Camelid nanobodies with high affinity for broad bean mottle virus: a possible promising tool to immunomodulate plant resistance against viruses

Abstract

Worldwide, plant viral infections decrease seriously the crop production yield, boosting the demand to develop new strategies to control viral diseases. One of these strategies to prevent viral infections, based on the immunomodulation faces many problems related to the ectopic expression of specific antibodies in planta. Camelid nanobodies, expressed in plants, may offer a solution as they are an attractive tool to bind efficiently to viral epitopes, cryptic or not accessible to conventional antibodies. Here, we report a novel, generic approach that might lead to virus resistance based on the expression of camelid specific nanobodies against Broad bean mottle virus (BBMV). Eight nanobodies, recognizing BBMV with high specificity and affinity, were retrieved after phage display from a large 'immune' library constructed from an immunized Arabic camel. By an in vitro assay we demonstrate how three nanobodies attenuate the BBMV spreading in inoculated Vicia faba plants. Furthermore, the in planta transient expression of these three selected nanobodies confirms their virus neutralizing capacity. In conclusion, this report supports that plant resistance against viral infections can be achieved by the in vivo expression of camelid nanobodies.

Nanobody-based enzyme immunoassay for ochratoxin A in cereal with high resistance to matrix interference

“…Recombinant expression of VHH can produce single domain antibody (sdAb) with dimensions in the nanometer range, which is also known as nanobody (Nb). High expression yield of Nbs can be obtained in various expression systems, such as bacteria, fungi and plants [10–12]. …”

Nanobody‐mediated resistance to Grapevine fanleaf virus in plants

“…Considering our results with GFLV and those of Ghannam et al . () with BBMV, it is tempting to speculate that antiviral activity is a common property of Nbs directed against plant viruses and they should therefore be considered as a reliable source of resistance. In addition, considering the difficulties often encountered to generate functional scFvs (Fiedler et al ., ; Safarnejad et al ., ), which are circumvented with Nbs due to their intrinsic single‐domain origin and structural specificities (Muyldermans, ), Nbs should be considered superior to other antibodies‐derived products when aiming at generating virus‐resistant plants.…”

Bispecific antibodies in cancer immunotherapy

“…97,98 Moreover, nanobodies were demonstrated to be as specific as regular antibodies. 99 The major concern with nanobodies is their immunogenicity in humans. However, as nanobodies are small, undergo rapid renal clearance, and their amino acid sequences are highly similar to that of human VH, no significant immunogenicity has been observed in mice or humans injected with nanobody-containing constructs.…”

“…103 The small size of nanobodies makes them amendable to bulk production in bacterial cells. 99 In general, nanobodies are cloned behind a secretion signal for bacterial expression. The proteins are produced in the periplasm where formation of disulfide bonds is possible.…”