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

Mouse models have been commonly used for evaluating vaccines for influenza A (H5N1) viruses isolated from humans [28] . Groups of nine mice were either immunized with 1.5610 6 or 3.0610 6 PFU of MVTT HA-QH and MVTT S , respectively, twice, with a one month interval. Immunized mice were challenged with either 100 MLD 50 of A/BhG/QH/1/05 or 100 MLD 50 of A/ VN/1194/04 at 3 weeks post second immunization. Body weight change, number of deaths and clinical signs were closely monitored after viral challenge twice a day. The animals were humanely euthanized by intraperitoneal injection of pentobarbital sodium salt (100 mg/kg) and followed by cervical dislocation, when weight loss is greater than 20% body weight at the start of the experiment for 72 hours. Pentobarbital sodium salt was used to minimize suffering of the animals. The percentage of survival was calculated as previously described [10] .