Immune Response after Skin Delivery of a Recombinant Heat-Labile Enterotoxin B Subunit of Enterotoxigenic Escherichia coli in Mice

Abstract

Enterotoxigenic Escherichia coli (ETEC) infections have been identified as a major cause of acute diarrhoea in children in developing countries, associated with substantial morbidity and mortality rates. Additionally, ETEC remains the most common cause of acute diarrhea of international travellers to endemic areas. The heat-labile toxin (LT) is a major virulence factor of ETEC, with a significant correlation between the presence of antibodies against LT and protection in infected patients. In the present work, we constructed a recombinant LTB unit (rLTB) and studied the capacity of this toxoid incorporated in microneedles (rLTB-MN) to induce a specific immune response in mice. MN were prepared from aqueous blends of the polymer Gantrez AN® [poly (methyl vinyl ether-co-maleic anhydride)], which is not cytotoxic and has been shown to possess immunoadjuvant properties. The mechanical and dissolution properties of rLTB-MNs were evaluated in an in vitro Parafilm M® model and in mice and pig skin ex vivo models. The needle insertion ranged between 378 µm and 504 µm in Parafilm layers, and MNs fully dissolved within 15 min of application inside porcine skin. Moreover, female and male BALB/c mice were immunized through ear skin with one single dose of 5 μg·rLTB in MNs, eliciting significant fecal anti-LT IgA antibodies, higher in female than in male mice. Moreover, we observed an enhanced production of IL-17A by spleen cells in the immunized female mice, indicating a mucosal non-inflammatory and neutralizing mediated response. Further experiments will now be required to validate the protective capacity of this new rLTB-MN formulation against this deadly non-vaccine-preventable disease.

A Novel Multiepitope Fusion Antigen as a Vaccine Candidate for the Prevention of Enterotoxigenic E. coli-Induced Calf Diarrhea

“…ETEC represents a prominent etiological agent responsible for calf diarrhea, typically occurring within the first month of life, resulting in either immediate mortality or a grim prognosis for the infected calves [23]. The presence of antigenic diversity presents a significant challenge in preventing ETEC infections due to the multitude of virulence factors and the absence of cross-protective immunity [24]. Numerous efforts have been undertaken to develop vaccines against ETEC in pigs and humans [25,26], but there is a dearth of research on bovine ETEC vaccines, with most studies focusing on F5 fimbriae [27].…”

Development of Two Mouse Models for Vaccine Evaluation against Cryptosporidiosis

“…The finding of induced fecal IgA but not systemic IgG is inconsistent with other studies in which mRNA and i.d. immunizations induce both systemic and mucosal (i.e., IgA in feces, saliva) immune responses ( 20 – 22 ). As for the other mRNA-immunized groups, it was not possible to determine whether the choice and formulation of mRNAs provided little or no protection at all or whether the lack of protection was due to limited model sensitivity when challenges contained high C. tyzzeri oocyst doses.…”

Ciprofloxacin-loaded dissolving polymeric microneedles as a potential therapeutic for the treatment of S. aureus skin infections

“…In a study to assess the insertion depth of microneedles in Parafilm, no significant difference was shown in the insertion depth between porcine skin and Parafilm for insertion forces of 10 and 40 N [36]. In a recent study, Parafilm was also studied as a model that simu- lates the mechanical and dissolution properties of mammalian skin [38]. Therefore, the ability of the microneedles to penetrate the Parafilm is an indication that microneedles are capable of penetrating human skin.…”