Animal models for SARS-Cov2/Covid19 research-A commentary

Targeting HSP90AA1 to overcome multiple drug resistance in breast cancer using magnetic nanoparticles loaded with salicylic acid

Multiple drug resistance (MDR) remains a major obstacle in effective breast cancer chemotherapy. This study explores the role of HSP90AA1 in driving MDR and evaluates the potential of magnetic nanoparticles (Fe3O4@SA) loaded with salicylic acid (SA) to counteract drug resistance. A comprehensive screening of 200 SA-related target genes identified nine core genes, including HSP90AA1. Pharmacophore analysis revealed that SA interacts with HSP90AA1, a key regulator of mitochondrial K+ channels. Fe3O4@SA nanoparticles demonstrated efficient cellular uptake and lysosomal escape, markedly improving the chemosensitivity of resistant breast cancer cells and promoting apoptosis. In vivo experiments further confirmed the anticancer efficacy of Fe3O4@SA, highlighting its potential as a promising therapeutic strategy to overcome MDR in breast cancer.

Immunometabolic Effect of Nitric Oxide on Human Macrophages Challenged With the SARS-CoV2-Induced Cytokine Storm. A Fluxomic Approach

The cytokine storm associated with SARS-CoV-2 infection is one of the most distinctive pathological signatures in COVID-19 patients. Macrophages respond to this pro-inflammatory challenge by reprogramming their functional and metabolic phenotypes. Interestingly, human macrophages fail to express the inducible form of the NO synthase (NOS2) in response to pro-inflammatory activation and, therefore, NO is not synthesized by these cells. The contribution of exogenously added NO, via a chemical NO-donor, on the immunometabolic changes associated with the cytokine storm is investigated. By using metabolic, transcriptomic, and functional assays the effect of NO in human macrophages is evaluated and found specific responses. Moreover, through integrative fluxomic analysis, pathways modified by NO that contribute to the expression of a particular phenotype in human macrophages are identified, which includes a decrease in mitochondrial respiration and TCA with a slight increase in the glycolytic flux. A significant ROS increase and preserved cell viability are observed in the presence of NO, which may ease the inflammatory response and host defense. Also, NO reverses the cytokine storm-induced itaconate accumulation. These changes offer additional clues to understanding the potential crosstalk between NO and the COVID-19 cytokine storm-dependent signaling pathways.

Juruaça virus taxonomy, tolerance and resistance to infection, and inflammatory response modulation in murine model

Juruaça virus (JUAV), previously unclassified, was isolated from bats and administered to neonatal and adult BALB/c mice to investigate acute and chronic disease progression. In this study, we conducted genomic sequencing to achieve taxonomic classification and utilized these models to explore the inflammatory response and sickness behavior in both neonatal and adult mice. Neonates received a single intranasal instillation of infected brain homogenate (20 µL), whereas 31-day-old mice were given the same volume intranasally for three consecutive days. Control groups were administered equal volumes of uninfected brain homogenate. Our findings reveal that intranasal JUAV infection-induced acute meningoencephalitis and death in neonates, while adult mice exhibited chronic infection with variable clinical signs, inflammatory mediator production, histopathological changes, and neuropathological features. Interestingly, only some adult mice showed sickness behavior post-infection, and among these, a subset continued to decline and die. The differential tissue damage observed in mice with and without overt disease symptoms suggests mechanisms of resistance or tolerance, where exceeding tolerance capacity resulted in pathological outcomes, including chronic dysfunction or death. This study provides the first evidence of JUAV's capability to infect mammals, demonstrating its distinct impact on bats and variable effects in neonatal and adult mice. We provisionally classified JUAV as closely related to the clade containing tombus-like virus 6 found in mute swan feces. Our research highlights the importance of understanding viral-host interactions and the inflammatory responses that contribute to disease variability, offering insights into tolerance and resistance mechanisms based on inflammatory response modulation.

