Amplification of the secretory IgA response toToxoplasma gondiiusing cholera toxin

Identification of differentially expressed genes and metabolism signaling pathway in the spleen of broilers supplemented with probiotic Bacillus spp

Probiotics are essential in the body's nutrients, improving the ratio of meat to meat, immune response, and preventing diseases. In this study, RNA-sequencing (RNA-seq) was used to identify the differentially expressed genes (DEGs), enriched related pathways, and Gene Ontology (GO) terms among blank negative control (NC), supplemented with Bacillus spp. (BS) and commercial probiotic (PC) groups after a 42-day fed supplementation. The results showed that 2005, 1356, and 2189 DEGs were significantly altered in BS vs. NC, PC vs NC, and BS vs PC groups, respectively. On the other hand, 9 DEGs were further validated by qRT-PCR, indicating that the qRT-PCR and RNA-Seq results were more consistent. Therefore, the GO and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of DEGs showed that the DEGs were mainly enriched to metabolism signalling pathways (alpha-linolenic acid metabolism, linoleic acid metabolism, tryptophan metabolism, tyrosine metabolism, ether lipid metabolism, and metabolic pathway, etc) and immune response pathways (cytokine-cytokine receptor interaction, MAPK signalling pathway, and intestinal immune network for IgA production, neuroactive ligand-receptor interaction etc). These results will provide a better understanding of the role of probiotics in chicken development and provide basic information on the genetic development of chickens.

Analysis of Differentially Expressed Genes in Necrotic Enteritis-infected Fayoumi Chickens using RNA Sequencing

We identified and evaluated differentially expressed genes (DEGs) by RNA-Sequencing (RNA-Seq) in the intestinal mucosa of two Fayoumi chicken lines, M5.1 and M15.2, that are affected by necrotic enteritis (NE); these chicken lines share the same genetic background but have different major histocompatibility complexes. RNA-Seq generated over 49 and 40 million reads for lines M5.1 and M15.2, respectively. The alignment of these sequences with the Gallus gallus genome database revealed the expression of more than 14,500 genes in two lines, among which 581, 1270, and 1140 DEGs were detected when lines M15.2 and M5.1 were compared with the control and compared between each other. The analysis of all DEGs using the gene ontology database revealed annotations for 111 biological processes, 32 cellular components, and 17 molecular functions, and KEEG pathway mapping indicated that the DEGs were primarily involved in immunity, responses to various stimuli, and signal transduction. In addition, we analyzed 183 innate immune genes that were differentially expressed in NE-induced chicken lines, including 46 CD molecular genes, 89 immune-related genes, and 13 β-defensin genes with 3 lineage-specific duplications. Taken together, the transcriptional profiles showed that line M5.1 was more resistant to NE than line M15.2 and that differential gene expression patterns were associated with host genetic differences in resistance to NE. qRT-PCR and RNA-Seq analyses showed that all the genes examined had similar responses to NE (correlation coefficient R=0.84 to 0.88, p<0.01) in both lines. To the best of our knowledge, this is the first study that describes NE-induced DEGs using RNA-seq in two lines with different levels of susceptibility to NE. These results will lead to increased insights on NE disease resistance mechanisms and the role of host genes in the control of the host immune response.

Effect of Diclazuril on the Bursa of Fabricius Morphology and SIgA Expression in Chickens Infected with Eimeria tenella

The effects of diclazuril on the bursa of Fabricius (BF) structure and secretory IgA (SIgA) expression in chickens infected with Eimeria tenella were examined. The morphology of the BF was observed by hematoxylin and eosin staining, while ultrastructural changes were monitored by transmission electron microscopy. E. tenella infection caused the BF cell volumes to decrease, irregularly arranged, as well as, enlargement of the intercellular space. Diclazuril treatment alleviated the physical signs of damages associated with E. tenella infection. The SIgA expression in BF was analyzed by immunohistochemistry technique. The SIgA expression increased significantly by 350.4% (P<0.01) after E. tenella infection compared to the normal control group. With the treatment of diclazuril, the SIgA was relatively fewer in the cortex, and the expression level was significantly decreased by 46.7% (P<0.01) compared with the infected and untreated group. In conclusion, E. tenella infection in chickens induced obvious harmful changes in BF morphological structure and stimulated the expression of SIgA in the BF. Diclazuril treatment effectively alleviated the morphological changes. This result demonstrates a method to develop an immunological strategy in coccidiosis control.

