Development and identification of a new Vero cell-based live attenuated influenza B vaccine by a modified classical reassortment method

Evaluation of the cross-protection of the Vero cell-derived attenuated influenza vaccines with compound adjuvant, through intranasal immunization

This study was to evaluate the sufficient safety and effect of the novel influenza vaccine program. It prepared new reassortant influenza virus, with high yield on Vero cells. According to the plaque counting, one dose LAIV was composed with 105 PFU of H1, H3, BY, and BV, respectively. Then mixed this LAIV with compound adjuvant, containing 500 μg/mL of carbopol971P and 50 μg/mL of tetanus toxin. That vaccination was called catt-flu. And it employed the GYZZ02 vaccine (commercialized freeze-dried LAIV, listed in China) as cohort analysis control. All mice received two doses of the vaccine, administered on days 0 and 14, respectively. That catt-flu program could induce more cross-protection with neutralizing antibody against heterogeneous types of influenza virus, not only based on HA but also NA protective antigen, through convenient nasal immunization, which had non-inferiority titter compared with the chicken embryo-derived GYZZ02 vaccine on safe and effect. The Vero cell-derived vaccine (LAIV) combined compound catt adjuvant (contain carbopol971P and tetanus toxin) could provide another safety and protective program of influenza vaccine by intranasal administration, as catt-flu program.

Construction and identification of influenza plasmid pool imparting high yields to candidate vaccine viruses in Vero cell at low temperature

We generated plasmid pools for the rapid preparation of candidate vaccine strains, which could grow in the Vero cells at low temperature. Firstly, we cloned in the pHW2000 plasmid each of the eight gene segments (PB2, PB1, PA, hemagglutinin [HA], neuraminidase [NA], NS, NP, M) of two master donor strains (MDS), respectively, A/Yunnan/1/2005Vca(H3N2) and B/Yunnan/2/2005Vca(By), which had Vca phenotype (cold‐adapted phenotype in Vero cells). Secondly, the similar operation was implemented with each of the HA, NA and NP segments of circulating strains with epidemic potential (parental strains). The virus rescue techniques were employed in this study, according to the homology rate of HA segments between MDS and parental strains. Then, we harvested amount of new Vca virus strains. By transmission electron microscope, it could observe new viruses' diameter and length were from 100 to 120 nm. Importantly, these reassortant viruses could get high‐yield production in Vero cells at 25℃ from the beginning to the fourth generation, which was significantly differ from their original parental viruses. Additional, these production 16 new Vca strains could maintain enough antibody binding capacity and attenuation phenotype, which consisted with their MDS. So these plasmid pools constructed by mount of different influenza A and B virus gene fragments could present desired working performance and provide convenience and realization for more Vca reassortant virus as candidate vaccine strain if needing.