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Emerging Microbes & Infections May 2024Lassa virus (LASV), a risk-group 4 pathogen, must be handled in biosafety level-4 (BSL-4) conditions, thereby limiting its research and antiviral development. Here, we...
Lassa virus (LASV), a risk-group 4 pathogen, must be handled in biosafety level-4 (BSL-4) conditions, thereby limiting its research and antiviral development. Here, we developed a novel LASV reverse genetics system which, to our knowledge, is the first to study the complete LASV life cycle under BSL-2 conditions. Viral particles can be produced efficiently when LASV minigenomic RNA harboring minimal viral -elements and reporter genes is transfected into a helper cell line stably expressing viral NP, GP, Z and L proteins. The resulting defective virions, named LASVmg, can propagate only in the helper cell line, providing a BSL-2 model to study the complete LASV life cycle. Using this model, we found that a previously reported cellular receptor α-dystroglycan is dispensable for LASVmg infection. Furthermore, we showed that ribavirin can inhibit LASVmg infection by inducing viral mutations. This new BSL-2 system should facilitate studying the LASV life cycle and screening antivirals.
PubMed: 38747061
DOI: 10.1080/22221751.2024.2356149 -
Nature Communications Apr 2024The black rat (Rattus rattus) is a globally invasive species that has been widely introduced across Africa. Within its invasive range in West Africa, R. rattus may...
The black rat (Rattus rattus) is a globally invasive species that has been widely introduced across Africa. Within its invasive range in West Africa, R. rattus may compete with the native rodent Mastomys natalensis, the primary reservoir host of Lassa virus, a zoonotic pathogen that kills thousands annually. Here, we use rodent trapping data from Sierra Leone and Guinea to show that R. rattus presence reduces M. natalensis density within the human dwellings where Lassa virus exposure is most likely to occur. Further, we integrate infection data from M. natalensis to demonstrate that Lassa virus zoonotic spillover risk is lower at sites with R. rattus. While non-native species can have numerous negative effects on ecosystems, our results suggest that R. rattus invasion has the indirect benefit of decreasing zoonotic spillover of an endemic pathogen, with important implications for invasive species control across West Africa.
Topics: Animals; Lassa virus; Lassa Fever; Introduced Species; Disease Reservoirs; Humans; Rats; Murinae; Zoonoses; Sierra Leone; Guinea; Ecosystem; Rodent Diseases
PubMed: 38678025
DOI: 10.1038/s41467-024-47991-1 -
Viruses Apr 2024Lymphocytic choriomeningitis virus (LCMV) and Lassa virus (LASV) share many genetic and biological features including subtle differences between pathogenic and...
Lymphocytic choriomeningitis virus (LCMV) and Lassa virus (LASV) share many genetic and biological features including subtle differences between pathogenic and apathogenic strains. Despite remarkable genetic similarity, the viscerotropic WE strain of LCMV causes a fatal LASV fever-like hepatitis in non-human primates (NHPs) while the mouse-adapted Armstrong (ARM) strain of LCMV is deeply attenuated in NHPs and can vaccinate against LCMV-WE challenge. Here, we demonstrate that internalization of WE is more sensitive to the depletion of membrane cholesterol than ARM infection while ARM infection is more reliant on endosomal acidification. LCMV-ARM induces robust NF-κB and interferon response factor (IRF) activation while LCMV-WE seems to avoid early innate sensing and failed to induce strong NF-κB and IRF responses in dual-reporter monocyte and epithelial cells. Toll-like receptor 2 (TLR-2) signaling appears to play a critical role in NF-κB activation and the silencing of TLR-2 shuts down IL-6 production in ARM but not in WE-infected cells. Pathogenic LCMV-WE infection is poorly recognized in early endosomes and failed to induce TLR-2/Mal-dependent pro-inflammatory cytokines. Following infection, Interleukin-1 receptor-associated kinase 1 (IRAK-1) expression is diminished in LCMV-ARM- but not LCMV-WE-infected cells, which indicates it is likely involved in the LCMV-ARM NF-κB activation. By confocal microscopy, ARM and WE strains have similar intracellular trafficking although LCMV-ARM infection appears to coincide with greater co-localization of early endosome marker EEA1 with TLR-2. Both strains co-localize with Rab-7, a late endosome marker, but the interaction with LCMV-WE seems to be more prolonged. These findings suggest that LCMV-ARM's intracellular trafficking pathway may facilitate interaction with innate immune sensors, which promotes the induction of effective innate and adaptive immune responses.