Comparison of cholera toxin A2/B and murine interleukin-12 as adjuvants of Toxoplasma multi-antigenic SAG1-ROP2 DNA vaccine

Toxoplasmosis can lead to severe pathology in both humans and animals. However, an effective vaccine for humans has not been successfully developed. In this study, we used multi-antigenic SAG1-ROP2 as a DNA vaccine and cholera toxin A2/B subunit and murine interleukin-12 to compare their effectiveness as genetic adjuvants. Bagg albino/c (BAL/c) mice were immunized intramuscularly with pcDNA3.1-SAG1-ROP2 alone (control group), or pcDNA3.1-SAG1-ROP2 with co-administration of pCTA2/B or pIL-12, respectively. After immunization, the effectiveness of these two adjuvants were compared using lymphocyte proliferation assay, cytokine and antibody measurements. The group co-administered pIL-12 elicited stronger humoral and Th1-type cellular immune responses than those immunized with pcDNA3.1-SAG1-ROP2 alone, while in the group co-administered pCTA2/B there was no obvious enhancement of immunity. When challenged with Toxoplasma gondii RH strain, mice immunized with pIL-12 co-administration had significantly higher survival rates, whereas there was no notable augmentation of immunity in pCTA2/B group. Therefore, since pIL-12 significantly enhanced the antigenicity of multi-antigenic DNA vaccine, this suggests that IL-12 is a better and more effective adjuvant than CTA2/B in this situation.

Immunodulation of rat serum and mucosal antibody responses to Entamoeba histolytica trophozoites by beta-1,3-glucan and cholera toxin

Systemic and mucosal and immune responses can be manipulated with immunomodulators. Here we show the modulatory effects of cholera toxin (CT) and beta-1,3-glucan (GLU) on the rat antiamebic serum and fecal antibody responses to one or four intraperitoneal (IP) or intragastric (IG) doses of glutaraldehyde-fixed Entamoeba histolytica trophozoites (GFT). One IP dose of GFT maximized serum IgM and IgG antiamebic antibodies on days 4 and 9, respectively; CT coadministration increased IgM antibodies, whereas IgG titers increased with CT or GLU; coproantibodies were undetectable after GFT alone or coadministered with GLU, whereas CT coadministration maximized fecal IgA antibodies on day 6. One IG dose of GFT alone increased serum IgM and IgG antibodies 2.5 times and no further increases were detected using GLU, whereas CT doubled serum IgG antibodies; GFT did not affect the coproantibody responses, whereas GLU coadministration maximized IgG coproantibody levels on day 6 and CT increased IgG and IgA coproantibody levels on the same day. On the other hand, four IG doses of GFT alone or with GLU induced tolerance, whereas GFT alone via the IP route increased serum antibodies slightly and GLU coadministration increased serum IgG antibody titers 300-fold. CT coadministration by both routes increased IgA coproantibodies, and simultaneous CT+GLU coadministration induced lower responses than either CT or GLU. Different antiamebic immune responses might therefore be attained through the use of different immunization routes and immunomodulators to induce protective immunity against intestinal or extraintestinal amebiasis.

Nasal immunization of mice with human papillomavirus type 16 (HPV-16) virus-like particles or with the HPV-16 L1 gene elicits specific cytotoxic T lymphocytes in vaginal draining lymph nodes

Human papillomavirus type 16 (HPV-16) infects the genital tract and is closely associated with the development of cervical cancer. HPV-16 initiates infection at the genital mucosal surface; thus, mucosal immune responses are likely to contribute to defense against HPV-16 infection. However, little information is available regarding the induction of immune responses in the genital tract mucosa. In this study, we evaluated the potential of intranasally administered papillomavirus vaccines to elicit both systemic and vaginal immune responses. HPV-16 virus-like particles (VLPs) produced by self-assembly of L1 protein and the HPV-16 L1 gene cloned into a mammalian expression vector were used as vaccines. Intranasally administered VLPs induced serum immunoglobulin G (IgG) and vaginal IgA secretory antibodies. Very weak serum IgG and vaginal IgA responses were found after DNA immunization. Both splenic and vaginal lymphocytes could be activated by intranasal immunization with VLPs and the HPV-16 L1 gene. Activated CD4(+) Th1-like T cells were shown to synthesize gamma interferon, and activated CD8(+) T cells were demonstrated to be cytotoxic.

