The CVN Development Programme
a 4-month update
Peter Simmonds
Centre for Infectious Diseases University of Edinburgh
CVN Development Programme
Initiative announced in 2009 to focus development
towards defined diagnostic issues:
Ascribing quantitative values to molecular assay
controls
– Calibration of NIBSC / SoGAT international standards into molecular copies
– Coordination with NIBSC / CVN quality control
Standardisation of EBV, HCMV and adenovirus
quantitation
– Predictive value of quantitative assays – Choice of specimen type
Applicants Development programme
– Viral diversity and effect on diagnostic assay sensitivity
– Role of parechoviruses and enteroviruses in severe neonatal disease
– Development of bioinformatic and virus sequence database resources
CVN Development Programme
Viral diversity and effect on diagnostic assay
sensitivity
– Species (ie. enteroviruses, rhinoviruses), genogroups (eg.
Norovirus) and genotypes (eg. RSV, hMPV)
– Viruses that have drifted away from reference isolate sequences (eg. PIVs)
Role of parechoviruses and enteroviruses in severe
neonatal disease
– Development of more sensitive and effective assays for CSF screening, protocols of obtaining other sample types
– EV and HPeV virus typing – investigation of specifically neurovirulent types (eg. HPeV3)
– Establishment of effective routine (sero)type identification methods for UK-wide surveillance
Development of bioinformatic and virus sequence
database resources
– Large-scale, updated sequence alignments – Software development and interfacing
CVN Development Programme
Viral diversity and effect on diagnostic assay
sensitivity
– Species (ie. enteroviruses, rhinoviruses), genogroups (eg.
Norovirus) and genotypes (eg. RSV, hMPV)
– Viruses that have drifted away from reference isolate sequences (eg. PIVs)
Role of parechoviruses and enteroviruses in severe
neonatal disease
– Development of more sensitive and effective assays for CSF screening, protocols of obtaining other sample types
– EV and HPeV virus typing – investigation of specifically neurovirulent types (eg. HPeV3)
– Establishment of rapid turnaround, effective routine
(sero)type identification methods for UK-wide surveillance
Development of bioinformatic and virus sequence
database resources
– Large-scale, updated sequence alignments – Software development and interfacing
CVN Development Programme
Viral diversity and effect on diagnostic assay
sensitivity
– Species (ie. enteroviruses, rhinoviruses), genogroups (eg.
Norovirus) and genotypes (eg. RSV, hMPV)
– Viruses that have drifted away from reference isolate sequences (eg. PIVs)
Role of parechoviruses and enteroviruses in severe
neonatal disease
– Development of more sensitive and effective assays for CSF screening, protocols of obtaining other sample types
– EV and HPeV virus typing – investigation of specifically neurovirulent types (eg. HPeV3)
– Establishment of rapid turnaround, effective routine
(sero)type identification methods for UK-wide surveillance
Development of bioinformatic and virus sequence
database resources
– Large-scale, updated sequence alignments – Software development and interfacing
Picornaviruses
Positive stranded RNA viruses
– Primarily infect mammals
– Capable of acute resolving or persistent infections
– Highly variable host ranges, disease associations and epidemiologies
Conserved design and replication strategy
– 14 genera identified to date, more to come!
