Search Results (239)

Understanding host cell response to viral infection could lead to the identification of molecular targets that can be used for the development of diagnostics and therapeutics. In this study, we investigated human dendritic cell (DC) response to infections with Vaccinia (VAC) virus, a highly immunogenic poxvirus, and Venezuelan Equine Encephalitis (VEE) virus, a single-stranded positive-strand RNA alphavirus, using human gene expression microarrays. Comparative changes in DC mRNA expression resulting from infection by the two viruses at 1, 8, and 12 h post-infection (hpi) revealed distinct temporal dynamics. VAC infection triggered early and robust activation of pathways related to chromatin organization, DNA damage, and antigen presentation, while VEE infection exhibited delayed activation of immune signaling pathways, including interferon signaling and cytokine production. Shared pathways, such as interferon signaling and inflammasome activation, highlight universal antiviral responses and potential therapeutic targets. These findings provide a molecular framework affected by VAC and VEE that need to be validated with additional experiments, such as functional assays or in vivo studies. The specific up- or downregulation of these pathways at different time points likely dictates the overall outcome of the viral infection and could potentially lead to better understanding of the temporal regulatory dynamics of virus host response. Full article

The 2022 global mpox outbreak represented a turning point in the Monkeypox virus (MPXV) epidemiology, highlighting the incredible capability of this virus to adapt to different conditions, also in a non-endemic context. To investigate the genomic dynamics of MPXV 2022 strains, we performed whole-genome sequencing of 40 clinical samples from 16 Italian patients across multiple anatomical sites and timepoints between May and December 2022. Combining single-nucleotide analysis with detailed investigation of short tandem repeats (STRs), we explored inter- and intra-host viral dynamics. We identified 19 STR loci located near or within genes involved in immune modulation and virion morphogenesis. While most STRs remained stable across patients, a subset displayed locus- or matrix-specific variation. Among these, STR-VII—embedded within the coding sequence of OPG153, an envelope-associated protein implicated in viral attachment—showed a 12-nucleotide in-frame deletion, resulting in the loss of four aspartic acid residues (Δ4D variant). Structural modeling indicated that this deletion slightly alters a disordered acidic loop without affecting the global fold, potentially modulating surface charge and immune recognition. Integrating STR profiling into genomic surveillance may enhance resolution in outbreak reconstruction and reveal subtle adaptive processes underlying poxvirus–host interaction and immune escape. Full article

Introduction: Despite the impressive progress carried out in the field of biomedical sciences in recent decades, the incidence of emerging and neglected lethal viral infections mainly belonging to the Coronaviridae, Filoviridae, Arenaviridae, Bunyaviridae, and Paramyxoviridae families has considerably impaired human health. The worldwide vaccination campaign at the end of the 1970s determined the eradication of smallpox. However, the growing number of cases of diseases linked to orthopoxvirus diseases, such as the recent epidemic of monkeypox zoonosis in various countries around the world, has increased the need for knowledge of these viral pathogens. To date, there is no specific treatement for Monkeypox virus (MPXV) infection. However, several antiviral drugs used to treat Smallpox and other viral infections could also be beneficial for Monkeypox disease. In this study we report the design and synthesis of new, variously substituted benzimidazole derivatives and the evaluation of their cytotoxicity and antiviral activity against representatives of the Orthopoxvirus genus, Vaccinia Virus (VV), closely related to variola virus and MPXV. Methods: A combination of cell-based assays and experimental techniques was used to investigate the cytotoxicity, antiviral activity, and mechanisms of action of the most interesting compound. Results: In our study, new, variously substituted benzimidazoles showed interesting EC₅₀ values against vaccinia and MPXV and a cytotoxic profile in the high micromolar range. Conclusions: Our work shows that the new tested benzimidazole derivatives possess appealing activity and selectivity, accompanied by low cytotoxicity. These results set a valid foundation with which to identify potent and selective anti-Poxvirus agents. Full article

