| The H5 subtype avian influenza is a highly pathogenic avian influenza, which has the characteristics of high infectivity and high fatality rate. The H5 subtype avian influenza outbreaks in our country are mostly H5N1, However, In recent two years, The epidemic situation of H5N2, H5N8, H5N6, H5N5 were significantly increased. A large number of influenza subtypes have brought great difficulties to the prevention and control of avian influenza. The development of an effective vaccine of H5 subtype avian influenza is an important way to control the epidemic situation of influenza H5.In order to investigate the role of different subtypes of NA gene in the inactivated vaccine of H5 subtype avian influenza virus,We selected SH7(H5N1), r SH7-674NA(H5N6), r SH7-LZFNA(H5N2) as the attack strains;SH7d HA(H5N1),SH7 d HA674NA(H5N6), SH7 d HALZFNA(H5N2) as vaccine strains.Then the cross immunity protection test was carried out on SPF chicken and SPF BALB/c mice respectively. The contents of the study were as follows:In the SPF chicken model, the 100 SPF chickens were divided into four groups, Four groups of chickens were immunized respectively with SH7 d HA, SH7 d HA674NA, SH7 d HALZFNA, PBS. HA-HI cross test and chick embryo neutralization test were carried out after 3 weeks of immunization. Then each group was divided into three groups, infected with diluted into 105EID50 three attack strains by intranasal instillation. After infected 2d,4dand 6d to collect swab. The viscera of 3 chickens were collected from each group after infected 4d.The remaining chickens were collected to test the HI titer after infected 14 d.Results show: a?After immunization, The cross HI was significantly increased in the range of 8.52log2~10.52log2, The cross HI titer was still at a high level in the range of 7.85log2~9.92log2. The results of chicken embryo neutralization test showed that three groups of immune serum against SH7 and r SH7-LZFNA antibody titer was higher in the range of 246~544, The antibody titer against r SH7-674 NA was lower in the range of 15~30. b?Swab test results show that the detoxification rate is higher after infected 2d, The detoxification rate is lower after infected 4d and 6d, r SH7-674NA/SH7 d HA674NA's detoxification rate is still high after infected 6d.In the control group, The lung virus titer was higher, and the log10EID50/0.2m Lvalue was in the range of 6.35~7.2, And the other organs could detect the virus. The lung virus titers of the immunized group were lower, and log10EID50/0.2m L value in the range of 1.75~3.75, The virus detection rate of other organs is low.c?The chickens of control group were died after infected 3d. The group of r SH7-674NA/SH7 d HALZFNA died 1 after infected 5d, The group of r SH7-674NA/SH7 d HA674NA died 2 after infected 7d.In the SPF BALB/c mouse model, The 144 mice were divided into four groups, Four groups of mice were immunized respectively with SH7 d HA, SH7 d HA674NA, SH7 d HALZFNA, PBS. The mice were immunized once more after 14 d.HA-HI cross test and total serum Ig G test were carried out after 4 weeks. Then each group was divided into three groups and then infected with diluted into 105EID50 three attack strains by nasal cavity. Three mice were killed after infected 4d, The nasal bones, lungs and brain were collected to detect virus titer. The content of total Ig G in serum of mice was measured after infected 4d and 14 d.Results show: a?After immunization, The cross titer of HI was significantly increased in the range of 6.75log2~8.4log2. The total Ig G content in serum was significantly increased in the range of 50294.7ng/m L~71066.9ng/m L. b?The chickens of control group were died after infected 2d and 3d, The other groups were not died. In the control group, The body weight of the mice increased first and then decreased, Other groups of mice weight change is not obvious. c?In the control group, The lung virus titer was higher, and the log10EID50/0.2m Lvalue was in the range of 2.88~5.5, the log10EID50/0.2m Lvalue of nasal turbinate virus titer was in the range of 1.5~2.33.The virus titer of r SH7-674NA/SH7 d HALZFNA was higher than that of r SH7-674NA/SH7 d HA in nasal turbinate and lung, The rest of immune groups were not detected virus in nasal turbinate and lung. d?The total Ig G content in serum was in the range of 42398ng/m L~128170ng/m L and 50294.7ng/m L~71066.9ng/m L after infected 4d and 14 d.In summary, In the SPF chicken model, The three H5 inactivated vaccine can induce high levels of cross HI titer, Those inactivated vaccine can induce cross protection againstattack strains.Different subtypes of NA gene have no significant effect on the H5 subtype avian influenza inactivated vaccine In the SPF BALB/c mouse model, The three H5 inactivated vaccine can induce high levels of cross HI titer and Ig G in serum, Those inactivated vaccine can induce cross protection against attack strains. N1 subtype of the vaccine against the N6 subtype of AIV protection than the N2 vaccine against N6 subtype of AIV relatively stronger protection. |
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