Infected Hamsters Research Articles

Proteomics of circulating extracellular vesicles reveals diverse clinical presentations of COVID-19 but fails to identify viral peptides

Extracellular vesicles (EVs) released by virus-infected cells have the potential to encapsulate viral peptides, a characteristic that could facilitate vaccine development. Furthermore, plasma-derived EVs may elucidate pathological changes occurring in distal tissues during viral infections. We hypothesized that molecular characterization of EVs isolated from COVID-19 patients would reveal peptides suitable for vaccine development. Blood samples were collected from three cohorts: severe COVID-19 patients (G1), mild/asymptomatic cases (G2), and SARS-CoV-2-negative healthcare workers (G3). Samples were obtained at two time points: during the initial phase of the pandemic in early 2020 (m0) and eight months later (m8). Clinical data analysis revealed elevated inflammatory markers in G1. Notably, non-vaccinated individuals in G1 exhibited increased levels of neutralizing antibodies at m8, suggesting prolonged exposure to viral antigens. Proteomic profiling of EVs was performed using three distinct methods: immunocapture (targeting CD9), ganglioside-capture (utilizing Siglec-1) and size-exclusion chromatography (SEC). Contrary to our hypothesis, this analysis failed to identify viral peptides. These findings were subsequently validated through Western blot analysis targeting the RBD of the SARS-CoV-2 Spike protein’s and comparative studies using samples from experimentally infected Syrian hamsters. Furthermore, analysis of the EV cargo revealed a diverse molecular profile, including components involved in the regulation of viral replication, systemic inflammation, antigen presentation, and stress responses. These findings underscore the potential significance of EVs in the pathogenesis and progression of COVID-19.

Differences in Susceptibility to SARS-CoV-2 Infection Among Transgenic hACE2-Hamster Founder Lines.

Animal models that are susceptible to SARS-CoV-2 infection and develop clinical signs like human COVID-19 are desired to understand viral pathogenesis and develop effective medical countermeasures. The golden Syrian hamster is important for the study of SARS-CoV-2 since hamsters are naturally susceptible to SARS-CoV-2. However, infected hamsters show only limited clinical disease and resolve infection quickly. In this study, we describe development of human angiotensin-converting enzyme 2 (hACE2) transgenic hamsters as a model for COVID-19. During development of the model for SARS-CoV-2, we observed that different hACE2 transgenic hamster founder lines varied in their susceptibility to SARS-CoV-2 lethal infection. The highly susceptible hACE2 founder lines F0F35 and F0M41 rapidly progress to severe infection and death within 6 days post-infection (p.i.). Clinical signs included lethargy, weight loss, dyspnea, and mortality. Lethality was observed in a viral dose-dependent manner with a lethal dose as low as 1 × 100.15 CCID50. In addition, virus shedding from highly susceptible lines was detected in oropharyngeal swabs on days 2-5 p.i., and virus titers were observed at 105.5-6.5 CCID50 in lung and brain tissue by day 4 p.i.. Histopathology revealed that infected hACE2-hamsters developed rhinitis, tracheitis, bronchointerstitial pneumonia, and encephalitis. Mortality in highly susceptible hACE2-hamsters can be attributed to neurologic disease with contributions from the accompanying respiratory disease. In contrast, virus challenge of animals from less susceptible founder lines, F0M44 and F0M51, resulted in only 0-20% mortality. To demonstrate utility of this SARS-CoV-2 infection model, we determined the protective effect of the TLR3 agonist polyinosinic-polycytidylic acid (Poly (I:C)). Prophylactic treatment with Poly (I:C) significantly improved survival in highly susceptible hACE2-hamsters. In summary, our studies demonstrate that hACE2 transgenic hamsters differ in their susceptibility to SARS-CoV-2 infection, based on the transgenic hamster founder line, and that prophylactic treatment with Poly (I:C) was protective in this COVID-19 model of highly susceptible hACE2-hamsters.

