Provided herein are methods of delivering “split” Cas9 protein or nucleobase editors into a cell, e.g., via a recombinant adeno-associated virus (rAAV), to form a complete and functional Cas9 protein or nucleobase editor. The Cas9 protein or the nucleobase editor is split into two sections, each fused with one part of an intein system (e.g., intein-N and intein-C encoded by dnaEn and dnaEc, respectively). Upon co-expression, the two sections of the Cas9 protein or nucleobase editor are ligated together via intein-mediated protein splicing. Recombinant AAV vectors and particles for the delivery of the split Cas9 protein or nucleobase editor, and methods of using such AAV vectors and particles are also provided.

A method for determining the number of nucleic acid molecules (NAMs) in a group of NAMs, comprising i) obtaining an amplified and mutagenized group of NAMs that was produced by a. subjecting the group of NAMs to a chemical mutagenesis which mutates only select nucleic acid bases in the group of NAMs at a rate of 10% to 90% thus forming a group of mutagenized NAMs (mNAMs), and b. amplifying the group of mNAMs; ii) obtaining sequences of the mNAMs in the group of amplified mNAMs; and iii) counting the number of different sequences obtained in step (ii) to determine the number of unique mNAMs in the group of mNAMS,

thereby determining the number of NAMs in the group of NAMs.

A method for determining the number of nucleic acid molecules (NAMs) in a group of NAMs, comprising i) obtaining an amplified and mutagenized group of NAMs that was produced by a. subjecting the group of NAMs to a chemical mutagenesis which mutates only select nucleic acid bases in the group of NAMs at a rate of 10% to 90% thus forming a group of mutagenized NAMs (mNAMs), and b. amplifying the group of mNAMs; ii) obtaining sequences of the mNAMs in the group of amplified mNAMs; and iii) counting the number of different sequences obtained in step (ii) to determine the number of unique mNAMs in the group of mNAMS,

thereby determining the number of NAMs in the group of NAMs.

The present disclosure provides systems, methods, and apparatus for preparing biological samples (e.g., plasma) for sequencing (e.g., DNA sequencing, e.g., third generation sequencing). Moreover, the present disclosure provides various systems, methods, and apparatus that employ this sample preparation technology in the identification of biomarkers for detection of a disease or condition. For example, in certain embodiments, the biological sample preparation method includes capturing fragments of cell free DNA (cfDNA) with capture probes, converting the captured DNA fragments into circular DNA, and amplifying the circular DNA by performing rolling circle amplification (RCA). In particular, it is presently found that by performing this sample preparation method, it is possible to more successfully distinguish true alterations (e.g., aberrant methylation status and/or genomic mutations) from technical/sequencing artifacts.

The present disclosure provides systems, methods, and apparatus for preparing biological samples (e.g., plasma) for sequencing (e.g., DNA sequencing, e.g., third generation sequencing). Moreover, the present disclosure provides various systems, methods, and apparatus that employ this sample preparation technology in the identification of biomarkers for detection of a disease or condition. For example, in certain embodiments, the biological sample preparation method includes capturing fragments of cell free DNA (cfDNA) with capture probes, converting the captured DNA fragments into circular DNA, and amplifying the circular DNA by performing rolling circle amplification (RCA). In particular, it is presently found that by performing this sample preparation method, it is possible to more successfully distinguish true alterations (e.g., aberrant methylation status and/or genomic mutations) from technical/sequencing artifacts.

According to a first aspect of the invention, a method for the generation of a cell line is provided, comprising the steps of (a) providing a plurality of mammalian B cells, wherein each of the plurality of B cells comprises a transgenic genomic DNA sequence encoding a marker protein inserted into an endogenous immunoglobulin locus comprised in said B cell, and wherein the transgenic genomic DNA sequence is amenable to cleavage by a site directed nuclease, particularly Cas9; (b) replacing the transgenic genomic DNA sequence encoding a marker protein with a second transgenic DNA sequence encoding a protein of interest; (c) sorting B cells based on the presence or absence of the marker protein; and (d) collecting B cells in which the marker protein is absent.

According to a first aspect of the invention, a method for the generation of a cell line is provided, comprising the steps of (a) providing a plurality of mammalian B cells, wherein each of the plurality of B cells comprises a transgenic genomic DNA sequence encoding a marker protein inserted into an endogenous immunoglobulin locus comprised in said B cell, and wherein the transgenic genomic DNA sequence is amenable to cleavage by a site directed nuclease, particularly Cas9; (b) replacing the transgenic genomic DNA sequence encoding a marker protein with a second transgenic DNA sequence encoding a protein of interest; (c) sorting B cells based on the presence or absence of the marker protein; and (d) collecting B cells in which the marker protein is absent.

According to a first aspect of the invention, a method for the generation of a cell line is provided, comprising the steps of (a) providing a plurality of mammalian B cells, wherein each of the plurality of B cells comprises a transgenic genomic DNA sequence encoding a marker protein inserted into an endogenous immunoglobulin locus comprised in said B cell, and wherein the transgenic genomic DNA sequence is amenable to cleavage by a site directed nuclease, particularly Cas9; (b) replacing the transgenic genomic DNA sequence encoding a marker protein with a second transgenic DNA sequence encoding a protein of interest; (c) sorting B cells based on the presence or absence of the marker protein; and (d) collecting B cells in which the marker protein is absent.

Methods and compositions for improving the genome-wide specificities of targeted base editing technologies.

Methods and compositions for improving the genome-wide specificities of targeted base editing technologies.