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# locigenesis
locigenesis is a tool that generates a human T-cell receptor (TCR), runs
it through a sequence reader simulation tool and extracts CDR3.
The goal of this project is to generate both HVR sequences with and
without sequencing errors, in order to create datasets for a Machine
Learning algorithm.
## Technologies
- [immuneSIM](https://github.com/GreiffLab/immuneSIM/): in silico
generation of human and mouse BCR and TCR repertoires
- [CuReSim](http://www.pegase-biosciences.com/curesim-a-customized-read-simulator/):
read simulator that mimics Ion Torrent sequencing
## Installation
This project uses [Nix](https://nixos.org/) to ensure reproducible
builds.
1. Install Nix (compatible with MacOS, Linux and
[WSL](https://docs.microsoft.com/en-us/windows/wsl/about)):
```bash
curl -L https://nixos.org/nix/install | sh
```
2. Clone the repository:
```bash
git clone https://git.coolneng.duckdns.org/coolneng/locigenesis
```
3. Change the working directory to the project:
```bash
cd locigenesis
```
4. Enter the nix-shell:
```bash
nix-shell
```
After running these commands, you will find yourself in a shell that
contains all the needed dependencies.
## Usage
An execution script that accepts 2 parameters is provided, the following
command invokes it:
```bash
./generation.sh <number of sequences> <number of reads>
```
- \<number of sequences\>: an integer that specifies the number of
different sequences to generate
- \<number of reads\>: an integer that specifies the number of reads
to perform on each sequence
The script will generate 2 files under the data directory:
|HVR.fastq | curesim-HVR.fastq |
|:----:|:-----:|
|Contains the original CDR3 sequence|Contains CDR3 after the read simulation, with sequencing errors |

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* locigenesis
locigenesis is a tool that generates a human T-cell receptor (TCR), runs it through a sequence reader simulation tool and extracts CDR3.
The goal of this project is to generate both HVR sequences with and without sequencing errors, in order to create datasets for a Machine Learning algorithm.
** Technologies
- [[https://github.com/GreiffLab/immuneSIM/][immuneSIM]]: in silico generation of human and mouse BCR and TCR repertoires
- [[http://www.pegase-biosciences.com/curesim-a-customized-read-simulator/][CuReSim]]: read simulator that mimics Ion Torrent sequencing
** Installation
This project uses [[https://nixos.org/][Nix]] to ensure reproducible builds.
1. Install Nix (compatible with MacOS, Linux and [[https://docs.microsoft.com/en-us/windows/wsl/about][WSL]]):
#+begin_src shell
curl -L https://nixos.org/nix/install | sh
#+end_src
1. Clone the repository:
#+begin_src shell
git clone https://git.coolneng.duckdns.org/coolneng/locigenesis
#+end_src
3. Change the working directory to the project:
#+begin_src shell
cd locigenesis
#+end_src
4. Enter the nix-shell:
#+begin_src shell
nix-shell
#+end_src
After running these commands, you will find yourself in a shell that contains all the needed dependencies.
** Usage
An execution script that accepts 2 parameters is provided, the following command invokes it:
#+begin_src shell
./generation.sh <number of sequences> <number of reads>
#+end_src
- <number of sequences>: an integer that specifies the number of different sequences to generate
- <number of reads>: an integer that specifies the number of reads to perform on each sequence
The script will generate 2 files under the data directory:
| HVR.fastq | Contains the original CDR3 sequence |
| CuReSim-HVR.fastq | Contains CDR3 after the read simulation, with sequencing errors |

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library(Biostrings) library(Biostrings)
library(parallel) library(parallel)
#' Import and process the TCR and VJ sequences
#'
#' @param file A file path with the sequences after applying a read simulator
#' @return A \code{list} with the TCR sequences and VJ sequences
parse_data <- function(file) { parse_data <- function(file) {
reversed_sequences <- Biostrings::readQualityScaledDNAStringSet(file) reversed_sequences <- Biostrings::readQualityScaledDNAStringSet(file)
sequences <- Biostrings::reverseComplement(reversed_sequences) sequences <- Biostrings::reverseComplement(reversed_sequences)
@@ -15,10 +11,6 @@ parse_data <- function(file) {
return(list(sequences, vj_segments)) return(list(sequences, vj_segments))
} }
#' Extracts the VJ metadata from the sequences read identifier
#'
#' @param metadata The read identifier of a sequence
#' @return A \code{list} with the V and J gene identifier
