Search Results (152)

The cross-species spillover of coronaviruses is considered a serious public health risk. Feline coronavirus (FCoV), canine coronavirus (CCoV), and transmissible gastroenteritis virus (TGEV) are all classified under Alphacoronavirus suis and infect companion animals and livestock. Due to their frequent contact with humans, these viruses pose a potential risk of future cross-species transmission. Molnupiravir, a prodrug of N4-hydroxycytidine, exhibits potent antiviral activity against SARS-CoV-2, a member of the Betacoronavirus genus, and has been approved for the treatment of COVID-19. Molnupiravir was recently shown to be effective against FCoV, suggesting broad-spectrum antiviral activity across coronavirus lineages. Based on these findings, the present study investigated whether molnupiravir is also effective against CCoV and TGEV, which belong to the same Alphacoronavirus suis species as FCoV. We examined the in vitro antiviral effects of molnupiravir using four viral strains: FCoV-1 and -2, CCoV-2, and TGEV. Molnupiravir inhibited plaque formation, viral antigen expression, the production of infectious viral particles, and viral RNA replication in a dose-dependent manner in all strains. IC₅₀ values for CCoV-2 and TGEV, calculated using a feline-derived cell line (fcwf-4), were significantly lower than those for FCoV, suggesting higher sensitivity to molnupiravir. These results demonstrate that molnupiravir exhibited broad antiviral activity against animal coronaviruses classified under Alphacoronavirus suis, providing a foundation for antiviral strategies to mitigate the future risk of cross-species transmission. Full article

The emergence of a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus closely related to SARS-CoV and officially known as Betacoronavirus pandemicum precipitated a substantial surge in vaccine development that culminated during the global COVID-19 pandemic. At present, there are dozens of vaccines for the prevention of SARS-CoV-2 being utilized across the globe. However, only 10 of these vaccines have been authorized by the World Health Organization (WHO). These include mRNA-based, viral vector, subunit and whole-virion inactivated vaccines. At the current end of the pandemic, there has been a decline in the global vaccination rate, both for the general population and for those most at risk of severe illness from the virus. This suggests that the effectiveness of the vaccines may be waning. The decline occurs alongside a decrease in testing and sequencing for SARS-CoV-2. Furthermore, the process of tracking viruses becomes increasingly complex, thereby providing a selective advantage for SARS-CoV-2 and allowing it to evolve stealthily. In this review, we provide a comprehensive overview of viral evolution and vaccine development. We also discuss ways to overcome viral variability and test universal vaccines for all SARS-CoV-2 variants. Full article

The recent COVID-19 pandemic has prompted the scientific community to prioritize the discovery of preventive methods and new therapeutics, including the investigation of natural compounds with antiviral potential. Fungal secondary metabolites (SMs) represent a promising source of antiviral drugs due to their structural diversity and intrinsic biocompatibility. Herein, the antiviral activity of 6-pentyl-α-pyrone (6PP) against bovine coronavirus (BCoV) has been evaluated in vitro. Considering that BCoV and SARS-CoV-2 are both members of the Betacoronavirus genus and share several key features, BCoV represents a valuable reference model for human coronavirus research. A non-cytotoxic dose of 6PP was used on MDBK cells to evaluate its antiviral activity against BCoV. Different experimental conditions were employed to examine cell monolayer protection both pre- and post-infection, as well as the potential inhibition of viral internalization. Overall, post-infection 6PP treatment reduced viral load and decreased viral internalization. Results were analyzed using viral titration and quantitative PCR, while data interpretation was performed by statistical software tools. This study presents a novel fluorescence quantification approach with high confidence demonstrated by its significant concordance with RT-qPCR results. These data suggest that 6PP could be an effective antiviral agent for BCoV, warranting further investigation of its role in coronavirus inhibition. Full article

