Immunity In Piglets Research Articles

Identification of E2 with improved secretion and immunogenicity against CSFV in piglets

BackgroundOutbreaks of Classical swine fever virus (CSFV) cause significant economic losses in the swine industry. Vaccination is the major method to prevent and control the disease. As live attenuated vaccines fail to elicit differentiable immunity between infected and vaccinated animals, subunit vaccine was considered as an alternative candidate to prevent and eradicate CSFV. Subunit vaccines present advantages in DIVA immunogenicity and safety. The technology was limited due to the low yield and the high cost with multiple and large doses. The native E2 signal peptide has not been well defined before. Here, the aim of this study is to develop a cost-effective and efficacious E2 vaccine candidate against CSFV with signal peptide and E2 sequence selection.ResultsA novel CSFV E2 sequence (E2ZJ) was identified from an epidemic strain of Zhejiang for outstanding secretion in baculovirus and enhanced immunogenicity. E2 secretion induced with the selected signal peptide, SPZJ (SP23), increase at least 50% as compared to any other signal peptides tested. Besides, unique antigenic features were identified in E2ZJ. As indicated with immunized sera in IFA against CSFV infection, E2ZJ elicited CSFV antibodies at the earlier stage than other E2 types tested in mice. Moreover, higher level of neutralizing and CSFV antibodies against CSFV with E2ZJ was detected than other E2s with the same dosage at 28 dpi. Further, E2ZJ successfully elicited neutralizing immunity in piglets. A single dose of 5 μg of E2ZJ was sufficient to induce protective antibodies against CSFV in piglets and provided 100% protection against lethal virus challenge.ConclusionsOur studies provide evidence that E2ZJ guided by a novel E2 signal peptide (SPZJ) was efficiently secreted and presented significantly improved immunogenicity than conventional E2 vaccines. Moreover, a single dose of 5 μg E2ZJ is efficacious against CSFV in piglets.

Engineered Recombinant Escherichia coli Probiotic Strains Integrated with F4 and F18 Fimbriae Cluster Genes in the Chromosome and Their Assessment of Immunogenic Efficacy in Vivo.

F4 (K88) and F18 fimbriaed enterotoxigenic Escherichia coli (ETEC) are the predominant causes of porcine postweaning diarrhea (PWD), and vaccines are considered the most effective preventive approach against PWD. Since heterologous DNA integrated into bacterial chromosomes could be effectively expressed with stable inheritance, we chose probiotic EcNc (E. coli Nissle 1917 prototype cured of cryptic plasmids) as a delivery vector to express the heterologous F4 or both F4 and F18 fimbriae and sequentially assessed their immune efficacy of anti-F4 and F18 fimbriae in both murine and piglet models. Employing the CRISPR-cas9 technology, yjcS, pcadA, lacZ, yieN/trkD, maeB, and nth/tppB sites in the chromosome of an EcNc strain were targeted as integration sites to integrate F4 or F18 fimbriae cluster genes under the Ptet promotor to construct two recombinant integration probiotic strains (RIPSs), i.e., nth integration strain (EcNcΔnth/tppB::PtetF4) and multiple integration strain (EcNc::PtetF18x4::PtetF4x2). Expression of F4, both F4 and F18 fimbriae on the surfaces of two RIPSs, was verified with combined methods of agglutination assay, Western blot, and immunofluorescence microscopy. The recombinant strains have improved adherence to porcine intestinal epithelial cell lines. Mice and piglets immunized with the nth integration strain and multiple integration strain through gavage developed anti-F4 and both anti-F4 and anti-F18 IgG immune responses. Moreover, the serum antibodies from the immunized mice and piglets significantly inhibited the adherence of F4+ or both F4+ and F18+ ETEC wild-type strains to porcine intestinal cell lines in vitro, indicating the potential of RIPSs as promising probiotic strains plus vaccine candidates against F4+/F18+ ETEC infection.

Correction of cellular immunity with biferon-C in piglets in case of specific prevention of circovirosis and mycoplasmosis

The results of studying the effect of biferon-C containing recombinant porcine interferons -alpha and -gamma on cellular nonspecific and adaptive immunity in piglets in case of specific prevention of circovirosis and mycoplasmosis are presented. The corrective effect of the drug on cellular immunity was stated, manifested by an increase in the absorption and functional and metabolic activity of phagocytes, the relative and absolute number of T- and B-lymphocytes, T-cells with helper activity and a lower formation of the level of T-suppressors, an increase in the T-helpers/T-suppressors ratio.

