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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 -
Blood Dec 2023
Topics: Animals; Arenaviridae; Arenaviridae Infections; Hemorrhage; Macaca
PubMed: 38095923
DOI: 10.1182/blood.2023022303 -
Journal of Immunology (Baltimore, Md. :... Feb 2024SHP-1 (Src homology region 2 domain-containing phosphatase 1) is a well-known negative regulator of T cells, whereas its close homolog SHP-2 is the long-recognized main...
SHP-1 (Src homology region 2 domain-containing phosphatase 1) is a well-known negative regulator of T cells, whereas its close homolog SHP-2 is the long-recognized main signaling mediator of the PD-1 inhibitory pathway. However, recent studies have challenged the requirement of SHP-2 in PD-1 signaling, and follow-up studies further questioned the alternative idea that SHP-1 may replace SHP-2 in its absence. In this study, we systematically investigate the role of SHP-1 alone or jointly with SHP-2 in CD8+ T cells in a series of gene knockout mice. We show that although SHP-1 negatively regulates CD8+ T cell effector function during acute lymphocytic choriomeningitis virus (LCMV) infection, it is dispensable for CD8+ T cell exhaustion during chronic LCMV infection. Moreover, in contrast to the mortality of PD-1 knockout mice upon chronic LCMV infection, mice double deficient for SHP-1 and SHP-2 in CD8+ T cells survived without immunopathology. Importantly, CD8+ T cells lacking both phosphatases still differentiate into exhausted cells and respond to PD-1 blockade. Finally, we found that SHP-1 and SHP-2 suppressed effector CD8+ T cell expansion at the early and late stages, respectively, during chronic LCMV infection.
Topics: Animals; Mice; CD8-Positive T-Lymphocytes; Lymphocytic Choriomeningitis; Lymphocytic choriomeningitis virus; Mice, Inbred C57BL; Mice, Knockout; Programmed Cell Death 1 Receptor; T-Cell Exhaustion
PubMed: 38088801
DOI: 10.4049/jimmunol.2300462 -
Emerging Microbes & Infections Dec 2024Identification of the diverse animal hosts responsible for spill-over events from animals to humans is crucial for comprehending the transmission patterns of emerging...
Identification of the diverse animal hosts responsible for spill-over events from animals to humans is crucial for comprehending the transmission patterns of emerging infectious diseases, which pose significant public health risks. To better characterize potential animal hosts of Lassa virus (LASV), we assessed domestic and non-domestic animals from 2021-2022 in four locations in southern Nigeria with reported cases of Lassa fever (LF). Birds, lizards, and domestic mammals (dogs, pigs, cattle and goats) were screened using RT-qPCR, and whole genome sequencing was performed for lineage identification on selected LASV positive samples. Animals were also screened for exposure to LASV by enzyme-linked immunosorbent assay (ELISA). Among these animals, lizards had the highest positivity rate by PCR. Genomic sequencing of samples in most infected animals showed sub-lineage 2 g of LASV. Seropositivity was highest among cattle and lowest in pigs. Though the specific impact these additional hosts may have in the broader virus-host context are still unknown - specifically relating to pathogen diversity, evolution, and transmission - the detection of LASV in non-rodent hosts living in proximity to confirmed human LF cases suggests their involvement during transmission as potential reservoirs. Additional epidemiological data comparing viral genomes from humans and animals, as well as those circulating within the environment will be critical in understanding LASV transmission dynamics and will ultimately guide the development of countermeasures for this zoonotic health threat.
Topics: Humans; Animals; Cattle; Dogs; Swine; Lassa virus; Lassa Fever; Nigeria; Genome, Viral; Public Health; Mammals
PubMed: 38088796
DOI: 10.1080/22221751.2023.2294859 -
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 -
Methods in Molecular Biology (Clifton,... 2024Several mammarenaviruses cause hemorrhagic fever (HF) disease in humans and pose a significant public health problem in their endemic regions. The Old World (OW)...
