Journal of Virology最新文献

{"title":"UNC0638 inhibits SARS-CoV-2 entry by blocking cathepsin L maturation.","authors":"Yongjun Chen, Yujin Shi, Xiaoyan Zuo, Xiaojing Dong, Xia Xiao, Lan Chen, Zichun Xiang, Lili Ren, Zhuo Zhou, Wensheng Wei, Xiaobo Lei, Jianwei Wang","doi":"10.1128/jvi.00741-25","DOIUrl":"https://doi.org/10.1128/jvi.00741-25","url":null,"abstract":"<p><p>Since the outbreak of SARS-CoV-2, viral mutations have posed significant challenges in identifying therapeutic targets and developing broad-spectrum antiviral drugs. Post-translational modifications of genes involved in interferon production and signaling pathways play a crucial role in regulating interferon responses. In this study, we employed CRISPR-Cas9 screening based on adenine base editors to investigate functional amino acids in 1,278 innate immune-related genes. This approach, which converts A-T base pairs into G-C base pairs to probe the functional importance of specific amino acids, allowed us to identify 17 vital factors involved in SARS-CoV-2 infection. Among the candidate genes, genetic knockdown of EHMT2 exhibited the strongest antiviral effect. Further analysis revealed that UNC0638, a selective inhibitor of EHMT2, significantly reduced the endosomal entry of SARS-CoV-2 in pseudovirus assays. The observed inhibitory effect was consistently observed across multiple SARS-CoV-2 variants, including Alpha, Beta, Delta, and Omicron. Mechanistically, UNC0638 reduced mature cathepsin L (CTSL) levels, impairing the proteolytic cleavage of SARS-CoV-2 spike protein and subsequent membrane fusion, a critical step for viral entry. Our findings uncover EHMT2 as a host dependency factor and reveal the antiviral mechanism of EHMT2 inhibitors through CTSL maturation blockade. These results advance the understanding of host factors in SARS-CoV-2 infection and provide a strategic framework for developing host-targeted antiviral therapies.IMPORTANCEIn this study, we demonstrated that knockdown or knockout of EHMT2 inhibited SARS-CoV-2 infection, and inhibitors of EHMT2, including UNC0638, UNC0642, and BIX01294 showed similar restrictive effects. Mechanistically, the EHMT2 inhibitor UNC0638 restricts spike-mediated cell entry by inhibiting the maturation of CTSL, a critical protease required for SARS-CoV-2 entry via the endosomal pathway. Importantly, CTSL is not only essential for SARS-CoV-2 but also plays a key role in the entry of other coronaviruses that utilize similar pathways. Therefore, EHMT2 inhibitors could have broader applications as pan-coronavirus therapeutic agents.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0074125"},"PeriodicalIF":4.0,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144326171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cellular miRNAs and viruses: trends in miRNA sequestering and target de-repression.","authors":"Bonita H Powell, Kenneth W Witwer, Mollie K Meffert","doi":"10.1128/jvi.00914-25","DOIUrl":"https://doi.org/10.1128/jvi.00914-25","url":null,"abstract":"<p><p>Altered gene regulation downstream of infection has been linked to devastating cancers and neurological diseases, highlighting the importance of understanding viral:host gene interactions. Historically, approaches based on bioinformatic binding prediction showed that host microRNAs (miRNAs) can target and regulate viral genes to impact viral replication and pathogenesis. More recently, Argonaute cross-linking and immunoprecipitation (AGO-CLIP) and advancements incorporating a miRNA:target RNA ligation step (AGO-CLIP + ligation) enable a global view of miRNA interactions with target cellular and viral transcripts. These genome-wide approaches paired with RNA sequencing reveal that miRNA binding to viral transcripts can not only act conventionally to regulate viral replication but can also act to reduce miRNA targeting of host genes with resulting de-repression of host target genes and downstream biological impacts. Viruses with accumulated evidence of miRNA sequestration are selected as examples for review and include hepatitis C virus (HCV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and respiratory syncytial virus (RSV). The significant impact of target de-repression on host cellular biology warrants a broader investigation of this mechanism. In this mini-review, we examine examples of crosstalk between host miRNAs and viral transcripts and highlight the advance and potential of analyses from AGO-CLIP + ligation with RNA-seq for expanding the identification of global miRNA:viral target interactions and interrogating the biological impacts of host miRNA sequestering and target de-repression. Host target de-repression by miRNA:viral target interactions could shed light on antiviral therapeutic candidates to aid in mitigating consequences such as malignancies and neurodegeneration.