The 2013 Ebola virus (EBOV) outbreak was the largest in history. Despite recent advances in both vaccines and monoclonal antibody therapies, 12 years later, EBOV still poses a substantial threat. Previously, we published a ligand discovery pipeline combining screening of compounds with a robust and rapid EBOV minigenome assay for early-stage inhibitor validation at Biological Safety Level 2. Here, we present the further use of this pipeline to identify three compounds that also inhibit EBOV minigenome transcription and replication. They are efficacious in the nM range, exhibited low cytotoxicity and were specific, with no effect on either a T7 RNA polymerase-driven firefly luciferase or a Bunyamwera virus minigenome. Furthermore, these small-molecule inhibitors exhibited the ability to block EBOV minigenome activity when applied after establishment of replication complexes, with implications for potential post-exposure EBOV treatment.

Marek's disease virus (MDV) is an alphaherpesvirus responsible for the development of T-cell lymphoma in chickens. Despite the identification of several pro-oncogenic viral molecules encoded by MDV, the processes leading to tumourigenesis remain poorly understood. Extracellular vesicles (EVs) are important mediators of intercellular communication, carrying bioactive molecules that can elicit profound physiological changes in recipient cells. Tumour cells can release significant amounts of EVs, which influence tumour development and growth, metastatic processes and resistance to cancer therapies. These EVs favour cancer cells to evade the immune response, particularly by establishing an immunosuppressive microenvironment. Here, we investigated whether EVs produced by MDV-transformed T lymphocytes affect the proliferation of avian immune cells, a determining feature in neoplastic processes. EVs were purified from an MDV-transformed cell line cultured . Using a proteomic approach, we confirmed the presence of specific markers and identified a panel of cellular proteins enriched in these EVs. Notably, no viral proteins were detected in the purified EVs. We also demonstrated that EVs are rapidly internalized by recipient chicken cells. Moreover, these EVs can induce a decrease in primary chicken B-cell proliferation, while promoting primary chicken T-cell proliferation. Our findings suggest that EVs released by MDV-transformed cells may contribute to immunosuppression and potentially facilitate lymphoma progression by enhancing T-cell proliferation.

After severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, a minority of patients experience persistent or emerging symptoms, termed 'long coronavirus disease (COVID)' or post-acute sequelae of COVID-19. The molecular causes of long COVID remain unclear, but disrupted immune functions, such as inflammation and immune deficit, have been posited as factors. In this retrospective cohort study, we measured markers of immune function in a group of patients with long COVID up to 40 months post infection. As proxies for immune function, we measured serum antibody levels, antibody neutralizing capability and production of IFN gamma (IFN-) and IL-2 against SARS-CoV-2 and other viral peptides. As expected, serum antibody levels increased over time with vaccinations and reinfections with later variants of SARS-CoV-2. Patients also showed corresponding increasing SARS-CoV-2-specific IL-2 responses and stable IFN- responses. We observed no significant differences in immune responses among patients with ongoing long COVID, those who had recovered from it or individuals who recovered from acute COVID-19. Overall, we found no indication of a reduction in these aspects of immune function after SARS-CoV-2 infection. This study provides a valuable foundation for further research aimed at understanding the causes of long COVID.

