“Mammalian Retrovirus-Like Protein PEG10 Packages Its Own MRNA and Can Be Pseudotyped for MRNA Delivery”, Michael Segel, Blake Lash, Jingwei Song, Alim Ladha, Catherine C. Liu, Xin Jin, Sergei L. Mekhedov, Rhiannon K. Macrae, Eugene V. Koonin, Feng Zhang2021-08-20 (gene editing)⁠:

Hitching a ride with a retroelement: Retroviruses and retroelements have inserted their genetic code into mammalian genomes throughout evolution.

Although many of these integrated virus-like sequences pose a threat to genomic integrity, some have been retooled by mammalian cells to perform essential roles in development. Segel et al. found that one of these retroviral-like proteins, PEG10, directly binds to and secretes its own mRNA in extracellular virus-like capsids.

These virus-like particles were then pseudotyped with fusogens to deliver functional mRNA cargos to mammalian cells. This potentially provides an endogenous vector for RNA-based gene therapy.

—DJ