Cell culture (Vero) derived whole virus (H5N1) vaccine based on wild-type virus strain induces cross-protective immune responses

doi:10.1016/j.vaccine.2007.05.013

Vaccine

Volume 25, Issue 32, 10 August 2007, Pages 6028-6036

https://doi.org/10.1016/j.vaccine.2007.05.013 Get rights and content

Abstract

The rapid spread and the transmission to humans of avian influenza virus (H5N1) have induced world-wide fears of a new pandemic and raised concerns over the ability of standard influenza vaccine production methods to rapidly supply sufficient amounts of an effective vaccine. We report here on a robust and flexible strategy which uses wild-type virus grown in a continuous cell culture (Vero) system to produce an inactivated whole virus vaccine. Candidate vaccines based on clade 1 and clade 2 influenza H5N1 strains were developed and demonstrated to be highly immunogenic in animal models. The vaccines induce cross-neutralising antibodies, highly cross-reactive T-cell responses and are protective in a mouse challenge model not only against the homologous virus but also against other H5N1 strains, including those from another clade. These data indicate that cell culture-grown whole virus vaccines, based on the wild-type virus, allow the rapid high yield production of a candidate pandemic vaccine.

Introduction

It is widely believed that the emergence of a new influenza pandemic caused by avian strains is only a matter of time and that a safe, effective and easily manufactured vaccine is required [1], [2], [3]. Pandemic H5N1 vaccine candidates tested to date were manufactured using attenuated reassortant viruses. These reassortants are generated using the hemagglutinin (HA) and the neuraminidase (NA) genes of the circulating wild-type (wt) virus and the six remaining genes of the H1N1 influenza strain A/PR/8/34 (6:2 reassortants) which usually confer high growth properties in embryonated hens’ eggs. This reassortant virus is also attenuated by removal of the polybasic cleavage site of the HA which is associated with high pathogenicity [4], [5], [6]. These reverse genetics(RG)-derived reassortants [7], [8] are then subjected to extensive safety testing before distribution to the influenza vaccine manufacturers. This procedure is essential to allow use of the virus under the biosafety level 2 enhanced, which is the highest safety level available in egg-based manufacturing facilities, and to generate the potential high growth phenotype required for adequate vaccine antigen yield. However, this derivation of new reassortants requires several weeks resulting in significant delay in the delivery of a new pandemic vaccine. In addition, the vaccine may provide an optimal antigenic fit with the wt circulating virus only with respect to the HA and NA genes and not with respect to the rest of the genes including the nucleoprotein and the matrix genes which are derived from the A/PR/8/34 virus. This report now describes the production and preclinical testing in animals of whole virus candidate vaccines based on wt H5N1 strains.

Section snippets

Viruses and cell lines

Influenza strains used were (abbreviations and source in parentheses): A/Vietnam/1203/2004(H5N1) (VN1203, CDC# 2004706280); A/Indonesia/05/2005(H5N1) (IN5/05, CDC #2005740199); A/HongKong/156/97(H5N1) (HK156, CDC #97013490); A/Vietnam/1194/2004(H5N1) (VN1194, CDC #2004706279); A/HongKong/213/2003(H5N1), (HK213, CDC #2/27/03); A/SP83/2004/Thai(H5N1), (Thai83, CDC #2004707254); A/FPV/Rostock/34(H7N1), (FPV/Ros, Univ. Giessen); B/Jiangsu/10/2003, (B/JS, NIBSC); A/NewCaledonia/20/99(H1N1),

Vaccine manufacturing based on H5N1 wild-type virus in Vero cells

A novel strategy was developed to avoid the delay associated with vaccine production using reverse genetics-derived reassortant virus. This involves use of wild-type virus to produce vaccine antigen in Vero cell culture, one of the most promising cell culture systems for production of influenza viruses [9], [12]. Large scale vaccine manufacture is carried out at BSL-3+, the level required by WHO for wild-type H5N1 [13], using state-of-the-art serum protein-free cell culture fermentation

Discussion

The pandemic potential of the highly pathogenic avian influenza H5N1 virus highlights the urgent need for an effective vaccine manufactured using a robust, secure production system capable of producing large amounts of vaccine in a short time-frame. Ideally, this vaccine should afford protection against the different H5N1 strains which may arise by antigenic drift. Standard technologies using 6:2 reassortant viruses and embryonated eggs to produce split or subunit vaccines may not fulfill all

Acknowledgements

We thank our co-workers and assistants for excellent work, the National Institute for Biological Standards and Control (NIBSC, UK) and Centers of Disease Control (CDC, Atlanta, USA) for reagents and virus strains.

This work was supported by the National Institutes of Health (NIH)–National Institute of Allergy and Infectious Diseases (NIAID), Bethesda, USA, under contract number N01-Al-05413/MBS-05413-24.

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¹: Present address: Martin Spruth, Intercell AG, Campus Vienna Biocenter 6, A-1030 Vienna, Austria.

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Cell culture (Vero) derived whole virus (H5N1) vaccine based on wild-type virus strain induces cross-protective immune responses

Abstract

Introduction

Section snippets

Viruses and cell lines

Vaccine manufacturing based on H5N1 wild-type virus in Vero cells

Discussion

Acknowledgements

Virology

Vaccine

Vaccine

Vaccine

J Biol Stand

Vaccine

Lancet

Lancet

Lancet

Virology

J Biol Stand

Influenza: emergence and control

J Virol

Influenza vaccines: present and future

J Clin Invest

Influenza: lessons from past pandemics, warnings from current incidents

Nat Rev Microbiol

Rescue of influenza A virus from recombinant DNA

J Virol

Generation of influenza A viruses entirely from cloned cDNAs

Proc Natl Acad Sci USA

A simple method of estimating fifty percent endpoints

Am J Hyg