Колостральний імунітет поросят до вірусу хвороби Ауєскі за активної імунопрофілактики свиноматок

The current question of today is the formation of effective immune protection in young pigs against infectious diseases, achieved by piglets vaccination in the first weeks of their life. It is known that one of the factors influencing the quality of vaccination is colostral antibodies, which are able to deactivate the vaccine antigen. Considering this, it is important to determine the duration of colostral immunity of piglets to antigens of the Aujeszky’s disease virus during active sows immunization. For this, was formed a group of sows of 2nd-3rd gestation periods with 25 animals in each. Sows were immunized parenterally against Aujeszky’s disease with the «Adivak» vaccine at a dose of 2 ml, by mass vaccination, three times per year. The level of specific antibodies to glycoproteins E (gE) and B (gB) was determined in the blood serum of piglets before sucking colostrum and every 7 days of life until 77 days from birth by enzyme-linked immunosorbent assay (ELISA). It was revealed that before consuming colostrum, piglets did not have specific antibodies to the antigens of the Aujeszky disease virus. From 7th till 70th days of life, all piglets had specific IgG to the antigens gB and gE of the Aujeszky disease virus, and by the seventy-seventh day, 29% of the animals were seronegative. Thus, newborn piglets before colostrum suckling do not have specific immune protection against the Aujeszky disease virus against the background of sow immunization. Consumption of colostrum by piglets promotes their formation of colostral immunity, specific to the antigens of the Aujeszky disease virus. The duration of colostral antibodies’ circulation specific to the antigens of the Aujeszky disease virus in the piglets peripheral blood is 70 days. On the seventy-seventh day from birth, the level of colostral immunoglobulins decreased sharply, which contributed to the appearance of seronegative animals and an increase in their sensitivity to the action of an epizootic strain of the virus.

An Escherichia coli-Expressed Porcine Reproductive and Respiratory Syndrome Virus Chimeric Protein Induces a Specific Immunoglobulin G Response in Immunized Piglets.

Porcine reproductive and respiratory syndrome virus (PRRSV) still poses a threat to the swine industry worldwide. Currently, commercial vaccines against PRRSV, which consist of modified live or inactivated virus, reduce symptoms and viremia in immunized pigs, but efficacy against heterologous strains is variable. This has led to the development of subunit vaccines that contain viral antigens that show the highest variability. In this work, a chimeric protein comprising short amino acid sequences from glycoprotein 3 (GP3), glycoprotein 4 (GP4), glycoprotein 5 (GP5), and M (matrix protein) proteins of PRRSV was designed and expressed in Escherichia coli. This protein, designated as PRRSVchim, was purified by immobilized metal affinity chromatography and evaluated. PRRSVchim was identified by immunoglobulin G (IgG) presence in serum samples from PRRSV-positive pigs. Also, the protein probed to be antigenic in immunized mice and piglets and provided some degree of protection against challenge with a PRRSV field isolate. These results show the potential of PRRSVchim protein for both PRRSV diagnostic and immunoprophylaxis.

Pathogenicity of porcine deltacoronavirus (PDCoV) strain NH and immunization of pregnant sows with an inactivated PDCoV vaccine protects 5‐day‐old neonatal piglets from virulent challenge

In this study, the pathogenicity of porcine deltacoronavirus (PDCoV) strain NH (passage 10, P10) was evaluated. We found that PDCoV strain NH is enteropathogenic in 5‐day‐old pigs. Pathogenicity experiments provided a challenge model for studying the protection efficiency of passive immunity. In order to investigate the protective efficacy of passive immunity in newborn piglets, pregnant sows were vaccinated with either a PDCoV‐inactivated vaccine at the Houhai acupoint (n = 5) or DMEM as a negative control (n = 2) using a prime/boost strategy 20 and 40 days before delivery. PDCoV spike (S)‐specific IgG and neutralizing antibody (NA) responses were detected in immunized sows and piglets born to immunized sows. PDCoV spike (S)‐specific sIgA was also detected in the colostrum and milk of immunized sows. Five days post‐farrowing, piglets were orally challenged with PDCoV strain NH (105 TCID50/piglet). Severe diarrhoea, high levels of viral RNA copies and substantial intestinal villus atrophy were detected in piglets born to unimmunized sows. Only 4 of 31 piglets (12.9%) born to immunized sows in the challenge group displayed mild to moderate diarrhoea, lower viral RNA copies and minor intestinal villi damage compared to piglets born to unimmunized sows post‐challenge. Mock piglets exhibited no typical clinical symptoms. The challenge experiment results indicated that the inactivated PDCoV vaccine exhibited 87.1% protective efficacy in the piglets. These findings suggest that the inactivated PDCoV vaccine has the potential to be an effective vaccine, providing protection against virulent PDCoV.

