Search Results (63)

The Syrian golden hamster (Mesocricetus auratus) is a universally accepted model for visceral leishmaniasis (VL) due to its ability to mimic human disease pathology. Mus musculus (BALB/c) is preferred for evaluating pharmaceutical and immunological responses. This study focuses on the precise role of gene signatures in L. donovani-infected M. auratus and M. musculus, using transcriptomic analysis. Principal component analysis (PCA) revealed distinct clustering among the four groups (uninfected vs. infected spleen samples from M. auratus and M. musculus). After differential expression analysis, 2054 genes in M. auratus and 1108 in M. musculus were found to be differentially expressed, with 153 genes common to both species. Except for 31 genes, most of the commonly dysregulated genes show a similar expression pattern. Although Th1-mediated immune signaling was observed in both cases, the overexpression of LAG3 in both infected groups underscores the important role of T cell exhaustion. Immunological responses against parasite infection in M. auratus appear to be more aggressive, while M. musculus seems more intense. Interestingly, only the M. musculus-infected group shows overexpression of IL-10. Without a definitive role for IL-10, the overexpression of Tgm2, Clec7a, and Adora2b in both species may drive disease outcome. These findings elucidate the immunological mechanisms driving the pathogenesis of VL in rodent models. Full article

Background/Objectives: Dyslipidemia and hepatic lipid buildup are key features of cardiometabolic disorders caused by high-fat, high-cholesterol diets. Both curcumin and flaxseed oil have been shown to improve lipid metabolism through different mechanisms. This study examined the effects of combining curcumin with flaxseed oil on lipid metabolism in hamsters fed a high-fat, high-cholesterol diet and further investigated the underlying mechanisms using liver and serum lipidomic analyses. Methods: Thirty-two male Golden Syrian hamsters were randomly divided into four groups (n = 8 per group): control, high-fat/high-cholesterol diet (HFD), HFD with low-dose curcumin–flaxseed oil mixture, and HFD with high-dose curcumin–flaxseed oil mixture. After 8 weeks, serum lipid profiles, hepatic triglyceride (TG) and total cholesterol (TC), fecal TG and TC excretion, hepatic mRNA expression of SREBP-1, ACC, and FAS, and untargeted lipidomic profiles in serum and liver were analyzed. Results: Compared with the HFD group, curcumin–flaxseed oil supplementation significantly reduced serum TG, TC, and LDL-C levels, while HDL-C remained unchanged. Hepatic TG and TC accumulation also decreased significantly, accompanied by increased fecal TG and TC excretion, with a more pronounced effect in the high-dose group. Hepatic SREBP-1 and ACC mRNA expression increased in the low-dose group, whereas FAS expression remained unchanged. Lipidomic analysis showed notable remodeling of diacylglycerol species in both liver and serum. A similar trend was observed in serum TG profiles, particularly TG 54:1 and TG 52:2, suggesting that changes in circulating lipids may mirror the hepatic lipidomic response. Conclusions: Curcumin combined with flaxseed oil improved dyslipidemia and hepatic lipid accumulation in hamsters fed a high-fat, high-cholesterol diet, potentially through increased lipid excretion and modulation of hepatic and circulating lipid profiles. Full article

