bioinformatics in the cdc biotechnology core facility branch
DESCRIPTION
Bioinformatics in the CDC Biotechnology Core Facility Branch . Computational Lab Scott Sammons Kevin Tang Chandni Desai. Sequencing Lab Mike Frace Missy Olsen-Rasmussen Marina Khristova Lori Rowe. Genome Sequencing Lab sequencing platforms – current and upcoming. AB 3730XL. - PowerPoint PPT PresentationTRANSCRIPT
Bioinformatics in the CDC Biotechnology Core Facility
Branch
Computational LabScott SammonsKevin TangChandni Desai
Sequencing LabMike FraceMissy Olsen-RasmussenMarina KhristovaLori Rowe
Pacific Biosciences SMRT sequencer
Ion Torrent Personal Gene Machine
AB 3730XL Roche 454 Titanium + Illumina GA IIx
Genome Sequencing Lab sequencing platforms – current and upcoming
3
Building 23 Server Room – Main ISLE
4
High Performance Computing Cluster (Aspen)• What is it?
• 35 compute nodes each with 12 processor cores, 48GB of memory, and 2 Tesla 2050 GPU cards
• Currently in the final stages of development in preparation for code-freeze and C&A
• What can it do today?• 25 cluster applications are currently enabled
for our phase-one deployment including MatLab, Geneious, Beast, Blast, and PacBio
• Collaboration with NCI via IAA will GPU scientific applications even further
• How fast is it?• By example, a Blast job that takes over 60 hours to complete on
our old cluster takes 2 hours on the new cluster*
• *NOT GPU OPTIMIZED CODE
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Isilon• What is it?
• High speed, scalable, and redundant Network Attached Storage• Currently in the process of being integrated with applications• Connected to both the CDC network and the Aspen HPC cluster
utilizing Infiniband• What can it do today?
• It provides user workspace for end-users and HPC applications
• Solves the problem of being out of disk space on individual servers
• What are we doing with it?• Data warehouse for all scientific equipment• Central network share for all scientific users• Integrating directly with ITSO’s Active Directory forest
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Private Cloud• What is it?
• Support science through front-end and back-end services• Implementation of virtualized infrastructure.• Currently in the process of being deployed.
• What can it do today?• Provide test environments for scientific projects• Lay the foundation for hardware consolidation
and migration• What are we doing with it?
• Standardize platforms• Centralize management• Support ongoing growth within the scientific
computing community while enabling science
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Scientific Computing InfrastructureThe Server Room
• 2 Linux High Performance Computing Clusters (~40 nodes each)• 1 Genomics Cluster• 4 Solaris Servers• 12 Stand-Alone Linux Servers • 1 Stand-Alone Database Server• 5 Stand-Alone Windows Servers• Virtualized Cluster with 15 VMs • 3 NAS Devices• 2 Tape Libraries• 2 Dedicated IP Subnets
• One C&A addressing all legacy production hardware (NCEZID) with several in-process for systems currently under development (NCIRD)
GSL sequencing 2011
NCEZID NCIRD CGH
Vibrio choleraVibrio sppCyclosporaBacillus anthracisListeraYersinia pestis Brucella spp.Klebsiella pneumonia Junin virusRift Valley Fever virusLujo virusMarburg virusCCHF virusLassa Fever virusClinical sample metagenomicsTick metagenomicsSoil metagenomics
