Envelope targeting: Hemagglutinin attachment specificity rather than fusion protein cleavage-activation restricts Tupaia paramyxovirus tropism

Christoph Springfeld, Veronika Von Messling, Christian A. Tidona, Gholamreza Darai, Roberto Cattaneo

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

To engineer a targeting envelope for gene and oncolytic vector delivery, we characterized and modified the envelope proteins of Tupaia paramyxovirus (TPMV), a relative of the morbilli- and henipaviruses that neither infects humans nor has cross-reactive relatives that infect humans. We completed the TPMV genomic sequence and noted that the predicted fusion (F) protein cleavage-activation site is not preceded by a canonical furin cleavage sequence. Coexpression of the TPMV F and hemagglutinin (H) proteins induced fusion of Tupaia baby fibroblasts but not of human cells, a finding consistent with the restricted TPMV host range. To identify the factors restricting fusion of non-Tupaia cells, we initially analyzed F protein cleavage. Even without an oligoor monobasic protease cleavage sequence, TPMV F was cleaved in F1 and F2 subunits in human cells. Edman degradation of the F1 subunit yielded the sequence IFWGAIIA, placing the conserved phenylalanine in position 2, a novelty for paramyxoviruses but not the cause of fusion restriction. We then verified whether the lack of a TPMV H receptor limits fusion. Toward this end, we displayed a single-chain antibody (scFv) specific for the designated receptor human carcinoembryonic antigen on the TPMV H ectodomain. The H-scFv hybrid protein coexpressed with TPMV F mediated fusion of cells expressing the designated receptor, proving that the lack of a receptor limits fusion and that TPMV H can be retargeted. Targeting competence and the absence of antibodies in humans define the TPMV envelope as a module to be adapted for ferrying ribonucleocapsids of oncolytic viruses and gene delivery vectors.

Original languageEnglish (US)
Pages (from-to)10155-10163
Number of pages9
JournalJournal of virology
Volume79
Issue number16
DOIs
StatePublished - Aug 2005

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Insect Science
  • Virology

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