Phase 0 trials/ Intra-Target-Microdosing (ITM) and the lung: a review

The COVID-19 pandemic has highlighted the importance of efficient drug discovery in respiratory disease. The traditional set up of clinical trials is expensive and allows for significant attrition of new drugs, many of which undergo extensive safety testing before being abandoned for lack of efficacy. Phase 0 trials, named as they sit between pre-clinical research and phase I, allow for the testing of sub-clinical microdoses in humans to gather early pharmacokinetic (PK), pharmacodynamic (PD) and mechanistic data, before deciding on which drugs to advance further. This early data can improve the efficiency and cost effectiveness of drug development and reduce the extent of animal testing. Phase 0 trials traditionally have utilised sub-therapeutic microdoses of compounds administered intravenously with readouts focusing on PK - measured using highly sensitive methods such as accelerator mass spectrometry (AMS) and liquid chromatography tandem mass spectrometry (LC-MS/MS) of peripheral blood, as well as whole-body positron emission tomography (PET). Mathematical models allow for extrapolation of this PK data to support the further testing of larger, systemically effective doses. However, this extrapolation method is limited at providing robust PD or target engagement/ mode of action data. Using an Intra-Target Microdosing (ITM) approach, a small compartment of the body (about 1% or less) is exposed to potentially clinically active local concentrations. This allows for the collection of PD data, evidence of target cell engagement, as well as the opportunity to extrapolate systemic PK and PD data. This approach has the potential within the pulmonary system for the study and rapid and cost-effective development of new and repurposed drugs.

Comparison of infection and human immune responses of two SARS-CoV-2 strains in a humanized hACE2 NIKO mouse model

The COVID-19 pandemic has sickened millions, cost lives and has devastated the global economy. Various animal models for experimental infection with SARS-CoV-2 have played a key role in many aspects of COVID-19 research. Here, we describe a humanized hACE2 (adenovirus expressing hACE2) NOD-SCID IL2Rγ^-/- (NIKO) mouse model and compare infection with ancestral and mutant (SARS-CoV-2-∆382) strains of SARS-CoV-2. Immune cell infiltration, inflammation, lung damage and pro-inflammatory cytokines and chemokines was observed in humanized hACE2 NIKO mice. Humanized hACE2 NIKO mice infected with the ancestral and mutant SARS-CoV-2 strain had lung inflammation and production of pro-inflammatory cytokines and chemokines. This model can aid in examining the pathological basis of SARS-CoV-2 infection in a human immune environment and evaluation of therapeutic interventions.

The COVID-19 pandemic's effects on SMEs and travel agencies: The critical role of corporate social responsibility

This study is based on the system resilience framework, which outlines the aspects of community behavior, employees, the environment, history, and corporate social responsibility. We used a partial least squares structural equation model to evaluate a sample of 300 Vietnamese SMEs and travel agencies. We discovered that SMEs' strategies positively influence performance and are co-created with corporate social responsibility. The dependability of internal integrity was then determined. The empirical results showed that the overall confidence index for all facilities ranged from 0.70 to 0.95, with values ranging from 0.809 to 0.931. Furthermore, the A and Cronbach's alpha reliability values ranged from 0.70 to 0.90. As a result, the reliability of internal consistency was established. The convergence validity of the configurations was assessed by comparing the extracted mean values of variance (AVE), which, for all configurations, exceeded the limit of 0.50. This approach emphasizes the impact of corporate social responsibility practices on communities, the environment, and heritage.