Topics: Lymphocytic choriomeningitis virus; Immunity, Innate; Animals; Virus Internalization; Humans; Mice; Toll-Like Receptor 2; Endosomes; NF-kappa B; Signal Transduction; Cell Line; Lymphocytic Choriomeningitis; Epithelial Cells
PubMed: 38675975
DOI: 10.3390/v16040635 -
Emerging Infectious Diseases May 2024We evaluated the in vitro effects of lyophilization for 2 vesicular stomatitis virus-based vaccines by using 3 stabilizing formulations and demonstrated protective...
We evaluated the in vitro effects of lyophilization for 2 vesicular stomatitis virus-based vaccines by using 3 stabilizing formulations and demonstrated protective immunity of lyophilized/reconstituted vaccine in guinea pigs. Lyophilization increased stability of the vaccines, but specific vesicular stomatitis virus-based vaccines will each require extensive analysis to optimize stabilizing formulations.
Topics: Animals; Guinea Pigs; Freeze Drying; Viral Vaccines; Vesicular Stomatitis; Disease Models, Animal; Vesiculovirus; Antibodies, Viral; Vaccine Efficacy; Vesicular stomatitis Indiana virus
PubMed: 38666640
DOI: 10.3201/eid3005.231248 -
PLoS Neglected Tropical Diseases Apr 2024Assay validation is an essential component of disease surveillance testing, but can be problematic in settings where access to positive control material is limited and a...
Assay validation is an essential component of disease surveillance testing, but can be problematic in settings where access to positive control material is limited and a safety risk for handlers. Here we describe a single non-infectious synthetic control that can help develop and validate the PCR based detection of the viral causes of Crimean-Congo hemorrhagic fever, Ebola virus disease, Lassa fever, Marburg virus disease and Rift Valley fever. We designed non-infectious synthetic DNA oligonucleotide sequences incorporating primer binding sites suitable for five assays, and a T7 promotor site which was used to transcribe the sequence. Transcribed RNA was used as template in a dilution series, extracted and amplified with RT-PCR and RT-qPCR to demonstrate successful recovery and determine limits of detection in a range of laboratory settings. Our results show this approach is adaptable to any diagnostic assay requiring validation of nucleic acid extraction and/or amplification, particularly where sourcing reliable, safe material for positive controls is infeasible.
Topics: Humans; Hemorrhagic Fevers, Viral; RNA, Viral; Real-Time Polymerase Chain Reaction; DNA Primers; Sensitivity and Specificity
PubMed: 38648254
DOI: 10.1371/journal.pntd.0011390 -
Emerging Microbes & Infections Dec 2024The Natal multimammate mouse () is the host of Lassa mammarenavirus, causing Lassa haemorrhagic fever in West Africa. As there is currently no operational vaccine and...