Evidence for SARS-CoV-2 infected Golden Syrian hamsters (Mesocricetus auratus) reducing daily energy expenditure and body core temperature

Golden Syrian hamsters (Mesocricetus auratus) are a well-established animal model for human infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) due to their susceptibility to SARS-CoV-2 infection, robust virus replication and pathological manifestations similar to human COVID-19 pneumonia. To investigate the physiological changes upon infection in this animal model, we explored the alterations in daily energy expenditure (DEE), water turnover, body mass, body temperature, and locomotor activity in non-infected and SARS-CoV-2 infected Golden Syrian hamsters for four days post SARS-CoV-2. DEE was measured using the doubly labelled water method, which allows for the accurate estimation of carbon dioxide production and, consequently, energy expenditure in animals. Additionally, we investigated total water intake (TWI), which comprises drinking water, preformed water in food, and metabolic water. Using intraperitoneally implanted data loggers, we also monitored body core temperature and locomotor activity in some of the animals. Here we provide evidence for infected hamsters exhibiting significantly lower DEE and TWI compared to non-infected animals. We also observed an increase in body weight in the non-infected animals, while infected animals experienced weight loss. Further, infected animals showed a significantly decreased body temperature, indicating a generally lowered metabolic rate.

Blockade of endothelin receptors mitigates SARS-CoV-2-induced osteoarthritis.

Joint pain and osteoarthritis can occur as coronavirus disease 2019 (COVID-19) sequelae after infection. However, little is known about the damage to articular cartilage. Here we illustrate knee joint damage after wild-type, Delta and Omicron variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in vivo. Rapid joint injury with cystic lesions at the osteochondral junction was observed in two patients with post-COVID osteoarthritis and recapitulated in a golden Syrian hamster model. SARS-CoV-2-activated endothelin-1 signalling increased vascular permeability and caused viral spike proteins leakage into the subchondral bone. Osteoclast activation, chondrocyte dropout and cyst formation were confirmed histologically. The US Food and Drug Administration-approved endothelin receptor antagonist, macitentan, mitigated cystic lesions and preserved chondrocyte number in the acute phase of viral infection in hamsters. Delayed macitentan treatment at post-acute infection phase alleviated chondrocyte senescence and restored subchondral bone loss. It is worth noting that it could also attenuate viral spike-induced joint pain. Our work suggests endothelin receptor blockade as a novel therapeutic strategy for post-COVID arthritis.

The triple combination of Remdesivir (GS-441524), Molnupiravir and Ribavirin is highly efficient in inhibiting coronavirus replication in human nasal airway epithelial cell cultures and in a hamster infection model

The use of fixed dose-combinations of antivirals with different mechanisms of action has proven key in the successful treatment of infections with HIV and HCV. For the treatment of infections with SARS-CoV-2 and possible future epi-/pandemic coronaviruses, it will be important to explore the efficacy of combinations of different drugs, in particular to avoid resistance development, such as in patients with immunodeficiencies. This work explores the effect of a combination of 3 broad-spectrum antiviral nucleosides on the replication of coronaviruses. To that end, we made use of primary human airway epithelial cell (HAEC) cultures grown at the air-liquid interface that were infected with the beta coronavirus OC43. We found that the triple combination of GS-441524 (the parent nucleoside of remdesivir), molnupiravir and ribavirin resulted in a more pronounced antiviral efficacy than what could be expected from a purely additive antiviral effect. The potency of this triple combination was next tested in SARS-CoV-2 infected hamsters in a prophylactic setup. To that end, for each of the drugs, intentionally suboptimal or even ineffective doses were selected. Yet, in the lungs of all hamsters that received triple prophylactic therapy (but not in those that received the respective double combinations) no infectious virus was detectable. Our findings indicate that co-administration of approved drugs for the treatment of coronavirus infections should be further explored but also against other families of viruses with epidemic and pandemic potential for which no effective antiviral treatment is available.