BSL2-compliant lethal mouse model of SARS-CoV-2 and variants of concern to evaluate therapeutics targeting the Spike protein

Since first reported in 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is rapidly acquiring mutations, particularly in the spike protein, that can modulate pathogenicity, transmission and antibody evasion leading to successive waves of COVID19 infections despite an unprecedented mass vaccination necessitating continuous adaptation of therapeutics. Small animal models can facilitate understanding host-pathogen interactions, target selection for therapeutic drugs, and vaccine development, but availability and cost of studies in BSL3 facilities hinder progress. To generate a BSL2-compatible in vivo system that specifically recapitulates spike protein mediated disease we used replication competent, GFP tagged, recombinant Vesicular Stomatitis Virus where the VSV glycoprotein was replaced by the SARS-CoV-2 spike protein (rVSV-SARS2-S). We show that infection requires hACE2 and challenge of neonatal but not adult, K18-hACE2 transgenic mice (hACE2tg) leads to productive infection of the lungs and brains. Although disease progression was faster in SARS-CoV-2 infected mice, infection with both viruses resulted in neuronal infection and encephalitis with increased expression of Interferon-stimulated Irf7, Bst2, Ifi294, as well as CxCL10, CCL5, CLC2, and LILRB4, and both models were uniformly lethal. Further, prophylactic treatment targeting the Spike protein (Receptor Binding Domain) with antibodies resulted in similar levels of protection from lethal infection against rVSV-SARS2-S and SARS-CoV-2 viruses. Strikingly, challenge of neonatal hACE2tg mice with SARS-CoV-2 Variants of Concern (SARS-CoV-2-α, -β, ϒ, or Δ) or the corresponding rVSV-SARS2-S viruses (rVSV-SARS2-Spike-α, rVSV-SARS2-Spike-β, rVSV-SARS2-Spike-ϒ or rVSV-SARS2-Spike-Δ) resulted in increased lethality, suggesting that the Spike protein plays a key role in determining the virulence of each variant. Thus, we propose that rVSV-SARS2-S virus can be used to understand the effect of changes to SARS-CoV-2 spike protein on infection and to evaluate existing or experimental therapeutics targeting spike protein of current or future VOC of SARS-CoV-2 under BSL-2 conditions.

Cell and Animal Models for SARS-CoV-2 Research

During the last two years following the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, development of potent antiviral drugs and vaccines has been a global health priority. In this context, the understanding of virus pathophysiology, the identification of associated therapeutic targets, and the screening of potential effective compounds have been indispensable advancements. It was therefore of primary importance to develop experimental models that recapitulate the aspects of the human disease in the best way possible. This article reviews the information concerning available SARS-CoV-2 preclinical models during that time, including cell-based approaches and animal models. We discuss their evolution, their advantages, and drawbacks, as well as their relevance to drug effectiveness evaluation.

Animal models for COVID-19: advances, gaps and perspectives

COVID-19, caused by SARS-CoV-2, is the most consequential pandemic of this century. Since the outbreak in late 2019, animal models have been playing crucial roles in aiding the rapid development of vaccines/drugs for prevention and therapy, as well as understanding the pathogenesis of SARS-CoV-2 infection and immune responses of hosts. However, the current animal models have some deficits and there is an urgent need for novel models to evaluate the virulence of variants of concerns (VOC), antibody-dependent enhancement (ADE), and various comorbidities of COVID-19. This review summarizes the clinical features of COVID-19 in different populations, and the characteristics of the major animal models of SARS-CoV-2, including those naturally susceptible animals, such as non-human primates, Syrian hamster, ferret, minks, poultry, livestock, and mouse models sensitized by genetically modified, AAV/adenoviral transduced, mouse-adapted strain of SARS-CoV-2, and by engraftment of human tissues or cells. Since understanding the host receptors and proteases is essential for designing advanced genetically modified animal models, successful studies on receptors and proteases are also reviewed. Several improved alternatives for future mouse models are proposed, including the reselection of alternative receptor genes or multiple gene combinations, the use of transgenic or knock-in method, and different strains for establishing the next generation of genetically modified mice.

