Oral Vaccination of Mice With Putative Serine Protease and Murine Interleukin-4 DNA Delivered by Invasive Elicits Protective Immunity.

Trichinellosis is a serious zoonotic parasitic disease caused by () that causes considerable economic losses for the global pig breeding and food industries. As such, there is an urgent need for a vaccine that can prevent infection. Previous studies have reported that recombinant invasive (LL) expressing fibronectin binding protein A (LL-FnBPA+) can transfer DNA vaccines directly to dendritic cells (DCs) across an epithelial cell monolayer, leading to significantly higher amounts of heterologous protein expression compared to non-invasive . In this study, the invasive bacterium () expressing FnBPA was used as a carrier to deliver a novel oral DNA vaccine consisting of adult putative serine protease (Ts-ADpsp) and murine interleukin (IL)-4 DNA to mouse intestinal epithelial cells. Experimental mice were orally immunized 3 times at 10-day intervals. At 10 days after the last vaccination, mice were challenged with 350 infective larvae by oral inoculation. Immunization with invasive harboring pValac-Ts-ADpsp/pSIP409-FnBPA induced the production of anti-Ts-ADpsp-specific IgG of serum, type 1 and 2 helper T cell cytokines of mesenteric lymph node (MLN) and spleen, secreted (s) IgA of intestinal lavage, and decreased burden and intestinal damage compared to immunization with non-invasive expressing Ts-ADpsp (pValac-Ts-ADpsp/pSIP409). Thus, invasive expressing FnBPA and IL-4 stimulates both mucosal and cellular immune response to protect against infection, highlighting its therapeutic potential as an effective DNA vaccine for trichinellosis.