Therapeutic potential of mesenchymal stem cell-derived extracellular vesicles in SARS-CoV-2 and H1N1 influenza-induced acute lung injury.

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have shown anti-inflammatory potential in multiple inflammatory diseases. In the March 2022 issue of the Journal of Extracellular Vesicles, it was shown that EVs from human MSCs can suppress severe acute respiratory distress syndrome, coronavirus 2 (SARS-CoV-2) replication and can mitigate the production and release of infectious virions. We therefore hypothesized that MSC-EVs have an anti-viral effect in SARS-CoV-2 infection in vivo. We extended this question to ask whether also other respiratory viral infections could be treated by MSC-EVs. Adipose stem cell-derived EVs (ASC-EVs) were isolated using tangential flow filtration from conditioned media obtained from a multi-flask cell culture system. The effects of the ASC-EVs were tested in Vero E6 cells in vitro. ASC-EVs were also given i.v. to SARS-CoV-2 infected Syrian Hamsters, and H1N1 influenza virus infected mice. The ASC-EVs attenuated SARS-CoV-2 virus replication in Vero E6 cells and reduced body weight and signs of lung injury in infected Syrian hamsters. Furthermore, ASC-EVs increased the survival rate of influenza A-infected mice and attenuated signs of lung injury. In summary, this study suggests that ASC-EVs can have beneficial therapeutic effects in models of virus-infection-associated acute lung injury and may potentially be developed to treat lung injury in humans.

SARS-CoV-2 Rapidly Infects Peripheral Sensory and Autonomic Neurons, Contributing to Central Nervous System Neuroinvasion before Viremia.

Neurological symptoms associated with COVID-19, acute and long term, suggest SARS-CoV-2 affects both the peripheral and central nervous systems (PNS/CNS). Although studies have shown olfactory and hematogenous invasion into the CNS, coinciding with neuroinflammation, little attention has been paid to susceptibility of the PNS to infection or to its contribution to CNS invasion. Here we show that sensory and autonomic neurons in the PNS are susceptible to productive infection with SARS-CoV-2 and outline physiological and molecular mechanisms mediating neuroinvasion. Our infection of K18-hACE2 mice, wild-type mice, and golden Syrian hamsters, as well as primary peripheral sensory and autonomic neuronal cultures, show viral RNA, proteins, and infectious virus in PNS neurons, satellite glial cells, and functionally connected CNS tissues. Additionally, we demonstrate, in vitro, that neuropilin-1 facilitates SARS-CoV-2 neuronal entry. SARS-CoV-2 rapidly invades the PNS prior to viremia, establishes a productive infection in peripheral neurons, and results in sensory symptoms often reported by COVID-19 patients.

Evaluating Molecular Mechanism of Viral Inhibition of Aerosolized Smart Nano-Enabled Antiviral Therapeutic (SNAT) on SARS-CoV-2-Infected Hamsters.

Smart Nano-enabled Antiviral Therapeutic (SNAT) is a promising nanodrug that previously demonstrated efficacy in preclinical studies to alleviate SARS-CoV-2 pathology in hamsters. SNAT comprises taxoid (Tx)-decorated amino (NH2)-functionalized near-atomic size positively charged silver nanoparticles (Tx-[NH2-AgNPs]). Herein, we aimed to elucidate the molecular mechanism of the viral inhibition and safety of aerosolized SNAT treatment in SARS-CoV-2-infected golden Syrian hamsters. High-resolution transmission electron microscopy (HR-TEM) coupled with energy dispersive spectroscopy (EDS) and ELISAs showed SNAT binds directly to the SARS-CoV-2 virus by interacting with intact spike (S) protein, specifically to S2 subunit. SNAT (≥1 µg/mL) treatment significantly lowered SARS-CoV-2 infections of Calu-3 cells. Extraction-free whole transcriptome assay was used to detect changes in circulatory micronome in hamsters treated intranasally with SNAT (two doses of 10 µg/mL of 2 mL each administered 24 h apart). Uninfected hamsters treated with SNAT had altered circulatory concentrations of 18 microRNAs (8 miRNAs upregulated, 10 downregulated) on day 3 post-treatment compared to uninfected controls. SNAT-induced downregulation of miR-141-3p and miR-200b-3p may reduce viral replication and inflammation by targeting Ythdf2 and Slit2, respectively. Further, SNAT treatment significantly lowered IL-6 expression in infected hamster lungs compared to untreated infected hamsters. Taken together, we demonstrate that SNAT binds directly to SARS-CoV-2 via the S protein to prevent viral entry and propose a model by which SNAT alters the cellular miRNA-directed milieu to promote antiviral cellular processes and neutralize infection. Our results provide insights into the use of low-dose intranasally delivered SNAT in treating SARS-CoV-2 infections in a hamster model.