Positive evidence that anti-Toxoplasma gondii IgA antibody exists in the intestinal tract of infected cats and exerts protective activity against the infection

The presence of anti-Toxoplasma gondii IgA antibody in the feces and intestinal tract of cats infected with this parasite was demonstrated using an immunoblotting assay. Cats (n = 5) were inoculated orally with T. gondii cysts and supernatants of feces and washings of the intestinal tract were assayed for secretory IgA specific for the parasite. The secretory IgA detected recognized tachyzoite antigens of m.w. 24, 34, 38 and 43 kDa and one sporozoite antigen of m.w. 24 kDa. No reactivity was shown against bradyzoites or enteroepithelial stage parasites. Tachyzoites preincubated with washings of the intestinal tract of infected cats showed decreased activity in penetration of feline fibroblast cells, as compared to tachyzoites preincubated with similar washings derived from non-infected cats. The addition of either anti-cat IgA or anti-cat IgG to the washings had no effect on the inhibitory activity which reduced the parasite's cell-penetration activity. However, the addition of both anti-cat IgA and anti-cat IgG to the washings diminished the inhibitory activity. These results suggest that anti-T. gondii antibodies of both classes, secretory IgA and IgG, exist in the intestinal tract of infected cats and these may be capable of preventing infection.

Oral immunization of rabbits against Pasteurella multocida with an alginate microsphere delivery system

Oral delivery of microencapsulated antigens is a potential means to vaccinate rabbits against Pasteurella multocida, a common bacterial pathogen. Groups of five rabbits were dosed orally on days 0, 7, and 14 with alginate microspheres prepared to contain no added protein, 5 mg of a potassium thiocyanate extract of P. multocida (PTE), or 5 mg of PTE with 200 micrograms of cholera toxin (CT). In addition, groups were dosed orally with 5 mg of soluble PTE with or without 200 micrograms CT, intranasally (IN) with 1 mg of soluble PTE, or with saline. Serum and nasal lavage samples collected prior to initial immunization and 10, 16, and 21 days later were assayed by ELISA for anti-PTE IgG and IgA. Strong nasal lavage IgA and serum IgG activities were found in samples from rabbits immunized with PTE IN or orally when incorporated into microspheres. Addition of CT did not significantly enhance either response. To examine the development of protective immunity, groups were similarly immunized and challenge-exposed IN on day 16 with 10(6) CFU of P. multocida. One week later, rabbits were euthanized, and specimens from the lungs, nasopharynx, liver, and inner ear were cultured for P. multocida. Less severe infections of the lung and nasopharynx developed in rabbits immunized with PTE IN or orally in microspheres, with or without added CT. In addition, culture of liver and tympanic bullae samples from these rabbits yielded growth of P. multocida less frequently compared to other P. multocida-challenged rabbits. Coadministration of CT and PTE did not significantly improve protective immunity to challenge.

Peritoneal macrophages from C57BL/6 mice orally immunized with Toxoplasma gondii antigens in association with cholera toxin possess an enhanced ability to inhibit parasite multiplication

Gamma-interferon (IFN-gamma) has been reported to be a major mediator of resistance to toxoplasma infection, mainly through macrophage activation. Cholera toxin used as oral adjuvant induces enhanced protection. Following oral immunization of C57BL/6 mice with a Toxoplasma gondii sonicate (TSo), in association with either cholera toxin (CT) or its B subunit (CTB), the ability of primed sensitized peritoneal macrophages (PM phi) to prevent T. gondii intracellular proliferation in vitro was examined both with and without rIFN-gamma activation. Under these conditions, the inhibition of T. gondii multiplication was greatly enhanced in PM phi from mice immunized with a TSo and CT as an oral adjuvant. In contrast, PM phi from mice immunized with a TSo in association with CTB showed a decrease in their microbiostatic activity towards T. gondii. This negative effect on IFN-gamma-treated PM phi was cancelled out by the addition of a small amount of CT in association with TSo and CTB in the immunization regimen. These data suggest that CT could act as an oral adjuvant in vaccination against toxoplasmosis by increasing the microbiostatic activity of M phi activated with IFN-gamma. Further studies, using intestinal effector cells such as enterocytes, are needed to confirm the value of CT for enhancing this major mechanism of protection against T. gondii infection.