The Natal multimammate mouse () is the host of Lassa mammarenavirus, causing Lassa haemorrhagic fever in West Africa. As there is currently no operational vaccine and therapeutic drugs are limited, we explored rodent control as an alternative to prevent Lassa virus spillover in Upper Guinea, where the disease is highly endemic in rural areas. In a seven-year experiment, we distributed rodenticides for 10-30 days once a year and, in the last year, added intensive snap trapping for three months in all the houses of one village. We also captured rodents both before and after the intervention period to assess their effectiveness by examining alterations in trapping success and infection rates (Lassa virus RNA and IgG antibodies). We found that both interventions reduced the rodent population by 74-92% but swiftly rebounded to pre-treatment levels, even already six months after the last snap-trapping control. Furthermore, while we observed that chemical control modestly decreased Lassa virus infection rates annually (a reduction of 5% in seroprevalence per year), the intensive trapping unexpectedly led to a significantly higher infection rate (from a seroprevalence of 28% before to 67% after snap trapping control). After seven years, we conclude that annual chemical control, alone or with intensive trapping, is ineffective and sometimes counterproductive in preventing Lassa virus spillover in rural villages. These unexpected findings may result from density-dependent breeding compensation following culling and the survival of a small percentage of chronically infected rodents that may spread the virus to a new susceptible generation of mice.
Topics: Mice; Animals; Lassa virus; Guinea; Rodent Control; Seroepidemiologic Studies; Disease Reservoirs; Lassa Fever; Murinae; Africa, Western
PubMed: 38597241
DOI: 10.1080/22221751.2024.2341141 -
Frontiers in Molecular Biosciences 2024Matriglycan, a recently characterized linear polysaccharide, is composed of alternating xylose and glucuronic acid subunits bound to the ubiquitously expressed protein... (Review)
Review
Matriglycan, a recently characterized linear polysaccharide, is composed of alternating xylose and glucuronic acid subunits bound to the ubiquitously expressed protein α-dystroglycan (α-DG). Pathogenic arenaviruses, like the Lassa virus (LASV), hijack this long linear polysaccharide to gain cellular entry. Until recently, it was unclear through what mechanisms LASV engages its matriglycan receptor to initiate infection. Additionally, how matriglycan is synthesized onto α-DG by the Golgi-resident glycosyltransferase LARGE1 remained enigmatic. Recent structural data for LARGE1 and for the LASV spike complex informs us about the synthesis of matriglycan as well as its usage as an entry receptor by arenaviruses. In this review, we discuss structural insights into the system of matriglycan generation and eventual recognition by pathogenic viruses. We also highlight the unique usage of matriglycan as a high-affinity host receptor compared with other polysaccharides that decorate cells.
PubMed: 38516183
DOI: 10.3389/fmolb.2024.1371551 -
BMC Infectious Diseases Mar 2024Lassa fever is a hemorrhagic disease caused by Lassa virus (LASV), which has been classified by the World Health Organization as one of the top infectious diseases...
BACKGROUND
Lassa fever is a hemorrhagic disease caused by Lassa virus (LASV), which has been classified by the World Health Organization as one of the top infectious diseases requiring prioritized research. Previous studies have provided insights into the classification and geographic characteristics of LASV lineages. However, the factor of the distribution and evolution characteristics and phylodynamics of the virus was still limited.
METHODS
To enhance comprehensive understanding of LASV, we employed phylogenetic analysis, reassortment and recombination detection, and variation evaluation utilizing publicly available viral genome sequences.
RESULTS
The results showed the estimated the root of time of the most recent common ancestor (TMRCA) for large (L) segment was approximately 634 (95% HPD: [385879]), whereas the TMRCA for small (S) segment was around 1224 (95% HPD: [10301401]). LASV primarily spread from east to west in West Africa through two routes, and in route 2, the virus independently spread to surrounding countries through Liberia, resulting in a wider spread of LASV. From 1969 to 2018, the effective population size experienced two significant increased, indicating the enhanced genetic diversity of LASV. We also found the evolution rate of L segment was faster than S segment, further results showed zinc-binding protein had the fastest evolution rate. Reassortment events were detected in multiple lineages including sub-lineage IIg, while recombination events were observed within lineage V. Significant amino acid changes in the glycoprotein precursor of LASV were identified, demonstrating sequence diversity among lineages in LASV.