Background/Objectives: In previous studies, chloroquine and ivermectin separately exhibited similar anticancer effects on various known cancer modulatory targets. This study aimed (1) to identify a non-toxic synergistic combination of chloroquine and ivermectin that suppresses hamster fibrosarcoma; (2) to verify combined antitumor efficacy using dose–response analysis; and (3) to investigate potential synergistic mechanisms by restoring tumor progression with the reciprocal cancer-modulating agent deoxycholic acid. Methods: A BHK-21/C13 cell culture was subcutaneously inoculated into Syrian golden hamsters randomly divided into groups (6 animals per group): (1) untreated control; treated daily (17 days after inoculation) with (2) chloroquine 50 mg/kg; (3) ivermectin 5 mg/kg; (4) a combination of chloroquine 50 mg/kg and ivermectin 5 mg/kg; (5) a combination of chloroquine 50 mg/kg, ivermectin 5 mg/kg and deoxycholic acid 100 mg/kg; (6) a combination of chloroquine 25 mg/kg and ivermectin 2.5 mg/kg; (7) a combination of chloroquine 12.5 mg/kg and ivermectin 1.25 mg/kg. Dose–response curves were generated for chloroquine and ivermectin combinations. Characteristics of tumors (growth kinetics, biophysical, histological, immunohistochemical, pathological), hamster organs, biochemical and hematological blood tests were compared among the groups. Results: The synergistic, dose-dependent anticancer effects of two antiparasitic agents, similar tumor-regulation modulators chloroquine and ivermectin, in doses equivalent to human doses were observed in fibrosarcoma in hamsters (both drugs approximately 1/10 LD₅₀) without toxicity and in various cell lines of human lung, colon and cervical carcinomas and hamster fibrosarcoma in vitro. The addition of a reciprocal modulator of cancer regulation, NF-κB stimulator deoxycholic acid, caused a huge rescue effect on fibrosarcoma and a reversal of the successful anticancer therapy using the combination. Conclusions: The chloroquine and ivermectin combination may be recommended for comprehensive additional preclinical and clinical evaluation due to its synergistic anticancer effects. Further preclinical and clinical exploration will be crucial to thoroughly define the optimal role of the combination therapy in the treatment of fibrosarcoma and potentially other cancer types. Full article

Atherosclerosis, a leading cause of cardiovascular disease, is driven by a complex interplay of dyslipidemia, inflammation, and arterial plaque formation and progression. Animal models are indispensable to elucidate the pathogenesis and develop novel therapies. Rodent models are widely utilized due to their cost-effectiveness, reproducibility, and rapid disease progression. However, notable species differences exist in lipoprotein composition and lipid metabolism pathways. Mice and rats exhibit an HDL-dominant profile, whereas Syrian golden hamsters express cholesteryl ester transfer protein (CETP) and display a higher LDL fraction, but lower than that of humans, offering a model closer to human metabolically. Divergent CETP activity across species further complicates the translational relevance of the findings from these models for atherosclerosis and related metabolic disorders. This review systematically examines the key factors in rodent model selection and optimization, with consideration on the roles of sex and age. We focus on three commonly used and well-characterized rodent strains prone to atherosclerosis: C57BL/6J mice, Sprague-Dawley (SD) rats, Wistar rats, and golden hamsters. On Apoe^−/− or Ldlr^−/− backgrounds, male C57BL/6 mice, owing to their pronounced hypercholesterolemia and extended survival with high-fat diet, are preferentially used in late-stage plaque stability studies. In contrast, male SD or Wistar rats develop atherosclerosis slowly with limited lesion progression, while hamsters, despite their human-like lipid metabolism, exhibit substantial individual variability and lesions that typically arrest at early fatty streaks with poor reproducibility. Therefore, rats and hamsters are better suited for studies focusing on early disease mechanisms and human-mimetic lipid metabolism. Full article

The agents of prion diseases have the capacity to efficiently infect susceptible hosts by peripheral routes and to project to clinical target areas of the central nervous system (CNS) via peripheral nerves. Understanding the process of prion spread from the site of infection to the CNS may allow us to identify novel therapeutic strategies. To investigate the mechanism involved in the intranerval transit of 263K scrapie prions in golden Syrian hamsters (GSHs), we transected the sciatic nerve at increasing times post-footpad injection and recorded the incubation periods as estimates of the efficiency of infection. We calculated that intranerval transit of this strain of scrapie is at least 10 times faster than previously reported and may reach 50 mm/day, similar to other neurotropic viruses. By in vivo exposure/injection of sciatic nerves to 263K infectivity, we have also shown that prion entry likely occurs via nerve terminals rather than by direct contact with the sciatic nerve. Application of this experimental approach in other forms of prion diseases could allow verification of the timing of neuroinvasion, a relevant parameter for the definition of therapeutic interventions. Full article

