Rachel Johnson

Publications (2)7.53 Total impact

• Article: An additional oligosaccharide moiety in the HA of a pandemic influenza H1N1 candidate vaccine virus confers increased antigen yield in eggs.

  Carolyn Nicolson, Ruth Harvey, Rachel Johnson, Kate Guilfoyle, Othmar G Engelhardt, James S Robertson
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  ABSTRACT: The H1N1 influenza pandemic in 2009 highlighted the need for the rapid generation of candidate vaccine viruses (CVVs) against an A/California/7/2009-like virus. The first available CVVs gave low protein yields in eggs but improved yields were achieved for second generation CVVs which contained amino acid substitutions compared to their precursor viruses. In this study, we investigated the basis for the increased virus protein yield of CVV NIBRG-121xp and whether the improved yield characteristics could be transferred between this virus and two other CVVs, NYMC X-179A and NYMC X-181. We generated variant viruses by reverse genetics to contain combinations of amino acid substitutions found in high yielding NIBRG-121xp and NYMC X-181. We found that the increase in total protein yield and functional HA yield of NIBRG-121xp in eggs is attributable to the single amino acid substitution K119N in the HA. We also found that the glycosylation of position 119 is essential for the improved virus protein yield in eggs. However, the K119N yield-enhancing effect was not transferable between viruses, nor was the N129D change found in high yielding NYMC X-181. However, position 119 may be a useful locus to monitor in future for viruses and CVVs with potentially high yield.
  Vaccine 11/2011; 30(4):745-51. · 3.77 Impact Factor
• Article: The development of vaccine viruses against pandemic A(H1N1) influenza.

  James S Robertson, Carolyn Nicolson, Ruth Harvey, Rachel Johnson, Diane Major, Kate Guilfoyle, Sarah Roseby, Robert Newman, Rebecca Collin, Chantal Wallis, [......], Pierre Rivailler, Kortney M Gustin, Jessica A Belser, Taronna R Maines, Terrence M Tumpey, Xiyan Xu, Jacqueline M Katz, Alexander Klimov, Nancy J Cox, Ruben O Donis
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  ABSTRACT: Wild type human influenza viruses do not usually grow well in embryonated hens' eggs, the substrate of choice for the production of inactivated influenza vaccine, and vaccine viruses need to be developed specifically for this purpose. In the event of a pandemic of influenza, vaccine viruses need to be created with utmost speed. At the onset of the current A(H1N1) pandemic in April 2009, a network of laboratories began a race against time to develop suitable candidate vaccine viruses. Two approaches were followed, the classical reassortment approach and the more recent reverse genetics approach. This report describes the development and the characteristics of current pandemic H1N1 candidate vaccine viruses.
  Vaccine 02/2011; 29(9):1836-43. · 3.77 Impact Factor