RESUMO
Objective:To evaluate the protective immunity by vaccination of BALB/c mice with rLV-HA-GCN4,a recombinant lentivirus expressing the trimeric HA of swine H1N1 influenza virus. Methods:The female mice were randomly divided into rLV-HA-GCN4,rLV-HA,LV and PBS groups. Mice were primed with plasmid and boosted with lentivirus by the administration of intramuscular thigh injections at an interval of two weeks. At day 28 post-prime immunization,mice were inoculated intranasally with 100TCID50 of swine H1N1 influenza virus in a 50 μl volume. The immune levels were assessed by the T lymphocyte transformation test, flow cytometry,indirect ELISA and the indexes of spleen and lung. Results:The spleen lymphocyte transformation rate was 0. 3±0. 11 in the rLV-HA-GCN4 group at day 14 post-boost immunization, showing a statistical significance ( P<0. 01 ) compared to the PBS group. Meanwhile,rLV-HA-GCN4 could cause T lymphocyte response mainly based on the Th1-type CD4+ T cells. The IgG antibody titer reached to 1:8 000 at day 14 post-boost immunization and approximately 1:7 000 at day 14 post challenge. After challenge,the spleen and lung indexes of rLV-HA-GCN4 group were significantly lower than those of PBS group (P<0. 05). The body weight of rLV-HA-GCN4 group demonstrated a slight decrease before 3 days post challenge and then a gradual increase compared to the LV and PBS groups (P<0. 05). Conclusion:rLV-HA-GCN4 can effectively induce cellular and humoral immune response in BALB/c mice against swine H1N1 influenza virus.