AT-9010 (2'-methyl-2'-fluoro guanosine triphosphate) is a GTP analog whose prodrug, AT-752 is under consideration in human medicine as a potential antiviral drug against certain flaviviruses. It was previously believed to inhibit viral replication by acting primarily as a chain terminator. However, it was discovered recently that it also binds the GTP binding site of the methyltransferase (MTase) domain of the orthoflavivirus polymerase, thus interfering with RNA capping. Here, we investigated the binding of AT-9010 to Ntaya and Zika virus MTases. Structural analysis using X-ray crystallography revealed similar interactions between the base and sugar moieties of AT-9010 and key residues in both MTases, although differences in hydrogen bonding were observed. Our analysis also suggested that the triphosphate part of AT-9010 is flexible. Despite minor variations, the overall binding mode of AT-9010 was found to be the same for all of the flaviviral MTases examined, suggesting a structural basis for the efficacy of AT-9010 against multiple orthoflavivirus MTases.

• MeSH
• antivirové látky * chemie   farmakologie   metabolismus   MeSH
• Flaviviridae * enzymologie   MeSH
• guanosintrifosfát * analogy a deriváty   metabolismus   chemie   MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• methyltransferasy * metabolismus   chemie   genetika   MeSH
• molekulární modely MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• virové proteiny * metabolismus   chemie   MeSH
• virus zika * enzymologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antivirové látky * MeSH
• guanosintrifosfát * MeSH
• methyltransferasy * MeSH
• virové proteiny * MeSH

The 37th International Conference on Antiviral Research (ICAR) was held in Gold Coast, Australia, May 20-24, 2024. ICAR 2024 featured over 75 presentations along with two poster sessions and special events, including those specifically tailored for trainees and early-career scientists. The meeting served as a platform for the exchange of cutting-edge research, with presentations and discussions covering novel antiviral compounds, vaccine development, clinical trials, and therapeutic advancements. A comprehensive array of topics in antiviral science was covered, from the latest breakthroughs in antiviral drug development to innovative strategies for combating emerging viral threats. The keynote presentations provided fascinating insight into two diverse areas fundamental to medical countermeasure development and use, including virus emergence at the human-animal interface and practical considerations for bringing antivirals to the clinic. Additional sessions addressed a variety of timely post-pandemic topics, such as the hunt for broad spectrum antivirals, combination therapy, pandemic preparedness, application of in silico tools and AI in drug discovery, the virosphere, and more. Here, we summarize all the presentations and special sessions of ICAR 2024 and introduce the 38th ICAR, which will be held in Las Vegas, USA, March 17-21, 2025.

• MeSH
• antivirové látky * terapeutické užití   farmakologie   MeSH
• COVID-19 MeSH
• farmakoterapie COVID-19 MeSH
• lidé MeSH
• objevování léků MeSH
• vyvíjení léků MeSH
• vývoj vakcíny MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• kongresy MeSH
• Geografické názvy
• Austrálie MeSH
• Názvy látek
• antivirové látky * MeSH

Nsp14 is an RNA methyltransferase (MTase) encoded by all coronaviruses. In fact, many viral families, including DNA viruses, encode MTases that catalyze the methylation of the RNA precap structure, resulting in fully capped viral RNA. This capping is crucial for efficient viral RNA translation, stability, and immune evasion. Our previous research identified nsp14 inhibitors based on the chemical scaffold of its methyl donor - the S-adenosyl methionine (SAM) - featuring a modified adenine base and a substituted arylsulfonamide. However, the binding mode of these inhibitors was based only on docking experiments. To uncover atomic details of nsp14 inhibition we solved the crystal structure of nsp14 bound to STM957. The structure revealed the atomic details of nsp14 inhibition such that the 7-deaza-adenine moiety of STM957 forms specific interactions with Tyr368, Ala353, and Phe367, while the arylsulfonamide moiety engages with Asn388 and Phe506. The large aromatic substituent at the 7-deaza position displaces a network of water molecules near the adenine base. Surprisingly, this was recently observed in the case of an unrelated monkeypox MTase VP39, where the 7-deaza modified SAH analogs also displaced water molecules from the vicinity of the active site.