Despite the current level of public immunity to SARS-CoV-2, the early inflammatory events associated with respiratory distress in COVID-19 patients are not fully elucidated. Syrian golden hamsters, facultative hibernators, recapitulate the phenotype of SARS-CoV-2-induced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—induced severe acute lung injury seen in patients. In this study, we describe the predominance of the innate immune response in hamsters inoculated with four different SARS-CoV-2 variants, underscoring phenotypic differences among them. Severe inflammatory lung injury was chronologically associated with acute and significant weight loss, mainly in animals inoculated with A.2 and Delta variants. Omicron-infected animals had lower overall histopathology scores compared to other variants. We highlight the central role of endothelial injury and activation in the pathogenesis of experimental SARS-CoV-2 infection in hamsters, characterised by the presence of proliferative type I and type II pneumocytes with abundant surfactant expression, thereby maintaining hyperinflated alveolar fields. Additionally, there was evidence of intrapulmonary lymphatic vessel proliferation, which was accompanied by a lack of detectable microthrombosis in the lung parenchyma. However, white microthrombi were observed in lymphatic vessels. Our findings suggest that the physiological compensatory mechanisms that maintain respiratory homeostasis in Golden Syrian hamsters prevent severe respiratory distress and death after SARS-CoV-2 infection. Full article

Animal models are indispensable in biomedical research, offering critical insights into disease mechanisms and therapeutic strategies. However, existing models often inadequately replicate human pathophysiology, leading to discrepancies between preclinical and clinical outcomes. Despite their contributions, many models exhibit significant limitations, especially concerning cancer and infectious diseases. Inaccurate modeling of human biological responses can result in failed clinical trials, escalated research costs, and delays in developing effective treatments. The golden hamster (Mesocricetus auratus) has emerged as a viable model, particularly in cancer and infectious disease research. Sharing physiological and immunological profiles similar to humans, the golden hamster offers distinct advantages over other rodent models, such as mice and rats. This review explores the benefits of using golden hamsters in cancer research, highlighting their contributions to scientific advancements while also addressing the limitations due to incomplete immunological and molecular knowledge about this species. Full article

Background/Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus Disease 2019 (COVID-19), has rapidly evolved, giving rise to multiple Variants of Concern—including Alpha, Beta, Gamma, Delta, and Omicron—which emerged independently across different regions. Licensed COVID-19 vaccines primarily target the highly mutable spike protein, resulting in reduced efficacy due to immune escape by emerging variants. Previously, we developed a live attenuated Francisella tularensis LVS ΔcapB single-vector platform COVID-19 vaccine, rLVS ΔcapB/MN, expressing the conserved membrane (M) and nucleocapsid (N) proteins from the early SARS-CoV-2 WA-01/2020 strain. In this study, we evaluate the efficacy of rLVS ΔcapB/MN and an enhanced version, rLVS ΔcapB::RdRp/MN, which additionally expresses the conserved RNA-dependent RNA polymerase (RdRp) protein from the same strain, in a hamster model. Methods: Both vaccine candidates were administered orally or intranasally to golden Syrian hamsters (equal numbers of males and females) and evaluated against intranasal challenge with SARS-CoV-2 Delta (B.1.617.2-AY.1) and Omicron (BA.5) variants. Results: Vaccinated animals developed robust, TH1-biased IgG responses specific to the nucleocapsid protein. Following SARS-CoV-2 challenge, immunized hamsters exhibited reduced weight loss, lower oropharyngeal and lung viral titers, and improved lung pathology scores compared with unvaccinated controls. Conclusion: These findings support the potential of this universal vaccine to provide broad protection against current and future SARS-CoV-2 variants, with minimal need for updating. Full article