Several mammarenaviruses cause hemorrhagic fever (HF) disease in humans and pose a significant public health problem in their endemic regions. The Old World (OW) mammarenavirus Lassa virus (LASV) is estimated to infect several hundred thousand people yearly in West Africa, resulting in high numbers of Lassa fever (LF) cases, a disease associated with high morbidity and mortality. No licensed vaccines are available to combat LASV infection, and anti-LASV drug therapy is limited to the off-label use of ribavirin whose efficacy remains controversial. The development of reverse genetics approaches has provided investigators with a powerful approach for the investigation of the molecular, cell biology and pathogenesis of mammarenaviruses. The use of cell-based minigenome systems has allowed examining the cis- and trans-acting factors involved in viral genome replication and gene transcription, assembly, and budding, which has facilitated the identification of several anti-mammarenavirus candidate drugs. Likewise, it is possible now to rescue infectious recombinant mammarenaviruses from cloned cDNAs containing predetermined mutations in their genomes to investigate virus-host interactions and mechanisms of viral pathogenesis. Reverse genetics have also allowed the generation of mammarenaviruses expressing foreign genes to facilitate virus detection, to identify antiviral drugs, and to generate live-attenuated vaccine (LAV) candidates. Likewise, reverse genetics techniques have allowed the generation of single-cycle infectious, reporter-expressing mammarenaviruses to study some aspects of the biology of HF-causing human mammarenavirus without the need of high security biocontainment laboratories. In this chapter, we describe the experimental procedures to generate recombinant (r)LASV using state-of-the-art plasmid-based reverse genetics.
Topics: Humans; Lassa virus; Reverse Genetics; Arenaviridae; Lassa Fever; Hemorrhagic Fevers, Viral; Plasmids
PubMed: 38064030
DOI: 10.1007/978-1-0716-3533-9_8 -
Molecular Therapy : the Journal of the... Feb 2024Harnessing the immune system to eradicate tumors requires identification and targeting of tumor antigens, including tumor-specific neoantigens and tumor-associated...
Harnessing the immune system to eradicate tumors requires identification and targeting of tumor antigens, including tumor-specific neoantigens and tumor-associated self-antigens. Tumor-associated antigens are subject to existing immune tolerance, which must be overcome by immunotherapies. Despite many novel immunotherapies reaching clinical trials, inducing self-antigen-specific immune responses remains challenging. Here, we systematically investigate viral-vector-based cancer vaccines encoding a tumor-associated self-antigen (TRP2) for the treatment of established melanomas in preclinical mouse models, alone or in combination with adoptive T cell therapy. We reveal that, unlike foreign antigens, tumor-associated antigens require replication of lymphocytic choriomeningitis virus (LCMV)-based vectors to break tolerance and induce effective antigen-specific CD8 T cell responses. Immunization with a replicating LCMV vector leads to complete tumor rejection when combined with adoptive TRP2-specific T cell transfer. Importantly, immunization with replicating vectors leads to extended antigen persistence in secondary lymphoid organs, resulting in efficient T cell priming, which renders previously "cold" tumors open to immune infiltration and reprograms the tumor microenvironment to "hot." Our findings have important implications for the design of next-generation immunotherapies targeting solid cancers utilizing viral vectors and adoptive cell transfer.
Topics: Mice; Animals; Lymphocytic choriomeningitis virus; CD8-Positive T-Lymphocytes; Neoplasms; Antigens, Neoplasm; Cancer Vaccines; Autoantigens; Tumor Microenvironment
PubMed: 38058126
DOI: 10.1016/j.ymthe.2023.11.026 -
Emerging Microbes & Infections Dec 2024The spread of Lassa virus (LASV) in Guinea, Liberia and Sierra Leone, which together are named the Mano River Union (MRU) area, was examined phylogeographically. To...