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0091425"},"PeriodicalIF":4.0,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144326162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distinct region-specific neutralization profiles of contemporary HIV-1 clade C against best-in-class broadly neutralizing antibodies.","authors":"Jyoti Sutar, Priyanka Jayal, Ranajoy Mullick, Sangeeta Chaudhary, Prajakta Kamble, Shilpa Bhowmick, Snehal Kaginkar, Varsha Padwal, Pratik Devadiga, Namrata Neman, Dale Kitchin, Haajira Kaldine, Nonhlanhla N Mkhize, Bongiwe Ndlovu, Kamini Gounder, Sohini Mukherjee, Shweta Shrivas, Neha Sharma, Chaman Prasad, Sonia Tewatia, Nainika Parihar, Naresh Kumar, Nandini Kasarpalkar, Balwant Singh, Shobha Mohapatra, Mohammad Aquil, C Vishal Kumar, Thongadi Ramesh Dinesha, Aylur Kailasom Srikrishnan, Jayanthi Shastri, Sachee Agrawal, Sushma Gaikwad, Sayantani Mondal, Bhaswati Bandyopadhyay, Subhasish Kamal Guha, Dipesh Kale, Debasis Biswas, Dhanashree Patil, Ramesh S Paranjape, Satyajit Mukhopadhyay, Hema, Ritika Das, Anand Kondapi, Vikrant Bhor, Suprit Deshpande, Devin Sok, Thumbi Ndung'u, Penny L Moore, Kailapuri Gangatharan Murugavel, Vainav Patel, Jayanta Bhattacharya","doi":"10.1128/jvi.00008-25","DOIUrl":"10.1128/jvi.00008-25","url":null,"abstract":"<p><p>While broadly neutralizing antibodies (bnAbs) have been clinically shown to prevent HIV-1 acquisition, their relative effectiveness against regionally relevant HIV-1 forms is not clear. In the present study, we examined the extent of neutralization susceptibility of contemporary HIV-1 Indian clade C at a population level along with a head-to-head comparison with that from South Africa against a panel of clinically relevant best-in-class bnAbs. Env-pseudotyped viruses encoding HIV-1 India clade C <i>env</i> were found to be best neutralized by the V3 glycan-directed bnAbs (10-1074 and BG18) and select CD4 binding site (CD4bs)-directed bnAbs (VRC07, N6, and 1-18); however, they demonstrated significant resistance to V1/V2 apex-directed bnAbs. Interestingly, the magnitude of the neutralization sensitivity differed between contemporary India and South Africa clade C. Neutralization resistance to key bnAbs was observed to be associated with differences in residues on Env that form bnAb contact sites, gp120 loop lengths, and potential N-linked glycans. Notably, the second generation CD4bs bnAbs (VRC07, N6, 1-18) showed neutralization of VRC01- and 3BNC117-resistant viruses but with two- to sevenfold reduced potency compared to the VRC01-sensitive counterparts, likely due to the enrichment of resistance-associated residues observed in loop D. Predictive analysis indicated that the combination of BG18, N6, and PGDM1400 can provide over 95% neutralization coverage of contemporary India clade C at 1 µg/mL (IC80), an observation distinct from that observed with Africa clade C. Our study clearly highlights that both the complementarity of bnAb classes and the regionally relevant HIV-1 forms are important in achieving clinical effectiveness.IMPORTANCEWhile the development of vaccines to prevent HIV infection remains a global priority, their potential effectiveness is limited by the extraordinarily diversified circulating forms of HIV-1. The prospect of best-in-class broadly neutralizing antibodies (bnAbs) as a potential prevention option has been demonstrated in several studies, including the phase 2b Antibody-Mediated Prevention trials; however, to be broadly applicable, bnAbs will need to overcome the substantial variability of HIV <i>env</i> circulating globally, beyond the regions where efficacy trials are conducted. The present study highlights that the region-specific contemporary HIV-1 clade C viruses not only vary in their degree of susceptibility to the best-in-class clinically relevant bnAbs, but also are evolving at a population level to become increasingly resistant to the best-in-class bnAbs. Overall, the outcome of this study highlights the need for periodic assessment of sequence and neutralization profiles of the circulating regionally relevant HIV-1 forms toward prioritizing the bnAb combination suitable for effective intervention.