Haemophilus influenzaeLegionella pneumophila Legionella spp. Mycoplasma pneumoniaWater cooling tower metagenomicsRespiratory filter metagenomicsBat metagenomics
GuineawormTaenia soliumAngiostrongylus
INFLUENZA
Position of E-PCR overlapping amplicons
A2 A4 A6 A8 A10 A12 A14 A16 A18
A1 A3 A5 A7 A9 A11 A13 A15 A17 End-R
D P O C E K H ML I F N A J B GSRQ
End-L
Primers designed using VAR-BSH and VAC-CPN sequencesPrimers target genes involved in reproduction & host
response Sequence sample: primers 40 sites, 1 enz. RFLP ~120 sitesPCR uses minimal DNA amounts, often no need to grow virusPCR uses hifi expand long-template Taq & Pwo enzymes
(Roche)
HindIII map
Sequencing: extended PCR
16
12
8
4
fold redundancy
First Pass Assembly: Seqmerge
Sequencing Assembly: Phred/Phrap/Consed
Gene Prediction
• Heuristic algorithm to assign quality scores to ORFs (from 1 to 100)
• Quality scores are based on a number of factors including– Gene Predictions (glimmer, genemark, getorf)– Primary sequence homology to known genes
(BLAST)– Presence of predicted promoter (MEME/MAST)– Size of predicted ORF– Presence of transcription terminal signals
Visualizing Gene Predictions and Differences
ITR
ITR
crm-D
ORFs of CPVXs from 4 different clades
B. American alastrim minor CFR <1%
C-1. non-West-African-African int CFR ~10%
C. Asian majorCFR ~5 - 35%
A. West African int. CFR ~10%
C-2. non-West-African African minor CFR <1%
45 Smallpox Strains
Unrooted tree phylogenetic relationships of ORF encoding the hemagglutinin protein
VACLS1Z99045
AY243312
AF377884
AF375102
Z99052
AF375096AF375099
AF375112
AF375095AF37511
3AF375098
AY523994AF22
9247
AF09
5689M14
783
AF3751
18AF375119AF375078
AY603355AY366477
X94355CPV9
1 ger
3
AY90
2253
AF375084AF375087AY902252
AF375086
AY90
2304
AY902303AF012825
Z99054
X69198X65516L22579
AF375135
AF375141
AF375143
JAP46 yamAF375142
AF375130 BRZ66 g
ar
AF375
138
AF375129
AF375093AF375081 AY
0090
89AY
9022
77AF
3750
85AY
9022
69AF
3750
90
AF377886 AF37
7878
AF377877
AY90
2260
AF3750
83
AY9022
83AY
9022
86AY
9023
01AY
9022
72AY
9022
99AY
9022
74AY
9022
75AY
9022
95AF
4827
58AY
9022
89AY
9022
94
AY902276
AY902257
AY902256AY902268AY902300
AY902308
AY298785
AY902270
AY902271
AY902287AY902297AY902288
AY902296
CPV90 ger2AF37
5088
AF377885
AY902298
AF375077AF375123NC 001559
Cowpox clade IVCPXV90_ger2
CamelpoxTaterapoxVariola
Ectromelia
Cowpox clade III(CPXV91_ger3)
Cowpox clade II
Cowpox clade IVaccinia
Monkeypox
AY298785
Next-Gen Diagnostic Sequencing Applications
‘Massively parallel’ sequencing not only produces throughput, it providessequences of potentially millions of individual molecules (instant cloning). By sequencing a PCR reaction it allows the detailed search for low expression quasi-species or mutations which may signal growing drug or vaccine resistance – a process called ultra-deep or amplicon sequencing.
Example: clinical case of poxvirus infection with samples exhibiting a reduced sensitivity to an antiviral drug.
Complex clinical, laboratory or environmental samples can be sequenced toprovide a diagnostic ‘snapshot’ of the resident organisms - an approach called metagenomic sequencing.
Examples: tissue culture, soil
Shotgun / Paired-End Sequencing: random shearing of DNA, even sequence coverage over entire genome.