The monkeypox virus (MPXV) is an emerging zoonotic pathogen responsible for mpox, a disease characterized by some smallpox-like symptoms, typically mild but occasionally fatal. The largest mpox recorded global outbreak began in May 2022, with over 162,000 cases across 140 countries. Herein, we have analyzed the intra-clonal diversity of MPXV obtained from a single skin lesion sample from a male patient (June 2022). Three viral clones were obtained following phenotypic evaluation of MPXV lysis plaque characteristics over a three-course infection in BSC-40 cells. Unlike the vaccinia virus Western Reserve (VACV-WR) strain, MPXV clones did not produce comet-like structures, suggesting reduced extracellular enveloped virus (EEV) morphotype release, which is associated with viral dissemination. Whole-genome sequencing and assembly identified subtle differences among clones. Comparative genomic analyses, including synteny and single nucleotide variation (SNV) calling, revealed intra-clonal differences and divergence from clade I and II references, although the variety of mutations found did not reveal possible variations at the protein level. Altogether, these findings suggest that although similar, it is possible that distinct MPXV variants may circulate together and can be found in a single exanthematous lesion. Full article

Protein kinase R (PKR) is an antiviral protein that is involved in molecular “arms races” with viral antagonists. As a result, some PKR inhibitors, including the vaccinia virus (VACV) protein K3 and its orthologs from other poxviruses only inhibit PKRs of selected species. We previously reported contrasting inhibition patterns of human, sheep, and cow PKRs by VACV K3 and the sheeppox virus (SPPV) K3 ortholog, SPPV 011. Here we show that the differential sensitivities of cow and sheep PKRs to VACV K3 were mediated by only two residues in PKR helix αG. In contrast, SPPV 011 sensitivities were governed by additional residues and regions. Analysis of the PKR sensitivities from 20 mammalian species to VACV K3 and SPPV 011 revealed four different sensitivity patterns: some PKRs were inhibited by only one K3 ortholog, as previously reported, whereas other PKRs were either resistant or sensitive to both inhibitors. Furthermore, we characterized a residue (K45) in VACV K3 that is involved in the species-specific inhibition of PKR. Mutating this residue increased the inhibition of sheep but not human PKR, whereas it decreased the inhibition of mouse PKR, highlighting that a single mutation in a viral protein can result in distinct species-dependent inhibition changes. Full article

Background: Poxviruses constitute a family of large dsDNA viruses that can infect a plethora of species including humans. Historically, poxviruses have caused a health burden in multiple outbreaks. The large genome of poxviruses favors reverse vaccinology approaches that can determine potential antigens and epitopes. Here, we propose the modeling of a user-friendly database containing the predicted antigens and epitopes of a large cohort of poxvirus proteomes using the existing PoxiPred method for reverse vaccinology of poxviruses. Methods: In the present study, we obtained the whole proteomes of as many as 37 distinct poxviruses. We utilized each proteome to predict both antigenic proteins and T-cell epitopes of poxviruses with the aid of an Artificial Intelligence method, namely the PoxiPred method. Results: In total, we predicted 3966 proteins as potential antigen targets. Of note, we considered that this protein may exist in a set of proteoforms. Subsets of these proteins constituted a comprehensive repository of 54,291 linear T-cell epitopes. We combined the outcome of the predictions in the format of a web tool that delivers a database of antigens and epitopes of poxviruses. We also developed a comprehensive repository dedicated to providing access to end-users to obtain AI-based screened antigens and T-cell epitopes of poxviruses in a user-friendly manner. These antigens and epitopes can be utilized to design experiments for the development of effective vaccines against a plethora of poxviruses. Conclusions: The TCEPVDB repository, already deployed to the web under an open-source coding philosophy, is free to use, does not require any login, does not store any information from its users. Full article

Lumpy Skin Disease Virus (LSDV), a member of the poxvirus family, represents a significant threat to global cattle industries. This review presents an analysis of LSDV-encoded proteins and their interactions with host systems, elucidating the molecular mechanisms governing viral life cycle progression and immune evasion strategies. We provide detailed characterization of the complex architecture of LSDV virions, including Intracellular Mature Virus (IMV), Extracellular Enveloped Virus (EEV), lateral bodies, and the core components, while summarizing the crucial functions of viral proteins throughout various stages of infection—entry, replication, transcription, translation, assembly, and egress. Particular attention is given to the immunomodulatory strategies employed by LSDV to subvert both innate and adaptive immune responses. These mechanisms encompass molecular mimicry of cytokines and chemokines, interference with antigen presentation pathways, inhibition of key immune signaling cascades, and modulation of apoptosis and autophagy processes. Through comparative analysis with homologs from related poxviruses, especially vaccinia virus, we highlight both evolutionarily conserved functions and potential unique adaptations in LSDV proteins. This review further identifies critical knowledge gaps in current understanding and proposes promising research directions. We emphasize that integrating multi-omics approaches with structural biology will be essential for advancing our understanding of LSDV pathogenesis and for developing novel preventive and therapeutic strategies against this important animal pathogen. Full article