Equine arteritis virus (EAV) is the causative agent of equine viral arteritis, a notifiable respiratory and reproductive disease of equids that causes significant losses to the equine industry. This study presents a comprehensive analysis of two EAV outbreaks in the UK in 2019, combining virus isolation, sequencing and phylogenetic analysis to provide a holistic understanding of EAV dynamics in these outbreaks. Genetic characterization revealed that all outbreak strains were similar to viruses detected in the UK and Europe from 2004 to 2011, belonging to phylogroup D and clustering in two groups as expected based on epidemiological profiling. Bayesian phylogenetic analysis indicated the direction of transmission. The 2019 EAV strains showed maximum variability in glycoprotein (GP) 3, followed by GP2, non-structural protein 2, GP4 and GP5, with one strain displaying a unique truncation in GP4 at position 149, a feature not previously identified in arteriviruses. Polymorphisms in the CXCL16 gene have been implicated in differential susceptibility to the establishment of long-term carrier states of EAV in stallions. Genotypic analysis of the CXCL16 gene revealed that one horse possessed the homozygous genotype associated with resistance to persistent infection. In contrast, the remaining four horses exhibited the heterozygous genotype, which has been linked to an increased risk of developing a long-term carrier state and contributing to ongoing viral transmission. All infected horses exhibited the presence of neutralizing antibodies in their serum. This study underscores the importance of early detection of silent infections to reduce the spread and prevent clinical outbreaks.

Hantaviruses are zoonotic, tri-segmented, negative-sense RNA viruses and a significant public health threat. Viral pathogenesis varies between host species, with rodent reservoir infection being asymptomatic and human infection resulting in severe, immune-mediated disease. Viral pathogenesis is highly dependent on virus replication efficiency since it affects the virus's ability to evade detection and determines the magnitude of the host immune response. However, the molecular replication kinetics for hantaviruses remain poorly defined. Therefore, we developed a sense- and segment-specific quantitative real-time PCR assay and an SYBR-based RT-qPCR assay, allowing us to quantify both negative-sense genome levels and total viral RNA synthesis of the small (S), medium (M), and large (L) segments of Seoul virus (SEOV). We then measured total viral RNA and genome accumulation in reservoir rat endothelial cells (RLMVEC), non-reservoir human endothelial cells (HUVEC-C), and Vero E6 epithelial cells. We also measured the ratio of each segment released into the culture supernatant, approximating the relative packaging efficiency. We found that, while the magnitude of viral RNA differed, RNA replication kinetics were largely similar between reservoir and non-reservoir endothelial cells. However, replication and release kinetics differed between infection of endothelial and Vero cells. We also found that the S, M, and L segments were not equally abundant during viral infection or release but instead followed a trend of M>L>S. Overall, this study validates two RT-qPCR assays to measure SEOV RNA, details the accumulation and release of each viral segment and demonstrates the impact of host cell type on hantavirus replication.

During the summer of 2020, West Nile virus (WNV) caused an important outbreak in south-western Spain, with the highest impact on humans in the country up to that time, resulting in 77 clinical cases (including eight fatalities). Concurrently, equine WNV foci were reported within the same region. Meanwhile, WNV circulation was also detected in horses and birds in north-eastern Spain (Catalonia), although no human cases were notified. This striking difference in human case incidence between these two affected areas may be due to characteristics of the strains circulating in each site. One of these intrinsic viral strain factors that may account for these differences is the competence of avian reservoir hosts. A higher host competence leads to a higher viral spread in the enzootic cycle, consequently, increasing the risk of spillover to humans and horses. To assess differences in host competence, WNV strains circulating in both areas during the summer of 2020 were studied through inoculation of a transmission-competent avian species susceptible to WNV infection, the red-legged partridge, autochthonous to the Iberian Peninsula. The south-western strain SPA20-02, belonging to lineage 1, and the north-eastern strain AC924, belonging to lineage 2, were inoculated in parallel in red-legged partridges. The SPA20-02 strain exhibited higher and longer viraemias than the AC924 strain, resulting in a higher competence index for this avian species. The lower competence index of red-legged partridges for transmission of AC924 suggests that this strain exhibits a lower transmission capacity and, consequently, lower spread risk. These findings indicate that the lower severity of the 2020 outbreak in north-eastern Spain could, at least partially, be explained by the reduced transmission potential of the AC924 strain.

