nf-flu is a Nextflow bioinformatics analysis pipeline for assembly and H/N subtyping of Influenza A and B viruses from Illumina or Nanopore sequencing data. Since Influenza has a segmented genome consisting of 8 gene segments, the pipeline will automatically select the top matching reference sequence from NCBI for each gene segment based on IRMA assembly and nucleotide BLAST against all Influenza sequences from NCBI. Users can also provide their own reference sequences to include in the top reference sequence selection process. After reference sequence selection, the pipeline performs read mapping to each reference sequence, variant calling and depth-masked consensus sequence generation.
Note: The officially supported version of the pipeline is CFIA-NCFAD/nf-flu. If you have issues with using the pipeline, please create an issue here on CFIA-NCFAD/nf-flu repo.
cat
) (if needed).Install Nextflow
(>=21.04.0
).
Install any of Docker
, Singularity
, Podman
, Shifter
or Charliecloud
for full pipeline reproducibility (please only use Conda
as a last resort)
Download the pipeline and test it on a minimal dataset with a single command:
For Illumina workflow test:
nextflow run CFIA-NCFAD/nf-flu -profile test_illumina,<docker/singularity/podman/shifter/charliecloud/conda> \
--max_cpus $(nproc) # use all available CPUs; default is 2
For Nanopore workflow test:
nextflow run CFIA-NCFAD/nf-flu -profile test_nanopore,<docker/singularity/podman/shifter/charliecloud/conda> \
--max_cpus $(nproc) # use all available CPUs; default is 2
- If you are using
singularity
then the pipeline will auto-detect this and attempt to download the Singularity images directly as opposed to performing a conversion from Docker images. If you are persistently observing issues downloading Singularity images directly due to timeout or network issues then please use the--singularity_pull_docker_container
parameter to pull and convert the Docker image instead. Alternatively, it is highly recommended to use thenf-core download
command to pre-download all of the required containers before running the pipeline and to set theNXF_SINGULARITY_CACHEDIR
orsingularity.cacheDir
Nextflow options to be able to store and re-use the images from a central location for future pipeline runs.- If you are using
conda
, it is highly recommended to use theNXF_CONDA_CACHEDIR
orconda.cacheDir
settings to store the environments in a central location for future pipeline runs.
Run your own analysis
[Optional] Generate an input samplesheet from a directory containing Illumina FASTQ files (e.g. /path/to/illumina_run/Data/Intensities/Basecalls/
) with the included Python script fastq_dir_to_samplesheet.py
before you run the pipeline (requires Python 3 installed locally) e.g.
python ~/.nextflow/assets/CFIA-NCFAD/nf-flu/bin/fastq_dir_to_samplesheet.py \
-i /path/to/illumina_run/Data/Intensities/Basecalls/ \
-o samplesheet.csv
Typical command for Illumina Platform
nextflow run CFIA-NCFAD/nf-flu \
--input samplesheet.csv \
--platform illumina \
--profile <docker/singularity/podman/shifter/charliecloud/conda>
Typical command for Nanopore Platform
nextflow run CFIA-NCFAD/nf-flu \
--input samplesheet.csv \
--platform nanopore \
--profile <docker/singularity/conda>
The nf-flu pipeline comes with:
Danecek, P., Bonfield, J.K., Liddle, J., Marshall, J., Ohan, V., Pollard, M.O., Whitwham, A., Keane, T., McCarthy, S.A., Davies, R.M., Li, H., 2021. Twelve years of SAMtools and BCFtools. Gigascience 10, giab008. https://doi.org/10.1093/gigascience/giab008
Altschul, S.F., Gish, W., Miller, W., Myers, E.W., Lipman, D.J., 1990. Basic local alignment search tool. J. Mol. Biol. 215, 403–410. https://doi.org/10.1016/S0022-2836(05)80360-2
Camacho, C., Coulouris, G., Avagyan, V., Ma, N., Papadopoulos, J., Bealer, K., Madden, T.L., 2009. BLAST+: architecture and applications. BMC Bioinformatics 10, 421. https://doi.org/10.1186/1471-2105-10-421
Zheng, Z., Li, S., Su, J., Leung, A.W.-S., Lam, T.-W., Luo, R., 2022. Symphonizing pileup and full-alignment for deep learning-based long-read variant calling. Nat Comput Sci 2, 797–803. https://doi.org/10.1038/s43588-022-00387-x
Freebayes is used for variant calling.
