No safe and effective vaccine exists against porcine enterotoxigenic Escherichia coli (ETEC) strains, which are the etiological agents of post-weaning diarrhoea (PWD), economically one of the most ...significant diseases of swine, which encountered for major productive losses in swine industry worldwide. The current study was designed to evaluate: (1) efficacy of an oral bivalent F4ac+/F18ac+ non-ETEC live vaccine candidate (VACCINE) in stimulating systemic and intestinal cellular immunity in 4-week-old weaned pigs, (2) the onset and duration of protective immunity of weaned pigs against naturally occurring PWD during the period of 6 weeks following weaning, and (3) the dietary supplement potential of zeolite clinoptilolite (CPL), an antimicrobial mineral and/or immunomodulator/ vaccine adjuvant (VACCINE + CPL). The pigs immunized either with the VACCINE or its combination with dietary CPL had significantly increased body weight gain from Day 7 to Day 42 (P<0.05) of the experiment, as compared to the control pigs (CONTROLS). Conversely, the pigs that were only supplemented with CPL had mostly significantly lower (P<0.05) body weight. The pigs that received VACCINE + CPL were neither diarrheic nor were there any mortalities during the entire period of the experiment. On Day 42 the total bacterial load in the jejunum was much lower in the pigs from all three principal groups than in the CONTROLS (30 x 108 vs. 18 x 107 vs. 14 x 107 vs. 13 x 107 CFU/mL, respectively). Regarding CD4+ and CD8+ T cells, specific immunization with either VACCINE or with VACCINE + CPL stimulated a significantly higher proportion of these cells (P<0.05) from Day 7 to Day 42 of the experiment. Quite similar findings were obtained for CD21+ B cells, as their proportion was significantly elevated in the pigs treated with either VACCINE or VACCINE + CPL (P<0.05 and P<0.05, respectively). The pigs from the VACCINE + CPL group had a significantly higher proportion of CD45+ lymphoid cells than the pigs from the CONTROL group (P<0.05). Quite sparsely distributed CD45RA+ naïve T lymphocytes were observed in the jejunal lamina propria of the intestinal villi, within the Lieberkühn crypts (LC) and in the submucosa of the CONTROLS and CPL supplemented pigs. The treatment with the VACCINE induced moderate recruitment of CD45 RA+ cells within both the IFA and FA of the jejunal PP of the pigs 6 weeks following the vaccination. In the CONTROLS, CD45 RC+ memory T cells were not abundant and were mostly dispersed in the middle of the villous lamina propria, but only rarely adjacent to the basal membrane of the intestinal enterocytes. These cells were more frequent within the lamina propria of the villi in the CPL group of pigs than in the CONTROLS. Even more numerous CD45 RC+ memory T cells were observed in the villous lamina propria of the jejunum of the pigs from the VACCINE group. These cells were predominantly found in the villous lamina propria and in the IFA, but were less frequent in the FA of the jejunal PP of the pigs that received the VACCINE and CPL. Due to the nature of the disease, challenges in PWD vaccine development will continue to exist. Although our research approach was at least partially successful, developing a safe and immunogenically effective live oral vaccine against PWD that will provide solid protection and sustained cellular and humoral immune responses remains a significant challenge.
