Aslam Sadaf, Rajendran Madhusudan, Kriti Divya, Kurland Andrew, Johnson Jeffrey, van Bakel Harm, Krammer Florian, García-Sastre Adolfo, Ayllon Juan
Department of Microbiology, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA.
Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA.
NPJ Vaccines. 2023 Feb 10;8(1):12. doi: 10.1038/s41541-023-00603-3.
Influenza B virus (IBV) strains are one of the components of seasonal influenza vaccines in both trivalent and quadrivalent formulations. The vast majority of these vaccines are produced in embryonated chickens' eggs. While optimized backbones for vaccine production in eggs exist and are in use for influenza A viruses, no such backbones exist for IBVs, resulting in unpredictable production yields. To generate an optimal vaccine seed virus backbone, we have compiled a panel of 71 IBV strains from 1940 to present day, representing the known temporal and genetic variability of IBV circulating in humans. This panel contains strains from the B/Victoria/2/87-like lineage, B/Yamagata/16/88-like lineage and the ancestral lineage that preceded their split to provide a diverse set that would help to identify a suitable backbone which can be used in combination with hemagglutinin (HA) and neuraminidase (NA) glycoproteins from any IBV strain to be incorporated into the seasonal vaccine. We have characterized and ranked the growth profiles of the 71 IBV strains and the best performing strains were used for co-infection of eggs, followed by serial passaging to select for high-growth reassortant viruses. After serial passaging, we selected 10 clonal isolates based on their growth profiles assessed by hemagglutination and plaque-forming units. We then generated reverse genetics systems for the three clones that performed best in growth curves. The selected backbones were then used to generate different reassortant viruses with HA/NA combinations from high and low titer yielding wild type IBV. When the growth profiles of the recombinant reassortant viruses were tested, the low titer yielding HA/NA viruses with the selected backbones yielded higher titers similar to those from high titer yielding HA/NA combinations. The use of these IBV backbones with improved replication in eggs might increase yields for the influenza B virus components of seasonal influenza virus vaccines.
乙型流感病毒（IBV）毒株是三价和四价季节性流感疫苗的成分之一。这些疫苗绝大多数是在鸡胚中生产的。虽然存在并正在使用用于在鸡蛋中生产疫苗的优化主干，且已用于甲型流感病毒，但对于IBV却不存在这样的主干，导致产量不可预测。为了生成最佳的疫苗种子病毒主干，我们汇集了一组从1940年至今的71株IBV毒株，它们代表了在人类中传播的IBV已知的时间和遗传变异性。该组包含来自B/维多利亚/2/87样谱系、B/山形/16/88样谱系及其分裂前的祖先谱系的毒株，以提供一个多样化的集合，这将有助于识别一个合适的主干，该主干可与来自任何要纳入季节性疫苗的IBV毒株的血凝素（HA）和神经氨酸酶（NA）糖蛋白结合使用。我们已经对71株IBV毒株的生长特性进行了表征和排序，性能最佳的毒株用于鸡蛋的共感染，然后进行连续传代以选择高生长重组病毒。连续传代后，我们根据通过血凝和蚀斑形成单位评估的生长特性选择了10个克隆分离株。然后，我们为在生长曲线中表现最佳的三个克隆生成了反向遗传学系统。然后使用选定的主干来生成具有来自高滴度和低滴度野生型IBV的HA/NA组合的不同重组病毒。当测试重组重组病毒的生长特性时，具有选定主干的低滴度HA/NA病毒产生的滴度更高，类似于来自高滴度HA/NA组合的滴度。使用这些在鸡蛋中复制得到改善的IBV主干可能会提高季节性流感病毒疫苗中乙型流感病毒成分的产量。