Cutavirus (CuV), the newest human protoparvovirus (PPV), has gained attention due to its significant association with cutaneous T-cell lymphoma (CTCL) and its precursor, parapsoriasis, whereas the other human PPVs, bufavirus and tusavirus, show no such link. Given this association, it is important to investigate the prevalence of CuV DNA in other tissues, particularly those affected by malignancy or inflammation. This study assessed, by multiplex quantitative PCR, the genoprevalences of all three PPVs in 427 fresh-frozen intestinal biopsies from inflammatory bowel disease (IBD), colorectal cancer, adenomas or healthy mucosa of 185 individuals, as well as in 94 formalin-fixed paraffin-embedded (FFPE) biopsies from malignant and non-malignant breast conditions of 85 patients. The study also compared the DNA prevalences of human herpesvirus (HHV)-6A, -6B and -7 in the breast tissues. CuV mRNA was assayed with reverse-transcription PCR, and corresponding FFPE sections underwent hybridization. CuV DNA was detected in intestinal IBD or healthy mucosa from 6/185 (3.2%) subjects, but no CuV mRNA or signals were detected. In breast biopsies, HHV-6B and HHV-7 DNAs were present in 20.3 and 5.1%, respectively, while all PPVs and HHV-6A were absent. Overall, CuV was absent in all 70 cancer tissues, underscoring its association with CTCL. The low CuV DNA loads and prevalences in intestinal and breast morbidities, and lack of activity, suggest that CuV is unlikely to play a role in these malignancies or inflammatory conditions. In contrast, HHV-6B may be more relevant to breast pathology, even though it is also widely detected in healthy tissues. Nevertheless, our study provides insight into persistent DNA viruses implicated in cancer and highlights their occurrence across various disease manifestations, laying a foundation for future studies.

Hepatitis B virus (HBV) is a hepatotropic DNA virus that infects over 250 million people worldwide and causes serious liver diseases. HBV infection can modulate host cellular processes, potentially inducing proteomic changes in hepatocytes. In this study, we investigated how acute HBV infection alters the proteome and secretome of primary human hepatocytes, a physiologically relevant model that retains essential liver-specific functions. Protein-level changes in cell lysates and culture supernatants were quantified 8 days post-infection using data-independent acquisition MS. We used HBV infection in the presence of the entry inhibitor bulevirtide as a control to separate the effects of productive infection from those caused by inoculum-associated components. Despite robust infection, active HBV replication induced only subtle changes in host protein levels. Orthogonal validation of MS-identified candidates confirmed reticulocalbin-2 as a novel host factor downregulated during productive HBV infection. The functional role of candidate proteins identified by MS was assessed by siRNA-mediated knockdown and measurement of viral replication markers. Knockdown had no impact on viral RNA or antigen levels, suggesting that the observed proteomic changes may reflect stress responses or broader modulation of the hepatic microenvironment. Our findings support the concept of HBV as a stealth virus and underscore the importance of carefully controlled experimental systems for studying host responses to infection .

Tomato spotted wilt virus (TSWV) is a highly destructive plant pathogen transmitted by thrips, including , in a circulative and propagative manner. To counter viral infections, thrips activate antiviral defences through C20 oxygenated polyunsaturated fatty acids (PUFAs), known as eicosanoids. However, at later stages of infection, C18 PUFAs, including epoxyoctadecamonoenoic acids (EpOMEs), modulate immune responses by preventing excessive and unnecessary activation. Our previous study demonstrated that TSWV elevates EpOME levels in thrips to suppress antiviral responses and enhance viral replication, with its nonstructural protein S (NSs) playing a key role in this process. In this study, we investigated the impact of NSs protein variation on vector immunity and virus-vector interactions. We assessed relative TSWV titres in thrips larvae and examined the role of eicosanoids, specifically 12,13-EpOME and PGE, in regulating viral load and apoptosis. Our results revealed that 12,13-EpOME significantly increased viral titres, whereas PGE reduced the viral accumulation by promoting apoptosis in the vector insect. Phylogenetic analysis identified distinct variations among TSWV isolates, with resistance-breaking (RB) and WT strains, which modulated differential infection patterns in thrips gut tissues, as visualized through fluorescence in situ hybridization. RB strains exhibited significantly higher viral titres, along with increased expression of EpOME biosynthetic gene () and decreasing expression of EpOME degradation gene (). Apoptosis assays using the terminal deoxynucleotidyl transferase dUTP nick-end labelling assay further indicated that RB strains suppressed the gut epithelial cell death in thrips by antagonizing a process regulated by PGE. Additionally, transient expression of the gene in a nontarget insect, , demonstrated the immunosuppressive effects by inducing EpOME level through upregulation of expression and downregulation of expression. Indeed, RB strains suppressed cellular immune responses more effectively than WT strains in . These findings provide novel insight into the role of genetic variation in TSWV transmission in the insect vector as well as in the host plants.