• Klíčová slova
• Crystal structure, Inhibitor, Methyltransferase,
• Publikační typ
• časopisecké články MeSH

The emergence of SARS-CoV-2, the causative agent of COVID-19, has highlighted the need for advanced antiviral strategies. Targeting the coronaviral methyltransferase nsp14, which is essential for RNA capping, offers a promising approach for the development of small-molecule inhibitors. We designed and synthesized a series of adenosine 5'-carboxamide derivatives as potential nsp14 inhibitors and identified coumarin analogs to be particularly effective. Structural modifications revealed the importance of the 5'-carboxyl moiety for the inhibitory activity, showing superior efficacy compared to other modifications. Notably, compound 18l (HK370) demonstrated high selectivity and favorable in vitro pharmacokinetic properties and exhibited moderate antiviral activity in cell-based assays. These findings provide a robust foundation for developing targeted nsp14 inhibitors as a potential treatment for COVID-19 and related diseases.

• Publikační typ
• časopisecké články MeSH

The search for new drugs against COVID-19 and its causative agent, SARS-CoV-2, is one of the major trends in the current medicinal chemistry. Targeting capping machinery could be one of the therapeutic concepts based on a unique mechanism of action. Viral RNA cap synthesis involves two methylation steps, the first of which is mediated by the nsp14 protein. Here, we rationally designed and synthesized a series of compounds capable of binding to both the S-adenosyl-l-methionine and the RNA-binding site of SARS-CoV-2 nsp14 N7-methyltransferase. These hybrid molecules showed excellent potency, high selectivity toward various human methyltransferases, nontoxicity, and high cell permeability. Despite the outstanding activity against the enzyme, our compounds showed poor antiviral performance in vitro. This suggests that the activity of this viral methyltransferase has no significant effect on virus transcription and replication at the cellular level. Therefore, our compounds represent unique tools to further explore the role of the SARS-CoV-2 nsp14 methyltransferase in the viral life cycle and the pathogenesis of COVID-19.

• Publikační typ
• časopisecké články MeSH

ORPs are lipid-transport proteins belonging to the oxysterol-binding protein family. They facilitate the transfer of lipids between different intracellular membranes, such as the ER and plasma membrane. We have solved the crystal structure of the ORP8 lipid transport domain (ORD8). The ORD8 exhibited a β-barrel fold composed of anti-parallel β-strands, with three α-helices replacing β-strands on one side. This mixed alpha-beta structure was consistent with previously solved structures of ORP2 and ORP3. A large cavity (≈1860 Å3) within the barrel was identified as the lipid-binding site. Although we were not able to obtain a lipid-bound structure, we used computer simulations based on our crystal structure to dock PS and PI4P molecules into the putative lipid-binding site of the ORD8. Comparative experiments between the short ORD8ΔLid (used for crystallography) and the full-length ORD8 (lid containing) revealed the lid's importance for stable lipid binding. Fluorescence assays revealed different transport efficiencies for PS and PI4P, with the lid slowing down transport and stabilizing cargo. Coarse-grained simulations highlighted surface-exposed regions and hydrophobic interactions facilitating lipid bilayer insertion. These findings enhance our comprehension of ORD8, its structure, and lipid transport mechanisms, as well as provide a structural basis for the design of potential inhibitors.

• Klíčová slova
• ER, ORD, ORP8, PI4P, PS, lipid transport, plasma membrane,
• MeSH
• biologický transport MeSH
• buněčná membrána metabolismus   MeSH
• lipidy * chemie   MeSH
• transportní proteiny * metabolismus   MeSH
• vazebná místa MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• lipidy * MeSH
• transportní proteiny * MeSH

Monkeypox, or mpox, is a disease that has recently resurfaced and spread across the globe. Despite the availability of an FDA-approved vaccine (JYNNEOS) and an effective drug (tecovirimat), concerns remain over the possible recurrence of a viral pandemic. Like any other virus, mpox virus must overcome the immune system to replicate. Viruses have evolved various strategies to overcome both innate and adaptive immunity. Poxviruses possess an unusual nuclease, poxin, which cleaves 2'-3'-cGAMP, a cyclic dinucleotide, which is an important second messenger in the cGAS-STING signaling pathway. Here, we present the crystal structure of mpox poxin. The structure reveals a conserved, predominantly β-sheet fold and highlights the high conservation of the cGAMP binding site and of the catalytic residues His17, Tyr138, and Lys142. This research suggests that poxin inhibitors could be effective against multiple poxviruses.

• MeSH
• lidé MeSH
• opičí neštovice * MeSH
• Poxviridae * MeSH
• racionální návrh léčiv MeSH
• signální transdukce MeSH
• virus opičích neštovic MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Monkeypox is a disease with pandemic potential. It is caused by the monkeypox virus (MPXV), a double-stranded DNA virus from the Poxviridae family, that replicates in the cytoplasm and must encode for its own RNA processing machinery including the capping machinery. Here, we present crystal structures of its 2'-O-RNA methyltransferase (MTase) VP39 in complex with the pan-MTase inhibitor sinefungin and a series of inhibitors that were discovered based on it. A comparison of this 2'-O-RNA MTase with enzymes from unrelated single-stranded RNA viruses (SARS-CoV-2 and Zika) reveals a conserved sinefungin binding mode, implicating that a single inhibitor could be used against unrelated viral families. Indeed, several of our inhibitors such as TO507 also inhibit the coronaviral nsp14 MTase.

