Development of Antibody-Fragment-Producing Rice for Neutralization of Human Norovirus

Nanobody Mediated Atrazine Resistance in Plants

In planta expression of recombinant antibodies has been proposed as a strategy for herbicide resistance but is not well advanced yet. Here, an atrazine nanobody gene fused with a green fluorescent protein tag was transformed to Arabidopsis thaliana, which was confirmed with PCR, ELISA, and immunoblotting. High levels of nanobody accumulation were observed in the nucleus, cytoderm, and cytosol. The nanobody expressed in the plant had similar affinity, sensitivity, and selectivity as that expressed in Escherichia coli. The T3 homozygous line showed resistance in a dose-dependent manner up to 380 g ai/ha of atrazine, which is approximately one-third of the recommended field application rate. This is the first report of utilizing a nanobody in plants against herbicides. The results suggest that utilizing a high-affinity herbicide nanobody gene rather than increasing the expression of nanobodies in plants may be a technically viable approach to acquire commercial herbicide-resistant crops and could be a useful tool to study plant physiology.

Food-Borne Biotoxin Neutralization in Vivo by Nanobodies: Current Status and Prospects

Food-borne biotoxins from microbes, plants, or animals contaminate unclean, spoiled, and rotten foods, posing significant health risks. Neutralizing such toxins is vital for human health, especially after food poisoning. Nanobodies (Nbs), a type of single-domain antibodies derived from the genetic cloning of a variable domain of heavy chain antibodies (VHHs) in camels, offer unique advantages in toxin neutralization. Their small size, high stability, and precise binding enable effective neutralization. The use of Nbs in neutralizing food-borne biotoxins offers numerous benefits, and their genetic malleability allows tailored optimization for diverse toxins. As nanotechnology continues to evolve and improve, Nbs are poised to become increasingly efficient and safer tools for toxin neutralization, playing a pivotal role in safeguarding human health and environmental safety. This review not only highlights the efficacy of these agents in neutralizing toxins but also proposes innovative solutions to address their current challenges. It lays a solid foundation for their further development in this crucial field and propels their commercial application, thereby contributing significantly to advancements in this domain.

Human norovirus cultivation systems and their use in antiviral research

Human norovirus (HuNoV) is a major cause of acute gastroenteritis and foodborne diseases, affecting all age groups. Despite its clinical needs, no approved antiviral therapies are available. Since the discovery of HuNoV in 1972, studies on anti-norovirals, mechanism of HuNoV infection, viral inactivation, etc., have been hampered by the lack of a robust laboratory-based cultivation system for HuNoV. A recent breakthrough in the development of HuNoV cultivation systems has opened opportunities for researchers to investigate HuNoV biology in the context of de novo HuNoV infections. A tissue stem cell-derived human intestinal organoid/enteroid (HIO) culture system is one of those that supports HuNoV replication reproducibly and, to our knowledge, is most widely distributed to laboratories worldwide to study HuNoV and develop therapeutic strategies. This review summarizes recently developed HuNoV cultivation systems, including HIO, and their use in antiviral studies.

Orally delivered single-domain antibodies against gastrointestinal pathogens

Single-domain antibodies (sdAbs) are exceptionally stable fragments derived from the antigen-binding domains of immunoglobulins. They can withstand extreme pH, high temperature, and proteolysis, making them suitable for controlling gastrointestinal (GI) infections in humans and animals. sdAbs may function in their native soluble form, although different derived protein formats and the use of delivery vehicles can be useful for improved oral delivery. We discuss selected examples of the use of orally delivered sdAbs for protecting humans and animals against GI infections caused by pathogenic bacteria, viruses, and parasites. We finally provide perspectives on how sdAbs may be applied industrially and what challenges should be overcome for orally delivered sdAbs to reach the market.

Lactobacilli as a Vector for Delivery of Nanobodies against Norovirus Infection

Passive administration of neutralizing antibodies (Abs) is an attractive strategy for the control of gastrointestinal infections. However, an unanswered practical concern is the need to assure the stability of sufficient amounts of orally administered neutralizing Abs against intestinal pathogens (e.g., norovirus) in the harsh environment of the gastrointestinal tract. To this end, we expressed a single-domain Ab (VHH, nanobody) against norovirus on the cell surface of Lactobacillus, a natural and beneficial commensal component of the gut microbiome. First, we used intestinal epithelial cells generated from human induced pluripotent stem cells to confirm that VHH 1E4 showed neutralizing activity against GII.17 norovirus. We then expressed VHH 1E4 as a cell-wall-anchored form in Lactobacillus paracasei BL23. Flow cytometry confirmed the expression of VHH 1E4 on the surface of lactobacilli, and L. paracasei that expressed VHH 1E4 inhibited the replication of GII.17 norovirus in vitro. We then orally administered VHH 1E4-expressing L. paracasei BL23 to germ-free BALB/c mice and confirmed the presence of lactobacilli with neutralizing activity in the intestine for at least 10 days after administration. Thus, cell-wall-anchored VHH-displaying lactobacilli are attractive oral nanobody deliver vectors for passive immunization against norovirus infection.

Nanobodies in the limelight: Multifunctional tools in the fight against viruses

Antibodies are natural antivirals generated by the vertebrate immune system in response to viral infection or vaccination. Unsurprisingly, they are also key molecules in the virologist's molecular toolbox. With new developments in methods for protein engineering, protein functionalization and application, smaller antibody-derived fragments are moving in focus. Among these, camelid-derived nanobodies play a prominent role. Nanobodies can replace full-sized antibodies in most applications and enable new possible applications for which conventional antibodies are challenging to use. Here we review the versatile nature of nanobodies, discuss their promise as antiviral therapeutics, for diagnostics, and their suitability as research tools to uncover novel aspects of viral infection and disease.

Development of spirulina for the manufacture and oral delivery of protein therapeutics

The use of the edible photosynthetic cyanobacterium Arthrospira platensis (spirulina) as a biomanufacturing platform has been limited by a lack of genetic tools. Here we report genetic engineering methods for stable, high-level expression of bioactive proteins in spirulina, including large-scale, indoor cultivation and downstream processing methods. Following targeted integration of exogenous genes into the spirulina chromosome (chr), encoded protein biopharmaceuticals can represent as much as 15% of total biomass, require no purification before oral delivery and are stable without refrigeration and protected during gastric transit when encapsulated within dry spirulina. Oral delivery of a spirulina-expressed antibody targeting campylobacter-a major cause of infant mortality in the developing world-prevents disease in mice, and a phase 1 clinical trial demonstrated safety for human administration. Spirulina provides an advantageous system for the manufacture of orally delivered therapeutic proteins by combining the safety of a food-based production host with the accessible genetic manipulation and high productivity of microbial platforms.