The influenza A H1N1pdm09 virus continues to pose a significant zoonotic threat, with implications for both animal and human health. Italy, which hosts one of the largest swine populations in Europe, is strategically positioned to monitor the evolution of influenza viruses in livestock. This study addresses the genetic diversity and transmission dynamics of H1N1pdm09 in Italian swine, using whole-genome sequencing and dynamic modelling of samples collected from farms across the country. Our findings indicate multiple independent introductions of H1N1pdm09 into Italy. While most were self-limiting, six distinct transmission clusters suggest localized and sustained spread across various regions. Although many introductions were contained, certain lineages demonstrated the ability to circulate within specific areas. Selective pressure analyses showed strong purifying selection across most viral genes in both swine and human hosts, with non-synonymous to synonymous substitution rate (dN/dS) ratios well below 1. The haemagglutinin gene exhibited a higher dN/dS ratio in swine (~0.28) than in humans (~0.22), indicating slightly relaxed selection in swine. Neuraminidase and non-structural proteins were similarly constrained in both hosts. This study underscores the importance of ongoing genomic surveillance to detect viral circulation and mitigate zoonotic risks. Italy's contribution supports global influenza monitoring and reinforces the need for a One Health approach that integrates human, animal and environmental health. These insights are crucial for informing public health strategies and improving preparedness for future outbreaks.

Pandemic preparedness requires vaccine platforms that are fast to produce, thermostable and suitable for broad deployment. DNA vaccines are well suited to this task but have historically suffered from poor immunogenicity when delivered by conventional intramuscular (IM) injection. Here, we evaluated high-density microarray patch (HD-MAP) delivery of a DNA vaccine encoding the influenza A/California/01/2009 (H1N1pdm09) haemagglutinin (HA) antigen. imaging of a luciferase reporter construct demonstrated earlier and higher expression following HD-MAP application compared to IM injection. HD-MAP delivery of the HA vaccine induced strong HA-specific IgG responses, whereas IM delivery did not. Upon challenge with a homologous H1N1 virus, all HD-MAP-vaccinated mice were protected from weight loss, while 50% of intramuscularly vaccinated mice met humane endpoints. These findings support the use of HD-MAPs to overcome delivery limitations of DNA vaccines and enhance their utility for future outbreak and pandemic response.

Defective viral genomes (DVGs) affect viral dynamics, pathogenicity and evolution, have been found in many viral infections, and in theory can be detected from sequencing data. We explored the utility of the currently available bioinformatic programs ViReMa, DI-tector, DVGfinder, DG-Seq and VODKA2 for identifying junction points in plant virus high-throughput sequencing data, looking at whether the outputs from these bioinformatic tools generally agree and exploring the possibility of using these tools to help us understand whether DVGs are consistently generated and maintained in a specific virus-host combination. We conducted a meta-analysis of eight previously published RNA sequencing datasets utilizing all five programs and compared the degree of output overlap, the most common junctions present in each output and whether these junctions match previously reported junctions for that virus. Our results demonstrate a low degree of agreement regarding identified junctions between programs, including the most frequently identified one, although the most frequently identified junctions typically corresponded to large, disruptive deletions. We found preliminary support for our prevalence hypothesis, although we ultimately conclude that a more robust dataset generated expressly for testing this hypothesis will be required for a convincing answer. Finally, we suggest that when using bioinformatic programs to search for DVGs, it is best to run the same dataset through multiple programs and look at the overlap to inform decisions on downstream characterization.

