A Replicating Modified Vaccinia Tiantan Strain Expressing an Avian-Derived Influenza H5N1 Hemagglutinin Induce Broadly Neutralizing Antibodies and Cross-Clade Protective Immunity in Mice

Xiao, Haixia; Liu, Li; Zhu, Qingyu; Tan, Zhiwu; Yu, Wenbo; Tang, Xian; Zhan, Dawei; Du, Yanhua; Wang, Haibo; Liu, Di; Li, Zhixin; Yuen, Kwok-Yung; Ho, David D.; Gao, George F.; Chen, Zhiwei

Highly pathogenic avian influenza A virus (HPAIV) H5N1 has long been carried by wild aquatic bird populations, spread throughout the world via either the poultry transportation or the migratory bird flyway, and has killed or led to the culling of hundreds of millions of birds [1, 2] . H5N1 was shown to be lethal to human in 1997 when 6 of the 18 infected human cases in Hong Kong died [3] [4] [5] . Although H5N1 viruses have not yet been transmitted between humans, cross-species transmission of these viruses to human has been documented in 633 cases, with a mortality rate of 59.6%, since the reemergence of H5N1 viruses in 2003 [6] . Several recent independent studies suggested that H5N1 viruses might require very few amino acid substitutions to become transmissible via respiratory droplets between mammals [7] [8] [9] . Therefore, great concern has been raised in the ability of H5N1 viruses to efficiently spread between humans and become a pandemic threat, thus making an H5N1 influenza vaccine an integral part of any pandemic preparedness plan [10] .