The influence of exogenous and endogenous nitric oxide on the human and animal body

It has been shown that the inhalation of gaseous NO (exogenous nitric oxide) leads to the formation of nitrosonium cations (NO+) in the circulating blood of humans and animals during the oxidation of NO, which can have a detrimental effect on pathogenic viruses and bacteria. When thiols enter the blood simultaneously with NO inhalation, they form S-nitrosothiols with NO+ and cause hypotensive effect in animals. The biological effect of endogenous NO, which is produced in cells and tissues with the participation of NO synthases in animals and humans, is mediated by the dinitrosyl iron complexes (DNIC) formed with thiol-containing ligands. As NO and NO+ donors, these complexes have a variety of regulatory and cytotoxic effects on the animal and human body. In particular, the NO+ released by DNIC was shown to suppress SARS-CoV-2 infection in Syrian hamsters.

Dynamics of Trypanosoma cruzi infection in hamsters and novel association with progressive motor dysfunction.

Chagas disease is a zoonosis caused by the protozoan parasite Trypanosoma cruzi. Clinical outcomes range from long-term asymptomatic carriage to cardiac, digestive, neurological and composite presentations that can be fatal in both acute and chronic stages of the disease. Studies of T. cruzi in animal models, principally mice, have informed our understanding of the biological basis of this variability and its relationship to infection and host response dynamics. Hamsters have higher translational value for many human infectious diseases, but they have not been well developed as models of Chagas disease. We transposed a real-time bioluminescence imaging system for T. cruzi infection from mice into female Syrian hamsters (Mesocricetus auratus). This enabled us to study chronic tissue pathology in the context of spatiotemporal infection dynamics. Acute infections were widely disseminated, whereas chronic infections were almost entirely restricted to the skin and subcutaneous adipose tissue. Neither cardiac nor digestive tract disease were reproducible features of the model. Skeletal muscle had only sporadic parasitism in the chronic phase, but nevertheless displayed significant inflammation and fibrosis, features also seen in mouse models. Whereas mice had normal locomotion, all chronically infected hamsters developed hindlimb muscle hypertonia and a gait dysfunction resembling spastic diplegia. With further development, this model may therefore prove valuable in studies of peripheral nervous system involvement in Chagas disease.

Human parainfluenza virus 3 vaccine candidates attenuated by codon-pair deoptimization are immunogenic and protective in hamsters