Garrison, E., Marth, G., 2012. Haplotype-based variant detection from short-read sequencing. arXiv:1207.3907 [q-bio]. https://doi.org/10.48550/arXiv.1207.3907
Shepard, S.S., Meno, S., Bahl, J., Wilson, M.M., Barnes, J., Neuhaus, E., 2016. Viral deep sequencing needs an adaptive approach: IRMA, the iterative refinement meta-assembler. BMC Genomics 17, 708. https://doi.org/10.1186/s12864-016-3030-6
Medaka is deprecated in favour of Clair3 for variant calling of Nanopore data.
Minimap2 is used for rapid and accurate read alignment to reference sequences.
Li, H., 2018. Minimap2: pairwise alignment for nucleotide sequences. Bioinformatics 34, 3094–3100. https://doi.org/10.1093/bioinformatics/bty191
Mosdepth is used for rapid sequencing coverage calculation and summary statistics.
Pedersen, B.S., Quinlan, A.R., 2017. Mosdepth: quick coverage calculation for genomes and exomes. Bioinformatics 34, 867–868. https://doi.org/10.1093/bioinformatics/btx699
MultiQC is used for generation of a single report for multiple tools.
Ewels, P., Magnusson, M., Lundin, S., Käller, M., 2016. MultiQC: summarize analysis results for multiple tools and samples in a single report. Bioinformatics 32, 3047–3048. https://doi.org/10.1093/bioinformatics/btw354
nf-flu relies on publicly available Influenza sequence data from NCBI available at the NCBI Influenza Virus Resource, which is downloaded from the FTP site.
NCBI Influenza Virus Resource:
Bao, Y., Bolotov, P., Dernovoy, D., Kiryutin, B., Zaslavsky, L., Tatusova, T., Ostell, J., Lipman, D., 2008. The influenza virus resource at the National Center for Biotechnology Information. J Virol 82, 596–601. https://doi.org/10.1128/JVI.02005-07
NCBI Influenza Virus Sequence Annotation Tool:
Bao, Y., Bolotov, P., Dernovoy, D., Kiryutin, B., Tatusova, T., 2007. FLAN: a web server for influenza virus genome annotation. Nucleic Acids Res 35, W280-284. https://doi.org/10.1093/nar/gkm354
nf-flu is implemented in Nextflow.
Tommaso, P.D., Chatzou, M., Floden, E.W., Barja, P.P., Palumbo, E., Notredame, C., 2017. Nextflow enables reproducible computational workflows. Nat Biotechnol 35, 316–319. https://doi.org/10.1038/nbt.3820
nf-core is a great resource for building robust and reproducible bioinformatics pipelines.
Ewels, P.A., Peltzer, A., Fillinger, S., Patel, H., Alneberg, J., Wilm, A., Garcia, M.U., Di Tommaso, P., Nahnsen, S., 2020. The nf-core framework for community-curated bioinformatics pipelines. Nat Biotechnol 38, 276–278. https://doi.org/10.1038/s41587-020-0439-x
seqtk is used for rapid manipulation of FASTA/Q files. Available from GitHub at lh3/seqtk
VADR is used for annotation of Influenza virus sequences.
Alejandro A Schäffer, Eneida L Hatcher, Linda Yankie, Lara Shonkwiler, J Rodney Brister, Ilene Karsch-Mizrachi, Eric P Nawrocki; VADR: validation and annotation of virus sequence submissions to GenBank. BMC Bioinformatics 21, 211 (2020). https://doi.org/10.1186/s12859-020-3537-3
table2asn is used for converting the VADR Feature Table format output to Genbank format to help with conversion to other formats such as FASTA and GFF.