At least three betacoronaviruses have spilled over from bats to humans and caused severe diseases, highlighting the threat of zoonotic transmission. Thus, it is important to enhance surveillance capabilities by developing tools capable of detecting a broad spectrum of bat-borne betacoronaviruses. Three monoclonal antibodies (mAbs) targeting the nucleocapsid (N) protein were generated using recombinant N proteins from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV). The cross-reactivities of these mAbs were evaluated against a panel of betacoronaviruses. Sandwich ELISAs (sELISAs) were subsequently developed to detect bat-borne betacoronaviruses that have high zoonotic potential. Among the mAbs, 7A7 demonstrated the broadest cross-reactivity, recognizing betacoronaviruses from the Sarbecovirus, Merbecovirus and Hibecovirus subgenera. The first sELISA, based on mAbs 7A7 and 6G10, successfully detected N protein in all clinical swab samples from COVID-19 patients with cycle threshold (Ct) values < 25, achieving 75% positivity overall (12/16). Using this as a reference, a second sELISA was established by pairing mAb 7A7 with mAb 8E2, which binds to multiple merbecoviruses. This assay detected the N protein of two merbecoviruses, namely the human MERS-CoV and bat-borne HKU5-CoV, at high sensitivity and has a limit of detection (LOD) that is comparable to the first sELISA used successfully to detect COVID-19 infection. These broadly reactive mAbs could be further developed into rapid antigen detection kits for surveillance in high-risk populations with close contact with wild bats to facilitate the early detection of potential zoonotic spillover events. Full article

Merbecovirus, a subgenus of Betacoronavirus, includes MERS-CoV and multiple bat-derived viruses with zoonotic potential. Given the unpredictable emergence of these viruses and their genetic diversity, development of broad-spectrum diagnostic tools is expected. In this study, we established a sandwich ELISA targeting the nucleocapsid (N) protein of merbecoviruses. We generated monoclonal antibodies (mAbs) using recombinant N protein of a bat merbecovirus, VsCoV-1, and selected cross-reactive clones for other merbecoviruses. Three mAbs showed strong reactivities with multiple merbecoviruses but not with SARS-CoV-2 or endemic human coronaviruses. Pairwise ELISA screening identified 1A8/10H6 mAbs as the optimal combination for detection of N protein from six merbecoviruses—VsCoV-1, EjCoV-3, MERS-CoV, NeoCoV, HKU4, and HKU5—with limits of detection (LODs) below 7.81 ng/mL, including 1.25 ng/mL for VsCoV-1. Infectious bat merbecovirus EjCoV-3 was detected at 1.3 × 10³ PFU/mL. No cross-reactivity was observed with non-merbecoviruses, indicating its high specificity. This sandwich ELISA offers a rapid, reproducible, and cost-effective diagnostic platform with potential for high-throughput screening and automation. Moreover, its design is amenable to adaptation into point-of-care formats such as lateral flow assays, highlighting its value for field-based surveillance and pandemic preparedness. Full article

Background/Objectives: The COVID-19 pandemic, caused by SARS-CoV-2, required the rapid development of diagnostic tests. SARS-CoV-2, part of the betacoronavirus genus, shares characteristics with SARS-CoV-1, including its ability to survive on surfaces, facilitating the spread of the infection. This study analyzes the technique of nasopharyngeal secretion collection for SARS-CoV-2 diagnosis and compares the accuracy of rapid antigen and molecular tests. Methods: This study had two components: study A assessed the healthcare personnel training in collecting nasopharyngeal secretions and the discomfort associated with applying a questionnaire. Study B compared rapid antigen test accuracy with RT-PCR among children, through a retrospective analysis. The data were statistically analyzed to assess compliance with the testing protocols. Results: In study A, 88 healthcare workers achieved an average compliance score of 7.60 out of 10 regarding the collection procedure. Over 70% of participants correctly followed the fundamental steps of the procedure. Many patients who underwent sample collection reported pain and symptoms such as coughing or sneezing. In study B, 198 pediatric patients were tested using rapid antigen tests, collected simultaneously with RT-PCR. The rapid tests showed a 50% sensitivity and 97.5% specificity. Conclusions: This study indicates that nasopharyngeal specimen collection techniques are based on international recommendations, but improvements could be made to reduce discomfort. Rapid antigen tests are helpful for screening due to their high specificity and negative predictive value. Continuous healthcare personnel training and the monitoring of diagnostic techniques remain essential in managing SARS-CoV-2 and other viral infections. Full article

