Immunogenicity And Safety Of Respiratory Syncytial Virus G Protein Subunit Vaccine

Respiratory syncytial virus(Respiratory syncytial virus RSV)is the most common viruses in acute respiratory infections in infants and young children.The World Health Organization estimates that every year RSV causes 64 million cases of infection and results in 160,000 deaths.To this day,a safe and effective vaccine for RSV infection is still unavailable.In this study,CX3C motif of truncated of RSV G protein(GCX3C)was replaced by CTL epitope.After transformation,we can get the GCTL protein.The two proteins immune mice with LT and CpG adjuvant respectively.After immunization,we measured the different immune indicators and evaluate the immunogenicity and safety of the vaccine.In E.coli BL21,use IPTG to induce the expression of GCX3C protein and GCTL protein.The two proteins are in the form of inclusion body expression.After the inclusion body with urea denaturation,they were then purified in the form of affinity chromatography.GCX3C protein,GCTL Lprotein purity were tested as 95%,97.4%.Next,purified GCX3C protein and GCTL protein were mixed and then used to immune mice adjuvant.The immunization groups are as follows:PBS group;GCX3C group;the GCTL group;LT group;GCX3C+LT group;GCTL+LT group;CpG group;GCX3C+CpG group;GCTL+CpG group.The total of 9 groups immuned in 0,2,4 weeks.After immunization,the various indicators of mouse lung lavage fluid and lung homogenates were tested.The results showed that:1)Lung lavage fluid of GCX3C+LT group and GCTL+LT group,the sIgA in the content and the neutralizing antibody titer was significantly higher than the other groups(P<0.05).2)INF-γ content and INF-γ/IL-4 ratio of CpG group and GCTL+CpG group in lung tissue homogenates was significantly higher(P<0.05).And ELISPOT experiments show that the CpG adjuvant can promote the secretion of INF-y in the number of spleen lymphocytes increased.3)IL-4,IgE and histamine in lung homogenates of use the GCTL protein immune groups is lower than GCX3C protein immunization group.After the last immunization,105 pfu RSV viruses are used to do an attack drug experiments.The results showed that:1)The weight of each group of mice were decreased,but the most serious decline can be found at GCTL+CpG group.2)Through observation at lung tissue sections we have found that the lung lesions of PBS group,LT group,CpG group are extremely severe.GCX3C group lesions are more severe than GCTL group.But the lesions of GCX3C+LT group and GCTL+LT group compared with the corresponding separate immuNohistochemistry have been alleviated.However,the GCTL+CpG group was more severe than GCX3C+CpG group.3)After inoculation,RSV virus titers in mouse lungs of GCX3C group,GCTL group,GCX3C+LT group and GCTL+LT group decreased more significantly than the PBS group and LT group(P<0.05).The experimental results show that the protein transformed GCX3C can effectively reduce the Th2 immune response.LT adjuvants can promote mucosal sites of the body to produce more efficient sIgA antibody.CpG adjuvant can play an important role in the immune balance to help the immune balance towards Th1 direction.This thesis evaluated the immunogenicity and safety of RSV G protein subunit vaccine.It laid a solid foundation for the future development of new RSV vaccine.