Mucosal immunity to infection with implications for vaccine development

The induction of effective mucosal immunity that also provides systemic immunity is a considerable challenge. Over the past two years, efforts to develop novel mucosal vaccine delivery systems to induce mucosal immunity against bacterial and viral diseases, including HIV, have dramatically increased. Here we cite novel vaccines and delivery systems being used to establish effective mucosal immunity.

Helper Th1 and Th2 cell responses following mucosal or systemic immunization with cholera toxin

We have used the potent mucosal immunogen cholera toxin (CT) to assess antigen-specific CD4+ T-cell responses, including Th1- and Th2-type cells in mucosa-associated tissues, e.g. Peyer's patches (PP), and systemic tissue, e.g. spleen (SP), for their regulatory role in the induction of CT-specific B-cell antibody responses in the gastrointestinal (GI) tract as well as in systemic sites. The CT was given by either oral or intravenous (i.v.) routes and the mice orally immunized with CT exhibited brisk IgA anti-CT antibody responses in faecal extracts and elevated IgG anti-CT antibody responses in serum. Further, significant IgA anti-CT spot-forming cells (SFCs) were seen in lamina propria lymphocytes (LPLs) from mice orally immunized with CT. In contrast, i.v. immunization with CT induced IgM and IgG anti-CT SFC responses in SP, and serum anti-CT antibodies of these two isotypes; no anti-CT responses were induced in the GI tract after immunization by this route. The CD4+ T cells isolated from PP and SP of mice orally immunized with CT were stimulated in vitro with CT-B-coated latex microspheres for 1-6 days, and the induction of IL-2 and interferon gamma (IFN-gamma) (Th1-type) or IL-4 and IL-5 (Th2-type) producing SFCs were analysed by a cytokine-specific ELISPOT and cytokine-specific mRNA was detected by reverse transcriptase (RT)-PCR assays.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of gastrointestinal antibody to Shiga toxin by orogastric immunization in mice

Shiga toxin (ST) is a protein toxin of Shigella dysenteriae type 1, a causative agent of severe diarrhoea and dysentery. In this report we describe the gastrointestinal secretory antibody response of mice following orogastric immunization with ST. Gastrointestinal secretions were sampled by a gastrointestinal lavage technique weekly for 5 weeks after initial immunization. Assay of lavage samples by ELISA showed that mice vaccinated orogastrically with various doses of ST developed gastrointestinal antibody to ST in a dose-dependent manner. Serum anti-ST activity developed by 5 weeks after initial immunization. The ability of ST to act as a mucosal immune adjuvant was investigated by coadministration of ST and keyhole limpet haemocyanin. In contrast to cholera toxin, a potent adjuvant, ST did not demonstrate adjuvant activity. The mouse gastrointestinal lavage model could be useful for further analysis of the cellular basis of ST immunogenicity.

Oral immunization with Toxoplasma gondii antigens in association with cholera toxin induces enhanced protective and cell-mediated immunity in C57BL/6 mice

Following oral immunization of C57BL/6 mice with a Toxoplasma gondii sonicate (TSo) in association with either cholera toxin (CT) or CT B subunit, the T. gondii-specific in vitro proliferation of splenic T lymphocytes was determined. Cytokines produced by these T cells were then characterized. After oral challenge with T. gondii 76K cysts, the percentage of cumulative survival was assessed, as was the number of brain cysts in the mice which survived. The TSo-specific proliferation of splenic T lymphocytes was greatly enhanced by the use of CT, whereas CT B subunit alone did not lead to amplification of splenic T-cell proliferation. The use of CT was associated with an increase of interleukin-2 (IL-2) and gamma interferon synthesis by TSo-stimulated splenic T cells, whereas no enhancement of IL-5 and IL-6 production was observed. IL-4 was not detected. A significant protection of mice immunized orally with TSo plus CT was observed in comparison with those immunized with TSo alone. This protection was associated with a large decrease in the number of brain cysts compared with the number found in naive mice infected orally with a sublethal dose of T. gondii 76K cysts. Further studies, using well-defined T. gondii proteins which are known to induce both mucosal and systemic immune responses, are needed to confirm the value of CT in the enhancement of protection against oral toxoplasmosis.