Zoonotic viruses such as hantaviruses and influenza A viruses present a threat to humans and livestock. There is thus a need for methods that are rapid, sensitive and relatively cheap to detect infections with these pathogens early. Here, we use an amplification-free clustered regularly interspaced short palindromic repeats-associated protein 13 (CRISPR-Cas13)-based assay, which is simple, cheap and field-deployable, to detect the presence or absence of genomic hantavirus or influenza A virus RNA. In addition, we evaluate whether the use of multiple CRISPR RNAs (crRNAs) can improve the sensitivity of this amplification-free method. We demonstrate that for the hantaviruses Tula virus (TULV) and Andes virus (ANDV), a combination of two or three crRNAs provides the best sensitivity for detecting viral RNA, whereas for influenza virus RNA detection, additional crRNAs provide no consistent benefit. We also show that the amplification-free method can be used to detect TULV and ANDV RNA in tissue culture infection samples, ANDV from hamster lung samples and influenza A virus RNA in clinical nasopharyngeal swabs. In clinical samples, the Cas13 assay has an 85% agreement with RT-qPCR for identifying a positive sample. Overall, these findings indicate that amplification-free CRISPR-Cas13 detection of viral RNA has potential as a tool for rapidly detecting zoonotic virus infections.

Plant virus infections pose a substantial threat to crop quality and productivity, contributing to considerable economic losses in global agriculture annually. Traditionally, laboratories have widely adopted serological techniques, such as ELISA, and molecular methods, including quantitative PCR, for virus diagnostics. More recently, sophisticated next-generation sequencing approaches have been introduced to improve the efficiency and reliability of virus detection and identification. However, the development of sensitive, rapid and low-cost methods for the on-site detection, quantification and identification of plant viruses remains an ongoing challenge and is still in its early days. Point-of-care technologies have not fully realized their potential in agriculture due to numerous challenges, such as the elevated cost of development, lack of standardized validation and insufficient field testing. Therefore, future success depends on addressing these technical, economic and regulatory hurdles, as well as considering the specific user needs within the agricultural context. In this mini-review, recent advancements in biosensing for on-site plant virus monitoring, involving nanotechnology-based sensors, clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems, electrochemical and modern field-effect transistor-based sensors offering high sensitivity, speed and portability, are discussed. These technologies, when integrated with smartphone applications and/or machine learning modules, could enable real-time, field-deployable diagnostics for early disease management and sustainable agriculture. The aim is to raise awareness among plant virologists about this panel of emerging diagnostic concepts that could help improve current methods, ultimately facilitating the management of plant viral diseases.

Rabies is a fatal zoonosis that impairs host immune function, yet effects on peripheral lymphoid architecture are poorly defined. During a 2021-2022 rabies virus (RABV) outbreak in South Africa, we collected cervical lymph nodes from 36 rabies-suspect dogs; RABV RNA was detected in 27. Canine distemper virus RNA was detected in a subset across both RABV-positive (RABV+) and RABV-negative (RABV-) groups and was not associated with clinical-sign count. We set up a computer-assisted histological analysis tool to quantify germinal-centre (GC) nucleus density and immunohistochemistry for CD20, PNA and IBA1 to profile B cells, GC activity and macrophages. Within the outbreak cohort, GC density and marker-based metrics did not differ between RABV+ and RABV- dogs. Two healthy dogs were included as reference tissues; values in outbreak dogs were generally lower, but these contrasts are contextual given the limited, non-matched controls. This study provides a reproducible framework for quantifying immune cell organization in field-collected tissues during natural RABV exposure and highlights the need for larger, geographically matched control groups and complementary functional immune measurements.

