My. Zhang et al., GST fusion proteins cause false positives during selection of viral movement protein specific single chain antibodies, J VIROL MET, 91(2), 2001, pp. 139-147
Glutathione S-transferase (GST) fusion proteins are used frequently for inv
estigating protein-protein and protein-DNA interactions. The present study
demonstrates that the use of GST fusion proteins caused false positives dur
ing selection of phage-displayed single-chain antibody fragments (scFvs) sp
ecific for three domains of the movement protein (NS,) of tomato spotted wi
lt virus (TSWV). To identify and exclude the false positives when using GST
as a fusion partner linked to the antigen of interest, indirect phage enzy
me-linked immunosorbent assay (ELISA) was compared with capture phage ELISA
. Of 210 enriched phage clones, indirect phage ELISA identified 106 clones
specific for binding to GST-domain fusions but not to GST. In contrast, usi
ng capture phage ELISA, all 106 selected clones were identified as false po
sitives, reacting with the GST fusion proteins and GST. This was confirmed
by characterization of soluble scFv antibodies. The data indicate that GST
fusion proteins seem unsuitable for screening of phage-displayed antibody f
ragments and it is essential to use capture phage ELISA, instead of the ind
irect phage ELISA used commonly to exclude false positives in characterizat
ion of selected clones with GST fusion proteins. (C) 2001 Elsevier Science
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