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Candidate pandemic H1N1 vaccine viruses ****

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Joined: 15 Dec 2007
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PostPosted: Tue Jul 14, 2009 10:46 am    Post subject: Candidate pandemic H1N1 vaccine viruses **** Reply with quote

The WHO: July 7, '09 Extraordinatory Meeting of SAGE

Antigenic Properties
Viruses from 28 countries in 5 of 6 WHO Regions analyzed in WHO CCs.
HI tests using post-infection ferret antisera, antigenically:
* homogeneous
* most closely related to A/California/7/2009(H1N1)v
* distinct from currently circulating seasonal influenza viruses
* similar to North American lineage triple-reassortant A(H1N1) swine influenza viruses
Genetic Properties
* viruses from 31 countries in 5 of 6 WHO Regions analyzed so far closely related to A/
Viruses from severe cases no different genetically and antigenically
Antiviral Susceptibility
* All viruses tested so far except 3 since last week (from Japan, Demark and HK)
sensitive to Oseltamivir
* All viruses tested so far, including the above 3 viruses, sensitive to Zanamivir
* All viruses tested so far resistant to Admantine (Amantadine and Rimantadine)

Available Candidates
Wild type vaccine viruses:
* A/California/4/2009
* A/California/7/2009
* A/Texas/5/2009
* A/England/195/2009
* A/New York/18/2009
Candidate reassortant vaccine viruses:
A. Classical reassortment: IVR-153 & NYMC X-179 A
B. Reverse genetics: IDCDC-RG15, NIBRG-121 & CBER-RG2
C. Characterization/safety testing of the above reassortants:
* Antigenic and genetic analysis completed
* Ferret testing completed for the first 4.
* For CBER-RG2, after consulting a vaccine safety expert group, no ferret safety testing needed for this reassortant.
All above vaccine viruses are available from WHO CCs and ERLs
by 3rd Jul a total of 341 shipments made

Candidates under development
Classical reassortment:
* A/New York/18/2009 @ New York Medical College & NIBSC
Reverse genetics:
* A/New York/18/2009 and A/Texas/5/2009 @ CDC
* A/Tennessee/1-560/2009 and A/Texas/SC06164/2009 @ St Jude Children's Research Hospital
* A/England/195/2009 @ NIBSC
* A/California/7/2009 @ NIID

Growth Property
Evaluation conducted jointly by ERLs and vaccine manufacturers
Yield evaluation
A. Wild type vaccine viruses:
A/California/7/2009 - similar to normal seasonal H1N1 component in Vero-cell
B. Reassortant vaccine viruses based on evaluation conducted so far:
* NYMC X-179A has highest yield - ~ 50% of seasonal H1N1 component
* CBER-RG2, evaluated in CBER with initial result ~50% of seasonal H1N1 component
C. Manufacturers further optimizing the yield

Vaccine Potency Reagents
General Preparation Process
A. Prepared independently by 4 ERLs (CBER/FDA, NIBSC, NIID and TGA)
B. Reference antigen = large amount of bulk antigen from manufacturers:
* Egg-based for testing of egg-based vaccines
* Cell-based for testing of cell-based vaccines
C. Reference antiserum - from sheep by ERLs or for ERLs by local manufacturers:
* Small amount of purified HA
D. Distribution:
* Exchange among ERLs immediately for calibration
* Once available, antigen and antisera distributed to requesting manufactures in parallel to the calibration among ERLs
* Requests directly to originating ERLs

First available pandemic vaccine reagents:
A. First available reference antigen:
* Egg-based (NYMC X-179A)
* Prepared by CSL and labelled by TGA
* 9000 vials to be filled and capped from Jul 8
* Expected distribution Jul 10-15 to requesting manufactures
B. First available reference antiserum:
* A/california/7/2009
* First lot prepared by NIBSC on Jun 24 = 2000 vials
* Limited ongoing distribution: 50 vials per ERL; 30 vials per manufacturers upon request
* Larger distribution from subsequent larger lots expected in 2-3 weeks

Subsequent expected availability of pandemic vaccine reagents
A. Reference antigen
* CBER - egg-based, 3rd week Jul
* NIBSC - cell-based and egg-based, end Jul
* NIID - egg-based, Aug-Sept
B. Reference antiserum
* CBER - end of Jul, A/California/7
* NIID and TGA - end Jul to early Aug, A/California/7

Calibration of first available reagents
By collaborative study among 4 ERLs
Assigned value for reference antigen (egg-based) expected end of Jul
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Joined: 15 Dec 2007
Posts: 1419


PostPosted: Mon Sep 28, 2009 10:32 am    Post subject: Reply with quote

Two new candidate reassortant vaccine viruses (X-181 and X-181A) were developed by New York Medical College, USA, using conventional reassortment technology. Both have a 5:3 gene constellation with three genes (PB1, HA and NA) obtained from A/California/07/2009 (H1N1)v and the remaining five genes originating from A/PR/8/1934. The PR/8 genes were provided by reassorting NYMC X-157 with A/California/07/2009 (H1N1)v.

Full characterization of two reassortant viruses has been conducted by the WHO Collaborating Centre for Surveillance, Epidemiology and Control of Influenza in the Centers for Disease Control and Prevention (CDC), Atlanta, USA. Antigenic and genetic analyses completed so far indicate that the X-181 and X-181A reassortant viruses meet the specifications in the recent WHO recommendation on viruses to be used in vaccine development.

The candidate reassortant vaccine viruses X-181 and X-181A contain infectious materials and should be handled only in appropriate containment facilities. As these reassortant candidate vaccine viruses have a 5:3 gene constellation similar to donor viruses previously tested in ferrets with satisfactory results and with expected gene sequences, ferret safety testing for the reassortant vaccine virus X-181 and X-181A may not be required. Vaccine production using these candidate reassortant viruses may proceed at BSL-2 enhanced level using fully trained and competent staff in accordance with national safety guidelines, as described in WHO Technical Report Series No. 941.4 Recipient laboratories must accept full responsibility for the use and disposal of all materials.
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