Modulation of hypoxia-inducible factor-1α/cyclo-oxygenase-2 pathway associated with attenuation of intestinal mucosa inflammatory damage by Acanthopanax senticosus polysaccharides in lipopolysaccharide-challenged piglets.

Intestinal barrier inflammatory damage is commonly accompanied by hypoxia. The hypothesis that dietary Acanthopanax senticosus polysaccharides (ASPS) might modulate the hypoxia-inducible factor-1α (HIF-1α) signalling pathway and contribute to attenuate intestinal injury was tested in lipopolysaccharide (LPS)-challenged piglets. Thirty-six weaned pigs were randomly allocated to one of the following three groups: (1) basal diet + saline challenge; (2) basal diet + LPS challenge; (3) basal diet with 800 mg/kg ASPS + LPS challenge. LPS was injected at 15, 18 and 21 d, and intestinal sections were sampled following blood collection at 21 d . The results showed ASPS reversed (P < 0·05) LPS-induced decrease in average daily feed intake and rise (P < 0·05) of diarrhoea incidence and index. Biochemical index reflecting gut barrier damage and function involving ileal pro-inflammatory cytokines (TNF-α and IL-1β) and enzyme activity (diamine oxidase and lactase), as well as circulatory d-xylose, was normalised (P < 0·05) in LPS-challenged piglets receiving ASPS. ASPS also ameliorated intestinal morphological deterioration of LPS-challenged piglets, proved by elevated ileal villus height (P < 0·05) and improved appearance of epithelial villus and tight junction ultrastructure. Moreover, ASPS prevented LPS-induced amplification of inflammatory mediators, achieved by depressed ileal mRNA abundance of TNF-α, inducible NO synthase and IL-1β concentration. Importantly, ileal protein expressions of HIF-1α, cyclo-oxygenase-2 (COX-2) and NFκB p65 were also suppressed with ASPS administration (P < 0·05). Collectively, these results suggest the improvement of mucosal inflammatory damage and diarrhoea in immune stress piglets is possibly associated with a novel finding where HIF-1α/COX-2 pathway down-regulation is involved in NFκB p65-inducible releasing of inflammatory cytokines by dietary ASPS.

Impact of Maternal Selenium Supplementation from Late Gestation and Lactation on Piglet Immune Function.

The present work aimed at assessing passive, innate, and acquired immunity in piglets from sows supplemented with either organic or inorganic selenium (Se). A total of 12 multiparous pregnant sows were randomly allocated to three groups: selenium-deficient, corn and soy-based diet base diet (BD),0.3mgSe/kg ashydroxy-selenomethionine (OH-SeMet), and 0.3mgSe/kg assodium selenite (SS). The feeding trial was carried out from gd 84 to weaning on postpartum day 21 (ppd 21). On gd 98 and 105, sows were vaccinated with hen egg white lysozyme (HEWL) to assess passive immunity. On ppd 23, weaned piglets were intramuscularly challenged with lipopolysaccharide (LPS) to trigger an acute-phase response. On ppd 14, 28, and 35, piglets were vaccinated with ovalbumin (OVA) to assess OVA-specific immunoglobulin G (IgG) and dermal hypersensitivity responses. Se levels in piglet plasma, muscle, and liver on ppd 21 were higher in OH-SeMet group. On ppd 2, piglet HEWL-specific IgG levels in OH-SeMet group were significantly increased. IL-10 and haptoglobin (HP) levels in OH-SeMet group were significantly increased 2h and 48h post-LPS simulation, respectively. The OVA-specific IgG levels in BD group were significantly higher than the other two groups, and the IL-4 concentration following whole blood ex vivo challenge with either OVA or mitogen was significantly increased in OH-SeMet group. OVA-specific skin swelling was lower in OH-SeMet and SS groups at 3h and 6h. This suggests that sow supplementation with OH-SeMet enhances mainly passive immunity through IgG maternal transfer and can influence piglet innate and acquired immunity.

