Monoclonal antibody produced in plants efficiently treats West Nile virus infection in mice

Abstract

Over the past decade, West Nile virus (WNV) has spread to all 48 of the lower United States as well as to parts of Canada, Mexico, the Caribbean, and South America, with outbreaks of neuroinvasive disease occurring annually. At present, no therapeutic or vaccine is available for human use. Epidemics of WNV and other emerging infectious disease threats demand cost-efficient and scalable production technologies that can rapidly transfer effective therapeutics into the clinical setting. We have previously reported that Hu-E16, a humanized anti-WNV mAb, binds to a highly conserved epitope on the envelope protein, blocks viral fusion, and shows promising postexposure therapeutic activity. Herein, we generated a plant-derived Hu-E16 mAb that can be rapidly scaled up for commercial production. Plant Hu-E16 was expressed at high levels within 8 days of infiltration in Nicotiana benthamiana plants and retained high-affinity binding and potent neutralizing activity in vitro against WNV. A single dose of plant Hu-E16 protected mice against WNV-induced mortality even 4 days after infection at rates that were indistinguishable from mammalian-cell-produced Hu-E16. This study demonstrates the efficacy of a plant-produced mAb against a potentially lethal infection several days after exposure in an animal challenge model and provides a proof of principle for the development of plant-derived mAbs as therapy against emerging infectious diseases.

Agroinfiltration as an Effective and Scalable Strategy of Gene Delivery for Production of Pharmaceutical Proteins

“…The collective results the delivered DNA [3]. The ability to deliver vectors to a majority of the have demonstrated that this system is robust and drives high levels of target protein accumulation up to 1 mg per gram of leaf fresh weight (LFW), within 7 to 10 days after agroinfiltration [5,6,24,28,29]. This system retains the speed and expression amplification of viral vectors, while gaining the flexibility of nuclear gene expression.…”

“…Finally, this system integrates the posttranslational processing capacity of eukaryotic plant cells, for producing complex proteins. Along with others, our laboratory has expressed numerous proteins from small subunit vaccines to large immune complexes, with this system [5,6,28,29]. The collective results the delivered DNA [3].…”

“…The potential scalability of vacuum infiltration makes it a prime candidate for this purpose. Our laboratory has established a vacuum infiltration procedure at the laboratory scale, and examined its scalability in several studies, with both VLP and mAbbased pharmaceutical candidates [5,6,37]. We use a desiccator connected to a vacuum pump to provide the vacuum for infiltration ( Figure 3A).…”

“…Leaf Biomass (g) Protein Yield (μg/g LFW ± SD) Reference NVCP VLP vaccine 100 420 ± 34.24 [5] NVCP VLP vaccine 500 402 ± 52.03 [5] NVCP VLP vaccine 15,000 418 ± 46.42 [5] WNV mAb therapeutic 10 727 ± 87.36 [6] WNV mAb therapeutic 100 740 ± 101.49 [6] WNV mAb therapeutic 500 697 ± 90.74 [6] WNV mAb therapeutic 5,000 598 ± 68.06 [6] LFW: leaf fresh weight; SD: standard deviation; NVCP: Norwalk virus capsid protein; VLP: virus-like particle; WNV: West Nile virus; mAb: monoclonal antibody. …”

“…Plants also outpace the scalability of other expression systems, as recombinant protein-expressing biomass can be produced on an agricultural scale, without the need to build duplicated bioreactors and associated facilities [2]. In contrast to bacterial cells, plants can produce large functional pharmaceutical proteins that require the proper posttranslational modification of proteins, including glycosylation and the assembly of multiple heterosubunits [6]. This is possible because plant cells utilize a eukaryotic endomembrane system that is similar to mammalian cells [7].…”