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0000825"},"PeriodicalIF":4.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7617755/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrophobic residue substitutions enhance the stability and <i>in vivo</i> immunogenicity of respiratory syncytial virus fusion protein.","authors":"Qiaoyun Song, Haixia Yang, Haoyue Zhu, Yun Hu, Wenling Shen, Huifeng Cheng, Jialiao Cai, Manlan Qiu, Yueyue Li, Yaolan Li, Wencai Ye, Ying Wang, Wei Tang","doi":"10.1128/jvi.00087-25","DOIUrl":"10.1128/jvi.00087-25","url":null,"abstract":"<p><p>Respiratory syncytial virus (RSV) entry into host cells is facilitated by viral fusion, wherein the metastable RSV fusion (F) protein undergoes a conformational change from a prefusion state to a highly stable postfusion structure. The prefusion F elicits a more robust human antibody response than its postfusion F and is a primary target for RSV vaccine development. However, the inherent instability of the prefusion F trimer and its low protein expression level in host cells are a significant challenge for developing a high-potency RSV vaccine. Here, we report that the introduction of four hydrophobic residue substitutions in the RSV F protein resulted in a highly stable prefusion F trimer (pre-F-IFLP). This engineered variant exhibits enhanced expression and stability compared to DS-Cav1, with improved thermal stability, increased resistance to acid and base, and extended storage life. Furthermore, pre-F-IFLP induced neutralizing antibody responses 72-fold higher than those elicited by DS-Cav1 following a second booster immunization and fully protected mice against RSV infection.</p><p><strong>Importance: </strong>In this study, we demonstrate that introducing four hydrophobic residue substitutions into the RSV F protein leads to the generation of a highly stable prefusion F trimer (pre-F-IFLP) with improved expression levels in cultured cells and superior stability compared to DS-Cav1, the first-generation prefusion F-stabilized RSV vaccine. Furthermore, pre-F-IFLP induced significantly higher neutralizing antibody responses than DS-Cav1 following both the first and second booster immunizations and conferred complete protection against RSV infection in a mouse model. These findings present an alternative approach for stabilizing the trimeric prefusion F protein, enhancing its expression, and significantly improving its protective efficacy for the prevention of RSV infection <i>in vivo</i>.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0008725"},"PeriodicalIF":4.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12172430/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144159697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Midnolin inhibits coronavirus proliferation by degrading viral proteins.","authors":"Yahe Wang, Wu Tong, Wenzhen Qin, Xinyu Yang, Hai Yu, Hao Zheng, Wen Zhang, Guangzhi Tong, Chunmei Wang, Ning Kong, Tongling Shan","doi":"10.1128/jvi.00366-25","DOIUrl":"10.1128/jvi.00366-25","url":null,"abstract":"<p><p>Cells utilize proteasomes and selective autophagy to degrade ubiquitin-labeled viral proteins and inhibit viral proliferation. Midnolin, a midbrain nucleolar protein, is reported to use ubiquitin-independent proteasomal degradation to degrade various nuclear proteins including transcription factors encoded by the immediate-early genes. However, it remains unclear whether midnolin can degrade viral protein to hinder viral replication. In this study, midnolin degraded porcine epidemic diarrhea virus (PEDV) S1/S2/M/E proteins to suppress PEDV proliferation. Midnolin has two essential structural domains: the Catch domain and the ubiquitin-like domain. We found that the Catch domain and the ubiquitin-like domain of midnolin concerted to target and degrade PEDV S1/S2/M/E proteins by both the proteasome and selective autophagy. Furthermore, this study indicated that the individual Catch domain of midnolin degraded PEDV S1/S2/M/E proteins through the autophagy pathway, which recruited the E3 ubiquitinating enzyme MARCH8 to ubiquitinate S1/S2/M/E proteins, and that the ubiquitinated proteins were recognized by Tollip and transported to the lysosome for degradation. Collectively, midnolin degraded viral proteins not only through the proteasomal