1991 Fiscal Year Final Research Report Summary
Molecular epidemiology of type C influenza
| Project/Area Number |
02454180
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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 | Yamagata University |
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Principal Investigator |
NAKAMURA Kiyoto Yamagata University School of Medicine Professor, 医学部, 教授 (00125775)
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| Co-Investigator(Kenkyū-buntansha) |
SUGAWARA Kanetsu Yamagata University School of Medicine Staff for Education and Research, 医学部, 教務職員 (60110673)
NISHIMURA Hidekazu Yamagata University School of Medicine Assistant, 医学部, 助手 (50172698)
KITAME Fumio Yamagata University School of Medicine Associate Professor, 医学部, 助教授 (40004676)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Influenza C virus / HE protein / antigenic structure / antigenic variation / monoclonal antibody |
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| Research Abstract |
1. We produced a total of 37 monoclonal antibodies (MAbs) against the hemagglutinin-esterase (HE) protein of influenza C virus, ten with hemagglutination-inhibition, hemolysis inhibition, and neutralization activities (group A) and 27 without the activities (group B). Operational and topological analyses with these antibodies revealed that at least nine non-over-lapping or partially overlapping antigenic sites were present on the HE protein, four recognized by group A MAbs (A-1-A-4) and five by group B (B-1 - B-5).
2. Neutralization-resistant variants of influenza C virus were selected with group A MAbs against four different antigenic sites (A-1-A-4), and their HE genes were sequenced to identify amino acid residues important for the integrity of each site. Although variants for antigenic site A-2 had a change at position 367, all substitutions in the variants for sites A-1, A-3, and A-4 occurred in the central region of the HE1 subunit spanning amino acid position 178 to 283. It was a
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lso found that many of the variants selected with antibodies to sites A-1 and A-3 were clustered within or near one of the three variable regions revealed previously by comparing amino acid sequences of the HEs among various influenza C isolates, which supports the notion that influenza C virus, like human influenza A viruses, may be exposed to a significant amount of immunological pressure.
3. Sixteen influenza C strains isolated in Yamagata City between April 1988 and May 1990 were compared by antigenic analysis with anti-HE HAbs and oligonucleotide mapping of total vRNAs. The results showed that the isolates could be classified into two groups : seven isolates were closely related to the influenza C strain isolated in 1981 in Aichi prefecture, (Aichi/1/81), and the remaining nine were very similar to the strain isolated in the same year in Yamagata prefecture (Yamagata/1/81). Thus it appears that two evolutionary linages of influenza C virus, different markedly from each other in the antigenicity of HE, were selected presumably by immunological pressure and became predominant at least in Yamagata city. Less
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