Since their discovery, single-domain, antigen-binding fragments of
camelid-derived heavy-chain-only antibodies, also known as nanobodies (Nbs),
have been of interest as therapeutics against human diseases and pathogens,
including viruses. However, their effect against phytopathogens remains
limited.

Caroline Hemmer from the Université de Strasbourg in France aimed to test
these nanobodies on the grapevine fanleaf virus (GFLV), the causal agent of
fanleaf degenerative disease. The team identified a nanobody specific to
GFLV that conferred strong resistance to GFLV upon expression in both
tobacco and grapevine, the natural host of the virus. The resistance proved
to be effective against a broad range of GFLV isolates. However, the
nanobody was useless against GFLV's close relative, Arabis mosaic virus.

These findings could be vital in developing resistance to GFLV in grapevine,
as well as the generation of new antiviral strategies in plants based on
nanobodies.

[onlinelibrary.wiley.com]