Human parainfluenza virus type 3 (HPIV3) is a major pediatric respiratory pathogen lacking available vaccines or antiviral drugs. We generated live-attenuated HPIV3 vaccine candidates by codon-pair deoptimization (CPD). HPIV3 open reading frames (ORFs) encoding the nucleoprotein (N), phosphoprotein (P), matrix (M), fusion (F), hemagglutinin-neuraminidase (HN), and polymerase (L) were modified singly or in combination to generate 12 viruses designated Min-N, Min-P, Min-M, Min-FHN, Min-L, Min-NP, Min-NPM, Min-NPL, Min-PM, Min-PFHN, Min-MFHN, and Min-PMFHN. CPD of N or L severely reduced growth in vitro and was not further evaluated. CPD of P or M was associated with increased and decreased interferon (IFN) response in vitro, respectively, but had little effect on virus replication. In Vero cells, CPD of F and HN delayed virus replication, but final titers were comparable to wild-type (wt) HPIV3. In human lung epithelial A549 cells, CPD F and HN induced a stronger IFN response, viral titers were reduced 100-fold, and the expression of F and HN proteins was significantly reduced without affecting N or P or the relative packaging of proteins into virions. Following intranasal infection in hamsters, replication in the nasal turbinates and lungs tended to be the most reduced for viruses bearing CPD F and HN, with maximum reductions of approximately 10-fold. Despite decreased in vivo replication (and lower expression of CPD F and HN in vitro), all viruses induced titers of serum HPIV3-neutralizing antibodies similar to wt and provided complete protection against HPIV3 challenge. In summary, CPD of HPIV3 yielded promising vaccine candidates suitable for further development.

A highly effective ferritin-based divalent nanoparticle vaccine shields Syrian hamsters against lethal Nipah virus.

The Nipah virus (NiV), a highly deadly bat-borne paramyxovirus, poses a substantial threat due to recurrent outbreaks in specific regions, causing severe respiratory and neurological diseases with high morbidity. Two distinct strains, NiV-Malaysia (NiV-M) and NiV-Bangladesh (NiV-B), contribute to outbreaks in different geographical areas. Currently, there are no commercially licensed vaccines or drugs available for prevention or treatment. In response to this urgent need for protection against NiV and related henipaviruses infections, we developed a novel homotypic virus-like nanoparticle (VLP) vaccine co-displaying NiV attachment glycoproteins (G) from both strains, utilizing the self-assembling properties of ferritin protein. In comparison to the NiV G subunit vaccine, our nanoparticle vaccine elicited significantly higher levels of neutralizing antibodies and provided complete protection against a lethal challenge with NiV infection in Syrian hamsters. Remarkably, the nanoparticle vaccine stimulated the production of antibodies that exhibited superior cross-reactivity to homologous or heterologous henipavirus. These findings underscore the potential utility of ferritin-based nanoparticle vaccines in providing both broad-spectrum and long-term protection against NiV and emerging zoonotic henipaviruses challenges.

Assessment of the therapeutic effect of the drug Molixan in the treatment of Syrian hamsters experimentally infected with the SARS-CoV-2 virus

Background. Studying the characteristics of the course of coronavirus infection caused by SARS-CoV-2 remains relevant due to the high mutagenicity of the virus and the prevalence of the disease in the world. The search for new drugs to eliminate clinical manifestations of COVID-19, as well as against its agent, is essential. During the pandemic caused by SARS-CoV-2, dexamethasone was recognized as the only effective anti-inflammatory drug for the treatment of patients with severe form of the disease, but its use leads to a large number of side effects.The aim. To study the therapeutic effect of the drug Molixan in the treatment of coronavirus infection in model animals – Syrian hamsters.Methods. To assess the effectiveness of the drug Molixan, we carried out a visual assessment of the condition of the lungs using light microscopy and the morphometry of the lung tissue of experimentally infected Syrian hamsters on the day 6 after infection under different Molixan treatment regimens and during dexamethasone therapy. The test drug was administered using three different doses (22.2 mg/kg, 44.4 mg/kg and 88.8 mg/kg, which are equivalent to doses of 3 mg/kg, 6 mg/kg and 12 mg/kg of human body weight) once daily or dividing the dose into two within 12 h interval in case of multiple (5 days) intramuscular administration. Dexamethasone (comparison drug) was administered at a dose of 20 mg/kg once daily for 5 days.Results. The studies showed statistically significant effectiveness of using Molixan at a dose of 44.4 mg/kg, divided into two doses, during 5 days. When compared with untreated hamsters, this treatment regimen reduces the degree of generalization and severity of the inflammatory process in the lungs; and the pathomorphological picture is similar to that observed during treatment with Dexamethasone.Conclusion. The studied drug Molixan is effective as an anti-inflammatory drug in the treatment of the disease caused by SARS-CoV-2.

