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Updated: Oct 23, 2025

Production of Pseudotyped Particles to Study Highly Pathogenic Coronaviruses in a Biosafety Level 2 Setting
Published on: March 1, 2019
Mammalian retrovirus-like protein PEG10 packages its own mRNA and can be pseudotyped for mRNA delivery
Michael Segel1,2,3,4,5, Blake Lash1,2,3,4,5, Jingwei Song1,2,3,4,5
1Howard Hughes Medical Institute, Cambridge, MA 02139, USA.
Abstract:
Eukaryotic genomes contain domesticated genes from integrating viruses and mobile genetic elements. Among these are homologs of the capsid protein (known as Gag) of long terminal repeat (LTR) retrotransposons and retroviruses. We identified several mammalian Gag homologs that form virus-like particles and one LTR retrotransposon homolog, PEG10, that preferentially binds and facilitates vesicular secretion of its own messenger RNA (mRNA). We showed that the mRNA cargo of PEG10 can be reprogrammed by flanking genes of interest with Peg10's untranslated regions. Taking advantage of this reprogrammability, we developed selective endogenous encapsidation for cellular delivery (SEND) by engineering both mouse and human PEG10 to package, secrete, and deliver specific RNAs. Together, these results demonstrate that SEND is a modular platform suited for development as an efficient therapeutic delivery modality.
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