Natural and genetically-modified animal models to investigate pulmonary and extrapulmonary manifestations of COVID-19

Coronavirus disease-19 (COVID-19), a pandemic caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), is a primarily respiratory tract disease. Suitable animal models for COVID-19 are required to study various aspects of pathogenesis, drug discovery, effective and safe vaccine development. Several laboratory animals including, non-human primates, hamsters, ferrets, transgenic mice, and zebrafish, have been used and proven their significance experimentally. Currently available animal models of SARS-CoV-2 can be broadly classified into two categories 1) natural animal models 2) genetically-modified that exhibit different degrees of susceptibility of SARS-CoV-2, tissue damage in respiratory and other organ systems. Not all the available animal models mimic COVID-19-like phenotype completely. Therefore, understanding various aspects of COVID-19 requires different animal models. In this review article, we provide an update on the immune response and clinical manifestations observed in naturally occurring and genetically-modified animals of COVID-19. We then review the transmission, viral replication, lung pathology, immunological aspects, and extrapulmonary phenotypes observed in various animal models. In the end, we put forth our perspective on the anticipated uses, disadvantages, and limitations of each type of animal model.

Are Hamsters a Suitable Model for Evaluating the Immunogenicity of RBD-Based Anti-COVID-19 Subunit Vaccines?

Currently, SARS-CoV-2 spike receptor-binding-domain (RBD)-based vaccines are considered one of the most effective weapons against COVID-19. During the first step of assessing vaccine immunogenicity, a mouse model is often used. In this paper, we tested the use of five experimental animals (mice, hamsters, rabbits, ferrets, and chickens) for RBD immunogenicity assessments. The humoral immune response was evaluated by ELISA and virus-neutralization assays. The data obtained show hamsters to be the least suitable candidates for RBD immunogenicity testing and, hence, assessing the protective efficacy of RBD-based vaccines.

Using in vivo animal models for studying SARS-CoV-2

INTRODUCTION

The search for an animal model capable of reproducing the physiopathology of the COVID-19, and also suitable for evaluating the efficacy and safety of new drugs has become a challenge for many researchers.

AREAS COVERED

This work reviews the current animal models for in vivo tests with SARS-CoV-2 as well as the challenges involved in the safety and efficacy trials.

EXPERT OPINION

Studies have reported the use of nonhuman primates, ferrets, mice, Syrian hamsters, lagomorphs, mink, and zebrafish in experiments that aimed to understand the course of COVID-19 or test vaccines and other drugs. In contrast, the assays with animal hyperimmune sera have only been used in in vitro assays. Finding an animal that faithfully reproduces all the characteristics of the disease in humans is difficult. Some models may be more complex to work with, such as monkeys, or require genetic manipulation so that they can express the human ACE2 receptor, as in the case of mice. Although some models are more promising, possibly the use of more than one animal model represents the best scenario. Therefore, further studies are needed to establish an ideal animal model to help in the development of other treatment strategies besides vaccines.

Experimental Model of Pulmonary Inflammation Induced by SARS-CoV-2 Spike Protein and Endotoxin

COVID-19 is characterized by a dysregulated and excessive inflammatory response and, in severe cases, acute respiratory distress syndrome. We have recently demonstrated a previously unknown high-affinity interaction between the SARS-CoV-2 spike (S) protein and bacterial lipopolysaccharide (LPS), leading to the boosting of inflammation. Here we present a mouse inflammation model employing the coadministration of aerosolized S protein together with LPS to the lungs. Using NF-κB-RE-Luc reporter and C57BL/6 mice followed by combinations of bioimaging, cytokine, chemokine, fluorescence-activated cell sorting, and histochemistry analyses, we show that the model yields severe pulmonary inflammation and a cytokine profile similar to that observed in COVID-19. Therefore, the model offers utility for analyses of the pathophysiological features of COVID-19 and the development of new treatments.