Shotgun / Paired-End Sequencing
De novo Assembly• Newbler• CLCBio• Mira• Geneious• Velvet• Celera
Reference Mapping• Newbler• CLCBio• Mosaik• Mira• Geneious• BWA
Genome Assembly Visualization
Genome Assembly Visualization
Amplicon (deep) sequencing project
• Clinical case of progressive vaccinia infection from smallpox vaccination of an immune compromised patient
• Pox antiviral ST-246 administered which targets pox gene F13L, a major envelope protein which mediates production of extracellular virus
• Oral ST-246 given daily and vaccination site sampled over 3 week period
Li, Damon - NCZEID/DVRD/PRB
A region of gene F13L was amplified from clinical samples, deep sequenced,and compared to the smallpox vaccine reference sequence (Acambis 2000)
Control swab prior to ST-246
2 weeks after ST-246
C > T869
T > A943
3 weeks after ST-246
C > T869
T > A943
What is Metagenomics?• Is the genomic study of DNA from uncultured
microorganisms, generally from environmental samples
• Related• Metatranscriptomics• Metaproteomics
Sample CoverageRarefaction Curves
Wooley JC, Godzik A, Friedberg I, 2010 A Primer on Metagenomics. PLoS Comput Biol 6(2)
Samples
Classification Techniques• Supervised Taxonomic Classification
• Homology-based• Database searching by similarity (BLAST, SW)
• BLAST, BLASTX: genbank, specialized DBs: NCBI-ENV-NT, NCBI-ENV-NR
• Composition-based• N-mer frequency
• Markov Models, Support Vector Machines (SVM), need training set
• Unsupervised Taxonomic Classification• Clustering methods
• SOM - self-organizing maps • PCA – principal component analysis
Viral Metagenomic Pipeline (Wash U scripts implemented at CDC)
Sample Collection
DNA
Library Construction
Sequencing
Basecalling
Vector Trimming
Assembly
Contigs, ReadsRemove redundant sequences
Unique sequencesMask repetitive and low complexity seqs
Good sequences
BLASTN against Human Genome (e ≤ 1e-10)
Non-human sequences
BLASTNvs nt
BLASTXvs nr
Report Generation, Display in MEGAN, inspect top hits
BLASTNvs GB-viral
Software for Taxonomic Classification• MEGAN – GUI interface for classification based on
blast searches• CARMA web-based classification using pFam
database and HMMER alignment of protein families• MG-RAST classification system utilizing protein
encoding databases and several ribosomal DBs. Can analyze user provided datasets, web use only
• Geneious – commercial product • NextGENe – commercial product• Phymm, PhymmBL – composition based
classification system
Software for Comparative Metagenomics
• Megan – can display two metagenome populations on the same phylogenetic tree, uses BLAST file as input
• STAMP – calculates statistical differences between sets of metagenomes
• XIPE-TOTEC – performs pairwise comparisons of every metagenome in the two sets, creates a distance matrix which is then used for clustering and PCA analysis to calculate statistical values of relatedness
Megan
Ugandan Outbreak Samples• 4 patients
• Total RNA from patient sera• 2 samples per 454 run
• ~ 565,000 reads/sample, avg length = 235nt• Sequences were screened for random library
amplication primers and low quality• Assembled each run de novo using the 454
gsAssembler• Performed a blastx database search using the
assembled contigs (overnight)• Visualized the blast output using MEGAN.
MEGAN (MetaGenomeANalyzer)
Ugandan Outbreak - results• Run1 - 5 contigs (out of 2463 > 100nt) matched YF
virus, covering 98% of the genome (10,441 of 10,823bp)
• Mapped each sample from Run1 using an Ethiopian YF virus as reference. 3229 individual reads from Sample 1 indentified as YF.
• Run 2 – no YF reads found
Phylogenetic analysis of yellow fever virus sequences
Laura McMullan (DHPP/VSPB)
Comparative Metagenomics – current work• One 454 run• Two samples
• Sample 1 – ~578,000 reads, avg read length 438 bases• Sample 2 – ~550,000 reads, avg read length 425 bases
• Total number of bases sequenced - ~488,000,000
Sample 1 – Rarefaction Curve
Sample 1 Taxa tree (collapsed at the Order level)
Comparison of Sample 1 and 2
Bioinformatics Tools• Bioinformatics Packages
– EMBOSS– BioInquiry
• General Tools– Java/BioJava– Perl/BioPerl– BLAST Suite– BioEdit– GFFtoPS
• Genome Comparison/Alignment Tools– Mavid– Mauve– Clustal– Muscle
• Gene Prediction– Glimmer– GeneMark
• Assembly/Mapping Tools– 454 Suite– Mosaik Tools– Mummer– CLC Bio– BWA– Velvet– AHA (pacbio)
• Functional Annotation– Manatee
• Phylogenetics– Paup– Phylip– MrBayes– Beauti/Beast– MEGA– DnaSP
• Metagenomics– MEGAN– Galaxy– Carma
• In-House– WAMS– POCs/VOCs
Challenges
Data Management – image files are large (1 run ~25G) moving these files around the network is slow
Assembly/Mapping Software – Some are provided with the instrument, but additional methods and algorithms are needed
Finishing Tools – gap filling, primer design
Visualization Tools – tools to graphically display contigs on reference sequence as well as genome multiple alignments
Generic Robust Annotation Tools – Researchers need tools to intelligently choose predicted ORFs as genes, assign function, and submit to GenBank
What are the weaknesses of current next-gen sequencers?