No safe and effective vaccine exists against porcine enterotoxigenic Escherichia coli (ETEC) strains, which are the etiological agents of post-weaning diarrhoea (PWD), economically one of the most ...significant diseases of swine, which encountered for major productive losses in swine industry worldwide. The current study was designed to evaluate: (1) efficacy of an oral bivalent F4ac.sup.+/F18ac.sup.+ non-ETEC live vaccine candidate (VACCINE) in stimulating systemic and intestinal cellular immunity in 4-week-old weaned pigs, (2) the onset and duration of protective immunity of weaned pigs against naturally occurring PWD during the period of 6 weeks following weaning, and (3) the dietary supplement potential of zeolite clinoptilolite (CPL), an antimicrobial mineral and/or immunomodulator/ vaccine adjuvant (VACCINE + CPL). The pigs immunized either with the VACCINE or its combination with dietary CPL had significantly increased body weight gain from Day 7 to Day 42 (P<0.05) of the experiment, as compared to the control pigs (CONTROLS). Conversely, the pigs that were only supplemented with CPL had mostly significantly lower (P<0.05) body weight. The pigs that received VACCINE + CPL were neither diarrheic nor were there any mortalities during the entire period of the experiment. On Day 42 the total bacterial load in the jejunum was much lower in the pigs from all three principal groups than in the CONTROLS (30 * 10.sup.8 vs. 18 * 10.sup.7 vs. 14 * 10.sup.7 vs. 13 * 10.sup.7 CFU/mL, respectively). Regarding CD4.sup.+and CD8.sup.+ T cells, specific immunization with either VACCINE or with VACCINE + CPL stimulated a significantly higher proportion of these cells (P<0.05) from Day 7 to Day 42 of the experiment. Quite similar findings were obtained for CD21.sup.+ B cells, as their proportion was significantly elevated in the pigs treated with either VACCINE or VACCINE + CPL (P<0.05 and P<0.05, respectively). The pigs from the VACCINE + CPL group had a significantly higher proportion of CD45.sup.+ lymphoid cells than the pigs from the CONTROL group (P<0.05). Quite sparsely distributed CD45RA.sup.+naive T lymphocytes were observed in the jejunal lamina propria of the intestinal villi, within the Lieberkiihn crypts (LC) and in the submucosa of the CONTROLS and CPL supplemented pigs. The treatment with the VACCINE induced moderate recruitment of CD45 RA.sup.+ cells within both the IFA and FA of the jejunal PP of the pigs 6 weeks following the vaccination. In the CONTROLS, CD45 RC.sup.+ memory T cells were not abundant and were mostly dispersed in the middle of the villous lamina propria, but only rarely adjacent to the basal membrane of the intestinal enterocytes. These cells were more frequent within the lamina propria of the villi in the CPL group of pigs than in the CONTROLS. Even more numerous CD45 RC.sup.+ memory T cells were observed in the villous lamina propria of the jejunum of the pigs from the VACCINE group. These cells were predominantly found in the villous lamina propria and in the IFA, but were less frequent in the FA of the jejunal PP of the pigs that received the VACCINE and CPL. Due to the nature of the disease, challenges in PWD vaccine development will continue to exist. Although our research approach was at least partially successful, developing a safe and immunogenically effective live oral vaccine against PWD that will provide solid protection and sustained cellular and humoral immune responses remains a significant challenge Key words: immunogenicity; bivalent; live vaccine; non-enterotoxigenic Escherichia coli; clinoptilolite; post-weaning diarrhoea; pigs