Background/Objectives: The ongoing COVID-19 pandemic has underscored the need for alternative prophylactic measures, particularly for populations for whom vaccines may not be effective or accessible. This study aims to evaluate the efficacy of intranasally administered IgY antibodies derived from hen egg yolks as a protective agent against SARS-CoV-2 infection in Syrian golden hamsters, a well-established animal model for COVID-19. Methods: Hens were immunized with the spike protein of SARS-CoV-2 to generate IgY antibodies. These antibodies were extracted from the egg yolks, purified, and their neutralizing activity was tested in vitro. Syrian golden hamsters were then treated with the IgY antibodies before being challenged with SARS-CoV-2. Viral loads were quantified using droplet digital PCR (ddPCR), and lung pathology was assessed through histopathological analysis. Results: The in vitro assays showed that IgY effectively neutralized SARS-CoV-2. In the in vivo hamster model, IgY treatment led to a significant reduction in viral loads and a marked decrease in lung consolidation and inflammation compared to the positive control group. Histopathological findings further supported the protective role of IgY in reducing lung damage caused by SARS-CoV-2. Conclusions: The results demonstrate that IgY antibodies exhibit strong antiviral activity and can significantly reduce SARS-CoV-2 viral loads and associated lung pathology in hamsters. These findings suggest that IgY could be a viable prophylactic option for preventing SARS-CoV-2 infection, particularly for individuals who cannot receive or respond to vaccines. Further studies are warranted to optimize dosage and explore the long-term efficacy of IgY antibodies. Full article

Favipiravir (FVP) and remdesivir (RDV) have demonstrable antiviral activity against SARS-CoV-2. Here, the efficacy of FVP, RDV, and FVP with RDV (FVP + RDV) in combination was assessed in Syrian golden hamsters challenged with SARS-CoV- 2 (B.1.1.7) following intraperitoneal administration. At day 4 post infection, viral RNA and viral antigen expression were significantly lower in lungs for all three treatment groups compared to the sham treatment. Similarly, viral titres in the lungs were lower in all treatment groups compared to the sham treatment. The FVP + RDV combination was the only treatment group where viral RNA in nasal turbinate and lung, virus titres in lung, and viral antigen expression (lung) were all lower than those for the sham treatment group. Moreover, lower viral titre values were observed in the FVP + RDV group compared to other treatment groups, albeit only significantly lower in comparison to those in the RDV-only-treated group. Further assessment of the potential utility of FVP in combination with RDV may be warranted. Future studies should also consider whether the combination of these two drugs may reduce the speed at which drug resistance mutations are selected. Full article

Background/Objectives: Influenza viruses and SARS-CoV-2 are currently cocirculating with similar seasonality, and both pathogens are characterized by a high mutational rate which results in reduced vaccine effectiveness and thus requires regular updating of vaccine compositions. Vaccine formulations combining seasonal influenza and SARS-CoV-2 strains can be considered promising and cost-effective tools for protection against both infections. Methods: We used a licensed seasonal trivalent live attenuated influenza vaccine (3×LAIV) as a basis for the development of a modified 3×LAIV/CoV-2 vaccine, where H1N1 and H3N2 LAIV strains encoded an immunogenic cassette enriched with conserved T-cell epitopes of SARS-CoV-2, whereas a B/Victoria lineage LAIV strain was unmodified. The trivalent LAIV/CoV-2 composition was compared to the classical 3×LAIV in the golden Syrian hamster model. Animals were intranasally immunized with the mixtures of the vaccine viruses, twice, with a 3-week interval. Immunogenicity was assessed on day 42 of the study, and the protective effect was established by infecting vaccinated hamsters with either influenza H1N1, H3N2 or B viruses or with SARS-CoV-2 strains of the Wuhan, Delta and Omicron lineages. Results: Both the classical 3×LAIV and 3×LAIV/CoV-2 vaccine compositions induced similar levels of serum antibodies specific to all three influenza strains, which resulted in comparable levels of protection against challenge from either influenza strain. Protection against SARS-CoV-2 challenge was more pronounced in the 3×LAIV/CoV-2-immunized hamsters compared to the classical 3×LAIV group. These data were accompanied by the higher magnitude of virus-specific cellular responses detected by ELISPOT in the modified trivalent LAIV group. Conclusions: The modified trivalent live attenuated influenza vaccine encoding the T-cell epitopes of SARS-CoV-2 can be considered a promising tool for combined protection against seasonal influenza and COVID-19. Full article

