| Project/Area Number |
06454209
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Virology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
IWAMOTO Aikichi University of Tokyo, Insitute of Medical Science, Professor, 医科学研究所, 教授 (10133076)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIKURA Hiroshi University of Tokyo, Faculty of Medicine, Professor, 医学部, 教授 (60012754)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 1995: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1994: ¥4,400,000 (Direct Cost: ¥4,400,000)
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| Keywords | retrovirus / Mous leukemia virus / host factor / Fv-1 |
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| Research Abstract |
When B-tropic murine leukemia virus (MLV) is cultured under the restriction by Fv-1^<n/n>, there could be two escape mutants theoretically : NB-tropic. and N-troopic However, only NB-tropic escape mutant has been reported so far. In this reseach, we found that from B-to NB-tropic escape is caused by a point mutation. We also found that from B-to N-tropic escape could happen through the recombination between the infecting B-tropic virus and endogenous N-tropic virus in the host cell.
We amplified, sequenced and compared the gag gene of the B-tropic MLV and an NB-tropic escape mutant established in our laboratory. The NB-tropic escape mutant had G to A transition at the 313th base of the gag gene, which would substitute the 105th amino acid of the capsid protein from aspartic acid to asparagine. Interestingly, the position of the point mutation was out of the known Fv-1 determinats (109th and 110th amino acid of capsid protein).
B-tropic MLV with E.Coli supF gene in its LTR was transfected to YH-7 cells (Fv-1^<b/b>) and cultured for four weeks. The overnight culture supernatant after 4 week culture was used as the B-tropic virus preparation. When this B-tropic virus was infected to NIH3T3 (Fv-1^<n/n>), N-tropic virus appeared immediately. Four out of 6 nucleotides at the Fv-1 tropism determinat was different bewteen this N-tropic escape MLV and original B-tropic MLV.Therefore, mutation was hardly the cause of the escape. YH-7 cells contained the endogenous viruses with N-tropic determinat. We identified that the N-tropic escape MLV had both N-tropic deteminat and the E.Coli supF gene. Therefore, it is inferred that recombination between the infecting B-topic MLV and the N-tropic endogenous virus resulted in the N-tropic escape mutant.
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