The recent COVID-19 pandemic has renewed interest in bats, as they are natural hosts for numerous viruses, some of which have crossed species boundaries. Despite continued efforts in the past, the ecology of bat-related viruses in a significant part of national territories, such as Italy, remains largely unexplored. Herein, we describe the detection and molecular characterization of bat coronaviruses, identified during a viral survey on selected potential zoonotic pathogens (lyssavirus and coronaviruses) carried out in Sicily, southern Italy. A total number of 330 samples were collected from 149 bats in a period (November 2020–April 2023) overlapping the COVID-19 pandemic. All samples tested negative for lyssavirus and SARS-CoV-2, while 12 bats (8.05%) tested positive to a pan-coronavirus assay. Both alphacoronaviruses and betacoronaviruses were identified in samples from three species (Miniopterus schreibersii, Rhinolophus ferrumequinum, and Rhinolophus hipposideros). Strain sequences were related to coronaviruses detected in the last decade in northern Italy as well as in other countries bordering the Mediterranean basin, suggesting a widespread diffusion of these strains. This study supports the need for further monitoring efforts and early detection of circulating coronavirus genotypes, particularly for those which have been repeatedly emerging as zoonotic spillovers. Full article

Oregano oil was successfully encapsulated into chitosan–albumin nanogel via emulsification and electrostatic gelation. The system was characterized with a mean diameter around 26 nm, narrow size distribution (PDI = 0.242) and approximately 40% encapsulation efficiency. The incorporation of the oil into the nanogel was confirmed by XRD and FTIR analyses, and the dissolution of the oil was enhanced after the encapsulation. Furthermore, the treatment of Betacoronavirus 1 infected bovine kidney MDBK cells with the oregano oil-loaded nanogel (25 µg/mL) showed more than 50% protection against the infection, as compared to the non-treated virus infected control. The cytopathic effect (CPE) of the virus was inhibited in a concentration-dependent manner. The system inhibited the virus replication, resulting in a decrease of the viral particles by more than half, as shown by the cytotoxicity and CPE assays. The virus titer in treated and non-treated samples was determined by digital droplet PCR and revealed Δ3 log diminishment of the virus particles in samples treated with 25 µg/mL encapsulated oregano oil. This study is a basis for further investigations on the pharmacodynamics of the nanogel and its possible combinations with clinically applied chemotherapeutics. Full article

SARS-CoV-2 has demonstrated a remarkable capacity for immune evasion. While initial studies focused on the Wuhan variant and adaptive immunity, later emerging strains such as Omicron exhibit mutations that may alter their immune-modulatory properties. We performed a comprehensive review of immune evasion mechanisms associated with SARS-CoV-2 viral proteins to focus on the evolutionary dynamics of immune modulation. We systematically analyzed and compared the impact of all currently known Wuhan and Omicron SARS-CoV-2 proteins on type I interferon (IFN) responses using a dual-luciferase reporter assay carrying an interferon-inducible promoter. Results revealed that Nsp1, Nsp5, Nsp14, and ORF6 are potent type I IFN inhibitors conserved across Wuhan and Omicron strains. Notably, we identified strain-specific differences, with Nsp6 and Spike proteins exhibiting enhanced IFN suppression in Omicron, whereas the Envelope protein largely retained this function. To extend these findings, we investigated selected proteins in primary human endothelial cells and also observed strain-specific differences in immune response with higher type I IFN response in cells expressing the Wuhan strain variant, suggesting that Omicron’s adaptational mutations may contribute to a damped type I IFN response in the course of the pandemic’s trajectory. Full article

