Enhancement of Influenza A Virus M2 Protein Antibody Response after Administration of DNA Vaccine
Date Issued
2005
Date
2005
Author(s)
Hsueh, Tun-Yun
DOI
zh-TW
Abstract
Influenza virus causes acute respiratory infection in humans. Epidemics occur annually. It can cause severe mortality especially in the elderly and children. The influenza vaccine being used now is composed of two inactivated Influenza A virus and one inactivated Influenza B virus. Due to the antigenic variation of viral surface proteins, hemagglutinin (HA) and nuraminidase (NA), the vaccine has to be evaluated and adjusted every year. In order to improve the situation, this study choses another virus surface protein, M2, which is highly conserved, to study. Trying to observe and analyze the specific immune response of recombinant M2 protein and to evaluate the potential of the plasmid DNA expressing recombinant M2 protein as influenza DNA vaccine.
The previous studies of our lab showed that administrating mice with plasmid containing the sequence of M2 gene（pcDNA-Mfull, pMfull）could induce antibody response. In addition, our lab also constructed the plasmid pcDNA3-MdFc（pMdFc）. The Md portion was formed by deleting the transmembrne domain of M2 protein and a linker contains 5 amino acid（G-G-G-G-S）was added between extracellular and intracellular domains. The secreting signal peptide of Staphylococcus aureus protein A was added to the N-terminus of Md and human IgG Fc fragment was added to the C-terminus of Md to form MdFc. The muce immunized with pMdFc and plasmid containing mouse IL-5 sequence（pIL-5）as the adjuvant were also induced high antibody response.
In this study, we continued previous studies and tried to enhance the expression and the immune responses of recombinant M2 protein. The different lengths of linker between Md and Fc was added, to construct a series of plasmids. On the other hand, the human IgG Fc fragment was moved to the N-terminus of Md, linkers with different length was added between Fc and Md to construct pFcMd group. Then we compared these two groups of plasmids with pMfull after tranfecting cell and administrating mice.
The mRNA of recombinant M2 protein could be detected after transfecting cells, however, there was no detectable recombinant M2 protein. The animal experiments showed that pMfull, pMdFc group, and pFcMd group all could induce high antibody responses, and the titers from high to low were in the order of pMfull, pMdFc group, and pFcMd group. Furthermore, immunization mice with pIL-5 as the adjuvant resulted in higher antibody responses than those without pIL-5. Analyzing the IgG subtype of induced antibody showed that pIL-5 not only could increase the amount of total antibodies but also significantly raise the amount of IgG1 antibodies. The result of ELISPOT, which detected the cellular immune responses, corresponded well to that of antibody response.
According to the study above, though there was still much left to be studied about M2 protein in the future, pMfull with appropriate adjuvant may be a potential DNA vaccine for influenza.
Subjects
M2
流行性感冒病毒
核酸疫苗
M2 protein
influenza A virus
DNA vaccine
SDGs
Type
other