Prime editing is a versatile and precise genome-editing tool. Most prime editors (PEs) rely on reverse transcriptase (RT) derived from Moloney murine leukemia virus (MMLV). Here, we established a PE, pvPE, using a RT derived from a porcine endogenous retrovirus (PERV) from a Bama mini-pig. Through various optimization strategies, including RT engineering, structural modifications, and La protein fusion, we gradually upgraded to pvPE-V4. This version achieved 24.38-101.69-fold higher efficiency compared with pvPE-V1 and up to 2.39-fold higher efficiency than another upgraded PE, PE7, with significantly fewer unintended edits across multiple mammalian cell lines. We further show that nocodazole (Noc) significantly enhanced pvPE efficiency by 2.25-fold on average. Using our pvPE system, we efficiently modified three genes simultaneously in porcine fibroblasts and subsequently generated cloned pigs that could serve as valuable models for Alzheimer's disease (AD) in humans. Our results highlight the broad application prospects of pvPE systems in mammalian genome editing.

Cytosine base editors (CBEs) and adenine base editors (ABEs) are recently developed CRISPR-mediated genome-editing tools that do not introduce double-strand breaks. In this study, five ABEs, ABE7.10, ABEmax, NG-ABEmax, ABE8e and NG-ABE8e, were used to generate A-to-G (T-to-C) conversions in five genome loci in porcine fetal fibroblasts (PFFs). Variable yet appreciable editing efficiencies and variable activity windows were observed in these targeting regions via these five editors. The strategy of two sgRNAs in one vector exhibited superior editing efficiency to that of using two separate sgRNA expression vectors. ABE-mediated start-codon mutation in APOE silenced its expression of protein and, unexpectedly, eliminated the vast majority of its mRNA. No off-target DNA site was detected for these editors. Substantial off-target RNA events were present in the ABE-edited cells, but no KEGG pathway was found to be significantly enriched. Our study supports that ABEs are powerful tools for A-to-G (T-to-C) point-mutation modification in porcine cells.

Although massive cell atlases are already available, it is still a challenge to obtain an atlas of all tissues within a single body, especially in fetuses and pregnant mothers. We present a transcriptomic atlas of 2.56 million single cells covering 115 and 119 tissues from one fetal pig and its pregnant mother, respectively. We found that a cluster of heart capillary endothelial cells with enhanced fatty acid transit capability was enriched for pregnancy but restored after gestation. We also deciphered that l -leucine transport insufficiency in the trophoblast causes fetal growth restriction by reducing a muscle type II myofiber subcluster. Our “all-from-one” strategy enabled the identification of tissue cell type–specific transcription factors and provided insights into pregnancy heart adaptation and fetal growth restriction.