3D imaging of SARS-CoV-2 infected hamster lungs by X-ray phase contrast tomography enables drug testing

X-ray Phase Contrast Tomography (XPCT) based on wavefield propagation has been established as a high resolution three-dimensional (3D) imaging modality, suitable to reconstruct the intricate structure of soft tissues, and the corresponding pathological alterations. However, for biomedical research, more is needed than 3D visualisation and rendering of the cytoarchitecture in a few selected cases. First, the throughput needs to be increased to cover a statistically relevant number of samples. Second, the cytoarchitecture has to be quantified in terms of morphometric parameters, independent of visual impression. Third, dimensionality reduction and classification are required for identification of effects and interpretation of results. To address these challenges, we here design and implement a novel integrated and high throughput XPCT imaging and analysis workflow for 3D histology, pathohistology and drug testing. Our approach uses semi-automated data acquisition, reconstruction and statistical quantification. We demonstrate its capability for the example of lung pathohistology in Covid-19. Using a small animal model, different Covid-19 drug candidates are administered after infection and tested in view of restoration of the physiological cytoarchitecture, specifically the alveolar morphology. To this end, we then use morphometric parameter determination followed by a dimensionality reduction and classification based on optimal transport. This approach allows efficient discrimination between physiological and pathological lung structure, thereby providing quantitative insights into the pathological progression and partial recovery due to drug treatment. Finally, we stress that the XPCT image chain implemented here only used synchrotron radiation for validation, while the data used for analysis was recorded with laboratory μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}CT radiation, more easily accessible for pre-clinical research.

#1902 Remdesivir ameliorates ferroptotic renal injury in hamster after SARS-CoV-2 infection

Abstract Background and Aims The purpose of this study was to see how remdesivir affected renal ferroptotic damage in hamsters following a human Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection. We evaluated the inhibitory effects of remdesivir on the ferroptosis of SARS-CoV-2 infection in a hamster infection model and in in vivo assays. Method To investigate the effect of SARS-CoV-2 on renal ferroptosis, we administered 2.5 × 104 p.f.u. SARS-CoV-2 via intranasal to hamster. In the initial study, animals were treated with remdesivir subcutaneously (s.c.) for 7 days beginning at various times in relation to virus challenge. After 5 days, kidney tissues were harvested. The effect of REMDESIVIR on SARS-CoV-2 infection and ferroptosis were evaluated by immunohistochemistry. Next, ferroptosis-related markers, glutathione peroxidase 4 (Gpx4), 4-hydroxynonenal (4-HNE), Acyl-CoA synthetase long chain family member 4 (Acsl4), nuclear factor erythroid-2-related factor 2 (Nrf2), heme oxygenase-1 (Ho-1) were evaluated by quantitative PCR. Results In hamsters, SARS-CoV-2 resulted in high viral protein expression in the renal tubules and decreased renal tubular luminal diameter in periodic acid-Schiff (PAS) stained kidney sections. Remdesivir treatment decreased SARS-CoV-2-induced viral spike protein, HO-1, ferritin heavy chain1 (FTH1), ferritin light chain (FTL), and 4-HNE expression in renal tubular epithelial cells of hamsters in a dose-dependent manner. GPX4 expression suppression after infection was ameliorated by remdesivir administration. Increased ferroptosis-related mRNA marker (Gpx4, 4-HNE, Acsl4, Nrf2, Ho-1) expression in hamster kidneys was suppressed by remdesivir treatment. Conclusion All of our data suggest that remdesivir treatment ameliorated SARS-CoV-2 infection-induced ferroptosis in the kidney in a hamster model.