4,4'-Diaponeurosporene-Producing Bacillus subtilis Promotes the Development of the Mucosal Immune System of the Piglet Gut.

Gut mucosal immune responses are known to act as the first line of defense against invasion of pathogenic microorganisms. Piglets have an incompletely developed gut mucosal immune system, making them sensitive to intestinal infections. Promoting the development of the mucosal immune system will increase the pathogen resistance of piglets. The aim of the present study was to investigate the effect of carotenoid (4,4'-diaponeurosporene)-producing Bacillus subtilis (B.s-Dia) on intestinal mucosal immunity in piglets. We showed that oral administration to piglets of B.s-Dia remarkably improved the development of Peyer's patches (PPs) (P < 0.01), and increased villus height (P < 0.01) and colon crypt depth (P < 0.01). In addition, B.s-Dia also increased the number of intraepithelial lymphocytes (P < 0.01), while Bacillus subtilis (B.s) had no significant influence on it (P > 0.05). Moreover, B.s-Dia also increased the number of SIgA+ cells (P < 0.01). Oral administration of either B.s or B.s-Dia increased the number of CD4+ and CD8+ cells in ileum lamina propria (P < 0.01). These results indicate that B.s-Dia contributes to a higher extent to porcine mucosal immune system development than B.s, and might serve as an immunopotentiator candidate. Anat Rec, 302:1800-1807, 2019. © 2019 American Association for Anatomy.

Lactobacillus reuteri KT260178 Supplementation Reduced Morbidity of Piglets Through Its Targeted Colonization, Improvement of Cecal Microbiota Profile, and Immune Functions.

Supplementing suckling piglets with Lactobacillus reuteri isolated from a homologous source improves L. reuteri colonization number in the gastrointestinal tract, which can have health benefits. This study investigated dietary L. reuteri supplementation on the growth and health-including immune status-of piglets, as well as its colonization. A total of 60 sows with similar parity and body weight were allocated into one of three groups after secretion (n = 20 each, with 10 neonatal piglets of each): untreated control, L. reuteri supplementation, and antibiotic treatment. The experimental duration was 28days, from birth of piglets to their group transferred. For the first 7days after birth, all neonatal piglets were fed by sows. Piglets in the L. reuteri supplementation group were administered with 1.0mlL. reuteri fermentation broth containing 5.0 × 107CFU. From 7 to 28days, piglets were given basal feed (control), basal feed supplemented with L. reuteri (1.0 × 107CFU/g), or aureomycin (150mg/kg). L. reuteri colonization in the distal jejunum and ileum was increased in piglets in the L. reuteri-supplemented as compared to the control group after 28days, as determined by fluorescence in situ hybridization and real-time PCR analysis. Total Lactobacillus and Bifidobacterium counts in the cecum were higher whereas total aerobic bacteria (Escherichia coli and Staphylococcus) counts were lower in the L. reuteri as compared to the control group. L. reuteri supplementation also improved body antioxidant status and immune function relative to control animals. Strain-specific L. reuteri administered to piglets colonizes the intestinal mucosa and improves cecal microbiota profile and whole-body antioxidant and immune status, leading to better growth and lower morbidity and mortality rates.

Показники неспецифічного імунітету поросят за змішаної нематодозно-протозоозної інвазії

Показники неспецифічного імунітету поросят за змішаної нематодозно-протозоозної інвазії

Poly (d,l-lactide-co-glycolide) nanoparticle-entrapped vaccine induces a protective immune response against porcine epidemic diarrhea virus infection in piglets.

