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Mammalian Retrovirus-Like Particles (PEG10-VLPs)

Overview of PEG10-VLPs

The mammalian retrovirus-like protein PEG10 is homologous to a retroviral capsid protein. PEG10 can encapsulate, secrete, and potentially deliver mRNA. It can also bundle specific RNA molecules to produce virus-like particles (VLPs), which are secreted in extracellular vesicles and mixed with their mRNA to facilitate functional transfer across cells. Figure 1 illustrates an enhanced system referred to as Selective Endogenous Encapsidation for Cellular Delivery (SEND), which serves as a VLP-based delivery mechanism capable of conveying cargo mRNA, thus presenting a new class of gene transfer vector. SEND is also recognized as PEG10-VLPs. The generation of PEG10-VLPs involves transfecting producer cells with three plasmids. One plasmid enables the transcription of cargo mRNA, comprising the mRNA sequence of the target gene flanked by untranslated regions (UTRs) from peg10, serving as packaging signals. The second plasmid facilitates the expression of native PEG10 devoid of its native UTRs, enhancing VLP production and binding to cargo mRNA via its UTRs. Meanwhile, the third plasmid encodes a fusogenic envelope protein resembling either VSVg (of viral origin) or SYNA (endogenous). Cargo plasmids are transcribed into cargo RNA, which accumulates in VLPs, forming PEG10-VLPs that carry the target mRNA.

The SEND acts as a VLP-based delivery mechanism, transporting cargo mRNA and introducing a new class of gene transfer vector. (Segel, et al, 2021)

Fig.1 Illustration of SEND's principle.1

Application of PEG10-VLPs

The use of endogenous PEG10 addresses the immunogenicity concerns related to mRNA nanoparticle delivery and substantially expands the scope of mRNA delivery therapy research. PEG10-VLPs could potentially offer greater competitiveness compared to mRNA delivery through lipid or polymeric nanoparticles, or even non-integrating viral vectors. This is attributed to their human origin and EV-like properties, which might help evade the activation of intracellular defense mechanisms. Figure 2 depicts the effective transfer of a ~5 kb SpCas9 mRNA into N2a cell lines expressing a sgRNA targeting MmKras. This process efficiently transfers SpCas9 flanked by either full-length or customized peg10 UTR sequences, leading to approximately 60% indels in recipient cells. Pending successful outcomes from preclinical trials validating both efficacy and safety, VLPs could emerge as promising candidates for future in vivo or ex vivo gene therapy initiatives.

The successful transfer of SpCas9 mRNA into N2a cell lines expressing a sgRNA targeting MmKras. (Segel, et al, 2021)

Fig.2 Schematic of SEND for genome engineering.1


Creative Biolabs is committed to offering high-quality PEG10-VLPs services for worldwide customers. Our PEG10-VLPs are generated by transfecting three plasmids including cargo plasmid, PEG10 plasmid, and envelope plasmid into producer cells. We provide plasmid construction, VLP packaging, purification, and in vitro and in vivotesting services. For further details, kindly reach out to us for a quotation. We commit to responding within 24 hours and tailoring an optimal approach for your project.


  1. Segel, Michael, et al. "Mammalian retrovirus-like protein PEG10 packages its own mRNA and can be pseudotyped for mRNA delivery." Science 373.6557 (2021): 882-889.
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