Complicated and time consuming library preparation
Requires amplification of library
Instruments require repetitive sequential ‘flows’ of reagents
Requires micrograms of DNA to begin3 days to prepare library
Low copy number polymorphisms may be missedEmulsion PCR is an inefficient, time consuming, oily messPotential to introduce PCR bias into sample
Repetitive flows of nucleotides, blocking/unblocking chemistry, washing out reaction byproducts all slow synthesis and hinder read-length Consumes liters of reagents ($) Repetitive flows and imaging extend sequence runs to days (or weeks)
Pacific Bioscience SMRT sequencer (single-molecule sequencer)
Ion Torrent Personal Gene Machine (solid-state sequencer)
Nanopore sequencing
Pacific Biosciences SMRT sequencer
Sponsor: Influenza Research Agenda
Individual ZMW with attached polymerase and DNA strand Laser excitation/detection volume
glass
Pacific Biosciences SMRT Technology
~ 50 nm Functional volume (red) is in zL!
SMRTcell = 160,000 ZMW SMRTcell array = 1.5 million ZMW
Nucleotide incorporation is a realtime data movie
100 ms
Pacific Biosciences Advantages
Read lengths of 1,000 – 10,000 bases No reagent ‘flows’ =10-fold increase in sequencing speed
Substitute reverse transcriptase for polymerase and sequence RNA directly
Bacteria genomes sequenced in hours
Sequence run costs 99$; take 15 minutes to complete
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454 Sequencing
• DNA Library Prep• emPCR Amplification• Sequencing• Data Analysis
454 Sequencing: DNA Prep• Nebulization
– sheared with high pressure nitrogen to create fragments ~300-800 bases long
• Repair Ends– double stranded pieces are purified, blunt ended, and phosphorylated
• Adaptor Ligation– two different adaptors are ligated to the fragment, A and B– 44 bases long: 20 base PCR primer, 20 base sequencing primer, 4
base key– B fragment contain a biotin tag for immobilization– This forms 4 different strands A-A, A-B, B-A, B-B
• Fragment Immobilization– These immobilized on streptavidin-coated magnetic beads, A-A strands
will not bind and are washed away • Single-strand Isolation
– bound fragments are denatured and the released strands (containing both an A and a B tag) form a single-stranded template DNA library
454 Sequencing: emulsionPCREmulsion-based clonal PCR• Annealing
– Fragments are annealed to primer tagged “catcher” beads
– optimized to anneal a single strand to a single bead• Distribution in a water-oil-emulsion
– the captured dna and beads along with amplication reagents are placed in a water-oil mixture
– Each bead is captured in a “bubble” and creates its’ own small “micro-reactor”
– thermocyled creating millions of copies of a single clonal fragment in individual “microreactors”
– cleaned up and denatured
454 Sequencing: Sequencing by Synthesis
• Bead Preparation - sequencing primer attached and polymerase and cofactors are added
• Bead Deposition – beads are layered on a picotiter plate (wells are 44 μm), then enzyme beads and packing beads are added
454 Sequencing: Sequencing by Synthesis (cont.)
• Sequencing– enzyme beads contain
sulfurylase and luciferase, packing beads help keep reaction beads in position
– a fluidics system delivers sequencing reagents, flowing the nucleotides one at a time in a specific order across the wells
454 Sequencing: Sequencing by Synthesis (cont.)
• Sequencing– if a nucleotide is incorporated, a
pyrophosphate is released which is converted to ATP by the sulfurylase
– the ATP is hydrolyzed by the luciferase enzyme producing oxyluciferase and light
– The light emission is measured with a CCD camera
– light intensity indicates nucleotide incorporation
454 Sequencing: Sequencing by Synthesis (cont.)
• Characteristics– Flow of the four nucleotides is repeated for
one hundred cycles, resulting in average read length of 300-500 bases
– system averages ~1,000,000 high quality wells
– therefore, a typical run yields over 400 million high quality bases
454 Sequencing: Paired End Protocol