Porcine epidemic diarrhea (PED) causes 80-100% mortality in neonatal piglets, and its causative agent, the porcine epidemic diarrhea virus (PEDV), poses an important threat to the swine industry worldwide. In this study, we prepared biodegradable poly (d,l-lactide-co-glycolide) (PLGA) nanoparticle-entrapped PEDV killed vaccine antigens (KAg) (PLGA-KAg). Late-term pregnant sows were intranasally inoculated with PLGA-KAg, and the mortality resulting from challenge with highly virulent PEDV was investigated in their passively immunized suckling piglets. PEDV-specific IgG and IgA antibody titers were enhanced in pregnant sows immunized with PLGA-KAg relative to the titers in sows inoculated with KAg. Similar results were seen in the passively immunized suckling piglets of these sows. Improved lymphocyte proliferation responses and IFN-γ levels were induced in pregnant sows immunized with PLGA-KAg compared with those vaccinated with KAg or with Montanide™ ISA 201 VG emulsified killed PEDV vaccine (201-KAg). Importantly, there was less piglet mortality in the group vaccinated with PLGA-KAg than in the groups vaccinated with KAg or 201-KAg. These results demonstrate that PLGA-KAg is a promising candidate vaccine that can provide protective immunity against PEDV infection in suckling piglets.

Human breast milk feeding induces stronger humoral immune response than formula feeding in neonatal porcine model

Several studies indicate stronger humoral immune responses in breast‐fed than formula‐fed infants. The key to the beneficial impact of breastmilk on the gastrointestinal (GI) tract and immune system development is the interaction between diet and the gut microbiome. A more comprehensive, mechanistic understanding of this interaction has been hampered by challenges of studying this dynamic relationship in vivo in neonates and infants. We have developed a unique human breast milk‐fed piglet model to address this issue. This approach reduces limitations associated with sow‐feeding (e.g., exposure to sow nipple epidermis, fecal material, etc.) and obviates challenges that arise with the collection and compositional assessment of sow's milk. Piglets born at a breeding farm were sow‐fed for 48 hours, then moved to an AAALAC‐approved animal facility, and fed equicaloric diets either with human breast‐milk (HBM) or a dairy‐based infant formula (F) through age 21 days. Sow‐fed piglets were housed at the farm until age 20 days and all diet groups were weaned to a common ad libitum solid diet until day 51. Piglets were immunologically challenged with oral choleratoxin and intramuscular DTaP antigens on days 21 and 35. Immune response was evaluated on day 48 by measuring IgG to tetanus antigen, and IgA to choleratoxin antigen. Relative to non‐immunized piglets, in all diet groups' immunized piglets had expected antigen specific immune responses. However, relative to F‐fed piglets, HBM‐fed piglets showed higher tetanus‐specific IgG response in serum (log 4.4 vs 4.9, p&lt;0.01), significantly more peripheral blood mononuclear cells (PBMCs) produced greater levels of IgG (p&lt;0.05). Furthermore, on day 51 choleratoxin‐specific IgA producing cells were significantly higher in Peyer's patch (p&lt;0.05) and mesenteric lymph nodes (MLN, p&lt;0.05) in HBM‐fed piglets than F‐fed piglets. These effects were associated with a greater IgA response in serum (log 3.7 vs 4.4, p&lt;0.05). Relative to F‐fed piglets, HBM‐fed showed significantly more NK (26% vs 13%), B (36% vs 10%) and Treg cell (11% vs 3.5%) populations in the mesenteric lymph nodes. In the Peyer's patch of F‐fed piglets significantly more gdT (11% vs 1%) and CD8 T (25% vs 15%) cells were observed. It is important to note that no major significant group differences were observed in the weight gain or general health throughout the feeding period. These data suggest that neonatal immune system development is influenced by specific factors in breast milk and further confirm findings from infant studies that breast milk feeding results in stronger mucosal and systemic immune responses. Furthermore, the sow‐fed group responses were similar to HBM‐fed piglets in most of the measurements suggesting that piglets fed with human breast‐milk may model breast‐fed infants. Mechanistic studies are underway to determine the role of microbiota in gut development and immune responses. This determination would be a major step toward translation between animal models and the human condition addressing challenges associated with procurement of GI tract samples under controlled conditions in infants.Support or Funding InformationFunding: USDA‐ARS Project 6026‐5100‐010‐05S

Imbalance of intestinal immune function in piglets infected by porcine circovirus type 2 during the fetal period.

