Virion Concentration and Purification Service
Purification and concentration of virus particles are the first and important steps to understand the structure and function of both viral and host proteins. These preparations of virions facilitate the application of techniques such as mass spectrometry (MS)-based proteomics. In order to further investigate virion proteins and ensure reproducible analysis by the wide variety of proteomic methods, high-quality sample preparation is essential. Creative Proteomics provides custom virion purification and concentration services according to the specific types of virus particles and the requirements of clients' proteomic analysis. Our specific services include virus purification and concentration, electron microscopy (EM) of purified virus particles, quality control (quantity and quality assessment) for proteomic analysis.
Viruses and virus-like particles
Viruses are amazingly diverse in composition, shape, size, pathogenesis, and tropism. There is a general feature of viruses that their genetic materials (either DNA or RNA) are encapsulated with a proteinaceous capsid. These robust, flexible, and dynamic proteinaceous capsids are crucial for viruses. On one hand, they allow the viruses to survive the harsh conditions as they jump between host cells. On the other hand, they allow for the timely and efficient release of viral genomic content when infecting a new cell. For nonenveloped viruses, the capsids make the first contact with the host cells and then mediate host recognition as well as cell entry. For enveloped viruses, there is an additional layer composed of lipids and viral glycoproteins around the capsid that recognizes the host and enters the cell. The detailed characterization of the virus assembly and maturation processes is essential, which can facilitate fighting against the viruses.
Service offering in Creative Proteomics
Coronavirus virions
In order to perform a fairly complete proteomic analysis of coronavirus virion, we collect higher amounts of viruses to get enough samples to study. Since the low growth rate of coronavirus and the need for further purifications, a concentration step is required. After concentration, we provide the optimal purification protocols to yield high-quality coronavirus. Our concentration and purification method can minimize virion disruption and spike loss, and can be applied to several coronaviruses that grow well in cultured cells, including severe acute respiratory syndrome-coronavirus (SARS-CoV), mouse hepatitis virus (MHV), coronavirus virus-like particles, and so on. To perform quality control for purified samples, we employ plaque assay and Cryo-electron microscopy (cryo-EM) as a retrospective measure of quality. As a robust imaging tool, cryo-EM is able to determine the ultrastructure of viruses at near-atomic resolution. Moreover, to confirm the presence of viral proteins in the final samples, western blot (WB) analysis is applied to detect viral structural proteins.
Rabies virus particles
Rabies is caused by the neurotropic rabies virus (RABV), which is a single-stranded RNA virus of the Lyssavirus family. A variety of mammalian vectors carry this virus, such as humans, dogs, and foxes. The genome of the rabies virus is relatively simple, which encodes five structural proteins, including nucleoprotein (N), glycoprotein (G), phosphoprotein (P), RNA polymerase (L), and matrix protein (M). Among these structural proteins, the envelope glycoprotein has been applied to induce virus-neutralizing antibodies and its protection has been proved in animal models. To harvest the high purity and intact structure of RABV, we purify the virus using centrifugation programs with iodixanol density gradients. The quality control parameters including the purity and integrity of the virions are checked by cryo-EM. Prior to proteomic analysis, the purified virion samples are further conducted with deglycosylation, SDS-PAGE, and WB analysis.
The workflow of our services
Ideal samples for proteomics should contain a high density of virions with intact structure, and relatively little non-viral material. Creative Proteomics aims to accelerate the research progress of worldwide customers by offering optimal strategies and comprehensive data analysis. If you don't see what you need, or have any other questions, please don't hesitate to contact us. We will reply to your message shortly.
Reference
- Zhang, Y., et al. (2019). "Proteomic profiling of purified rabies virus particles." Virologica Sinica, 1-13.
* For research use only.