parse_metadata <- function(metadata) { parse_metadata <- function(metadata) {
id_elements <- unlist(strsplit(metadata, split = " ")) id_elements <- unlist(strsplit(metadata, split = " "))
v_identifier <- id_elements[2] v_identifier <- id_elements[2]
@@ -26,28 +18,12 @@ parse_metadata <- function(metadata) {
return(list(v_id = v_identifier, j_id = j_identifier)) return(list(v_id = v_identifier, j_id = j_identifier))
} }
#' Fetches the sequence that matches the VJ gene identifier
#'
#' @param names The names of the VJ sequences
#' @param vdj_segments A \code{DNAStringSet} containing the VJ sequences
#' @param id The read identifier of a sequence
#' @return A \code{character} containing the gene sequence
match_id_sequence <- function(names, vdj_segments, id) { match_id_sequence <- function(names, vdj_segments, id) {
matches <- grep(names, pattern = id) matches <- grep(names, pattern = id)
if(id == "TRBJ2-2"){
row <- matches[2]
} else {
row <- matches[1] row <- matches[1]
}
return(as.character(vdj_segments[row])) return(as.character(vdj_segments[row]))
} }
#' Gets the V and J sequences for a particular read identifier
#'
#' @param metadata The read identifier of a sequence
#' @param names The names of the VJ sequences
#' @param vdj_segments A \code{DNAStringSet} containing the VJ sequences
#' @return A \code{list} with the V and J sequences
get_vj_sequence <- function(metadata, names, vdj_segments) { get_vj_sequence <- function(metadata, names, vdj_segments) {
identifiers <- parse_metadata(metadata) identifiers <- parse_metadata(metadata)
v_sequence <- match_id_sequence(names, vdj_segments, id = identifiers["v_id"]) v_sequence <- match_id_sequence(names, vdj_segments, id = identifiers["v_id"])
@@ -55,11 +31,6 @@ get_vj_sequence <- function(metadata, names, vdj_segments) {
return(list(v_seq = v_sequence, j_seq = j_sequence)) return(list(v_seq = v_sequence, j_seq = j_sequence))
} }
#' Obtains the VJ sequences for all the TCR sequences
#'
#' @param sequences A \code{QualityScaledDNAStringSet} with the TCR sequences
#' @param vdj_segments A \code{DNAStringSet} containing the VJ sequences
#' @return A \code{data.frame} with the V and J sequences
fetch_vj_sequences <- function(sequences, vdj_segments) { fetch_vj_sequences <- function(sequences, vdj_segments) {
vj_sequences <- sapply(names(sequences), vj_sequences <- sapply(names(sequences),
names(vdj_segments), names(vdj_segments),
@@ -70,11 +41,6 @@ fetch_vj_sequences <- function(sequences, vdj_segments) {
return(results) return(results)
} }
#' Perform a pairwise alignment of a sequence with the canonical V or J sequence
#'
#' @param sequence A \code{DNAString} containing the TCR sequences
#' @param vdj_segment A \code{DNAString} containing the V or J sequence
#' @return A \code{PairwiseAlignments}
align_sequence <- function(sequence, vdj_segment) { align_sequence <- function(sequence, vdj_segment) {
return(Biostrings::pairwiseAlignment( return(Biostrings::pairwiseAlignment(
subject = sequence, subject = sequence,
@@ -84,13 +50,6 @@ align_sequence <- function(sequence, vdj_segment) {
)) ))
} }
#' Computes the coordinate shift of the Cysteine due to indels
#'
#' @param insertion An \code{IRanges} containing the insertions
#' @param deletion An \code{IRanges} containing the deletions
#' @param cys A \code{list} with the Cysteine coordinates
#' @param alignment A \code{PairwiseAlignments}
#' @return A \code{list} with the delta of the Cysteine coordinates
handle_indels <- function(insertion, deletion, cys, alignment) { handle_indels <- function(insertion, deletion, cys, alignment) {
ins_start <- sum(Biostrings::width(deletion[start(deletion) <= cys$start])) ins_start <- sum(Biostrings::width(deletion[start(deletion) <= cys$start]))
ins_end <- sum(Biostrings::width(deletion[end(deletion) <= cys$end])) ins_end <- sum(Biostrings::width(deletion[end(deletion) <= cys$end]))
@@ -101,27 +60,16 @@ handle_indels <- function(insertion, deletion, cys, alignment) {
return(list("start" = ins_start - gaps, "end" = ins_end - gaps)) return(list("start" = ins_start - gaps, "end" = ins_end - gaps))
} }
#' Find the coordinates of the first Cysteine of the HVR
#'
#' @param alignment A \code{PairwiseAlignments}
#' @return A \code{list} with the Cysteine coordinates
get_cys_coordinates <- function(alignment) { get_cys_coordinates <- function(alignment) {
cys <- list("start" = 310, "end" = 312) cys <- list("start" = 310, "end" = 312)
insertion <- unlist(Biostrings::insertion(alignment)) insertion <- unlist(Biostrings::insertion(alignment))
deletion <- unlist(Biostrings::deletion(alignment)) deletion <- unlist(Biostrings::deletion(alignment))