Hepatitis C virus (HCV) infection induces extensive rearrangements of host cytoplasmic membranes, leading to the formation of multiple membranous structures that facilitate RNA replication. Current knowledge of these membranous structures has largely relied on correlative light and electron microscopy techniques using chemical fixation and resin embedding. To overcome these limitations, cryo-preserved cells were prepared using cryo-focused ion beam (cryo-FIB) milling and cryo-ultramicrotomy. For the first time, the contents within the membranous structures have been observed using cryo-electron tomography (cryo-ET) performed on lamellae (prepared via cryo-FIB) and on ultrathin sections (prepared via cryo-ultramicrotomy) from HCV subgenomic replicon-harbouring cells. Observations from 112 cryo-electron tomograms of cryo-FIB-derived samples revealed the presence of densities within the inner vesicles of a subset of single- and double-membrane vesicles, as well as within multi-vesicular bodies, which are consistent with the presence of the viral genome replication machinery. Notably, this study also presents the first direct visualization of densities within a multi-membrane vesicle observed by cryo-electron microscopy of vitreous sections. The cryo-ET methodologies established here lay the groundwork for future investigations into the architecture of the HCV replication complex, leveraging advanced computational tools for deeper structural and functional analyses.

Over the last decade, heterologous prime-boost vaccination regimens have been established as a promising strategy to enhance immune responses and make optimal use of the advantages of different vaccine platforms. Modified vaccinia virus Ankara (MVA), a replication-deficient poxviral vector with an established safety profile, is under clinical investigation as a versatile recombinant vaccine platform against various infectious diseases. In the context of coronavirus disease 2019 (COVID-19), a recombinant MVA-based vaccine candidate expressing the prefusion-stabilized severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein (MVA-ST) has demonstrated safety, immunogenicity and protection in preclinical studies using different animal models. Furthermore, a phase Ib clinical trial in healthy adults showed that MVA-ST is safe, well-tolerated and immunogenic when used as a booster following mRNA priming. In this study, we evaluated heterologous prime-boost vaccination regimens using MVA-ST as a booster in Syrian hamsters. Hamsters were primed with an mRNA vaccine (BNT162b2, BioNTech/Pfizer) or the adenoviral vector vaccine Ad26.COV2.S (Janssen) and subsequently boosted with MVA-ST at a dose of 10⁸ p.f.u. These heterologous vaccination regimens induced robust protection against severe SARS-CoV-2 disease, with superior immunogenicity compared to homologous MVA-ST vaccination. Notably, even a lower booster dose (10⁷ p.f.u.) of MVA-ST following mRNA priming conferred strong protection against SARS-CoV-2 challenge infection, while still associated with limited viral shedding from the upper respiratory tract. These findings highlight the potential of MVA-ST as a heterologous booster to enhance the immunogenicity and protective efficacy of existing COVID-19 vaccines and also to improve vaccination strategies against other emerging pathogens.

Vertical transmission of human cytomegalovirus (HCMV) during pregnancy is a major cause of congenital disease. In the absence of robust vaccination strategies, antiviral drug regimens are being developed to inhibit the vertical transmission of the virus. Recent clinical data have indicated that valaciclovir, an orally bioavailable form of aciclovir, was effective at limiting vertical transmission of HCMV when administered during pregnancy. However, there is no widely cited analysis of valaciclovir's antiviral effect against HCMV, and it is possible, like aciclovir, that valaciclovir has poor anti-HCMV activity. The antiviral effects of aciclovir and valaciclovir against HCMV were compared to the widely used anti-HCMV drug ganciclovir. Compared to ganciclovir, the anti-HCMV effects of either aciclovir or valaciclovir were poor, and robust anti-HCMV activity in all cell lines tested (adult fibroblast, foetal fibroblast or trophoblast cells) was only observed at high drug concentrations. All drugs had no obvious effects on the viability of uninfected cells. Overall, valaciclovir had poor anti-HCMV activity, and its anti-HCMV efficacy upon administration during pregnancy may rely on a combination of factors. These data argue for the continued development of valaciclovir and anti-HCMV compounds to inhibit vertical virus transmission.

