Potent In Vitro and In Vivo Activity of Plantibody Specific for Porphyromonas gingivalis FimA

Delivery of biologics: Topical administration

Biologics are unaffordable to a large majority of the global population because of prohibitively expensive fermentation systems, purification and the requirement for cold chain for storage and transportation. Limitations of current production and delivery systems of biologics were evident during the recent pandemic when <2.5% of vaccines produced were available to low-income countries and ∼19 million doses were discarded in Africa due to lack of cold-chain infrastructure. Among FDA-approved biologics since 2015, >90% are delivered using invasive methods. While oral or topical drugs are highly preferred by patients because of their affordability and convenience, only two oral drugs have been approved by FDA since 2015. A newly launched oral biologic costs only ∼3% of the average cost of injectable biologics because of the simplified regulatory approval process by elimination of prohibitively expensive fermentation, purification, cold storage/transportation. In addition, the cost of developing a new biologic injectable product (∼$2.5 billion) has been dramatically reduced through oral or topical delivery. Topical delivery has the unique advantage of targeted delivery of high concentration protein drugs, without getting diluted in circulating blood. However, only very few topical drugs have been approved by the FDA. Therefore, this review highlights recent advances in oral or topical delivery of proteins at early or advanced stages of human clinical trials using chewing gums, patches or sprays, or nucleic acid drugs directly, or in combination with, nanoparticles and offers future directions.

Recombinant FimH, a fimbrial tip adhesin of Vibrio parahaemolyticus, elicits mixed T helper cell response and confers protection against Vibrio parahaemolyticus challenge in murine model

Vibrio parahaemolyticus causes vibriosis in wide range of marine organisms, and is responsible for food borne illnesses in humans through consumption of contaminated uncooked/partially cooked seafood. Continued and widespread antibiotics usage to increase the productivity has led to antibiotics resistance development. This has necessitated the need to develop alternative methods to control its infection. Use of safe and effective vaccines against the virulence factors not only protects from infection, it also minimizes antibiotic usage. The colonization of V. parahaemolyticus in the host and disease development requires several adhesins present on the cell surface, and thereby make them attractive vaccine candidates. V. parahaemolyticus produces extracellular type 1 fimbriae that have been shown to play a role in adhesion, biofilm formation and virulence. FimH is one of the minor components of the type 1 fimbriae occurring on its very tip. Being present on the cell surface, it is highly immunogenic, and can be targeted as a potential vaccine candidate. The present study describes the immunogenic and vaccine potential of recombinant V. parahaemolyticus FimH (rVpFimH) expressed in E. coli. Immunization of BALB/c mice with the rVpFimH elicited a strong mixed immune response, T-cell memory (evidenced by antibody isotyping, cytokine profiling and T-cell proliferation assay), and agglutination positive antibodies. FACS analysis and immunogold labeling showed that the polyclonal anti-rVpFimH antibodies were able to recognize the FimH on V. parahaemolyticus cells. In vivo challenge of the rVpFimH-immunized mice with 2×LD₅₀ dose of live bacteria showed one hundred percent survival. Thus, our findings clearly demonstrate the potential of FimH as an effective vaccine candidate against V. parahaemolyticus.

Will plant-made biopharmaceuticals play a role in the fight against COVID-19?

Given the dramatic impact of the COVID-19 pandemic, it is imperative to divulge all the available technologies with the potential to fight against this virus. Plant biotechnology offers potential solutions to this pandemic through the development of low-cost vaccines and antibodies useful for therapy, prophylaxis, and diagnosis. The technology to produce plant-made biopharmaceuticals is already established; two examples of these are: a therapeutic enzyme that has entered the market and the influenza vaccines that are currently under clinical trials with encouraging results. Thus far, some companies have started developing anti-COVID-19 antibodies and vaccines. In particular, plant-made antibodies might be timely produced and approved for human use in the short term, while the development of vaccines will take longer time (clinical evaluations could be concluded by the end of 2021); nonetheless, the candidates obtained will be valuable tools for future outbreaks. The key aspects that will define the exploitation of this technology in the fight against COVID-19 are discussed.