delta_coordinates <- handle_indels(insertion, deletion, cys, alignment) delta_coordinates <- handle_indels(insertion, deletion, cys, alignment)
read_start <- unlist(start(Biostrings::Views(alignment))) cys_start <- cys$start + delta_coordinates$start
cys_start <- cys$start + delta_coordinates$start + read_start - 1 cys_end <- cys$end + delta_coordinates$end
cys_end <- cys$end + delta_coordinates$end + read_start
return(list("start" = cys_start, "end" = cys_end)) return(list("start" = cys_start, "end" = cys_end))
} }
#' Delimit the hypervariable region (HVR) for each TCR sequence
#'
#' @param sequences A \code{QualityScaledDNAStringSet} with the TCR sequences
#' @param vdj_segments A \code{DNAStringSet} containing the VJ sequences
#' @param cores Number of cores to apply multiprocessing
#' @return A \code{QualityScaledDNAStringSet} containing the HVR
get_hvr_sequences <- function(sequences, vdj_segments, cores = detectCores()) { get_hvr_sequences <- function(sequences, vdj_segments, cores = detectCores()) {
df <- fetch_vj_sequences(sequences, vdj_segments) df <- fetch_vj_sequences(sequences, vdj_segments)
v_alignment <- parallel::mcmapply(sequences, v_alignment <- parallel::mcmapply(sequences,
@@ -131,7 +79,7 @@ get_hvr_sequences <- function(sequences, vdj_segments, cores = detectCores()) {
) )
cys_coordinates <- parallel::mclapply(v_alignment, FUN = get_cys_coordinates) cys_coordinates <- parallel::mclapply(v_alignment, FUN = get_cys_coordinates)
cys_df <- as.data.frame(do.call(rbind, cys_coordinates)) cys_df <- as.data.frame(do.call(rbind, cys_coordinates))
remaining <- Biostrings::subseq(sequences, start = unlist(cys_df$end) + 1) remaining <- Biostrings::subseq(sequences, start = unlist(cys_df$end))
j_alignment <- parallel::mcmapply(remaining, j_alignment <- parallel::mcmapply(remaining,
df$j_seq, df$j_seq,
FUN = align_sequence, FUN = align_sequence,
@@ -150,4 +98,4 @@ get_hvr_sequences <- function(sequences, vdj_segments, cores = detectCores()) {
data <- parse_data(file = "data/curesim_sequence.fastq") data <- parse_data(file = "data/curesim_sequence.fastq")
hvr <- get_hvr_sequences(sequences = data[[1]], vdj_segments = data[[2]]) hvr <- get_hvr_sequences(sequences = data[[1]], vdj_segments = data[[2]])
Biostrings::writeXStringSet(hvr, "data/curesim-HVR.fastq", format = "fastq") Biostrings::writeXStringSet(hvr, "data/CuReSim-HVR.fastq", format = "fastq")

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library(immuneSIM) library(immuneSIM)
library(Biostrings) library(Biostrings)
#' Generate the beta chain of a human T-cell receptor (TCR)
#'
#' @param number_of_sequences Number of different sequences to generate
#' @return A \code{data.frame} with the sequences, V and J genes and CDR3
generate_repertoire <- function(number_of_sequences) { generate_repertoire <- function(number_of_sequences) {
return(immuneSIM( return(immuneSIM(
number_of_seqs = number_of_sequences, number_of_seqs = number_of_sequences,
@@ -14,9 +10,6 @@ generate_repertoire <- function(number_of_sequences) {
)) ))
} }
#' Saves the sequences and CDR3 to FASTQ files
#'
#' @param data A \code{data.frame} with the preprocessed TCR sequences and CDR3
save_data <- function(data) { save_data <- function(data) {
Biostrings::writeXStringSet(data$sequence, Biostrings::writeXStringSet(data$sequence,
"data/sequence.fastq", "data/sequence.fastq",
@@ -25,11 +18,6 @@ save_data <- function(data) {
Biostrings::writeXStringSet(data$junction, "data/HVR.fastq", format = "fastq") Biostrings::writeXStringSet(data$junction, "data/HVR.fastq", format = "fastq")
} }
#' Applies the reverse complement and amplifies the number of sequences
#'
#' @param data A \code{data.frame} containing the TCR sequences and CDR3
#' @param reads Number of times to amplify each sequence
#' @return A \code{data.frame} with reverse complement sequences and VJ metadata
process_data <- function(data, reads) { process_data <- function(data, reads) {
dna_sequence <- Biostrings::DNAStringSet(data$sequence) dna_sequence <- Biostrings::DNAStringSet(data$sequence)
data$sequence <- Biostrings::reverseComplement(dna_sequence) data$sequence <- Biostrings::reverseComplement(dna_sequence)
@@ -40,9 +28,6 @@ process_data <- function(data, reads) {
return(amplified_data) return(amplified_data)
} }
#' Checks the number of command line arguments and captures them
#'
#' @return A \code{vector} containing the command line arguments
parse_cli_arguments <- function() { parse_cli_arguments <- function() {
args <- commandArgs(trailingOnly = TRUE) args <- commandArgs(trailingOnly = TRUE)
if (length(args) != 2) { if (length(args) != 2) {