Invivo evaluation of Andrographis paniculata and Boesenbergia rotunda extract activity against SARS-CoV-2 Delta variant in Golden Syrian hamsters: Potential herbal alternative for COVID-19 treatment

The ongoing COVID-19 pandemic has triggered extensive research, mainly focused on identifying effective therapeutic agents, specifically those targeting highly pathogenic SARS-CoV-2 variants. This study aimed to investigate the in vivo antiviral efficacy and anti-inflammatory activity of herbal extracts derived from Andrographis paniculata and Boesenbergia rotunda, using a Golden Syrian hamster model infected with Delta, a representative variant associated with severe COVID-19. Hamsters were intranasally inoculated with the SARS-CoV-2 Delta variant and orally administered either vehicle control, B. rotunda, or A.paniculata extract at a dosage of 1000 mg/kg/day. Euthanasia was conducted on days 1, 3, and 7 post-inoculation, with 4 animals per group. The results demonstrated that oral administration of A. paniculata extract significantly alleviated both lethality and infection severity compared with the vehicle control and B. rotunda extract. However, neither extract exhibited direct antiviral activity in terms of reducing viral load in the lungs. Nonetheless, A. paniculata extract treatment significantly reduced IL-6 protein levels in the lung tissue (7278 ± 868.4 pg/g tissue) compared to the control (12,495 ± 1118 pg/g tissue), indicating there was a decrease in local inflammation. This finding is evidenced by the ability of A. paniculata extract to reduce histological lesions in the lungs of infected hamsters. Furthermore, both extracts significantly decreased IL-6 and IP-10 mRNA expression in peripheral blood mononuclear cells of infected hamsters compared to the control group, suggesting systemic anti-inflammatory effects occurred. In conclusion, A. paniculata extract's potential therapeutic application for SARS-CoV-2 arises from its observed capacity to lessen inflammatory cytokine concentrations and mitigate lung pathology.

Syrian Hamsters Model Does Not Reflect Human-like Disease after Aerosol Exposure to Encephalitic Alphaviruses.

Venezuelan (VEE), eastern (EEE), and western (WEE) equine encephalitis viruses are encephalitic New World alphaviruses that cause periodic epizootic and epidemic outbreaks in horses and humans that may cause severe morbidity and mortality. Currently there are no FDA-licensed vaccines or effective antiviral therapies. Each year, there are a limited number of human cases of encephalitic alphaviruses; thus, licensure of a vaccine or therapeutic would require approval under the FDA animal rule. Approval under the FDA animal rule requires the disease observed in the animal model to recapitulate what is observed in humans. Currently, initial testing of vaccines and therapeutics is performed in the mouse model. Unfortunately, alphavirus disease manifestations in a mouse do not faithfully recapitulate human disease; the VEEV mouse model is lethal whereas in humans VEEV is rarely lethal. In an effort to identify a more appropriate small animal model, we evaluated hamsters in an aerosol exposure model of encephalitic alphavirus infection. The pathology, lethality, and viremia observed in the infected hamsters was inconsistent with what is observed in NHP models and humans. These data suggest that hamsters are not an appropriate model for encephalitic alphaviruses to test vaccines or potential antiviral therapies.

Attractiveness of Golden Hamster infected with Leishmania amazonensis (Kinetoplastida: Trypanosomatidae) to laboratory-reared Lutzomyia longipalpis (Diptera: Psychodidae)

Lutzomyia longipalpis is the primary vector of Leishmania infantum in the Americas and a permissive vector for Leishmania amazonensis. Previous studies showed that Leishmania infantum-infected hosts can release different volatile organic compounds (VOCs) compared with uninfected hosts, presenting a higher attractiveness to vectors. In this study, we aimed to evaluate a possible effect of L. amazonensis infection of golden hamsters in three parameters: attractiveness to Lu. longipalpis females; blood volume ingested by sand fly females; and VOCs released by the animals.. Attractiveness was measured indirectly by the number of Lu. longipalpis females that blood fed in each L. amazonensis-infected and uninfected animal. For VOCs extraction, solid phase micro extraction fibers were used, which were analyzed by gas chromatography-mass spectrometry. Behavioral trials did not show any effect of L. amazonensis infection on the attraction of sand flies nor difference on blood meal rates of Lu. longipalpis fed in both goups of hamsters. Additionally, there was no difference between the VOCs profiles of L. amazonensis-infected or uninfected hamsters.

