Učinak levamisola na brojnost crijevnih vrčastih stanica odbijene prasadi pokusno cijepljene protiv kolibaciloze

Postweaning colibacillosis (PWC) is an etiologically complex disease commonly induced by porcine F4ac+ enterotoxigenic Escherichia coli (ETEC) for which no effective vaccine is available. The objective of this study was to determine the nonspecific immunomodulatory effect of levamisole in combination with specific intragastric immunization of weaned pigs with a candidate F4ac+ non-ETEC oral vaccine on the population of intestinal goblet cells (GC). The pigs were immunized with F4ac+ non-ETEC strain, in combination with or without levamisole. Seven days after immunization the pigs were challenged with F4ac+ ETEC strain and 14 days following immunization they were euthanatized for sampling of specimens of the small intestine for immunohistochemistry and morphometric analyses. Samples of the ileum were tested for the presence of acidic and neutral carbohydrates, components of mucus produced and secreted by the intestinal goblet cells (GC). The volume density (VV) of the PAS+ and AB+/PAS+ GC was determined using the stereological point-counting method. The Vv of the ileal PAS+ GC was lowest (0.130 ± 0.075 mm3) in the pigs that were immunized with the vaccine candidate F4ac+ non-ETEC strain. Interestingly, AB+/PAS+ GC Vv were found to be highest (0.262 ± 0.091 mm3) in this group of pigs. The Vv of PAS+ GC was the largest (0.201 ± 0.064 mm3) in the negative control group of pigs. Pigs from the levamisole pretreated group were shown to have the lowest Vv (0.166 ± 0.051 mm3) of AB+/PAS+ GC. According to the data presented, there was no significant influence of nonspecific/specific immunization on the nonimmune defence mechanism of the intestinal mucosa, as measured by GC Vv in weaned pigs. Hence, it is likely that the production of mucus was not affected and that nonspecific protection of porcine intestines provided by mucus layer was not compromised following peroral immunization against PWC. Also, presumably the anti-inflammatory effect of levamisole was observed as the population of ileal mast cells was not considerably affected by non-specific/specific immunization and challenge infection.Kolibaciloza odbijene prasadi (KOP) etiološki je složena bolest, najčešće izazvana svinjskim F4ac+ enterotoksigenim sojevima bakterije Escherichia coli (ETEC), za koju nema djelotvorne vakcine. Namjera ovoga rada bila je da se utvrdi imunomodulacijski učinak levamisola, u kombinaciji sa specifičnom intragastričnom imunizacijom odbijene prasadi pokusnim vakcinalnim F4ac+ ne-ETEC sojem, na populaciju crijevnih vrčastih stanica (VS). Prasad je bila imunizirana F4ac+ ne-ETEC sojem u kombinaciji s levamisolom ili bez njega, sedam dana nakon toga bila je izazivački inficirana F4ac+ ETEC sojem, a 14 dana nakon imunizacije bila je usmrćena radi uzimanja uzoraka crijeva za imunohistokemijske i morfometrijske analize. Uzorci ileuma testirani su na prisutnost kiselih i neutralnih ugljikohidrata, sastavnica sluzi koju proizvode i izlučuju VS. Volumna gustoća (Vg) VS koje se boje kombinacijom alcijanskoga modrila (AM) i periodičnoga kiseloga Schiffovoga (PKS) reagensa određivana je pomoću stereologijske metode brojanja točaka. Vg ilealnih PKS+ VS bila je najniža (0,130 ± 0,075 mm3) u prasadi imunizirane pokusnim vakcinalnim F4ac+ ne-ETEC sojem. Međutim, zanimljivo je da je utvrđena najveća Vg AM+/PKS+ VS (0,262 ± 0,091 mm3) u prasadi iz te skupine. U prasadi iz negativne kontrolne skupine utvrđena je najveća Vg PKS+ VS (0,201 ± 0,064 mm3), dok je prasad iz skupine obrađene levamisolom i vakcinalnim ne-ETEC sojem imala najnižu Vv ukupnih (AM+/PKS+) VS (0,159 ± 0,023 mm3). Primjereno dobivenim rezultatima, nije utvrđen značajan utjecaj nespecifične/specifične imunizacije na neimunosne obrambene mehanizme crijevne sluznice vrednovane temeljem Vg i distribucije VS u odbijene prasadi. Stoga je vrlo vjerojatno da proizvodnja sluzi nije umanjena i da nespecifična zaštita crijeva prasadi slojem sluzi ne bi bila slabija nakon peroralne imunizacije protiv KOP. Također je zapažen potencijalni protuupalni učinak levamisola s obzirom na činjenicu da populacija ilealnih mastocita nije bila znatnije stimulirana nespecifičnom/specifičnom imunizacijom i izazivačkom infekcijom