The World Health Organization (WHO) declared the mpox (MPX) outbreak a public health emergency of international concern (PHEIC) on 23 July 2022, and 14 August 2024, respectively, underscoring the confirmed and concerning global spread of the disease. A gap exists in our fundamental understanding of the mpox virus (MPXV), despite its genetic relatedness to the variola virus (VARV). This knowledge deficit is evident in the performance of current medical countermeasures; vaccines and antiviral therapies adapted from smallpox programs demonstrate only partial efficacy and are constrained by issues of safety and suboptimal effectiveness against MPXV. In this context, the development of MPX-specific vaccines and antiviral drugs has become a critical priority in the global effort to combat MPX. However, MPXV employs multiple strategies to evade host immune responses, such as producing specific and poxvirus homologous proteins that suppress both innate immunity (including the six principal innate immune signaling pathways and antiviral strategies, notably the interferon [IFN] pathway) and adaptive immunity, thereby complicating vaccine and drug development. Insights from research on vaccinia virus (VACV) and VARV may inform the investigation of MPXV pathogenesis and immune evasion mechanisms. Drawing on relevant scientific literature, this review systematically examines key aspects of MPX infection, pathogenicity, and immune evasion, as well as the coordination between innate and adaptive immune responses. Furthermore, this review elucidates the current application and deployment landscape of the three principal therapeutics and three major vaccines for MPX, aiming to provide a theoretical foundation for future research and development of vaccines and targeted antiviral agents. Full article

Ovine gammaherpesvirus 2 (OvGHV2) is a Macavirus and the cause of sheep-associated malignant catarrhal fever (SA-MCF) in susceptible mammalian hosts worldwide. OvGHV2 may produce typical clinical manifestations of SA-MCF or subclinical infections. Additionally, OvGHV2 is associated with cutaneous lesions in ruminants, with few documented reports of this unusual manifestation worldwide. This paper presents the pathological, immunohistochemical (IHC), and molecular findings observed in outbreaks of OvGHV2-related skin infections in dairy cattle from Southern Brazil. Cutaneous scrapings (n = 35) and biopsies (n = 6) were obtained from dairy cows derived from three farms. All cows (n = 35) developed widespread, ulcerative to scaly and erythematous skin lesions, and had no contact with sheep or goats. The biopsies were evaluated for histopathological diagnosis and then used in IHC analyses designed to detect malignant catarrhal fever virus (MCFV) antigens and to evaluate the inflammatory response. All scrapings and biopsies were used in PCR assays to amplify OvGHV2. Additionally, all biopsies were used in PCR assays to detect bovine gammaherpesvirus 6 (BoGHV6), bovine alphaherpesvirus 1 (BoAHV1), and poxvirus. Histopathology revealed chronic folliculitis in all biopsies. IHC detected intralesional, intracytoplasmic MCFV antigens in most (83.3%; 5/6) of the cutaneous lesions with folliculitis. These skin lesions showed a strong T-cell response, macrophage clusters, and caspase-positive follicular keratinocytes. OvGHV2 DNA was detected in 66.7% (4/6) of the cutaneous biopsies that contained MCFV antigens and in 8.6% (3/35) of the cutaneous scrapings. The DNA of BoGHV6, BoAHV1, and Poxvirus was not amplified from any of the cutaneous biopsies. These findings demonstrated that OvGHV2 was associated with the cutaneous lesions in dairy cows at these farms and represent the first description of OvGHV2-related skin disease in ruminants from Brazil and the entire Latin America. A review of previous cases of skin lesions associated with infections by OvGHV2 revealed that most cases had a histological diagnosis of folliculitis, suggesting that folliculitis may be associated with OvGHV2-related skin infections. Additionally, this investigation contrasts all previous reports of OvGHV2-related skin disease in ruminants, since the infected cows herein identified were not reared concomitantly or within proximity of the asymptomatic reservoir host. Furthermore, the possible form of OvGHV2 dissemination to the susceptible cows during this study is discussed. Full article

