Viral Protein Analysis Techniques

This excellent, new paper by Tiambeng et. al. describes studies on characterization of adeno-associated virus capsid proteins using denaturing size-exclusion chromatography coupled with mass spectrometry. Quoting from the abstract: "Recombinant adeno-associated viruses (AAVs) are a highly effective platform for gene delivery for the treatment of many human diseases. Characterization of AAV viral protein attributes (VP), such as serotype identity, VP stoichiometry, and VP post-translational modifications, is essential to ensure product and process consistency. While size-exclusion chromatography (SEC) coupled with mass spectrometry (MS) is commonly used in the biopharmaceutical industry for analyzing protein therapeutics, its application to intact AAV VP components has not gained traction, presumably due to difficulties in achieving adequate resolution of VP(1−3) monomers. Herein, we describe the development of a denaturing SEC method and optimization of SEC parameters, including stationary phase pore size, column temperature, and mobile phase composition, to achieve effective chromatographic separation of VP(1−3). We demonstrate that an optimized dSEC-MS method featuring MS-compatible formic acid, can effectively separate VP(1−3) across AAV1, 2, 5, 6, 8, and 9 serotypes using a single column and mobile phase condition. A case study was included to showcase successful application of the dSEC-MS method in analyzing changes across different AAV production processes, yielding similar conclusions to an orthogonal approach, such as hydrophilic interaction chromatography (HILIC)- MS. Additionally, dSEC integrated with fluorescence (FLR) and ultraviolet (UV) detection can be used to semi-quantitatively identify both AAV DNA and VP components from empty and full AAV samples. Overall, this robust and MS-friendly methodological advancement could greatly streamline the development and analytical quality control processes for AAV-based gene therapies, providing a highly sensitive method for intact VP characterization."

🚀 Breaking Down Viral Defenses: A New Frontier in Antibody Therapy & Vaccine Design 🦠💡 Neutralizing antibodies (NAbs)  play a critical role in combating viral infections, guiding both therapeutic strategies and vaccine development. However, viral evolution and immune evasion present ongoing challenges, necessitating a deeper understanding of antibody mechanisms. A groundbreaking study from Yang Huang and colleagues at Xiamen University reveals how a powerful antibody, 7H13, neutralizes #rotavirus (#RV) by exploiting a hidden vulnerability in its VP4 “#spike” protein—a discovery with far-reaching implications for combating viral evolution and designing universal vaccines! Utilizing advanced cryo-electron microscopy (#cryoEM) and cryo-electron tomography (#cryoET), scientists revealed how 7H13 induces irreversible damage to the viral VP4 protein, effectively blocking the virus's adsorption process. Read the full study to dive deeper into this! 🔗 https://lnkd.in/dWv7e4N5 🔑 Insights: 🔍 Broad-Spectrum Power: 7H13 targets a conserved epitope on VP4, enabling neutralization across diverse RV genotypes and protecting mice from infection. 🔍  Essential Structural Insights: Structure-guided mutations confirmed the crucial role of the 7H13 heavy chain I54 in activating the 'molecular switch' of F418 and initiating VP4 disruption. This destabilizes the spike’s meta-stable structure, irreversibly disabling the virus. Cryo-EM’s Crucial Role: 📌 By employing a low-temperature, time-resolved cryo-EM technique, scientists captured a series of intermediate states of viral immune complexes and elucidated the high-resolution structure of the VP4:7H13 complex. 📌 Time-resolved cryo-EM unveiled dynamic, asymmetric antibody binding and intermediate states of viral disruption—a feat impossible with traditional methods. This highlights cryo-EM’s critical role in resolving complex biological mechanisms at near-atomic resolution. 💥 Why This Matters: Viruses like RV rely on dynamic, unstable proteins to invade host cells. By targeting these structural Achilles’ heels, antibodies like 7H13 offer escape-resistant therapies and blueprints for broad-spectrum vaccines and therapeutics against rotaviruses. 🌍 The Bigger Picture: As viral evolution outpaces conventional therapies, understanding how antibodies dismantle pathogens is critical. This work not only expands our toolkit against RV but also sets a paradigm for tackling other viruses—from influenza to coronaviruses—by targeting conserved, conformationally fragile sites. #AntiviralResearch #CryoEM #BroadlyNeutralizingAntibodies #Rotavirus #VaccineDevelopment #StructuralBiology #Biotechnology #HealthcareInnovation

