An H5N1-based matrix protein 2 ectodomain tetrameric peptide vaccine provides cross-protection against lethal infection with H7N9 influenza virus

Leung, Ho-Chuen; Chan, Chris Chung-Sing; Poon, Vincent Kwok-Man; Zhao, Han-Jun; Cheung, Chung-Yan; Ng, Fai; Huang, Jian-Dong; Zheng, Bo-Jian

To examine whether H5N1-M2e vaccination could inhibit viral infection and tissue damage in the lungs of mice challenged with a lethal dose of H7N9 virus, six mice per group were sacrificed at day 6 postchallenge and their lungs were collected for detection of viral load and tissue damage. As detected by TCID 50 assay and QRT-PCR, virus titers ( Figure 4A ) and viral RNA copies ( Figure 4B ) in the lungs of mice vaccinated with H5N1-M2e were significantly reduced, which was approximately 2 logs lower than that in the mice vaccinated with FA, SAS, or PBS (P , 0.01). Consistent with this result, H&E staining showed that the lung pathology of mice vaccinated with H5N1-M2e was less severe than mice vaccinated with adjuvant or PBS. Severe damage of lung tissue was observed in adjuvant-or PBS-vaccinated mice, which included damage to the bronchial epithelium with denatured pneumocytes, neutrophils, and mononuclear cells, marked infiltration of lymphocytes, and fused alveoli wall with focal hemorrhage ( Figure 4C ).