Comparison of adjuvants with respect to serum IgG antibody response in orally immunized chickens

Plant extracts as supplements for lactating sows: effects on piglet performance, sow food intake and diet digestibility

The objective of this study was to evaluate the ability of the plant extracts Yucca shidigera, Quillaja saponaria and a combination (a blend of capsicum, carvacrol and cinnamaldehyde) to stimulate piglet and sow performance when used as supplements in the diets of lactating sows. These extracts were selected for their potential benefits to health, appetite and digestion. Eighty hybrid sows were housed in conventional indoor farrowing crates from day 107 of gestation until weaning. Sows were allocated according to parity, live weight, fatness and past reproductive performance, to one of four dietary treatments: control (C), combination (COM, 100 g/t food), yucca (Y, 200 g/t), quillaja (Q, 250 g/t). Between days 107 to 114 of gestation, sows received 2·5 kg food per day of their respective diet. During lactation food was offered ad libitum with sow food intake (FI) recorded daily. Faecal samples were obtained from sows daily in order to measure diet digestibility using titanium dioxide as an external marker. Piglet live weight and sow P2 backfat were recorded on days 1, 7, 14 and 21 and at weaning on day 23 (s.e.2·5). Piglet live weight and rectal temperature were measured at birth and 24 h of age. Piglet growth between birth and 24 h was significantly affected by sow treatment. Litters from COM sows held the greatest advantage (117 v. C 99, Q 77, Y 107 g per pig per day, P < 0·01, s.e. = 7·9). Piglet body temperature at birth was also higher in COM litters when compared with treatment C (38·58 v. 37·95oC, P < 0·05)). Q and Y piglets were intermediate between the two. Sow treatment had no effect on piglet performance between day 1 and 14 of lactation. However, between days 15 and 21, piglets from COM sows again significantly outperformed all other treatments (COM 290, C 246, Q 235, Y 255 g per pig per day, P < 0·001, s.e. = 9·3). Piglet weights on day 21 were also significantly greater for the COM sows (6878 g v. C 6584 g, Q 6330 g, Y 6498 g, P < 0·05 s.e. = 132). No benefit was seen from supplementation with either yucca or quillaja extracts on piglet growth. Sow FI and P2 backfat loss between parturition and weaning were unaffected by treatment. However, diet digestibility was enhanced by all supplements during week 1 of lactation in terms of dry matter, organic matter and crude protein. It is concluded that some plant extracts may enhance piglet and sow performance prior to weaning.

Assessment of potential adjuvanticity of Cry proteins

Genetically modified (GM) crops have achieved success in the marketplace and their benefits extend beyond the overall increase in harvest yields to include lowered use of insecticides and decreased carbon dioxide emissions. The most widely grown GM crops contain gene/s for targeted insect protection, herbicide tolerance, or both. Plant expression of Bacillus thuringiensis (Bt) crystal (Cry) insecticidal proteins have been the primary way to impart insect resistance in GM crops. Although deemed safe by regulatory agencies globally, previous studies have been the basis for discussions around the potential immuno-adjuvant effects of Cry proteins. These studies had limitations in study design. The studies used animal models with extremely high doses of Cry proteins, which when given using the ig route were co-administered with an adjuvant. Although the presumption exists that Cry proteins may have immunostimulatory activity and therefore an adjuvanticity risk, the evidence shows that Cry proteins are expressed at very low levels in GM crops and are unlikely to function as adjuvants. This conclusion is based on critical review of the published literature on the effects of immunomodulation by Cry proteins, the history of safe use of Cry proteins in foods, safety of the Bt donor organisms, and pre-market weight-of-evidence-based safety assessments for GM crops.

Effects of Anti-diarrhoeal Herbs on Growth Performance, Nutrient Digestibility, and Meat Quality in Pigs

Two studies were conducted to investigate the effects of anti-diarrhoeal herbs on growth performance, nutrient digestibility, and meat quality in pigs. In Exp 1, 150 weanling-growing piglets (average BW = 7.5±0.24 kg, average age = 27±1 d) were allotted into one of the five dietary treatments, including: i) CON, basal diet, ii) DP, basal diet+1 g/kg date pits, iii) JH, basal diet+0.5 g/kg Japanese-honeysuckle, iv) HCT, basal diet+1 g/kg houttuynia cordata thunb, and v) LE, basal diet+1 g/kg laquer tree extract. From wk 0 to 5, the JH, HCT and LE groups presented higher (p<0.05) ADFI, ADG and gain/feed ratio (G/F) than CON and DP groups. During wk 5 to 10, Pigs fed JH, HCT and LE diets indicated higher (p<0.05) ADG and ADFI than the pigs fed CON and DP diets. During the entire experimental period, a significant increase of ADG appeared in JH, HCT and LE (p<0.05). Pigs fed JH, HCT and LE diets got a higher (p<0.05) ADFI than the pigs fed CON and DP diets. Pigs fed diets with supplementations of herb additives revealled lower (p<0.05) score of diarrhea pigs during d 2 to d 6 compared with pigs fed CON diet. In Exp 2, 60 growing-finishing barrows and gilts (average BW = 54.10±1.20 kg, average age = 54±3 d) were allotted to three treatments: i) CON, basal diet; ii) YG, basal diet+1 g/kg yellow ginger and iii) HR, basal dietary+1 g/kg hoantchy root, respectively. From wk 0 to 5, Dietary supplementation of YG and HR enhanced (p<0.05) ADG. No difference was found between YG and HR treatments. During, wk 5 to 10, ADG also was observed higher in YG and HR treatments than CON group (p<0.05). Additional, YG had the highest ADG (p<0.05) among treatments. There was always an increase of ADG in YG and HR (p<0.05) through all periods. HR treatment showed a lower (p<0.05) score of diarrhoeal pigs on d 1and d 2 compared with CON treatment. Pigs fed YG and HR diets had a higher (p<0.05) longissimus muscle area (LMA) than pigs fed CON diet. In conclusion, anti-diarrhoeal herbs can improve growth performance, and prevent diarrhea incidence in pigs, it can also increase LMA in finishing pigs.