• MeSH
• COVID-19 * MeSH
• infekce virem zika * MeSH
• lidé MeSH
• methyltransferasy metabolismus   MeSH
• RNA virová genetika   MeSH
• RNA MeSH
• SARS-CoV-2 genetika   MeSH
• virové nestrukturální proteiny chemie   MeSH
• virus opičích neštovic genetika   metabolismus   MeSH
• virus zika * genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• methyltransferasy MeSH
• RNA virová MeSH
• RNA MeSH
• virové nestrukturální proteiny MeSH

Seven coronaviruses have infected humans (HCoVs) to-date. SARS-CoV-2 caused the current COVID-19 pandemic with the well-known high mortality and severe socioeconomic consequences. MERS-CoV and SARS-CoV caused epidemic of MERS and SARS, respectively, with severe respiratory symptoms and significant fatality. However, HCoV-229E, HCoV-NL63, HCoV-HKU1, and HCoV-OC43 cause respiratory illnesses with less severe symptoms in most cases. All coronaviruses use RNA capping to evade the immune systems of humans. Two viral methyltransferases, nsp14 and nsp16, play key roles in RNA capping and are considered valuable targets for development of anti-coronavirus therapeutics. But little is known about the kinetics of nsp10-nsp16 methyltransferase activities of most HCoVs, and reliable assays for screening are not available. Here, we report the expression, purification, and kinetic characterization of nsp10-nsp16 complexes from six HCoVs in parallel with previously characterized SARS-CoV-2. Probing the active sites of all seven by SS148 and WZ16, the two recently reported dual nsp14 / nsp10-nsp16 inhibitors, revealed pan-inhibition. Overall, our study show feasibility of developing broad-spectrum dual nsp14 / nsp10-nsp16-inhibitor therapeutics.

• Klíčová slova
• Coronavirus, Enzyme kinetics, Enzyme purification, RNA methyltransferase, RNA virus, Viral protein, nsp10-nsp16 complex,
• MeSH
• COVID-19 * MeSH
• lidé MeSH
• methyltransferasy chemie   MeSH
• pandemie MeSH
• RNA MeSH
• SARS-CoV-2 genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• methyltransferasy MeSH
• NSP10 protein, SARS-CoV-2 MeSH Prohlížeč
• NSP16 protein, SARS-CoV-2 MeSH Prohlížeč
• RNA MeSH
• SS148 MeSH Prohlížeč
• WZ16 MeSH Prohlížeč

SARS-CoV-2 nsp10-nsp16 complex is a 2'-O-methyltransferase (MTase) involved in viral RNA capping, enabling the virus to evade the immune system in humans. It has been considered a valuable target in the discovery of antiviral therapeutics, as the RNA cap formation is crucial for viral propagation. Through cross-screening of the inhibitors that we previously reported for SARS-CoV-2 nsp14 MTase activity against nsp10-nsp16 complex, we identified two compounds (SS148 and WZ16) that also inhibited nsp16 MTase activity. To further enable the chemical optimization of these two compounds towards more potent and selective dual nsp14/nsp16 MTase inhibitors, we determined the crystal structure of nsp10-nsp16 in complex with each of SS148 and WZ16. As expected, the structures revealed the binding of both compounds to S-adenosyl-L-methionine (SAM) binding pocket of nsp16. However, our structural data along with the biochemical mechanism of action determination revealed an RNA-dependent SAM-competitive pattern of inhibition for WZ16, clearly suggesting that binding of the RNA first may help the binding of some SAM competitive inhibitors. Both compounds also showed some degree of selectivity against human protein MTases, an indication of great potential for chemical optimization towards more potent and selective inhibitors of coronavirus MTases.

• Klíčová slova
• COVID-19, SARS-CoV-2, SS148, WZ16, nsp10, nsp16,
• MeSH
• farmakoterapie COVID-19 * MeSH
• lidé MeSH
• methyltransferasy chemie   MeSH
• RNA virová metabolismus   MeSH
• SARS-CoV-2 * MeSH
• virové nestrukturální proteiny chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• methyltransferasy MeSH
• RNA virová MeSH
• virové nestrukturální proteiny MeSH