SARS-CoV-2 strains bearing Omicron BA.1 spike replicate in C57BL/6 mice.

SARS-CoV-2, the cause of the COVID pandemic, is an RNA virus with a high propensity to mutate. Successive virus variants, including variants of concern (VOC), have emerged with increased transmission or immune escape. The original pandemic virus and early variants replicated poorly, if at all, in mice at least partly due to a mismatch between the receptor binding domain on the viral spike protein and the murine angiotensin converting enzyme 2 (ACE2). Omicron VOC emerged in late 2021 harboring > 50 new mutations, 35 of them in the spike protein. This variant resulted in a very large wave of infections, even in the face of prior immunity, albeit being inherently less severe than earlier variants. Reflecting the lower severity reported in humans, Omicron displayed attenuated infection in hamsters and also in the K18-hACE2 mouse model. K18-hACE2 mice express both the human ACE2 as well as the endogenous mouse ACE2. Here we infected hACE2 knock-in mice that express only human ACE2 and no murine ACE2, or C57BL/6 wildtype mice with SARS-CoV-2 D614G (first-wave isolate), Delta or Omicron BA.1 variants and assessed infectivity and downstream innate immune responses. While replication of SARS-CoV-2 Omicron was lower in the lungs of hACE2 knock-in mice compared with SARS-CoV-2 D614G and VOC Delta, it replicated more efficiently than the earlier variants in C57BL/6 wildtype mice. This opens the opportunity to test the effect of host genetics on SARS-CoV-2 infections in wildtype mice. As a proof of principle, we tested Omicron infection in mice lacking expression of the interferon-alpha receptor-1 (IFNAR1). In these mice we found that loss of type I IFN receptor signaling resulted in higher viral loads in the lungs were detected. Finally, using a chimeric virus of first wave SARS-CoV-2 harboring the Omicron spike protein, we show that Omicron spike increase infection of C57BL/6 wildtype mice, but non-spike genes of Omicron confer attenuation of viral replication. Since this chimeric virus efficiently infected C57BL/6 wildtype mice, and replicated in their lungs, our findings illustrate a pathway for genetic mapping of virushost interactions during SARS-CoV-2 infection.

Some Specific Biological Risks of SARS-CoV-2 Infected Syrian Hamsters at Animal Biosafety Level - Lab 3

The emergence of novel severe acute respiratory syndrome 2 (SARS-CoV-2) has prompted extensive research to identify its pathogenesis, transmission, and reservoir entry in animals. Syrian hamsters (Mesocricetus auratus) are being identified as an ideal animal model for the study of SARS-CoV-2 infection due to their susceptibility and respiratory symptoms similar to that observed in humans. This study focused on the specific biological risks associated with the use of infected Syrian hamsters in animal biosafety level 3 (ABSL-3) laboratories. The professional and psychological training of professionals working with laboratory animals should be a priority. Biological safety requires the involvement of all parties from technical staff to top management. The COVID-19 pandemic has shown a limitation in experimental studies when obtaining the right strain of mice proved difficult. A rare experimental model of Syrian hamsters started to be used in the work, which Syrian hamsters have several distinctive characteristics associated with increased aggressiveness of females, leading to a requirement to keep them isolated and some technical difficulties during manipulations in the biological safety cabinet. Therefore, a risk-based approach must be introduced to reduce the additional risks to workers to an acceptable level. This includes enhanced accuracy in the use of personal protective equipment (PPE), rigorously following biosecurity protocols, and monitoring staff health to detect potential risk of zoonotic transmission. The implementation of international standards and regulations on biological safety and biosecurity is of paramount importance.