pathway but also revealed a new mechanism of midnolin-mediated virus restriction, where the Catch domain degraded viral proteins using the midnolin (Catch)-MARCH8-Tollip-autophagosome pathway.IMPORTANCEProteasomes and selective autophagy are two ways that inhibit viral proliferation in cells. Midnolin can degrade nuclear proteins. However, whether midnolin can degrade viral protein is unknown. In this study, we found that midnolin degraded porcine epidemic diarrhea virus (PEDV) S1/S2/M/E proteins to suppress PEDV proliferation. During the degradation, two domains of midnolin exerted a vital role. The Catch domain and the ubiquitin-like domain concerted to interact and degrade PEDV S1/S2/M/E proteins through the proteasome pathway. In addition, the individual Catch domain of midnolin degraded PEDV S1/S2/M/E proteins through the autophagy pathway using the midnolin (Catch)-MARCH8-Tollip-autophagosome pathway. Overall, we have discovered a new mechanism of midnolin which acts as a host factor for antiviral function.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0036625"},"PeriodicalIF":4.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12172420/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144174054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early short-course treatment fails to prevent disease or relapse upon discontinuance of treatment in infections in addition to COVID-19.","authors":"Arthur M Friedlander","doi":"10.1128/jvi.00381-25","DOIUrl":"10.1128/jvi.00381-25","url":null,"abstract":"","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0038125"},"PeriodicalIF":4.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12172411/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144000104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cellular transcription factor TFII-I represses adenovirus gene expression.","authors":"Rachel L White, Patrick Hearing","doi":"10.1128/jvi.00618-25","DOIUrl":"10.1128/jvi.00618-25","url":null,"abstract":"<p><p>To successfully replicate, viruses must overcome innate cellular antiviral responses. With human adenovirus (HAdV), a key viral repressor of cellular antiviral responses is the early protein E4ORF3. E4ORF3 relocalizes numerous cellular antiviral proteins, particularly those involved in the interferon (IFN) and DNA damage response (DDR) pathways, to sequester them from viral replication sites in the nucleus. E4ORF3 also directs SUMO modification of a subset of its targets, some of which are subsequently targeted for proteasomal degradation. We previously identified TFII-I, a cellular transcription factor and DNA repair protein, as one of the proteins most highly SUMOylated by E4ORF3, as well as one of the E4ORF3 degradation targets. In this study, we characterized the effect of TFII-I knockout (KO) on HAdV replication. TFII-I KO significantly increased the infectious virus yield from infected cells, supporting the hypothesis that TFII-I acts as a restriction factor during HAdV infection. TFII-I KO also significantly increased viral genome replication, as well as both early and late gene and protein expression. Our results do not support TFII-I acting as a part of either the DDR or IFN responses during HAdV infection. Our results characterize a novel antiviral function for TFII-I against HAdV that occurs during the early stage of the viral replication cycle and highlight the importance of studying viral countermeasures to the cellular antiviral response, like E4ORF3, to better understand how cells restrict viral infection.IMPORTANCEThe cellular transcription factor TFII-I was previously shown to bind to HAdV late promoters and to E4-mutant viral genomes during replication. More recently, TFII-I was shown to be a degradation target of HAdV protein E4ORF3. Due to the long-established importance of E4ORF3 in countering cellular antiviral responses, this raised the question of whether TFII-I possesses an undiscovered antiviral role against HAdV. It was hypothesized that whether TFII-I played an antiviral role in HAdV infection, it was most likely to be as a repressor of the late transcriptional program. Here, we show the first direct evidence of TFII-I repressing HAdV infection and demonstrate that the inhibitory effect can be detected much earlier in the viral life cycle than previously predicted. Our findings provide insight into the role of TFII-I in the cellular antiviral response.