Abstract: Provided herein are compositions, systems, and methods for delivering cargo to a target cell. The compositions, systems, and methods comprise one or more polynucleotides encoding one or more LTR retroelement polypeptides for forming a delivery vesicle and one or more capture moieties for packaging a cargo within the delivery vesicle. The one or more LTR retroelement polypeptides for forming a delivery vesicle may comprise two or more of an LTR retroelement gag protein, a retroelement envelope protein, a an LTR retroelement reverse transcriptase, or a combination thereof. The LTR retroelement polypeptide alone, the LTR retroelement envelope protein alone, or both the LTR retroelement-derived polypeptide and LTR retroelement envelope protein may be endogenous.

Abstract: The present invention relates to adeno-associated virus (AAV) capsid proteins that have been modified to insert an amino acid sequence and/or methods of targeting microglia or brain macrophages using the AAV capsid proteins of the invention.

Abstract: Systems and methods for targeted gene modification, targeted insertion, perturbation of gene transcripts, and nucleic acid editing. Novel nucleic acid targeting systems comprise components of CRISPR systems and non-LTR retrotransposon elements.

Abstract: Provided herein are compositions, systems, and methods for delivering cargo to a target cell. The compositions, systems, and methods comprise one or more polynucleotides encoding one or more endogenous retroviral elements for forming a delivery vesicle and one or more capture moieties for packaging a cargo within the delivery vesicle. The one or more endogenous retroviral elements for forming a delivery vesicle may comprise two or more of a retroviral gag protein, a retroviral envelope protein, a retroviral reverse transcriptase or a combination thereof. The retroviral gag protein alone, the retroviral envelope protein alone, or both the retroviral gag protein and retroviral envelope protein may be endogenous.