CONCLUSION
This study comprehensively elucidated the transmission and evolution of LASV in West Africa, providing detailed insights into reassortment events, recombination events, and amino acid variations.
Topics: Humans; Lassa virus; Phylogeny; Lassa Fever; Amino Acids; Liberia
PubMed: 38486143
DOI: 10.1186/s12879-024-09200-8 -
PLoS Neglected Tropical Diseases Feb 2024West African Mastomys rodents are the primary reservoir of the zoonotic Lassa virus (LASV). The virus causes haemorrhagic Lassa fever and considerable mortality in...
West African Mastomys rodents are the primary reservoir of the zoonotic Lassa virus (LASV). The virus causes haemorrhagic Lassa fever and considerable mortality in humans. To date, the role of Mastomys immunogenetics in resistance to, and persistence of, LASV infections is largely unknown. Here, we investigated the role of Major Histocompatibility Complex class I (MHC-I) on LASV infection status (i.e., active vs. cleared infection, determined via PCR and an immunofluorescence assay on IgG antibodies, respectively) in Mastomys natalensis and M. erythroleucus sampled within southwestern Nigeria. We identified more than 190 and 90 MHC-I alleles by Illumina high throughput-sequencing in M. natalensis and M. erythroleucus, respectively, with different MHC allele compositions and frequencies between LASV endemic and non-endemic sites. In M. natalensis, the MHC allele ManaMHC-I*006 was negatively associated with active infections (PCR-positive) and positively associated with cleared infections (IgG-positive) simultaneously, suggesting efficient immune responses that facilitate LASV clearance in animals carrying this allele. Contrarily, alleles ManaMHC-I*008 and ManaMHC-I*021 in M. natalensis, and MaerMHC-I*008 in M. erythroleucus, were positively associated with active infection, implying susceptibility. Alleles associated with susceptibility shared a glutamic acid at the positively selected codon 57, while ManaMHC-I*006 featured an arginine. There was no link between number of MHC alleles per Mastomys individual and LASV prevalence. Thus, specific alleles, but not MHC diversity per se, seem to mediate antibody responses to viremia. We conclude that co-evolution with LASV likely shaped the MHC-I diversity of the main LASV reservoirs in southwestern Nigeria, and that information on reservoir immunogenetics may hold insights into transmission dynamics and zoonotic spillover risks.
Topics: Animals; Humans; Lassa virus; Alleles; Antibody Formation; Kinetics; Lassa Fever; Immunoglobulin G
PubMed: 38421939
DOI: 10.1371/journal.pntd.0011984 -
Frontiers in Cellular and Infection... 2024Lassa virus (LASV) causes an acute multisystemic hemorrhagic fever in humans known as Lassa fever, which is endemic in several African countries. This manuscript focuses...
An atlas of gross and histologic lesions and immunohistochemical immunoreactivity during the temporal progression of aerosolized Lassa virus induced hemorrhagic fever in cynomolgus macaques.
Lassa virus (LASV) causes an acute multisystemic hemorrhagic fever in humans known as Lassa fever, which is endemic in several African countries. This manuscript focuses on the progression of disease in cynomolgus macaques challenged with aerosolized LASV and serially sampled for the development and progression of gross and histopathologic lesions. Gross lesions were first noted in tissues on day 6 and persisted throughout day 12. Viremia and histologic lesions were first noted on day 6 commencing with the pulmonary system and hemolymphatic system and progressing at later time points to include all systems. Immunoreactivity to LASV antigen was first observed in the lungs of one macaque on day 3 and appeared localized to macrophages with an increase at later time points to include immunoreactivity in all organ systems. Additionally, this manuscript will serve as a detailed atlas of histopathologic lesions and disease progression for comparison to other animal models of aerosolized Arenaviral disease.
Topics: Humans; Animals; Lassa virus; Lassa Fever; Macaca fascicularis; Antigens, Viral; Viremia
PubMed: 38404292
DOI: 10.3389/fcimb.2024.1341891