Cryo-Electron Microscopy
Viruses are extremely diverse in shape and size, evolution has led to a vast number of viral chasses or lineages. With the advances of imaging related techniques, such as the introduction of direct electron detectors (DEDs) and the optimzation in image processing, it is possible to study the high-resolution structure of viral assembly, viral proteins and viral antibody immune complexes using cryo-electron microscopy (cryo-EM). In the past two decades, cryo-EM has been used to investigate virus morphology, involving Ebola, HIV, Zika, and coronaviruses. These examples of the successful application of cryo-EM in virology highlighted the critical and diversity of information that cryo-EM can provide researchers.
Overview of cryo-EM in virology
Based on the development of better microscopes, direct electron detection camera (DED) technologies, and sophisticated reconstruction algorithms, cryo-EM has been developed as a powerful high-resolution technique in structural biology research. So far, this technology has been applied to investigate 3D imaging of virus structure, viral proteins as well as virus-antibody immune complexes. In contrast to negatively-stained methods, which need tedious sample preparation, such as typical negative staining or chemical fixation, cryo-EM is able to rapidly freeze virus particles in a thin layer of vitreous ice, thus preserving the virus's native conformation and allowing for high-resolution analysis.
Single particle analysis (SPA) and cryo-electron tomography (cryo-ET) are two major 3D cryo-EM analysis strategies. Both of the two approaches have been applied for structural studies on viral assemblies as well as the interactions occurring between whole virions or viral components and their associated antibodies. As a cryo-EM technique, SPA can be used to determine the structures of macromolecular complexes at high-resolution. While cryo-ET can provide structural information with broader cellular context.
Overview of cryo-EM and cryo-ET workflow, from data acquisition to 3D model.(IntechOpen.et al, 2020)
Service offering
Based on the advanced equipment and years of experience in cryo-EM services, we are proud to offer custom cryo-EM services for virus research. Our services include the two major 3D cryo-EM analysis strategies. Importantly, we offer one-stop services, ranging from sample preparation, cryo-EM imaging and data processing, to model building and refinement.
Single particle analysis (SPA)
SPA has become a popular and effective approach for investigation of the structure of biologically significant molecules at a near-atomic resolution. Combined with data from several thousands of purified virus particles, the method can be applied to study some viruses that are highly ordered in structure, especially those with icosahedral symmetries.
Cryo-electron tomography (cryo-ET)
Cryo-ET is an advanced technology for frozen hydrated biologic samples. The method can bridge the gap between ultrastructural compartmentalization and the structural analysis of molecular inhabitants. Cryo-ET procedures at ~25-Å resolution can be applied to achieve 3D reconstruction of pleomorphic viruses. Sub-tomogram averaging techniques are further applied to map better structural details for repeating structures.
Advantages of our cryo-electron microscopy services
- Able to determine the high-resolution structures of many viral assemblies, viral proteins, and virus-antibody immune complexes.
- Able to detect the conformational epitopes of sequentially discontinuous residues on icosahedral virions.
- Able to analyze highly glycosylated viral glycoproteins and other intrinsic heterogeneous samples.
- Promote the standardized process of rapid and high-quality vaccine development.
For more detailed information, please feel free to contact us or directly send us an inquiry.
Reference
- IntechOpen. et al. (2020). "Cryo-electron microscopy for the study of virus assembly." Nature chemical biology, 16(3), 231-239.
* For research use only.