Protective vaccination against infectious bursal disease virus with whole recombinant Kluyveromyces lactis yeast expressing the viral VP2 subunit

Here we report on vaccination approaches against infectious bursal disease (IBD) of poultry that were performed with complete yeast of the species Kluyveromyces lactis (K. lactis). Employing a genetic system that enables the rapid production of stably transfected recombinant K. lactis, we generated yeast strains that expressed defined quantities of the virus capsid forming protein VP2 of infectious bursal disease virus (IBDV). Both, subcutaneous as well as oral vaccination regiments with the heat-inactivated but otherwise untreated yeast induced IBDV-neutralizing antibodies in mice and chickens. A full protection against a subsequent IBDV infection was achieved by subcutaneous inoculation of only milligram amounts of yeast per chicken. Oral vaccination also generated protection: while mortality was observed in control animals after virus challenge, none of the vaccinees died and ca. one-tenth were protected as indicated by the absence of lesions in the bursa of Fabricius. Recombinant K. lactis was thus indicated as a potent tool for the induction of a protective immune response by different applications. Subcutaneously applied K. lactis that expresses the IBDV VP2 was shown to function as an efficacious anti-IBD subunit vaccine.

Targeted delivery with peptidomimetic conjugated self-assembled nanoparticles

Peptides produce specific nanostructures, making them useful for targeting in biological systems but they have low bioavailability, potential immunogenicity and poor metabolic stability. Peptidomimetic self-assembled NPs can possess biological recognition motifs as well as providing desired engineering properties. Inorganic NPs, coated with self-assembled macromers for stability and anti-fouling, and conjugated with target-specific ligands, are advancing imaging from the anatomy-based level to the molecular level. Ligand conjugated NPs are attractive for cell-selective tumor drug delivery, since this process has high transport capacity as well as ligand dependent cell specificity. Peptidomimetic NPs can provide stronger interaction with surface receptors on tumor cells, resulting in higher uptake and reduced drug resistance. Self-assembled NPs conjugated with peptidomimetic antigens are ideal for sustained presentation of vaccine antigens to dendritic cells and subsequent activation of T cell mediated adaptive immune response. Self-assembled NPs are a viable alternative to encapsulation for sustained delivery of proteins in tissue engineering. Cell penetrating peptides conjugated to NPs are used as intracellular delivery vectors for gene expression and as transfection agents for plasmid delivery. In this work, synthesis, characterization, properties, immunogenicity, and medical applications of peptidomimetic NPs in imaging, tumor delivery, vaccination, tissue engineering, and intracellular delivery are reviewed.

Effect of dietary supplementation of sows with quillaja saponins during gestation on colostrum composition and performance of piglets suckled

The objective of this study was to assess the effect of dietary saponins, extracted from the plant Quillaja saponaria, on the concentrations of immunoglobulins in sow colostrum and milk, and additionally to observe any effect on piglet performance. Twenty-two sows were allocated to each of two dietary treatments on day 72 of gestation, balancing for parity, fatness and past reproductive performance. Treatments were : control (C) and supplemented (Q; 2.5 g saponin per day as a top-dressing). Sows received 2.5 kg food once per day throughout gestation. Between days 72 and 93 of gestation Q sows received a saponin top-dressing as described. After day 93, all sows were given the same diet and managed in an identical manner. Colostrum samples were taken from all sows at farrowing on delivery of the first piglet then 4, 8, 24 and 72 h later and again on day 21 of lactation. A group of eight sows from each treatment were also blood sampled at farrowing, day 3 and day 21 of lactation. Concentrations of immunoglobulins IgG and IgA in the colostrum, milk and blood were not affected by sow treatment during gestation at any sampling point. Fat, lactose and cell counts were also similar across treatments in colostrum and milk. Protein tended to be higher in milk on day 3 but lower on day 21 (P< 0.1) in Q sows. Piglet performance was not affected by sow treatment during week 1 of lactation. However pigs suckling Q sows grew more slowly between days 8 to 14 (P< 0.05) and days 15 to 21 (P< 0.1). Q sows also had fewer stillborn piglets in their litters at farrowing (7.67 v. 13.25%,P< 0.05, s.e. = 1.93). It is concluded that dietary quillaja saponin given during this time period has no influence on sow lacteal immunoglobulin secretions. However an adverse effect on performance of the sucking piglet was observed, the reasons for which are unclear, but may be related to reduced milk protein concentrations. Dietary quillaja saponin during gestation does however appear to reduce the incidence of stillborn piglets.