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0061825"},"PeriodicalIF":4.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12172414/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144002740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Endemic coronavirus infection is associated with SARS-CoV-2 Fc receptor-binding antibodies.","authors":"David J Bean, Yan Mei Liang, Frida Avila, Xianbao He, Archana Asundi, Manish Sagar","doi":"10.1128/jvi.00550-25","DOIUrl":"10.1128/jvi.00550-25","url":null,"abstract":"<p><p>Recent documented infection with an endemic coronavirus (eCoV) is associated with less severe coronavirus disease 2019 (COVID-19), yet the immune mechanism behind this protection has not been fully explored. We measured both antibody and T-cell responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in SARS-CoV-2-naïve individuals, classified into two groups: those with or without presumed recent eCoV infections. There was no difference in neutralizing antibodies and T-cell responses against SARS-CoV-2 antigens between the two groups. SARS-CoV-2-naïve individuals with recent presumed eCoV infection, however, had higher and significantly correlated levels of Fc receptor (FcR)-binding antibodies against eCoV spikes (S) and SARS-CoV-2 S2. Recent eCoV infection boosts cross-reactive antibodies that can mediate Fc effector functions, and this may play a role in the observed heterotypic immune protection against severe COVID-19.</p><p><strong>Importance: </strong>With the recent emergence of SARS-CoV-2 and other pathogenic coronaviruses, it is important to understand how the immune system may protect against disease from future coronavirus outbreaks. We investigated the adaptive immune responses elicited from a \"common cold\" eCoV and measured the cross-reactivity against SARS-CoV-2 in individuals classified as having or not having a recent eCoV infection. Although both groups had similar cross-reactive T-cell and neutralizing antibody responses, individuals with a recent eCoV infection had higher antibody levels capable of Fc receptor binding. Antibodies with enhanced Fc receptor binding could mediate the killing of virally infected cells through mechanisms such as antibody-dependent cellular cytotoxicity, which may reduce the severity of COVID-19. Antibodies capable of mediating Fc effector functions may be critical for therapies and vaccines against future pathogenic coronavirus outbreaks.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0055025"},"PeriodicalIF":4.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12172460/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144094078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Drosophila melanogaster</i> Toll-9 elicits antiviral immunity against Drosophila C virus.","authors":"Manish Chauhan, Peter E Martinak, Benjamin M Hollenberg, Alan G Goodman","doi":"10.1128/jvi.02214-24","DOIUrl":"10.1128/jvi.02214-24","url":null,"abstract":"<p><p>The Toll pathway plays a pivotal role in innate immune responses against pathogens. The evolutionarily conserved pattern recognition receptors (PRRs), including Toll-like receptors (TLRs), play a crucial role in recognition of pathogen-associated molecular patterns (PAMPs). The <i>Drosophila</i> genome encodes nine Toll receptors that are orthologous to mammalian TLRs. While mammalian TLRs directly recognize PAMPs, most <i>Drosophila</i> Tolls recognize the proteolytically cleaved ligand Spätzle to activate downstream signaling cascades. In this study, we demonstrated that Toll-9 is crucial for antiviral immunity against Drosophila C virus (DCV), a natural pathogen of <i>Drosophila</i>. A transposable element insertion in the <i>Toll-9</i> gene renders the flies more susceptible to DCV. The stable expression of Toll-9 in <i>Drosophila</i> S2 cells results in increased <i>Dicer2</i> induction and reduced AKT phosphorylation, collectively establishing an antiviral state that inhibits DCV replication. Toll-9 localizes to endosomes, where it binds viral double-stranded RNA (dsRNA), highlighting its role in detecting viral replication intermediates. Together, these findings identify Toll-9 as a key player in antiviral immunity against DCV infection, acting through its ability to recognize dsRNA and drive <i>Dicer2</i> expression, along with other AKT-mediated antiviral responses.