Histomorphometric characteristics of immune cells in small intestine of pigs perorally immunized with vaccine candidate F18ac+ nonenterotoxigenic E. coli strain

Abstract

Colidiarrhea and colienterotoxemia caused by F4+ and/or F18 + enterotoxigenic E. coli (ETEC) strains are the most prevalent infections of suckling and weaned pigs. Here we tested the immunogenicity and protective effectiveness of attenuated F18ac + non-ETEC vaccine candidate strain against challenge infection with F4ac + ETEC strain by quantitative phenotypic analysis of small intestinal leukocyte subsets in weaned pigs.We also evaluated levamisole as an immune response modifier (IRM) and its adjuvanticity when given in the combination with the experimental vaccine. The pigs were parenterally immunized with either levamisole (at days -2, -1 and 0) or with levamisole and perorally given F18ac + and myeloid SWC3 + cell subsets were identified in jejunal and ileal epithelium, lamina propria and Peyer's patches using the avidin-biotin complex method, and their numbers were determined by computer-assisted histomorphometry. Quantitative immunophenotypic analyses showed that levamisole treated pigs had highly increased numbers of jejunal CD3 + , CD45RC + and SWC3 + cells (p<0.05) as compared to those recorded in nontreated control pigs.In the ileum of these pigs we have recorded that only CD21 + cells were significantly increased (p<0.01). The pigs that were treated with levamisole adjuvanted experimental vaccine had significantly increased numbers of all tested cell subsets in both segments of the small intestine. It was concluded that levamisole adjuvanted F18ac + non-ETEC vaccine was a requirement for the elicitation of protective gut immunity in this model; nonspecific immunization with levamisole was less effective, but confirmed its potential as an IRM.

In-feed supplementation of clinoptilolite favourably modulates intestinal and systemic immunity and some production parameters in weaned pigs

“…The primary mAbs reactive with CD45RA + lymphoid cells and secondary polyclonal Abs conjugated with horseradish peroxidase that were used to study in situ identification, distribution and quantification patterns of these cells residing in the ileal mucosa of weaned pigs have been described previously (Valpotic et al 2014). Histomorphometric analyses of CD45RA + lymphoid cells within compartments of ileal mucosa such as interfollicular areas (IFA) and follicular areas (FA) of Peyer's patches (PP) were performed using the Lucia G commercial software imaging program (version 4.11) for digital image analysis (DIA) as described previously (Kovsca-Janjatovic et al 2009;Valpotic et al 2014).…”

Effect of mannan oligosaccharide supplementation on blood and intestinal immune cells, bacteria numbers and performance in weaned pigs

“…The paraplast-embedded sections were processed for an indirect immunoperoxidase (IP) method using primary and secondary Abs as detailed earlier (Lacković et al 1997;Valpotić et al 2014). Histomorphometric analysis of CD45RA + lymphoid cells within compartments of ileal mucosa was performed using commercial software imaging program Lucia G (version 4.11) for digital image analysis (DIA) as described before (Kovšca-Janjatović et al 2009;Valpotić et al 2014). …”

Evaluation of the prophylactic potential of non-enterotoxigenic Escherichia coli (non-ETEC) vaccine immunization and dietary mannan oligosaccharide competitive exclusion benefits against ETEC infections in weaned pigs

“…The recombinant nontoxigenic F4ac + vaccine candidate strain 2407 (O9: K36: H19: F4ac:LT -STb) was attenuated, as detailed earlier (CASEY and MOON, 1990). The vaccine candidate F18ac + non-ETEC strain 2143 (O157: K119: F18ac) was attenuated by a slightly modified culturing procedure, as briefly described earlier (KOVŠCA JANJATOVIĆ et al, 2009), to reduce its toxicity, as previously suggested (GORDON et al, 1992. ) Both strains were kindly donated, as acknowledged more recently (KOVŠCA JANJATOVIĆ et al, 2011) and kept in glycerol broth at -80 o C until used.…”

“…Actually, no closely related or at least comparable references on the latter issue were available to us, and thus, we must discuss these issues by objectively analysing our earlier data. Moreover, we also tested mucosal cellular and humoral immunity, in particular secretory IgA + (sIgA) cells, by histomorphometric identification and quantification of their proliferation patterns, in order to assess their protective potential following immunization with either F4 + and/or F18 + non-ETEC vaccine candidate strains (VIJTIUK et al, 2005;BOŽIĆ et al, 2006;KOVŠCA JANJATOVIĆ et al, 2009;KOVŠCA JANJATOVIĆ et al, 2010;KOVŠCA JANJATOVIĆ et al, 2011). Also, we examined the immunogenic/antigenic potential of pathogenic F4ac + ETEC strains (VALPOTIĆ et al, 1994;LACKOVIĆ et al, 1997).…”

“…The vaccination strategies applied against PWD include oral subunit vaccines based on the concept of fimbriae as colonization factors with a crucial role in the occurrence of ETEC infections ( VAN den BROCK et al, 1999). Improvement of the stability and efficacy of this approach opens new possibilities in the development of a combined vaccine against both F4 and F18 fimbrial antigens (VALPOTIĆ et al, 1994;VIJTIUK et al, 2005;BOŽIĆ et al, 2006;KOVŠCA JANJATOVIĆ et al, 2009;KOVŠCA JANJATOVIĆ et al, 2010;FAIRBROTHER et al, 2017). However, these ETEC vaccines are of the live attenuated or the live wild type (comprising non-ETEC and non-pathogenic avirulent E. coli strains) for oral delivery.…”