein of lymphocytic choriomeningitis virus (LCMV), a naturally persisting mouse pathogen. When the heavy chain of the LCMV-neutralizing antibody KL25 was paired with its unmutated ancestor light chain, most B cells underwent receptor editing, a behavior reminiscent of autoreactive clones. In contrast, monoclonal B cells expressing the same heavy chain in conjunction with the hypermutated KL25 light chain did not undergo receptor editing but exhibited low levels of surface IgM, suggesting that light chain hypermutation had lessened KL25 autoreactivity. Upon viral challenge, these IgM cells were not anergic but up-regulated IgM, participated in germinal center reactions, produced antiviral antibodies, and underwent immunoglobulin class switch as well as further affinity maturation. These studies on a persisting virus in its natural host species suggest that central tolerance mechanisms prune the protective antiviral B cell repertoire.
Topics: Animals; Mice; Central Tolerance; B-Lymphocytes; Antibodies, Viral; Lymphocytic choriomeningitis virus; Antiviral Agents; Immunoglobulin M
PubMed: 38446855
DOI: 10.1073/pnas.2318657121