Avian poxvirus was diagnosed in eight wild Stone-curlews (Burhinus oedicnemus) from the Canary Islands, based on a combination of pathological and molecular analysis. Affected birds exhibited lesions consistent with poxvirus infection; three of four with mild lesions (≤2 on pelvic limbs, excluding phalanges) were successfully rehabilitated and released, while four with moderate (≤2 on phalanges) to severe lesions (≥3 on phalanges) potentially faced impaired mobility, increased predation risk, and reduced foraging efficiency. Histopathology of six individuals revealed Bollinger bodies, characteristic of Avipoxvirus infection, and molecular analysis confirmed the presence of viral DNA in six cases. Three genetically distinct viral variants were identified, each associated with different phylogenetic clades and subclades, suggesting substantial viral diversity within this host species. Co-infection with Aspergillus fumigatus was also detected in six of the eight birds, confirmed by molecular analysis in either skin lesions or lung tissue. To our knowledge, this represents the first report of A. fumigatus co-infection in Stone-curlews with Avipoxvirus. Additionally, one individual presented a tumor-like lesion, expanding the known pathological manifestations of the disease. These findings provide new insights into avian pox and highlight the importance of considering fungal co-infections in the differential diagnosis, given their potential to exacerbate disease severity. Full article

Myxoma virus (MYXV) is a leporipoxvirus that causes lethal disease in Leporids. Hares and rabbits belong to the Leporidae family and are believed to have had a common ancestor 12 million years ago. After seventy years of contact with European hares without causing mortalities or disease manifestation, a recombinant MYXV infected Iberian hares (Lepus granatensis) causing high mortalities. Like all poxviruses, MYXV encodes a wealth of immune modulators required for successful virulence that also mediate host species jumping, for example, into hares. Here, we summarize the data of known MYXV immune modulators, their cellular functions, and their effects on European rabbits. Additionally, we suggest that the critical restrictions MYXV would encounter in colonizing a potentially new host species stem from their interactions with the host’s innate immune environment. Lastly, we synthesize our understanding of some poxvirus genome architectural features that might have facilitated the host species jump of MYXV into hares from rabbits. Full article

Brazilian porcupinepox virus (BPoPV) is a recently described pathogen associated with severe cutaneous and systemic disease in Coendou spp. porcupines, posing potential conservation and zoonotic risks. Given the solitary behavior of porcupines and the unclear mechanisms of BPoPV transmission, this study investigated the presence of BPoPV DNA in porcupines and their associated ectoparasites (ticks and lice). We analyzed ticks and lice collected from 17 porcupines (C. longicaudatus and C. spinosus), with or without clinical signs of BPoPV infection. Ectoparasites were identified morphologically, separated into distinct pools for ticks and lice by host, and screened by PCR. BPoPV DNA was detected in all symptomatic porcupines and their ectoparasites—including Amblyomma longirostre, A. sculptum ticks, and Eutrichophilus spp. lice—except for one tick pool. Notably, an asymptomatic, BPoPV-negative porcupine harbored A. longirostre ticks that tested positive for the virus. Sequencing confirmed 100% identity with the BPoPV reference strain. These findings suggest that Eutrichophilus lice, A. sculptum, and particularly A. longirostre ticks may play a role in BPoPV transmission. Further studies are needed to elucidate whether these ectoparasites act as biological or mechanical vectors and to assess the zoonotic potential of BPoPV in contact with humans and domestic animals. Full article

