| Project/Area Number |
59440034
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Virology
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| Research Institution | Kobe University School of Medicine |
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Principal Investigator |
HOMMA Morio School of Medicine Kobe University, Professor, 医学部, 教授 (10004566)
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| Co-Investigator(Kenkyū-buntansha) |
HOTTA Hak School of Medicine Kobe University, Research Associate, 医学部, 助手 (40116249)
MURAKAMI Isamu School of Medicine Kobe University, Research Associate, 医学部, 助手 (60107951)
FUJITA Nobuya School of Medicine Kobe University, Lecturer, 医学部, 講師 (30030844)
TAKEHARA Manabu School of Medicine Kobe University, Associate Professor, 医学部, 助教授 (40030829)
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| Project Period (FY) |
1984 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥26,500,000 (Direct Cost: ¥26,500,000)
Fiscal Year 1986: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1985: ¥8,500,000 (Direct Cost: ¥8,500,000)
Fiscal Year 1984: ¥14,000,000 (Direct Cost: ¥14,000,000)
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| Keywords | Sendai virus / Protease-activation mutant / Trypsin / Chymotrypsin / Cleavage site mutant / 開裂部位変位 / 生ワクチン / マウス感染防御 / 同居感染 / 遺伝子解析 |
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| Research Abstract |
Sendai virus penetrates the cells by fusing the envelope with the cytoplasmic membranes. We found that F protein of the envelope was specifically cleaved into smaller glycoproteins, F1 adn F2, by trypsin or trypsin-like enzymes, through which a new hydrophobic amino acid sequence appeared at the N-terminus of F1. On the basis of the above findings, we looked for the mechanism of preferential pneumopathogenicity of Sendai virus in mice and found that a trypsin-like enzyme present in the bronchiolar epithelium was responsible for the cleavage of F protein and the virus thus activated could replicate in multi-steps, causing pneumonia. To prove that, we obtained a protease-activation mutant, TR, which was resistant to trypsin but activated by chymotrypsin, instead. The activated TR could replicate in the lung but only in a single step and did not cause pneumonia. However, the mice became resistant to the challenge with the wild type virus. The present study aimed to analyse the property of TR as well as the mechanism of its protection and to determine the eligibility of TR as a candidate of a new type of live vaccine.
The results obtained were as follows. 1. The property of TR. TR had an enhanced sensitivity to chymotrypsin compared to the wild type virus besides the resistance to trypsin, for both of which was responsible a point mutation at the cleavage site. 2. The mechanism of TR-induced protection. The protection of TR against the challenge with the virulent virus was far solid compared to the usual inactivated split vaccine. This was mainly based on the induction of the virus specific cytotoxic T lymphocytes. 3. Applicability of TR as a new type of live vaccine. The protection was observed among several lines of mice so far tested and could be strengthend by a booster injection. The virus did not spread from the infectors of TR to the contacts int he same cage.
In conculsion, TR is competent as a novel live vaccine of Sendai virus in mice.
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