Most human emerging infectious diseases are zoonotic, originating in animal hosts prior to spillover to humans. Prioritizing the surveillance of wildlife that overlaps with humans and human activities can increase the likelihood of detecting viruses with a high potential for human infection. Here, we obtained fecal swabs from two fruit bat species—Eidolon helvum (n = 6) and Epomophorus wahlbergi (n = 43) (family Pteropodidae)—in peridomestic habitats in Nairobi, Kenya, and used metagenome sequencing to detect microorganisms. A near-complete genome of a novel virus assigned taxonomically to the Coronaviridae family Betacoronavirus genus and Nobecovirus subclade was characterized from E. wahlbergi. Phylogenetic analysis indicates this unique Nobecovirus clade shares a common ancestor with Eidolon/Rousettus Nobecovirus subclades isolated from Madagascar, Kenya, and Cameroon. Recombination was detected across open reading frames, except the spike protein, in all BOOTSCAN analyses, indicating intra-host coinfection and genetic exchange between genome regions. Although Nobecoviruses are currently bat-specific and are not known to be zoonotic, the propensity of coronaviruses to undergo frequent recombination events and the location of the virus alongside high human and livestock densities in one of East Africa’s most rapidly developing cities justifies continued surveillance of animal viruses in high-risk urban landscapes. Full article

The emergence of zoonotic viral diseases, notably exemplified by the recent coronavirus disease pandemic in 2019 (COVID-19), underscores the critical need to understand the dynamics of viruses circulating in wildlife populations. This study aimed to investigate the diversity of coronaviruses in bat populations from northeastern Brazil, particularly in the state of Ceará, where little research on bat pathogens has been conducted previously. Bat sampling was performed between March 2021 and March 2022 across three municipalities, resulting in the collection of oral and rectal swabs from 298 captured individuals. Molecular analyses revealed alphacoronaviruses in multiple bat species. Additionally, a novel Betacoronavirus was identified in Artibeus planirostris, which did not fall within an established subgenus. Phylogenetic placement of these new coronavirus sequences suggests that closely related coronavirus lineages can infect a wide range of bat species sampled in distantly related Brazilian states and biomes. No SARS-CoV-2 and influenza A viruses were found in the sampled bats. These findings expand our understanding of coronavirus diversity in Brazilian bats. The detection of coronaviruses in various bat species underscores the importance of bats as reservoirs for these viruses. The absence of SARS-CoV-2 in the sampled bats indicates a lack of spillback events from human or environmental sources. However, the potential for future transmission events underscores the importance of ongoing surveillance and transmission mitigation protocols in wildlife management practices. Full article

The betacoronavirus genus contains five of the seven human coronaviruses, making it a particularly critical area of research to prepare for future viral emergence. We utilized three human betacoronaviruses, one from each subgenus—HCoV-OC43 (embecovirus), SARS-CoV-2 (sarbecovirus), and MERS-CoV (merbecovirus)—, to study betacoronavirus interactions with the PKR-like ER kinase (PERK) pathway of the integrated stress response (ISR)/unfolded protein response (UPR). The PERK pathway becomes activated by an abundance of unfolded proteins within the endoplasmic reticulum (ER), leading to phosphorylation of eIF2α and translational attenuation. We demonstrate that MERS-CoV, HCoV-OC43, and SARS-CoV-2 all activate PERK and induce responses downstream of p-eIF2α, while only SARS-CoV-2 induces detectable p-eIF2α during infection. Using a small molecule inhibitor of eIF2α dephosphorylation, we provide evidence that MERS-CoV and HCoV-OC43 maximize viral replication through p-eIF2α dephosphorylation. Interestingly, genetic ablation of growth arrest and DNA damage-inducible protein (GADD34) expression, an inducible protein phosphatase 1 (PP1)-interacting partner targeting eIF2α for dephosphorylation, did not significantly alter HCoV-OC43 or SARS-CoV-2 replication, while siRNA knockdown of the constitutive PP1 partner, constitutive repressor of eIF2α phosphorylation (CReP), dramatically reduced HCoV-OC43 replication. Combining GADD34 knockout with CReP knockdown had the maximum impact on HCoV-OC43 replication, while SARS-CoV-2 replication was unaffected. Overall, we conclude that eIF2α dephosphorylation is critical for efficient protein production and replication during MERS-CoV and HCoV-OC43 infection. SARS-CoV-2, however, appears to be insensitive to p-eIF2α and, during infection, may even downregulate dephosphorylation to limit host translation. Full article