Dijareja nakon odbića (DNO) prasadi uzrokuje glavninu proizvodnih gubitaka u svinjogojskoj industriji širom svijeta. Ne postoji sigurno i učinkovito cjepivo protiv svinjskih enterotoksigenih sojeva ...bakterije Escherichia coli (ETEC) koji se smatraju etiološkim uzročnicima DNO. Ovo je istraživanje planirano radi vrednovanja: (1) učinkovitosti oralnog bivalentnog F4ac+/F18ac+ ne-ETEC pokusnog živog cjepiva (cjepivo) u stimuliranju sistemske i crijevne stanične imunosti 4 tjedna stare odbijene prasadi, (2) pojave i trajanja zaštitne imunosti odbijene prasadi protiv prirodnog zaražavanja uzročnicima DNO tijekom razdoblja od 6 tjedana nakon odbića i (3) potencijala dodatka hrani zeolita klinoptilolita (KPL), antimikrobnog minerala i/ili imunomodulatora/adjuvansa cjepiva (CJEPIVO + KPL). Prasad imunizirana ili cjepivom ili njegovom kombinacijom s dodatkom hrani KPL-om imala je znakovito povećan prirast tjelesne mase od 7. do 42. dana (P<0,05) pokusa u usporedbi s kontrolnom skupinom prasadi (KONTROLA). Suprotno tome, prasad koja su primila samo dodatak hrani KPL, imala su pretežito znakovito nižu (P<0,05) tjelesnu masu. Prasad koja je primila CJEPIVO + KPL nije imala ni dijareju, niti je bilo uginuća tijekom razdoblja trajanja pokusa. Ukupni broj izdvojenih bakterija iz jejunuma bio je mnogo manji u prasadi iz sve tri pokusne skupine od onoga u kontrolne prasadi (30 x 108 vs. 18 x 107 vs. 14 x 107 vs. 13 x 107 CFU/mL). Specifična imunizacija s CJEPIVOM
ili CJEPIVOM + KPL stimulirala je znakovit porast udjela CD4+ i CD8+ T stanica (P<0,05) od 7. do 42. dana pokusa. Vrlo su slični nalazi dobiveni za CD21+ B stanice, s obzirom da je njihov udjel bio znakovito povišen u prasadi tretirane ili s CJEPIVOM ili s CJEPIVOM + KPL (P<0,05 ili P<0,05). Prasad iz skupine koja je primila CJEPIVO + KPL, imala je značajno viši udjel CD45+ lifoidnih stanica od prasadi iz KONTROLA skupine (P<0,05). Rijetko raspodjeljeni CD45RA+ naivni T limfociti opaženi su u lamini propriji crijevnih resica jejunuma, u Lieberkühnovim kriptama te u submukozi prasadi KONTROLE skupine i skupine hranjene s dodatkom KPL. Tretman CJEPIVOM izazvao je umjerenu proliferaciju CD45RA+ u interfolikularnim (IFP) i folikularnim područjima (FP) Peyerovih ploča (PP) jejunuma u prasadi 6 tjedana nakon cijepljenja. U KONTROLNE prasadi, CD45RC+ memorijske T stanice nisu bile brojne i uglavnom su bile dispergirane u sredini lamine proprije resica, a samo rijetko u blizini bazalne membrane crijevnih enterocita. Te su stanice brojnije u lamini propriji resica u prasadi iz KPL skupine u odnosu na KONTROLNU prasad. No, CD45RC+ memorijske T stanice još su brojnije, što je primijećeno u lamini propriji resica jejunuma prasadi koja je primila CJEPIVO. Te su stanice pretežito nađene u lamini propriji resica i u IFP-u, ali su manje brojne u FP-u jejunalnih Peyerovih ploča u prasadi koja je primila CJEPIVO i KPL. Zbog naravi bolesti, izazovi vezani za razvoj cjepiva protiv DPO će i dalje postojati. Premda je naš istraživački pristup bio samo djelomično uspješan, razvoj sigurnog i imunogeno učinkovitog živog oralnog cjepiva protiv DPO, koje će pružati solidnu zaštitu i održive stanične i humoralne imunosne odgovore, i nadalje je izvanredan izazov.
U svinjogojskoj proizvodnji, veliki i tvrdokorni problem predstavljaju gubici među sisajućom, a napose odbijenom prasadi, uzrokovani infekcijama najčešće F4ac+ i/ili F18ac+ enterotoksigenim sojevima ...bakterije Escherichia coli (ETEC). U istraživanjima u okviru projekta 053-0532265-2255 utrđen je zadovoljavajući imunoprofilaktički učinak pokusnih oralnih F4ac+ i/ili F18ac+ ne-ETEC cjepiva protiv kolidijareje i kolinterotoksemije odbijenika. Međutim, u m. longissimus dorsi svinja koje su peroralno cjepljene s dvovaljanim cjepivom (sadrži dva soja bakterije E. coli /F4ac+ ne ETEC soj 2407 i F18ac+ ne ETEC soj 2143) kemijskom analizom je utvrđena statistički neznačajna promjena u odnosu na kemijski sastav m. longissimus dorsi porijeklom od necjepljenih svinja.