Crude saponins improve the immune response to an oral plant-made measles vaccine

Millions of people live in areas where infectious diseases, such as measles, are endemic and resources are scarce. Heat-stable vaccines that are delivered orally will greatly enhance vaccination programs in these areas. A stumbling block in the development of oral vaccines is the availability of safe and effective mucosal adjuvants, especially for use with subunit vaccines. The experiments presented here examine the ability of CTB/CT, LT(R192G) and crude Quillaja saponin extracts to stimulate MV-specific immune responses in mice, following oral immunisation with plant-made measles virus hemagglutinin (MV-H) protein. LT(R192G) and crude saponin extracts both functioned as potent mucosal adjuvants when ad-mixed with plant-made MV-H protein, and were more effective than CTB/CT. MV-H protein supplemented with saponin extract induced the strongest MV-specific responses, in the greatest number of mice. Crude saponins are routinely used by the food and beverage industry at concentrations greater than those required for adjuvanticity, and as such, they have a better safety profile than bacterial enterotoxins. This study demonstrates their potential as adjuvants for use with oral plant-made vaccines.

Immunogenicity of ad libitum drinking water administration of bovine serum albumin in Leghorn chickens

Oral administration of protein antigen in solution routinely leads to development of oral tolerance in most mammals but has been reported to be fully immunogenic in chickens. Previous studies, including several performed by our laboratory, have demonstrated that oral administration of discrete amounts of BSA for 6 consecutive days is fully immunogenic. This study was performed to determine immunoresponsiveness to protein antigen administered ad libitum at low levels in drinking water compared with i.p. and oral gavage routes of administration. Seven days following the last oral immunization, serum was assayed for IgG, bile for IgA, and tissue culture supernatant from 3 distinct lower intestinal regions for IgG and IgA in immunized and nonimmunized single-comb White Leghorn chickens. Systemic responses in the serum of experimental birds revealed a greater (P < 0.001) IgG response when BSA was administered via i.p. injection or by drinking water compared with gavage administration or nonimmunized controls. Responses measured in bile revealed that BSA administration in the drinking water resulted in a greater (P < 0.001) secretory IgA response compared with i.p. or gavage administration, and negative control groups. Intestinal antigen specific IgG, but not IgA, was elevated (P < 0.05) in all intestinal areas tested in birds immunized against BSA by drinking water and i.p. routes of administration, compared with other experimental groups. Taken together, the present experiments demonstrate that ad libitum drinking water administration of a protein antigen is as effective as i.p. administration or gavage routes of antigen exposure and potentially describe a novel approach to immunization of commercial poultry with purified protein antigens.

Passive immunization of mice pups through oral immunization of dams with a plant-derived vaccine

Passive immunization plays an important role in protecting young mammals against pathogens before the maturation of their own immune systems. Although many reports have shown active immunization of animals and human through the use of plant-derived vaccines, only one report has given evidence of passive immunization of offspring through oral immunization of parents using plant-derived vaccines. In this case, a challenge alone provided the evidence of passive immunization and the mechanism through which this occurred was not investigated. This report describes the first step in elucidating the mechanism of passive immunization of offspring through actively immunizing the female parent through an orally delivered, plant-derived vaccine. The authors found passive immunization of offspring was caused by transfer of antigen-specific IgG through either transplacental transfer or ingesting colostrum. Future studies will investigate the roles of transplacental antibody transfer and ingesting colostrum in passive immunization and the possible involvement of IgA in this immunization route.

Immune responses of chickens to dietary protein antigens. I. Induction of systemic and intestinal immune responses following oral administration of soluble proteins in the absence of adjuvant

Oral administration of protein antigens in solution leads to the development of oral tolerance in most mammals but rarely so in the chicken. As dietary proteins are not expected to be immunogenic, the present study was undertaken to evaluate immunological consequences following oral exposure to protein antigens in chicks, and to determine whether or not this form of antigen is ignored. Chicks and turkey poults were fed solutions containing bovine serum albumin (BSA), porcine serum albumin, beta-lactoglobulin or bovine hemoglobin over a period of 6 days (25mg/chick/day). At different time points after feeding serum and bile were examined for presence of specific antibodies by ELISA. Surprisingly, the fed antigens induced robust antibody responses in the absence of added adjuvant. This immune response was further characterised to show that (1) a daily feeding regimen was more immunogenic than single dose feedings, (2) by using a daily feeding regimen, as little as 2mg/chick/day was fully immunogenic, (3) effective immunization was attained in chicks older than 10 day of age, (4) the main antibody class in the serum was IgG, and (5) high IgA levels were detected in the bile after booster feedings. These observations are difficult to reconcile with current concepts on peripheral tolerance to innocuous antigens, and indicate that the bird regulates tolerance and response in a manner different from that described in mammals.