The nucleocapsid (N) protein is the most expressed protein in later stages of SARS-CoV-2 infection with several important functions. It is translated from a subgenomic mRNA (sgmRNA) formed by template switching during transcription. A recently described translation initiation site (TIS) with a CTG codon in the leader sequence (TIS-L) is out of frame with most structural and accessory genes including the N gene and may act as a translation suppressor. We analyzed multiple sequenced samples infected by SARS-CoV-2 and found that any single variant of this virus produces multiple isoforms of the N sgmRNA. The main isoform starting at TIS-L is out of frame, but two secondary dominant isoforms (present in nearly all samples) were found to restore the reading frame and likely involved in the regulation of N protein production. Analysis of sequenced samples infected by other coronaviruses revealed that such isoforms are also produced in their transcriptomes. In SARS-CoV, they restore the reading frame for a putative TIS (also a CTG codon) in the same relative position as in SARS-CoV-2. Positions of junction breakpoints relative to stem loop 3 in the 5′-UTR suggest similar mechanisms in SARS-CoV, SARS-CoV-2, and OC43, but not in MERS-CoV. These observations may be pertinent for antisense-based antiviral strategies. Full article

SARS-CoV-2 (Betacoronavirus pandemicum) is responsible for the disease identified by the World Health Organization (WHO) as COVID-19. We designed “CHIVAX 2.1”, a multi-epitope vaccine, containing ten immunogenic peptides with conserved B-cell and T-cell epitopes in the receceptor binding domain (RBD) sequences of different SARS-CoV-2 variants of concern (VoCs). We evaluated the immune response of mice immunized with 20 or 60 µg of the chimeric protein with two different alum adjuvants (Alhydrogel^® and Adju-Phos^®), plus PHAD^®, in a two-immunization regimen (0 and 21 days). Serum samples were collected on days 0, 21, 31, and 72 post first immunization, with antibody titers determined by indirect ELISA, while lymphoproliferation assays and cytokine production were evaluated by flow cytometry. The presence of neutralizing antibodies was assessed by surrogate neutralization assays. Higher titers of total IgG, IgG₁, and IgG_2a antibodies, as well as increased proliferation rates of specific CD4⁺ and CD8⁺ T cells, were observed in mice immunized with 60 μg of protein plus Adju-Phos^®/PHAD^®. This formulation also generated the highest levels of TNF-α and IFN-γ, in addition to the presence of neutralizing antibodies against Delta and Omicron VoC. These findings indicate the potential of this chimeric multi-epitope vaccine with combined adjuvants as a promising platform against viral infections, eliciting a T_H1 or T_H1:T_H2 balanced cell response. Full article

COVID-19 is an infectious disease caused by the SARS-CoV-2 virus. During and after COVID-19, audiovestibular symptoms and impairments have been reported. Objectives: This study aimed to investigate the impacts of COVID-19 on the peripheral and central auditory systems of children and adolescents following the acute COVID-19 phase based on behavioral, electroacoustic, and electrophysiological audiological assessments. Methods: This is a primary, prospective, observational, and cross-sectional study of 23 children aged 8 to 15 years who acquired confirmed COVID-19 and who, before infection, had not had any auditory complaints or school complications. The results were compared with pre-pandemic data collected from a similar group of 23 children who had normal peripheral and central hearing and good school performance. Each participant answered a questionnaire about child development, school, and health history and underwent tests including pure-tone audiometry and high-frequency audiometry, imitanciometry, transient evoked otoacoustic emissions, and distortion product otoacoustic emissions. They also received tests of Brainstem Auditory Evoked Potentials, Long Latency Auditory Evoked Potentials, Dichotic Digits Test, Sentence Identification Test, Dichotic Consonant–Vowel Test, Frequency Pattern Test, and Gaps-In-Noise Test. Results: Significant differences were observed between the groups, with the study group showing worse thresholds compared to the control group at both standard audiometric frequencies and at higher frequencies, although both groups were still within normal limits (p ≤ 0.05). In addition, the study group had a higher prevalence of absent responses, as identified by otoacoustic emissions and acoustic reflexes. In terms of central auditory performance, the study group showed ABRs with significantly longer latencies of waves I, III, and V compared to the control group. The study group also performed less well on the Dichotic Digits and Pediatric Speech Identification tests. Conclusions: COVID-19 appears to alter the auditory system, both peripherally at the level of the outer hair cells and more centrally. Full article