The spread of Lassa virus (LASV) in Guinea, Liberia and Sierra Leone, which together are named the Mano River Union (MRU) area, was examined phylogeographically. To provide a reliable evolutionary scenario, new rodent-derived, whole LASV sequences were included. These were generated by metatranscriptomic next-generation sequencing from rodents sampled between 2003 and 2020 in 21 localities of Guinea and Sierra Leone. An analysis was performed using BEAST to perform continuous phylogeographic inference and EvoLaps v36 to visualize spatio-temporal spread. LASV was identified as expected in its primary host reservoir, the Natal multimammate mouse (), and also in two Guinean multimammate mice () in northern Sierra Leone and two rusty-bellied brush-furred mice () in southern Sierra Leone. This finding is consistent with the latter two species being secondary host reservoirs. The strains in these three species were very closely related in LASV lineage IV. Phylogenetic analysis indicated that the most recent common ancestor of lineage IV existed 316-374 years ago and revealed distinct, well-supported clades from Sierra Leone (Bo, Kabala and Kenema), Guinea (Faranah, Kissidougou-Guekedou and Macenta) and Liberia (Phebe-Ganta). The phylogeographic scenario suggests southern Guinea as the point of origin of LASV in the MRU area, with subsequent spread to towards Mali, Liberia and Sierra Leone at a mean speed of 1.6 to 1.1 km/year.
Topics: Mice; Animals; Lassa virus; Lassa Fever; Phylogeny; Africa, Western; Murinae
PubMed: 38047354
DOI: 10.1080/22221751.2023.2290834 -
Expert Review of Vaccines 2024
Topics: Humans; Vaccines; Virus Replication; Lassa virus; Lassa Fever; Arenaviridae Infections
PubMed: 38044877
DOI: 10.1080/14760584.2023.2290683 -
Zhong Nan Da Xue Xue Bao. Yi Xue Ban =...The differentiation of CD4 T cells is regulated by a complex and fine signaling pathway composed of many molecules during immune response, and the molecular mechanism...
OBJECTIVES
The differentiation of CD4 T cells is regulated by a complex and fine signaling pathway composed of many molecules during immune response, and the molecular mechanism for regulating T-bet expression is unclear. Mediator complex subunit 1 (Med1) can combine with a variety of co-factors to regulate gene transcription, promote cell proliferation and survival, and affect invariant natural killer T cell (iNKT) development. This study aims to investigate the effect of Med1 on T cell development and CD4 T cell differentiation in immune response.
METHODS
Mice with T cell-specific knockout of gene (Med1CD4cre, KO) were constructed and verified. The percentage and number of CD4 and CD8 T cells in thymus, spleen, and lymph nodes of KO mice and control (Con) mice (Med1CD4cre) were detected by flow cytometry. After 8 days of infection with lymphocytic choriomeningitis virus (LCMV), the percentage and number of CD4 T cells or antigen-specific (GP66) CD4 T cells, the percentage and number of Th1 cells (Ly6cPSGL1) in CD4 T cells or antigen-specific CD4 T cells were examined in the spleen of mice. Moreover, the fluorescence intensity of T-bet in CD4 T cells or antigen-specific CD4 T cells was analyzed.
RESULTS
Compared with the Con group, the percentage and number of CD4 T cells and CD8 T cells in the thymus, CD4 T cells in the spleen and lymph nodes of the KO group showed no significant differences (all >0.05), but the percentage and number of CD8 T cells in the spleen and lymph nodes of the KO group were diminished significantly (all <0.05). After 8 days of infection with LCMV, there was no significant difference in the percentage and number of CD4 T cells or antigen-specific CD4 T cells in the spleen between the KO group and the Con group (all >0.05), while in comparison with the Con group, the percentage and number of Th1 cells in CD4 T cells or antigen-specific CD4 T cells, and the expression of T-bet in CD4 T cells or antigen-specific CD4 T cells were significantly reduced in the spleen of the KO group (all <0.05).
CONCLUSIONS
Specific knockout of in T cells does not affect the development of CD4 and CD8 T cells in the thymus, but does affect the maintenance of peripheral CD8 T cells. In the immune response, gene deletion affects the expression of transcription factor T-bet, which in turn to reduce Th1 cell differentiation.
Topics: Mice; Animals; CD8-Positive T-Lymphocytes; Mediator Complex Subunit 1; Immunity; Cell Differentiation; Lymphocytic choriomeningitis virus; Th1 Cells; CD4-Positive T-Lymphocytes; Mice, Inbred C57BL
PubMed: 38044640
DOI: 10.11817/j.issn.1672-7347.2023.220633