tetano
Editor, Senior Moderator
Development of a high yield live attenuated H7N9 influenza vaccine that provides protection against homologous and heterologous H7 wild-type viruses in ferrets
Zhongying Chen1#,
Mariana Baz2,
Janine Lu1,
Myeisha Paskel2,
Celia Santos2,
Kanta Subbarao2,
Hong Jin1 and
Yumiko Matsuoka2
1MedImmune LLC, 319 North Bernardo Ave., Mountain View, CA, USA
2Laboratory of Infectious Diseases, NIAID, NIH, Bethesda, MD 20892, USA
ABSTRACT
Live attenuated H7N9 influenza vaccine viruses that possess the hemagglutinin (HA) and neuraminidase (NA) gene segments from the newly emerged wild-type (wt) A/Anhui/1/2013 (H7N9) and six internal protein gene segments from the cold-adapted influenza virus A/Ann Arbor/6/60 (AA ca) were generated by reverse genetics. The reassortant virus containing the original wt A/Anhui/1/2013 HA and NA sequences replicated poorly in eggs. Multiple variants with amino acid substitutions in the HA head domain that improved viral growth were identified by viral passage in eggs and MDCK cells. The selected vaccine virus containing two amino acid changes (N133D/G198E) in the HA improved viral titer by more than 10-fold (reached a titer of 108.6 Fluorescent Focus Units/mL) without affecting viral antigenicity. Introduction of these amino acid changes into an H7N9 PR8 reassortant also significantly improved viral titers and HA protein yield in eggs. The H7N9 ca vaccine virus was immunogenic in ferrets. A single dose of vaccine conferred complete protection of ferrets from homologous wt A/Anhui/1/2013 (H7N9) and near complete protection from heterologous wt A/Netherlands/219/2013 (H7N7) challenge infection. Therefore, this H7N9 LAIV candidate has been selected for vaccine manufacture and clinical evaluation to protect humans from wt H7N9 virus infection.
IMPORTANCE In response to the recent avian H7N9 influenza virus infection in humans, we developed a live attenuated H7N9 influenza vaccine (LAIV) with two amino acid substitutions in the viral HA protein that improved vaccine yield by 10-fold in chicken embryonated eggs, the substrate for vaccine manufacture. The two amino acids also improved the antigen yield for inactivated H7N9 vaccines, demonstrating that this finding could great facilitate the efficiency of H7N9 vaccine manufacture. The candidate H7N9 LAIV was immunogenic and protected ferrets against homologous and heterologous wild-type H7 virus challenge, making it suitable for use in protecting humans from H7 infection.
http://jvi.asm.org/content/early/2014/04/03/JVI.00100-14.abstract
Zhongying Chen1#,
Mariana Baz2,
Janine Lu1,
Myeisha Paskel2,
Celia Santos2,
Kanta Subbarao2,
Hong Jin1 and
Yumiko Matsuoka2
1MedImmune LLC, 319 North Bernardo Ave., Mountain View, CA, USA
2Laboratory of Infectious Diseases, NIAID, NIH, Bethesda, MD 20892, USA
ABSTRACT
Live attenuated H7N9 influenza vaccine viruses that possess the hemagglutinin (HA) and neuraminidase (NA) gene segments from the newly emerged wild-type (wt) A/Anhui/1/2013 (H7N9) and six internal protein gene segments from the cold-adapted influenza virus A/Ann Arbor/6/60 (AA ca) were generated by reverse genetics. The reassortant virus containing the original wt A/Anhui/1/2013 HA and NA sequences replicated poorly in eggs. Multiple variants with amino acid substitutions in the HA head domain that improved viral growth were identified by viral passage in eggs and MDCK cells. The selected vaccine virus containing two amino acid changes (N133D/G198E) in the HA improved viral titer by more than 10-fold (reached a titer of 108.6 Fluorescent Focus Units/mL) without affecting viral antigenicity. Introduction of these amino acid changes into an H7N9 PR8 reassortant also significantly improved viral titers and HA protein yield in eggs. The H7N9 ca vaccine virus was immunogenic in ferrets. A single dose of vaccine conferred complete protection of ferrets from homologous wt A/Anhui/1/2013 (H7N9) and near complete protection from heterologous wt A/Netherlands/219/2013 (H7N7) challenge infection. Therefore, this H7N9 LAIV candidate has been selected for vaccine manufacture and clinical evaluation to protect humans from wt H7N9 virus infection.
IMPORTANCE In response to the recent avian H7N9 influenza virus infection in humans, we developed a live attenuated H7N9 influenza vaccine (LAIV) with two amino acid substitutions in the viral HA protein that improved vaccine yield by 10-fold in chicken embryonated eggs, the substrate for vaccine manufacture. The two amino acids also improved the antigen yield for inactivated H7N9 vaccines, demonstrating that this finding could great facilitate the efficiency of H7N9 vaccine manufacture. The candidate H7N9 LAIV was immunogenic and protected ferrets against homologous and heterologous wild-type H7 virus challenge, making it suitable for use in protecting humans from H7 infection.
http://jvi.asm.org/content/early/2014/04/03/JVI.00100-14.abstract