Porcine circovirus type 2- (PCV2-) associated reproductive disorders and enteritis have commonly been observed on PCV2-contaminated pig farms in recent years. In order to investigate disorders of intestinal immunity in piglets infected by PCV2 during the fetal period, 9 PCV2b-infected piglets and 6 non-infected piglets at one day of age were selected and euthanised prior to suckling. Samples of mesenteric lymph nodes (MLNs) and duodena were collected to investigate factors related to intestinal immunity and to detect lymphocytic apoptosis. The results indicated that there were no significant changes in the levels of IL-2, IL-10 and transforming growth factor-β (TGF-β) in the PCV2b-infected piglets but IFN-γ levels were significantly lower (P < 0.01) and IL-4 levels were significantly higher (P < 0.05) in infected piglets than in the controls. Furthermore, lymphocytic apoptosis increased in PCV2b-infected piglets and CD4+ to CD8+ ratios were lower in these piglets than in the controls. These findings suggest vertical transmission of PCV2b to fetuses, leading to an imbalance of intestinal immune function in piglets.

Вплив пробіотика та фітобіотика на показники Т- і В-клітинного імунітету відлучених поросят за гастроентериту незаразної етіології

In the use of colostral protective factors and insufficient activity of piglets immune system, against the background of immunodeficiency after weaning from sows developing diseases, often caused by conditionally-pathogenic or pathogenic microorganisms, including non-contagious gastroenteritis. The article presents analyzes of T- and B-cell immunity parameters in weaned piglets with non-contagious gastroenteritis and after their treatment with probiotic TOYOCERIN 10⁹ and phytobiotic EXTRACT™ 6930 as part of the basic diet in combination with antibiotic (10 % solution of enrofloxacin hydrochloride) in the modern pig farm. It was established that in piglets after weaning with non-contagious gastroenteritis decreased of T- and B-cell immunity parameters. In particular, in blood decreased number of total and active T-lymphocytes, T-helpers and T-suppressors also decreased number of B-lymphocytes, which may indicate the development in these immunodeficient condition. It was established positive effect of probiotic and phytobiotic in combination with antibiotic on T-cell immunity of pigs, as indicated by the increased number of total T-lymphocytes in blood to the clinical healthy animals level. A similar tendency was observed in the number of T-helper cells, their number was higher in groups of weaned piglets which added probiotic TOYOCERIN 10⁹ and phytobiotic EXTRACT™ 6930. As to the immunoregulatory index, which is a quantitative ratio of T-helper to T-suppressor, there was no significant alteration of values in control and experimental groups of pigs. It was established positive effect of probiotic and phytobiotic in humoral immunity of piglets by increasing number of B-lymphocytes to the level of clinical healthy animals which indicate increased body ability to the active synthesis of protective antibodies. The use of probiotic TOYOCERIN 10⁹ and phytobiotic EXTRACT™ 6930 for weaned piglets with non-contagious gastroenteritis normalized number of T- and B-lymphocytes, which are the leading immunocompetent blood cells that characterize the level of animal body defense and condition of specific immunity. Perspectives for further research will be directed at determining the therapeutic effectiveness of probiotic TOYOCERIN 10⁹ and phytobiotic EXTRACT™ 6930 for weaned piglets with non-contagious gastroenteritis.

ФУНКЦІОНУВАННЯ ІМУННОГО БАР'ЄРУ КИШЕЧНИКА ПОРОСЯТ ЗА ДІЇ ТЕХНОЛОГІЧНОГО СТРЕСУ

The article presents the results of the study of the functional state structures intestinal immune piglets growing industrial and post–action process stress–weaning. It was established that the small intestine of piglets before and after weaning operates a big yeyuno–ilealPeyer’s patche and small Peyer’s patches. The structure of yeyuno–ileal Peyer’s patche of pigs 28–day age (weaning) at the macroscopic level allocated separate nodules that are intensely stained and clearly different, especially in the caudal part that can point to a marked reactivity of lymphoid tissue that forms their basis. At the stage of resistance (30 days after weaning) in the structure of yeyuno–ileal Peyer’s patche of pigs at the macroscopic level dome–shaped nodules are tight, so no free fields are not registered. At the histological level ofyeyuno–ileal Peyer’s patche of piglets before weaning registered primary and secondary nodules with reactive centers of reproduction, which is a sign of complete morphofunctional maturity lymphoid tissue, whereas when the piglets after weaning secondary nodules turned out far less, some of them have clearly formed shell, which may indicate the inhibition of immune responses within mucosal lymphoid tissue of the gastrointestinal tract or the development of immunodeficiency state of cellular immunity as a result of the stress of weaning.

