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Further Characterization of the Rabies Virus Glycoproteins Produced by Virus‐Infected and G cDNA‐Transfected Cells Using a Monoclonal Antibody, #1‐30‐44, Which Recognizes an Acid‐Sensitive Epitope
Author(s) -
Kankanamge Pushpa Jenette,
Irie Takashi,
Shoji Jun'ichi,
Tochikura Tadafumi S.,
Kawai Akihiko
Publication year - 2003
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2003.tb03405.x
Subject(s) - rabies virus , monoclonal antibody , biology , epitope , virology , rhabdoviridae , glycoprotein , complementary dna , lyssavirus , virus , microbiology and biotechnology , transfection , antibody , cell culture , biochemistry , immunology , gene , genetics
Expression of rabies virus glycoprotein (G) by G cDNA‐transfected mammalian cells resulted in the production of only a fusion‐negative form. Low pH‐dependent fusion activity, however, was seen when the expression was done under control of the T7 promoter with the help of recombinant vaccinia virus (RVV‐T7) that provided T7 RNA polymerase. Fusion‐inactive G proteins were transported to the cell surface as being detected by a conformational epitope‐specific monoclonal antibody (mAb; #1‐46‐12). The fusion‐inactive G proteins were recognized by most of our 13 conformation‐specific mAbs, except for one mAb, #1‐30‐44, that recognized the low pH‐sensitive conformational epitope. When the G gene expression was done with the help of RVV‐T7, although most G proteins remained in the epitope‐negative form, a small fraction of G gene products were 1‐30‐44 epitope‐positive, and cell fusion activity could be seen when cells were exposed to low pH conditions. From these results, we conclude that acquisition of low pH‐dependent fusion activity is closely related to structural maturation of the G protein to form the low pH‐sensitive 1‐30‐44 epitope. Such maturation seems to be dependent on certain rabies virus‐induced cellular conditions or functions, which might also be provided in part by the vaccinia virus infection. We further assume that expression of G cDNA alone mostly results in the production of mis‐folded and/or differently folded forms of G protein, and only a small fraction is correctly folded even under RVV‐T7‐mediated expression conditions.