The SARS-CoV-2 pandemic has highlighted the challenges posed by the emergence and rapid global spread of previously unknown viruses. Early investigations on the pathogenesis of newly identified viruses are often hampered by a lack of appropriate sample material and conventional detection methods. In this study, viral replication within the lungs of SARS-CoV-2-infected Syrian golden hamsters was assessed by immunolabeling dsRNA intermediates with three different monoclonal antibodies in formalin-fixed, paraffin-embedded tissue samples. The presence of dsRNA was compared to viral antigen levels, viral titers, and genomic RNA replicates using three different variants of concern and an ancestral virus strain at a single time point and during the course of infection with an ancestral variant, and then validated using fluorescent 2-plex in situ hybridization. The results indicate that the detection of viral infection using anti-dsRNA antibodies is restricted to an early phase of infection with high viral replication activity. Additionally, the combined detection of dsRNA intermediates and viral antigens may help to bridge the interpretation gaps between viral antigen levels and viral titers at a single time point. Further testing in other viral infections or species is needed to assess the potential of dsRNA as an early marker for viral infections. Full article

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 × 10^0.15 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 10^5.5−6.5 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. Full article

Background and Aims: Hypercholesterolemia leads to cardiovascular diseases and atherosclerosis. Previous studies have highlighted the crucial role of gut microbiota in alleviating atherosclerosis progression and reducing plasma cholesterol. However, the protective effects of Houttuynia cordata Thunb (HCT), a well-known fishy Chinese herb, against hypercholesterolemia and vasculopathy remain largely unknown. This study aims to explore the effects of HCT extracts on vascular health and gut microbiota in golden Syrian hamsters with hypercholesterolemia. Methods: The hypercholesterolemia hamster model was established by feeding with a high-cholesterol diet. Aqueous or ethanolic HCT extracts were mixed with diet and concurrently given to hamsters for Six weeks. Plasma lipid profiles were evaluated. Aortas were collected to detect fatty streak areas. Feces were collected to analyze the abundance of microorganisms in the gut microbiota. Results: HCT ethanolic extract treatment remarkedly decreased plasma levels of total cholesterol and high-density lipoprotein cholesterol in hypercholesterolemic hamsters. Notably, both aqueous and ethanolic extracts of HCT reduced atherosclerotic plaques in hamsters fed with a high-cholesterol diet. Strikingly, the effects of HCT ethanolic extract in reducing atherosclerotic plaques are greater than aqueous extract. Furthermore, at the phylum level, the relative abundance of Firmicutes was decreased in hamsters treated with aqueous and ethanolic extracts of HCT. By contrast, the abundance of Bacteroidetes was increased by HCT treatment. At the family level, HCT extract favourably modulated the relative abundance of Porphyromonadaceae and Bacteroidales_S24-7_group. These findings indicate that HCT extracts may facilitate the growth of short-chain fatty acids-producing bacteria to alter gut microbiota composition, contributing to the reduction of plasma lipid levels. Conclusions: This study offers evidence demonstrating the effects of HCT extracts on alleviating atherosclerosis and lowering plasma cholesterol levels in the male hypercholesterolemic hamster model, offering novel insights into the pharmacological effects and promoting the application of HCT. This study highlights the potential of HCT as a dietary supplement to alleviate atherosclerosis, lower plasma cholesterol, and modulate the abundance of microorganisms in gut microbiota. Full article

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. Full article