Inflammasomes and SARS-CoV-2 Infection

SARS-CoV-2 is a new type of coronavirus that has caused worldwide pandemic. The disease induced by SARS-CoV-2 is called COVID-19. A majority of people with COVID-19 have relatively mild respiratory symptoms. However, a small percentage of COVID-19 patients develop a severe disease where multiple organs are affected. These severe forms of SARS-CoV-2 infections are associated with excessive production of pro-inflammatory cytokines, so called "cytokine storm". Inflammasomes, which are protein complexes of the innate immune system orchestrate development of local and systemic inflammation during virus infection. Recent data suggest involvement of inflammasomes in severe COVID-19. Activation of inflammasome exerts two major effects: it activates caspase-1-mediated processing and secretion of pro-inflammatory cytokines IL-1β and IL-18, and induces inflammatory cell death, pyroptosis, via protein called gasdermin D. Here, we provide comprehensive review of current understanding of the activation and possible functions of different inflammasome structures during SARS-CoV-2 infection and compare that to response caused by influenza A virus. We also discuss how novel SARS-CoV-2 mRNA vaccines activate innate immune response, which is a prerequisite for the activation of protective adaptive immune response.

Global Pandemic as a Result of Severe Acute Respiratory Syndrome Coronavirus 2 Outbreak: A Biomedical Perspective

In December 2019, a novel coronavirus had emerged in Wuhan city, China that led to an outbreak resulting in a global pandemic, taking thousands of lives. The infectious virus was later classified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Individuals infected by this novel virus initially exhibit nonspecific symptoms such as dry cough, fever, dizziness and many more bodily complications. From the “public health emergency of international concern” declaration by the World Health Organisation (WHO), several countries have taken steps in controlling the transmission and many researchers share their knowledge on the SARS-COV-2 characteristics and viral life cycle, that may aid in pharmaceutical and biopharmaceutical companies to develop SARS-CoV-2 vaccine and antiviral drugs that interfere with the viral life cycle. In this literature review the origin, classification, aetiology, life cycle, clinical manifestations, laboratory diagnosis and treatment are all reviewed.

A Combined Adjuvant TF-Al Consisting of TFPR1 and Aluminum Hydroxide Augments Strong Humoral and Cellular Immune Responses in Both C57BL/6 and BALB/c Mice

TFPR1 is a novel adjuvant for protein and peptide antigens, which has been demonstrated in BALB/c mice in our previous studies; however, its adjuvanticity in mice with different genetic backgrounds remains unknown, and its adjuvanticity needs to be improved to fit the requirements for various vaccines. In this study, we first compared the adjuvanticity of TFPR1 in two commonly used inbred mouse strains, BALB/c and C57BL/6 mice, in vitro and in vivo, and demonstrated that TFPR1 activated TLR2 to exert its immune activity in vivo. Next, to prove the feasibility of TFPR1 acting as a major component of combined adjuvants, we prepared a combined adjuvant, TF-Al, by formulating TFPR1 and alum at a certain ratio and compared its adjuvanticity with that of TFPR1 and alum alone using OVA and recombinant HBsAg as model antigens in both BALB/c and C57BL/6 mice. Results showed that TFPR1 acts as an effective vaccine adjuvant in both BALB/c mice and C57BL/6 mice, and further demonstrated the role of TLR2 in the adjuvanticity of TFPR1 in vivo. In addition, we obtained a novel combined adjuvant, TF-Al, based on TFPR1, which can augment antibody and cellular immune responses in mice with different genetic backgrounds, suggesting its promise for vaccine development in the future.

COVID-19: Lung-Centric Immunothrombosis

The respiratory tract is the major site of infection by SARS-CoV-2, the virus causing COVID-19. The pulmonary infection can lead to acute respiratory distress syndrome (ARDS) and ultimately, death. An excessive innate immune response plays a major role in the development of ARDS in COVID-19 patients. In this scenario, activation of lung epithelia and resident macrophages by the virus results in local cytokine production and recruitment of neutrophils. Activated neutrophils extrude a web of DNA-based cytoplasmic material containing antimicrobials referred to as neutrophil extracellular traps (NETs). While NETs are a defensive strategy against invading microbes, they can also serve as a nidus for accumulation of activated platelets and coagulation factors, forming thrombi. This immunothrombosis can result in occlusion of blood vessels leading to ischemic damage. Herein we address evidence in favor of a lung-centric immunothrombosis and suggest a lung-centric therapeutic approach to the ARDS of COVID-19.