1740 Effects of different sources and routes of administration of copper and vitamins A and D on gut volatile fatty acids and gene expression involved in regulation of innate and acquired immunity in piglets

1740 Effects of different sources and routes of administration of copper and vitamins A and D on gut volatile fatty acids and gene expression involved in regulation of innate and acquired immunity in piglets

Maternally Derived Immunity Extends Swine Influenza A Virus Persistence within Farrow-to-Finish Pig Farms: Insights from a Stochastic Event-Driven Metapopulation Model.

Swine Influenza A Viruses (swIAVs) have been shown to persist in farrow-to-finish pig herds with repeated outbreaks in successive batches, increasing the risk for respiratory disorders in affected animals and being a threat for public health. Although the general routes of swIAV transmission (i.e. direct contact and exposure to aerosols) were clearly identified, the transmission process between batches is still not fully understood. Maternally derived antibodies (MDAs) were stressed as a possible factor favoring within-herd swIAV persistence. However, the relationship between MDAs and the global spread among the different subpopulations in the herds is still lacking. The aim of this study was therefore to understand the mechanisms induced by MDAs in relation with swIAV spread and persistence in farrow-to-finish pig herds. A metapopulation model has been developed representing the population dynamics considering two subpopulations—breeding sows and growing pigs—managed according to batch-rearing system. This model was coupled with a swIAV-specific epidemiological model, accounting for partial passive immunity protection in neonatal piglets and an immunity boost in re-infected animals. Airborne transmission was included by a between-room transmission rate related to the current prevalence of shedding pigs. Maternally derived partial immunity in piglets was found to extend the duration of the epidemics within their batch, allowing for efficient between-batch transmission and resulting in longer swIAV persistence at the herd level. These results should be taken into account in the design of control programmes for the spread and persistence of swIAV in swine herds.

Characterization of the immune response and evaluation of the protective capacity of rSsnA against Streptococcus suis infection in pigs.

The efforts made to develop vaccines against Streptococcus suis have failed because of lack of common antigens cross-reactive against different serotypes of this species. The cell wall-anchored proteins can be good vaccine candidates due to their high expression and accessibility to antibodies, among these, a cell-wall protein, DNA-nuclease (SsnA), present in most of the S. suis serotypes and clinical isolates collected from infected pigs, was selected. An experimental challenge against S. suis serotype 2 in a pig model was used to validate the efficacy of recombinant SsnA combined with aluminium hydroxide plus Quil A as adjuvants, previously tested in mice by our research group with good results. In our study, clinical characteristics, bacterial load and spread, haematological and immunological parameters and the antibody response, including the opsonophagocytosis analysis of the sera were evaluated. Moreover the composition of peripheral blood leukocyte populations was studied in infected animals. The results show that the immunization of piglets with rSsnA elicits a significant humoral antibody response. However, the antibody response is not reflected in protection of pigs that are challenged with a virulent strain in our conventional vaccination model. Further studies are necessary to evaluate the use of rSsnA as a vaccine candidate for swine.

The effect of colostrum ingestion during the first 24 hours of life on early postnatal development of piglet immune systems.

It has been suggested that colostrum is important not only for direct protection from pathogens but also for proper development of immune systems in piglets. In this study, we focused on the effect of colostrum ingestion during the first 24 h of life on early postnatal development of piglet immune systems. Thirty-six piglets from five litters were divided into colostrum-fed (CoF) and colostrum-deprived (CoD) groups. The former group was allowed to suckle normally while formula milk was fed to the latter group during the first 24 h of life. At the weaning period, the concentrations of fecal immunoglobulin (Ig) A and plasma IgG as well as the number of blood leukocyte subsets were analyzed. Fecal IgA and plasma IgG concentrations in the CoF group were more than twice as high as those in the CoD group (P < 0.01). In addition, the number of blood B cells was significantly higher in the CoF group than that in the CoD group (P < 0.05). This study demonstrates that colostrum ingestion during the first 24 h plays a significant role in early postnatal development of both mucosal and systemic immunity of piglets.