– No clear idea of the time frame over which different groups (genera, species, serotypes evolved)
Enterovirus Species
The Enterovirus genus classified
into:
– 5 enterovirus species, A-E – 3 rhinovirus species, A-C – 2 simian species, A, B – 2 bovine species, A, B – 1 porcine species
Differ substantially from each
other through genome (>35%)
– Shared 5’UTRs through recombination
Each species comprises a
variable number of serologically
distinct serotypes
– Identifiable by cross-neutralisation assay
– 93 EV serotypes, 160 HRV types
Only sequences from the capsid
region identify serotype
Enterovirus diagnosis
EVs readily isolatable in a variety of cell lines
– Standard method for EV detection until molecular tests developed
– Serotype identification by cross-neutralisation
– Isolation more effective for certain serotypes and species (eg. species B)
– Time-consuming, serotype identification technically difficult (increasing number of types identified)
Enterovirus molecular diagnostics
– Highly conserved 5’UTR typically targeted by PCR-based screening assays
– Highly sensitive, eg. much more effective detection of EV RNA in CSF
– Screening equally effective for different species – greater role of species A in clinical presentations than recognised previously
Enterovirus typing
– 5’UTR sequence alone is unable to identify species or serotype – VP1 sequences allow accurate type identification
– Reliable typing assays problematic to develop because of variability in target region
EV and HPeV transcript standards
Investigation of the effectiveness of screening assays for
different EV species
– Analytical sensitivity, required for CSF screening – Interpretation of late rises in Ct value
Cross-reactivity with human rhinoviruses (with similar
5’UTR sequence)
Effectiveness of typing assays for each species
Full length transcripts to allow
assays targeting different regions
to be evaluated
– Species A: CVA16
– Species B: Echo7, Echo30 – Species C: CVA21
– Species D: EV70
EV and HPeV transcript standards
Dilution series of 10
10– 10
-2RNA copies / ul created for
each transcript
Aliquoted and stored at -40
oC
Used to evaluate sensitivity of
– RIE diagnostic PCR
– EV/HPeV multiplexed PCR
– EV species A, B, C and D VP1 primers used for virus typing
RNA expressed quantified by
nanodrop / Agilent
Integrity assessed by
denaturing gel electrophoresis
Storage and dilution
– Citrate buffer, pH6.0 – 0.05 ug/ml carrier tRNA – 0.1 U / ml RNAsin
Real time PCR
examples
CAV16 transcript
– Replicate testing from 9 x 105 to 9 x 10-1 RNA copies – Positive down to 90 copies
Similar results for
other transcripts
Reproducible
between species
Real time PCR
examples
CAV16 transcript
– Replicate testing from 9 x 105 to 9 x 10-1 RNA copies – Positive down to 90 copies
Similar results for
other transcripts
Reproducible
between species
A-D
Inter-lab variability – Belfast
Method 1
*Method 2
***H O’Neill (EV) and Benschop K, Beld M et al JCV 41 (2008) 69-74; Oberste MS et al JMV 58
(1999) 178-181 (PEV)
Edinburgh
Glasgow
Belfast 1
Sensitivity of reference testing and typing assays
Nested PCR for 5’UTR EV serotype identification
– Nested PCR amplification
– sequencing of VP1 (species A, B, D) or VP2 (species C)
Primers RNA 5 x 104 5 x 103 5 x 102 5 x 101 5 x 100 5 x 10-1 5’UTR A + + + + + -5’UTR B + + + + + -5’UTR C + + + + + -5’UTR D + + + + - -5’UTR HRV-B + + + + + -Sp. A A 4/4 4/4 0 0 Sp. B B 4/4 1/4 0 0 Sp. C C 4/4 2/4 2/4 0 Sp. D D 4/4 3/4 1/4 0
EV, HRV and HPeV standards
EV species variability
– Little or no effect on 5’UTR based PCR
– Equivalent amplification dynamics and sensitivity
– 2-9 copy control produces Ct values >36, frequently low, interpretation difficulties
HPeV detection
– Highly comparable to EV detection – No cross-reactivity between assays
HRV detection
– Standard detection of HRV-1B (species A)
– Approximately 10-fold reduction in amplification efficiency for HRV-14 (species B)
• Likely caused by terminal base mismatch in sense primer
Assay evaluation of EV, HPeV and HRV screening
– HRV-C transcript to be added – Reference laboratory testing
Respiratory viruses
Representation of controls generated from viruses currently circulating the UK
– Full length clones inappropriate / unavailable
Whole gene transcripts from major respiratory viruses:
– RSV genotypes A and B* – hMPV genotypes A and B*
– Influenza A H1N1*, H3N2**, H5N1 and sH1N1** – Influenza B (x 3)**
– Parainfluenza viruses 1-3 (x 2 each)**
Variability in regions targeted by diagnostic PCR – RSV and hMPV: Nucleoprotein
– IFA: Matrix, IFB: NP – PIV 1-3: HN protein
Second round of transcripts from alternative gene targets
Future Plans
Additional respiratory viruses
Extension to enteric viruses later in the year
*Available now (contact Peter Simmonds / Nigel McLeish)
Thanks to…
Virus Evolution Group, Centre for Infectious Diseases
– Nigel McLeish, Carol Leitch, Jeroen Witteveldt, Elly
Gaunt
Specialist Virology Laboratory, Royal Infirmary of Edinburgh
– Heli Harvala, Kate Templeton – Ingo Johannessen
Regional Virology Laboratory, Glasgow– Susan Bennett, Rory Gunson
Virology Laboratory, Belfast
– Susan Feeney, Alison Watt, Peter Coyle
EV and HPeV Molecular Clones
– Biological Sciences, University of Warwick,
• David J. Evans
– Biological Sciences, University of Essex
• Glyn Stanway