S. Sakamoto et al., Studies on the structures and antigenic properties of rabies virus glycoprotein analogues produced in yeast cells, VACCINE, 17(3), 1999, pp. 205-218
We investigated two forms (designated as yGI and yGII) of rabies virus glyc
oprotein (G) analogues produced in the G cDNA-transfected yeast cells. Mole
cular weights of yGI and yGII were estimated as 66 and 56 kDa, respectively
, according to their relative mobility in SDS-PAGE. Although being produced
in large amounts, yGI was present mostly in insoluble forms and hardly ext
ractable with non-ionic detergents. The yGI reacted with polyclonal anti-a
antibodies, but did not react with our conformational epitope-specific anti
-G monoclonal antibodies (G-MAbs). No protective immunity was induced by yG
I in guinea pigs nor in mice. On the other hand, yGII was Triton-soluble, b
ut was only small in amount (at most 1% of total G proteins) and was shown
to lack the cytoplasmic domain. The yGII, however, reacted with the G-MAbs
and induced protective immunity in guinea pigs as well. When the G-cDNA was
expressed in animal cells in culture, a single form (about 66 kDa) of G pr
otein was produced, which displayed similar behaviors as seen in its reacti
vity with the MAbs and intracellular distribution as seen in the virus-infe
cted cells. These results suggest that most G protein molecules were not pr
ocessed normally in yeast cells, resulting in abnormal folding and multimer
formation, while only a small fraction were occasionally folded normally t
o have conformational epitopes but were mostly deprived of the C-terminal p
ortion. (C) 1998 Elsevier Science Ltd. All rights reserved.