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Background: Norovirus (NoV) is the most common cause of diarrheal episodes globally. Issues with in vitro cultivation systems, genetic variation, and animal models have hindered vaccine development. Plant-derived virus-like particles (VLPs) may address some of these concerns because they are highly immunogenic, can be administered by different routes, and can be rapidly produced to accommodate emerging viral strains., Methods: NoV VLPs (NoVLP) composed of the surface viral protein (VP) 1 of the GI and GII genogroups were produced in Nicotiana benthamiana using an Agrobacterium tumefaciens-based recombinant transient expression system. Leaves from infiltrated plants were harvested and NoVLPs were extracted and purified. The safety and immunogenicity of the GII.4 NoVLP, the genotype currently causing most human disease, were subsequently examined in rabbits and mice., Results: Fifteen GI and GII NoVLPs were successfully expressed in N. benthamiana and were structurally similar to NoV virions, as determined by cryogenic transmission electron microscopy. The NoVLP was well-tolerated, with no local or systemic signs of toxicity in rabbits. Three intramuscular doses of the GII.4 NoVLP adjuvanted with aluminum hydroxide induced robust IgG titers, IgG-secreting cells, histo-blood group antigen blocking titers, and IFNγ-secreting T cells in mice. In addition to circulating antibodies, oral administration of the NoVLP in mice induced significant IgA levels in feces, indicative of a mucosal response., Conclusions: The plant-made NoVLP vaccine was safe and immunogenic in mice and rabbits. Multi-modal vaccination, combining oral and intramuscular administration could be considered for future clinical development to maximize systemic and mucosal immune responses., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: GA, DB, MAD, BJW, MMC, MD, POL, SP, and ST are employees of Medicago Inc. JS is employee of the Center for Vaccine Preventable Diseases, Dalla Lana School of Public Health, University of Toronto, ON, Canada, where she is supported by a postdoctoral fellowship from the Canadian Immunization Research Network. HH is employee of Research Institute of the McGill University Health Centre (under MITACS Elevate post-doctorate fellowship), Montreal, QC, Canada. MB and CD are employees of Providence Therapeutics. NL is employee of PharmaJet, CO, USA., (Copyright © 2023. Published by Elsevier Ltd.)

Recent issues regarding efficacy of influenza vaccines have re-emphasized the need of new approaches to face this major public health issue. In a phase 1-2 clinical trial, healthy adults received one intramuscular dose of a seasonal influenza plant-based quadrivalent virus-like particle (QVLP) vaccine or placebo. The hemagglutination inhibition (HI) titers met all the European licensure criteria for the type A influenza strains at the 3μg/strain dose and for all four strains at the higher dosages 21days after immunization. High HI titers were maintained for most of the strains 6months after vaccination. QVLP vaccine induced a substantial and sustained increase of hemagglutinin-specific polyfunctional CD4 T cells, mainly transitional memory and TEMRA effector IFN-γ(+) CD4 T cells. A T cells cross-reactive response was also observed against A/Hong-Kong/1/1968 H3N2 and B/Massachusetts/2/2012. Plant-based QVLP offers an attractive alternative manufacturing method for producing effective and HA-strain matching seasonal influenza vaccines., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

This work has concerned the description of a method suitable for the measurement, on living trout, of the intestinal alkaline phosphatase activity. The experiments consist in the perfusion, in the lumen, of an appropriate substrate and in the prevention of its absorption or that of the products of its hydrolysis. This condition has not been satisfied by using paranitrophenyl phosphate which has been replaced by glucose-1-phosphate. The absorption of glucose produced has been inhibited by phloridzin (10(-4) M) in a KCl (150 mM) solution. Under these conditions an hydrolysis of glucose phosphate has been shown at alkaline pH, which remains linear with time up to 60 min. A research of the Km of the enzyme activity has been carried out.