Isakova-Sivak Irina, Chen Li-Mei, Bourgeois Melissa, Matsuoka Yumiko, Voeten J Theo M, Heldens Jacco G M, van den Bosch Han, Klimov Alexander, Rudenko Larisa, Cox Nancy J, Donis Ruben O
Influenza Division, Centers for Disease Control and Prevention, Department of Health and Human Services, Atlanta, Georgia, USA.
Clin Vaccine Immunol. 2014 May;21(5):722-31. doi: 10.1128/CVI.00819-13. Epub 2014 Mar 19.
Live attenuated influenza vaccines (LAIV) offer significant advantages over subunit or split inactivated vaccines to mitigate an eventual influenza pandemic, including simpler manufacturing processes and more cross-protective immune responses. Using an established reverse genetics (rg) system for wild-type (wt) A/Leningrad/134/1957 and cold-adapted (ca) A/Leningrad/134/17/1957 (Len17) master donor virus (MDV), we produced and characterized three rg H5N1 reassortant viruses carrying modified HA and intact NA genes from either A/Vietnam/1203/2004 (H5N1, VN1203, clade 1) or A/Egypt/321/2007 (H5N1, EG321, clade 2) virus. A mouse model of infection was used to determine the infectivity and tissue tropism of the parental wt viruses compared to the ca master donor viruses as well as the H5N1 reassortants. All ca viruses showed reduced replication in lungs and enhanced replication in nasal epithelium. In addition, the H5N1 HA and NA enhanced replication in lungs unless it was restricted by the internal genes of the ca MDV. Mice inoculated twice 4 weeks apart with the H5N1 reassortant LAIV candidate viruses developed serum hemagglutination inhibition HI and IgA antibody titers to the homologous and heterologous viruses consistent with protective immunity. These animals remained healthy after challenge inoculation with a lethal dose with homologous or heterologous wt H5N1 highly pathogenic avian influenza (HPAI) viruses. The profiles of viral replication in respiratory tissues and the immunogenicity and protective efficacy characteristics of the two ca H5N1 candidate LAIV viruses warrant further development into a vaccine for human use.
减毒活流感疫苗（LAIV）相较于亚单位或裂解灭活疫苗，在缓解可能出现的流感大流行方面具有显著优势，包括更简单的生产工艺和更具交叉保护作用的免疫反应。利用针对野生型（wt）A/列宁格勒/134/1957和冷适应（ca）A/列宁格勒/134/17/1957（Len17）主供体病毒（MDV）建立的反向遗传学（rg）系统，我们制备并鉴定了三种rg H5N1重配病毒，它们携带来自A/越南/1203/2004（H5N1，VN1203，1 系）或A/埃及/321/2007（H5N1，EG321，2 系）病毒的修饰 HA 基因和完整 NA 基因。利用小鼠感染模型，比较了亲代 wt 病毒与 ca 主供体病毒以及 H5N1 重配病毒的感染性和组织嗜性。所有 ca 病毒在肺部的复制均减少，而在鼻上皮中的复制增强。此外，H5N1 HA 和 NA 在肺部的复制增强，除非受到 ca MDV 内部基因的限制。每隔 4 周用 H5N1 重配 LAIV 候选病毒对小鼠进行两次接种后，小鼠产生了针对同源和异源病毒的血清血凝抑制（HI）和 IgA 抗体滴度，这与保护性免疫一致。在用致死剂量的同源或异源 wt H5N1 高致病性禽流感（HPAI）病毒进行攻击接种后，这些动物保持健康。两种 ca H5N1 候选 LAIV 病毒在呼吸道组织中的病毒复制情况、免疫原性和保护效力特征，值得进一步开发成供人类使用的疫苗。