</p><p><strong>Importance: </strong>Insects rely on innate immunity and RNA interference (RNAi) to combat viral infections. Our study underscores the pivotal role of <i>Drosophila</i> Toll-9 in antiviral immunity, aligning with findings in <i>Bombyx mori</i>, where Toll-9 activation upregulates the RNAi component <i>Dicer2</i>. We demonstrate that <i>Drosophila</i> Toll-9 functions as a pattern recognition receptor (PRR) for double-stranded RNA (dsRNA) during Drosophila C virus (DCV) infection, akin to mammalian Toll-like receptors (TLRs). Toll-9 activation during DCV infection leads to the upregulation of <i>Dicer2</i> and <i>Argonaute2</i> and dephosphorylation of AKT. This study also reveals that Toll-9 localizes in endosomal compartments where it interacts with dsRNA. These insights enhance our understanding of <i>Drosophila</i> innate immune mechanisms, reflecting the evolutionary conservation of immune responses across diverse species and providing impetus for further research into the conserved roles of TLRs across the animal kingdom.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0221424"},"PeriodicalIF":4.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12172494/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143971056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determinants of susceptibility to SARS-CoV-2 infection in murine ACE2.","authors":"Takashi Kondo, Rigel Suzuki, Hisano Yajima, Sachiho Kawahara, Kodai Yamaya, Takaya Ichikawa, Shuhei Tsujino, Saori Suzuki, Tomokazu Tamura, Takao Hashiguchi, Takasuke Fukuhara","doi":"10.1128/jvi.00543-25","DOIUrl":"10.1128/jvi.00543-25","url":null,"abstract":"<p><p>Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizes angiotensin-converting enzyme 2 (ACE2) as a receptor to enter host cells, and primary receptor recognition of the spike protein is a major determinant of the host range of SARS-CoV-2. Since the emergence of SARS-CoV-2, a considerable number of variants have emerged. However, the determinants of host tropism of SARS-CoV-2 remain elusive. We conducted infection assays with chimeric recombinant SARS-CoV-2 carrying the spike protein from 10 viral variants, assessing their entry efficiency using mammalian ACE2 orthologs from species that have close contact with humans. We found that only murine ACE2 exhibited different susceptibilities to infection with the SARS-CoV-2 variants. Moreover, we revealed that the mutation N501Y in the viral spike protein has a crucial role in determining the infectivity of cells expressing murine ACE2 and of mice <i>in vivo</i>. Next, we identified six amino acid substitutions at 24, 30, 31, 82, 83, and 353 in murine ACE2 that allowed for viral entry of the variants to which murine ACE2 was previously resistant. Furthermore, we showed that ACE2 from a species closely related to mice, <i>Mus caroli</i>, is capable of supporting entry of the viral variants that could not use murine ACE2. These results suggest that few ACE2 orthologs have different susceptibility to infection with SARS-CoV-2 variants as observed for murine ACE2. Collectively, our study reveals critical amino acids in ACE2 and the SARS-CoV-2 spike protein that are involved in the host tropism of SARS-CoV-2, shedding light on interspecies susceptibility to infection.IMPORTANCESARS-CoV-2 can infect many species besides humans, leading to the evolution of the virus and adaptation to other animal hosts, which could trigger a new COVID-19 wave. The SARS-CoV-2 spike protein utilizes ACE2 as a receptor for entry into host cells. The interaction of ACE2 with the spike protein determines the host range of SARS-CoV-2. In this study, using chimeric viruses carrying the spike protein of SARS-CoV-2 variants to infect cells expressing different ACE2 orthologs from species humans come in close contact with, we confirmed murine ACE2 alone showed different susceptibility to the variants. We identified residues in murine ACE2 and the viral spike that restrict viral entry. Furthermore, an ACE2 ortholog from a species genetically close to mice mediated entry of SARS-CoV-2 variants incapable of infecting mice. This research highlights the uniquely limited susceptibility of mice to different SARS-CoV-2 variants and provides invaluable insights into the host tropism of SARS-CoV-2.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0054325"},"PeriodicalIF":4.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12172435/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144006375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}