Human cytomegalovirus (HCMV) is a ubiquitous human pathogen of high clinical relevance. In terms of pathogenic determination, the regulatory factors of HCMV-host interaction play a crucial role, and recently we reported on virus-supportive functions of the cellular peptidyl-prolyl / isomerase Pin1. Notably, Pin1 is able to recognize phosphorylated serine/threonine-proline motifs and regulate the structural conformation, stability and function of its substrate proteins. During HCMV replication, Pin1 facilitates viral nuclear egress by inducing site-specific rearrangements of the nuclear lamina through the / conversion of lamin type A/C. To this end, we developed readout systems to decipher details of HCMV-Pin1 regulatory interaction. Notably, together with primary human foreskin fibroblasts (HFFs) and recombinant lamin-modified cell populations, the molecular mechanisms of Pin1 interaction with both the nuclear lamina and viral proteins were illustrated. Our new results demonstrate the following: (i) currently available Pin1-inhibitory small molecules, similar to the antiviral drug maribavir (MBV), exert an antiviral activity against human and non-human primate cytomegaloviruses (CMVs); (ii) site-specific phosphorylation at serine 22, a Pin1 recognition motif within lamin A/C, is consistently mediated by the pUL97 kinase homologs of these viruses; (iii) the phosphorylation of serine 22 is sensitive to the virus-specific kinase inhibitor MBV; (iv) a doxycycline-inducible expression of autofluorescent lamin A/C-red fluorescent protein (RFP) fusion constructs in HFFs supports the productive HCMV replication; (v) these lamin A/C-RFP reporter cells indicated a virus-induced formation of lamina-depleted areas (LDAs), dependent on serine 22 but independent of the infecting CMV species; and (vi) treatment of CMV-infected cells with kinase or Pin1 inhibitors exerted distinct effects on the magnitude of LDA formation. Combined, the study is consistent with our concept that the mode of nuclear egress shows parallels between human and non-human primate CMVs. Thus, the role of Pin1 may play an important regulatory role in determining virus infection and replication efficiency.

Laboratory of genetics and physiology 2 (LGP2, also known as DHX58) is unique among members of the RIG-I-like receptor (RLR) family as it lacks the caspase activation and recruitment domain. Although LGP2 per se cannot directly activate downstream antiviral signalling, it plays important regulatory roles, primarily by modulating innate immune responses mediated by RIG-I and MDA5. However, the detailed mechanisms by which LGP2 is induced in mammalian cells during viral infection remain incompletely understood. Herein, we show that LGP2 is strongly upregulated by dsRNA stimulation or virus infection in cultured human cell lines via TLR3 and RLRs, respectively, and that substantial induction of LGP2 remains when paracrine/autocrine signalling of IFNs and/or inflammatory cytokines is abrogated by genetic deletion or chemical inhibition. The latter observation is in stark contrast to the case of myxovirus resistance proteins, the induction of which is strictly IFN-dependent. Mechanistically, we found LGP2 expression to be upregulated by ectopic expression of IRF3-5D, a phospho-mimetic mutant of activated IRF3, or to a lesser extent, by overexpression of RELA, the p65 subunit of NFκB, in an IFN-independent fashion. Additionally, we demonstrated that this regulation operated transcriptionally at the promoter level. Altogether, a fraction of LGP2 induction in viral infection is IFN- and cytokine-independent, highlighting exquisite gene expression control in antiviral innate immunity and representing an evolutionary advantage, which ensures uninterrupted supply of this RLR member protein in host responses to invading viruses in the event that IFN production and/or signalling is disabled by viral means.