Abstract:

The aim of this study was to investigate a safe and effective universal vaccine. A consensus HA gene sequence was found by phylogenetic analysis all of the HA gene sequences of H1 subtype classical swine influenza virus and influenza A virus from GenBank and optimized according to the swine bias codon usages（optimized consensus, opti-CS）, we also selected another two HA genes and optimized (one is from A/Swine/Guangdong/1/01 strain and the other one is from rPan09 strain),then the three opti-HAs were inserted into pCAGGS vector, and constructed three recombinant plasmids named pCA-opti-CS, pCA-opti-G11 and pCA-opti-r09, respectively. The HA protein transiently expressed in 293T cell was detected in indirect immunofluorescence. Groups of six to eight week-old BALB/c were intramuscular inoculated singly with pCA-opti-CS, pCA-opti-G11, pCA-opti-r09 and PCAGGS vector, respectively. A total of immunity was three times interval of three weeks with the same dosage. Mice of each Group were divided into two parts after two weeks of the third immunity, then challenged with 10^3.87EID₅₀ of A/Swine/Guangdong/1/01(H1N1) and 10^7.45EID₅₀ of rPan09, respectively. Sera were collected, antibodies to HA and HI antibodies, level of IL-4 and IFN-γ were detected. The lungs were used for virus titer detection and histopathological observation. The result showed that HA can be expressed in 293T cell, plasmid pCA-opti-CS can induce high level of HA antibodies, high HI titer and can induce high level of IL-4 and IFN-γ. The result of determination of virus content in lungs and histopathological observation were showed that pCA-opti-CS DNA vaccine could effectively limited viral replication and attenuated histopathological damage in mice lungs. Based on our research, we conclude that recombinant plasmid pCA-opti-CS can induced high level of humoral and cellular immune response and own a good heterologous protecting capacity. Our study had made beneficial exploration in universal vaccine against influenza virus.