🔬 𝐀𝐝𝐯𝐚𝐧𝐜𝐞𝐬 𝐢𝐧 𝐈𝐄𝐗/𝐌𝐒 𝐟𝐨𝐫 𝐈𝐧𝐭𝐚𝐜𝐭 𝐏𝐫𝐨𝐭𝐞𝐢𝐧 & 𝐏𝐫𝐨𝐭𝐞𝐨𝐟𝐨𝐫𝐦 𝐂𝐡𝐚𝐫𝐚𝐜𝐭𝐞𝐫𝐢𝐳𝐚𝐭𝐢𝐨𝐧 💡 The characterization of intact proteins and their charge variants remains a critical step in understanding protein heterogeneity—especially in therapeutic contexts such as mAbs, ADCs, and viral vectors. This comprehensive review explores the recent evolution of non-denaturing IEX–MS, with a strong focus on pH-gradient-based methods as an alternative to traditional salt gradients. These developments are particularly valuable for native MS applications, enabling analysis while preserving protein structure and non-covalent interactions. ⚖️ 𝐊𝐞𝐲 𝐭𝐞𝐜𝐡𝐧𝐢𝐜𝐚𝐥 𝐭𝐡𝐞𝐦𝐞𝐬 𝐜𝐨𝐯𝐞𝐫𝐞𝐝 𝐢𝐧𝐜𝐥𝐮𝐝𝐞: 🧪 𝑝𝐻-𝑔𝑟𝑎𝑑𝑖𝑒𝑛𝑡 𝑠𝑡𝑟𝑎𝑡𝑒𝑔𝑖𝑒𝑠 → Chromatofocusing → Linear pH gradients → Salt-mediated pH gradients 💧 𝑉𝑜𝑙𝑎𝑡𝑖𝑙𝑒 𝑏𝑢𝑓𝑓𝑒𝑟 𝑠𝑦𝑠𝑡𝑒𝑚𝑠 → Challenges in achieving linear pH gradients using MS-compatible additives like ammonium acetate and formate → Emerging use of novel volatile buffers (e.g., DFEA, TFEA) to fill critical pH gaps 🧱 𝑆𝑡𝑎𝑡𝑖𝑜𝑛𝑎𝑟𝑦 𝑝ℎ𝑎𝑠𝑒𝑠 𝑎𝑛𝑑 𝑐𝑜𝑙𝑢𝑚𝑛 𝑠𝑒𝑙𝑒𝑐𝑡𝑖𝑜𝑛 → Emphasis on nonporous polymeric materials for enhanced resolution → Role of particle size, hydrophilicity, and charge density in minimizing protein denaturation 🧬 𝐷𝑖𝑟𝑒𝑐𝑡 𝐼𝐸𝑋–𝑀𝑆 𝑐𝑜𝑢𝑝𝑙𝑖𝑛𝑔 𝑡𝑒𝑐ℎ𝑛𝑖𝑞𝑢𝑒𝑠 → Micro/nano-flow LC → Post-column flow splitting → Dopant-enriched nitrogen → Multi-nozzle ESI and nano-IEX–MS for ultra-sensitive detection The review also outlines how IEX–MS supports precise identification of charge variants arising from PTMs, including deamidation, sialylation, phosphorylation, and C-terminal modifications—essential insights for CQA profiling of biopharmaceuticals. 🎯 𝐊𝐞𝐲 𝐓𝐚𝐤𝐞-𝐀𝐰𝐚𝐲𝐬: • ⚛️ pH gradient-based IEC enables MS-compatible, non-denaturing separation of charge variants in intact proteins. • 🧫 Volatile buffer system development is a bottleneck in achieving linear pH control and high-resolution separations. • 💡 Salt-mediated pH gradients offer enhanced selectivity and better MS performance with reduced ion suppression. • 🔍 Column material, flow rate, and ESI strategies critically impact resolution, sensitivity, and native MS compatibility. • 🧬 IEX–MS is becoming increasingly essential for high-resolution profiling of therapeutic protein heterogeneity. #Proteomics #MassSpectrometry #IonExchangeChromatography #Biopharmaceuticals #AnalyticalScience #ProteinCharacterization #TopDownProteomics #NativeMS #ChargeVariants #PTMs #CQA #mAbs #ADC #ViralVectors Ziran Zhai, Thomas Holmark, Lars J. & Andrea Gargano University of Amsterdam