A Broad and Potent H1-Specific Human Monoclonal Antibody Produced in Plants Prevents Influenza Virus Infection and Transmission in Guinea Pigs

Although seasonal influenza vaccines block most predominant influenza types and subtypes, humans still remain vulnerable to waves of seasonal and new potential pandemic influenza viruses for which no immunity may exist because of viral antigenic drift and/or shift. Previously, we described a human monoclonal antibody (hMAb), KPF1, which was produced in human embryonic kidney 293T cells (KPF1-HEK) with broad and potent neutralizing activity against H1N1 influenza A viruses (IAV) in vitro, and prophylactic and therapeutic activities in vivo. In this study, we produced hMAb KPF1 in tobacco plants (KPF1-Antx) and demonstrated how the plant-produced KPF1-Antx hMAb possesses similar biological activity compared with the mammalian-produced KPF1-HEK hMAb. KPF1-Antx hMAb showed broad binding to recombinant HA proteins and H1N1 IAV, including A/California/04/2009 (pH1N1) in vitro, which was comparable to that observed with KPF1-HEK hMAb. Importantly, prophylactic administration of KPF1-Antx hMAb to guinea pigs prevented pH1N1 infection and transmission in both prophylactic and therapeutic experiments, substantiating its clinical potential to prevent and treat H1N1 infections. Collectively, this study demonstrated, for the first time, a plant-produced influenza hMAb with in vitro and in vivo activity against influenza virus. Because of the many advantages of plant-produced hMAbs, such as rapid batch production, low cost, and the absence of mammalian cell products, they represent an alternative strategy for the production of immunotherapeutics for the treatment of influenza viral infections, including emerging seasonal and/or pandemic strains.

The Roles of Two Type VI Secretion Systems in Cronobacter sakazakii ATCC 12868

The type VI secretion system (T6SS), which has been found in 25% of gram-negative bacteria, is a crucial virulence factor in several pathogens. Although T6SS gene loci have been discovered in Cronobacter species, one of the major opportunistic foodborne pathogens, its function has not been elucidated. In this study, the roles of two phylogenetically distinct T6SS gene clusters in Cronobacter sakazakii ATCC12868 were investigated. Analysis of 138 genome sequences of C. sakazakii strains, we found that one T6SS gene cluster (T6SS-1) was ubiquitous in all examined strains, whereas another (T6SS-2) was absent or degenerated in a large proportion of the strains (n = 97). In addition, we confirmed the T6SS-1 antibacterial function through an in-frame deletion in the vasK and hcp genes. Compared with the wild-type strain, the T6SS-2-deficient mutant presented a much stronger colonization of organs when infecting neonatal rats. Thus, we proposed that T6SS-2 plays a role in pathogenic processes. This is the first study to investigate the functions of T6SS in C. sakazakii, and the results will extend our understanding of the pathogenic and phylogenetic characteristics of C. sakazakii.

Measuring Antibody-Antigen Binding Kinetics Using Surface Plasmon Resonance

Surface plasmon resonance (SPR) is now widely embraced as a technology for monitoring a diverse range of protein-protein interactions and is considered almost de rigueur for characterizing antibody-antigen interactions. The technique obviates the need to label either of the interacting species, and the binding event is visualized in real time. Thus, it is ideally suited for screening crude, unpurified antibody samples that dominate early candidate panels following antibody selection campaigns. SPR returns not only concentration and affinity data but when used correctly can resolve the discrete component kinetic parameters (association and dissociation rate constants) of the affinity interaction. Herein, we outline some SPR-based generic antibody screening configurations and methodologies in the context of expediting data-rich ranking of candidate antibody panels and ensuring that antibodies with the optimal kinetic binding characteristics are reliably identified.

Evaluation of the crystal structure of a fimbrillin (FimA) from Porphyromonas gingivalis as a therapeutic target for photo-activated disinfection with toluidine blue O

BACKGROUND

Porphyromonas gingivalis is one of the etiological agents in the initiation of combined periodontal-endodontic (perio-endo) lesions. Successful treatment of perio-endo lesions with photo-activated disinfection (PAD) as a novel therapeutic approach depends on the selection of an appropriate target site, specific photosensitizer (PS), and wavelength of light. Since the fimbrillin (FimA) is the most important pathogenic agent in P. gingivalis it was evaluated as a target site against PAD with toluidine blue O (TBO) as a PS.

MATERIALS AND METHODS

We evaluated the potential of FimA using a number of bioinformatic tools and computer simulation molecular modeling. In silico analysis was done to predict the hierarchical nature of structure, topology, backbone, physicochemical properties, and functional characterization of FimA.

RESULTS

The predicted structure of FimA exhibited that it is an anionic protein with negative charge (-7.00) in pH7 and random coil which dominates other secondary structures located outside the cell. It has three motifs with seven ligand binding site residues and one active site residue which can be a site of interaction for cationic TBO.

CONCLUSION

Based on the results of this study cationic TBO tends to interact with FimA during PAD as a major target to increase the efficiency of treatment of perio-endo lesions.