Myxoma virus (MYXV), a rabbit-specific poxvirus and non-pathogenic in humans and mice, is an excellent candidate oncolytic virus for cancer therapy. MYXV also has immunotherapeutic benefits. In ovarian cancer (OC), immunosuppressive tumor-associated macrophages (TAMs) are key to inhibiting antitumor immunity while hindering therapeutic benefit by chemotherapy and dendritic cell (DC) vaccine. Because MYXV favors binding/entry of macrophages/monocytes, we examined the therapeutic potential of MYXV against TAMs. We found previously that a replication-defective MYXV with targeted deletion of an essential gene, M062R, designated ΔM062R MYXV, activated both the host DNA sensing pathway and the SAMD9 pathway. Treatment with ΔM062R confers therapeutic benefit comparable to that of wild-type replicating MYXV in preclinical models. Here we found that ΔM062R MYXV, when integrated with cisplatin and DC immunotherapy, further improved treatment benefit, likely through promoting tumor antigen-specific T cell function. Moreover, we also tested ΔM062R MYXV in targeting human immunosuppressive TAMs from OC patient ascites in a co-culture system. We found that ΔM062R treatment subverted the immunosuppressive properties of TAMs and elevated the avidity of cytokine production in tumor antigen-specific CD4⁺ T cells. Overall, ΔM062R presents a promising immunotherapeutic platform as a beneficial adjuvant to chemotherapy and DC vaccine. Full article

Background: Protein kinase R (PKR) inhibits general mRNA translation by phosphorylating the alpha subunit of eukaryotic translation initiation factor 2 (eIF2). PKR also modulates NF-κB signaling during viral infections, but comparative studies of PKR-mediated NF-κB responses across mammalian species and their regulation by viral inhibitors remain largely unexplored. This study aimed to characterize the conserved antiviral and inflammatory roles of mammalian PKR orthologs and investigate their modulation by poxviral inhibitors. Methods: Using reporter gene assays and quantitative RT-PCR, we assessed the impact of 17 mammalian PKR orthologs on general translation inhibition, stress-responsive translation, and NF-κB-dependent induction of target genes. Congenic human and rabbit cell lines infected with a myxoma virus strain lacking PKR inhibitors were used to compare the effects of human and rabbit PKR on viral replication and inflammatory responses. Site-directed mutagenesis was employed to determine key residues responsible for differential sensitivity to the viral inhibitor M156. Results: All 17 mammalian PKR orthologs significantly inhibited general translation, strongly activated stress-responsive ATF4 translation, and robustly induced NF-κB target genes. Inhibition of these responses was specifically mediated by poxviral K3 orthologs that effectively suppressed PKR activation. Comparative analyses showed human and rabbit PKRs similarly inhibited virus replication and induced cytokine transcripts. Amino acid swaps between rabbit PKRs reversed their sensitivity to viral inhibitor M156 and NF-κB activation. Conclusions: Our data show that the tested PKR orthologs exhibit conserved dual antiviral and inflammatory regulatory roles, which can be antagonized by poxviral K3 orthologs that exploit eIF2α mimicry to modulate the PKR-NF-κB axis. Full article

Objectives: Understanding the antibody response in monkeypox virus (MPXV)-infected and uninfected individuals is essential for developing next-generation MPXV vaccines. This study aimed to characterize neutralizing antibody (NAb) and antibody-dependent cellular cytotoxicity (ADCC) responses in both groups, providing insights into immune protection and vaccine design. Methods: A recombinant vaccinia Tian Tan (VTT) virus was utilized to develop high-throughput luciferase-reporter-based neutralization and ADCC assays. These assays were applied to evaluate the presence and levels of poxvirus-specific antibodies in MPXV-infected and uninfected individuals, including those vaccinated with vaccinia-based vaccines. Results: Poxvirus-specific NAbs were detected in MPXV-negative individuals with prior vaccinia vaccination. However, MSM individuals exhibited significantly lower pre-existing NAb levels than non-MSM individuals, potentially contributing to their higher susceptibility to MPXV infection. In individuals with mild MPXV infection, robust NAb and ADCC responses were observed, regardless of vaccination status. Additionally, HIV-positive individuals demonstrated comparable antibody responses following MPXV infection. Conclusions: These findings highlight the potential role of pre-existing NAbs in MPXV susceptibility and the strong immune response elicited by mild MPXV infection. Further research is needed to determine whether MPXV-specific antibodies mitigate disease progression, which could inform the development of effective MPXV vaccines. Full article