🇪🇸 🇫🇮 Unveiling the Assembly Secrets of Two-MCP Viruses: Cryo-EM Structures of HCIV-1 and HHIV-2 Provide New Insights The fundamental building blocks of viruses, called major capsid proteins (MCPs), typically adopt a single-β-barrel fold. However, the recent discovery of viruses with two MCPs, resembling the PRD1-adenovirus lineage, challenged our understanding of viral assembly. This study sheds light on this mystery by revealing the high-resolution cryo-electron microscopy (cryo-EM) structures of two such viruses: Haloarcula californiae icosahedral virus 1 (HCIV-1) and Haloarcula hispanica icosahedral virus 2 (HHIV-2). Deconstructing the Viral Architecture: A Dance of Proteins and Membranes The intricate structures of HCIV-1 and HHIV-2, determined at near-atomic resolution (3.7 and 3.8 Å, respectively), showcase a fascinating interplay of proteins and membranes. Beneath the capsid's surface, two distinct types of capsomers – two-tower and three-tower – harbor unique protein components. These proteins act as hidden puppeteers, orchestrating the precise positioning of pre-assembled MCP heterodimers, the fundamental building blocks of the viral shell. Interestingly, the vertices, the corners of the icosahedral capsid, are adorned with homopentameric membrane proteins, playing a crucial role in anchoring and orienting the MCPs. Beyond Two MCPs: Unraveling Assembly Principles for Diverse Viruses The detailed cryo-EM maps, combined with proteomic data, offer valuable insights into the assembly mechanism of these two-MCP viruses. This knowledge extends beyond just HCIV-1 and HHIV-2, providing a springboard for understanding the assembly of other viruses with similar MCP architectures, even those lacking an internal membrane. This paves the way for a deeper appreciation of the diverse strategies employed by viruses to build their infectious coats. From Viruses to Vaccines: A Potential Application Understanding viral assembly mechanisms holds immense potential for developing novel antiviral strategies. For instance, the identified proteins involved in HCIV-1 and HHIV-2 assembly could serve as targets for antiviral drugs, potentially inhibiting their ability to replicate and spread. Additionally, insights into capsid formation could aid in the design of more effective virus-based vaccines by enabling the engineering of stable, immunogenic viral particles. 📝 Article, Open Access https://lnkd.in/eHPQYEfb 📷 EM Map Analysis https://lnkd.in/eQYsKW-a 📎 Free Use and License https://lnkd.in/gpbw3cEg 📌 About EM Data Bank https://lnkd.in/ePU9n4kv Santos-Perez I, Charro D, Gil-Carton D, Azkargorta M, Elortza F, Bamford DH, Oksanen HM, Abrescia NGA. Nat Commun (2019) #disease #research #structuralbiology #merize

A simple and sensitive differential digestion method to analyze adeno-associated virus residual host cell proteins by LC-MS Highlights •The manuscript discusses the development of a new method for identifying residual host cell proteins (HCPs) in adeno-associated virus (AAV) using liquid chromatography-mass spectrometry (LC-MS). •The method, known as differential digestion, is highly sensitive and effective, and it maintains the integrity of AAV while preferentially digesting HCPs under denaturing and reducing conditions. •This method requires only a small amount of sample and significantly improves the identification of HCPs. •This research fills a gap in AAV HCP analysis by providing a sensitive and robust strategy for detecting, monitoring, and measuring HCPs. https://lnkd.in/e5zKbsWr