Host Immunity and Vaccine Development to Coccidia and <I>Salmonella</I> Infections in Chickens

Prophylactic and Therapeutic Efficacy of Ultrasonicated Rosmarinus officinalis Ethanolic Extract and its Chitosan-Loaded Nanoparticles Against Eimeria tenella Infected Broiler Chickens

PURPOSE

The in vivo efficacy of ultrasonicated Rosmarinus officinalis ethanolic extract (UROEE) and its chitosan-loaded nanoparticles (UROEE-CsNPs) was investigated as a dietary prophylactic agent and as a therapeutic treatment against Eimeria tenella infected broiler chickens.

METHODS

Chickens were infected with 4 × 104 E. tenella oocysts at 21 days old for primary infection and with 8 × 104 oocysts at 35 days old for secondary infection. Eleven experimental groups were conducted. Dietary addition of 100 mg/kg UROEE and 20 mg/kg for CsNPs as well as UROEE-CsNPs were included for prophylactic groups from day 1 to 42. The same doses were used for therapeutic treatment groups for 5 constitutive days. Oocyst output in feces was counted. Histopathological and immunohistochemical studies were conducted. Gene expression of pro-inflammatory cytokines as IFN-γ, IL-1β and IL-6 as well as anti-inflammatory cytokines as IL-10 and TGF-β4 was analyzed using semi-quantitative reverse transcriptase-PCR.

RESULTS

The results showed an efficacy of UROEE, CsNPs and UROEE-CsNPs in reduction of oocyst excretion and improving the cecal tissue architecture. CD4+ and CD8+ T lymphocytes protein expression were reduced. E. tenella infection lead to upregulation of pro-inflammatory cytokines as IFN-γ, IL-1β, IL-6 and anti-inflammatory cytokines as TGF-β4 following primary infection, while their expression was downregulated following secondary infection.

CONCLUSION

The dietary prophylactic additives and therapeutic treatments with UROEE, CsNPs and UROEE-CsNPs could decrease the inflammatory response to E. tenella as indicated by oocyst output reduction, histopathological improvements, CD4+ and CD8+ T cells protein expression reduction as well as reducing mRNA expression levels of the tested cytokines following primary and secondary infections. Consequently, these results will help to develop better-combating strategies for the control and prevention of coccidiosis on poultry farms as a dietary prophylactic agent or as a therapeutic treatment.

Impacts of Eimeria coinfection on growth performance, intestinal health and immune responses of broiler chickens

Coccidiosis caused by Eimeria is one of the most severe chicken diseases and imposes huge economic losses to the poultry industry globally. Multi-Eimeria species coinfections are common with the most prevalent combination being mixtures of Eimeria acervulina and Eimeria tenella. Although detrimental impacts of either E. acervulina or E. tenella on chicken health are well recognized, no information is available regarding their coinfection effects so far. This study was designed to investigate the influence of coinfection with E. acervulina and E. tenella on broiler chickens. 144 one-day-old broiler chickens within each of trials (trial I or II) were divided into four groups, namely, control group (CG), E. acervulina infection group (EAIG), E. tenella infection group (ETIG) and dual (E. acervulina and E. tenella) infection group (DIG). Then, chickens were measured for weight loss, lesion scores, oocyst outputs, histological changes and expressions of pro-inflammatory (interleukin [IL]-6, IL-8 and IL-18), regulatory (IL-10 and IL-22) cytokines and Toll-like receptors (TLR; TLR2 and TLR4) as well as intestinal barrier (mucin 2 [MUC2] and fattey acid-bingding proteins 2 and 6 [FABP2 and FABP6])- and tight junction (TJ; zonula occluden-1 [ZO-1], occludin [OCLN], and claudins 1 and 5 [CLDN1 and CLDN5])-related proteins at 3, 5, 7, 10, 14 and 21 days post-infection, respectively. Our results consistently showed that although ETIG and DIG exhibited a higher level of weight loss and a more amount of oocyst excretion than EAIG, DIG had lighter lesions than EAIG in the early phase because of coinfection with E. tenella. A higher (P < 0.05) ratio of duodenal villous height to crypt depth was also observed in DIG than EAIG. Moreover, histological changes in the duodenum and cecum varied by single and dual Eimeria infections. Expressions of the intestinal barrier- and TJ-related genes of EAIG, ETIG and DIG were significantly (P < 0.05) upregulated but their levels exhibited differential changes among infected chickens. Similarly, the infected chickens showed significant (P < 0.05) inflammatory responses and higher (P < 0.05) expressions of TLRs in the intestines in comparison to CG. These results presented a comprehensive physiological, pathological and immunological characterization of E. acervulina and E. tenella coinfection in broiler chickens and also shed insights into pathogenesis of multi-coccidia coinfections.

Applying different morphometric intestinal mucosa methods and the correlation with broilers performance under Eimeria challenge

The intestinal wall has on its surface, protrusions called villi that are responsible for the absorption of nutrients. Commonly, these structures have their dimensions measured to related more area surface with better absorption. However, the measurement of these villi neglects the inflammation and the presence of immature cells that increase the surface area but affect negatively the absorption and compromise the animal performance. The measurements of villi/crypt are traditional tools in animal research; however, they may overlook alterations that impact the mucosal functionality. This study aimed to compare the morphometry of the intestinal villi/crypt with the I See Inside (ISI) scoring methodology, exploring their correlation with zootechnical performance. Therefore, broilers were grouped as nonchallenged (NC) and challenged with Eimeria (CH) and jejunum samples were collected at 22 d for histological analysis. The same villi were submitted to the ISI methodology, which is based on the scoring of 8 parameters related to the inflammatory process, and the measurements of villus height (VH), villus width (VW), crypt depth (CD), crypt width (CW), VH:CD ratio and villi absorptive surface (VAS). The CH group presented higher ISI total score, VW, CD, CW and lower VH, VH:CD, and VAS in comparison to the NC group. While the villi/crypt morphometry did not exhibit correlations with performance, the presence of Eimeria oocysts and the ISI total score was positively correlated (P < 0.05) with the feed conversion ratio (FCR), demonstrating a statistical interaction between high ISI scores and worse performance. In conclusion, a larger villus is not related to better intestinal functionality when this enlargement is unleashed by the immune processes occurring inside. The scoring system that evaluates the type of alteration observed has a direct impact on the animal's zootechnical performance which is not observed with the single metric surface evaluation.

Coccidiosis: Recent Progress in Host Immunity and Alternatives to Antibiotic Strategies

Coccidiosis is an avian intestinal disease caused by several distinct species of Eimeria parasites that damage the host’s intestinal system, resulting in poor nutrition absorption, reduced growth, and often death. Increasing evidence from recent studies indicates that immune-based strategies such as the use of recombinant vaccines and various dietary immunomodulating feed additives can improve host defense against intracellular parasitism and reduce intestinal damage due to inflammatory responses induced by parasites. Therefore, a comprehensive understanding of the complex interactions between the host immune system, gut microbiota, enteroendocrine system, and parasites that contribute to the outcome of coccidiosis is necessary to develop logical strategies to control coccidiosis in the post-antibiotic era. Most important for vaccine development is the need to understand the protective role of the local intestinal immune response and the identification of various effector molecules which mediate anti-coccidial activity against intracellular parasites. This review summarizes the current understanding of the host immune response to coccidiosis in poultry and discusses various non-antibiotic strategies which are being developed for coccidiosis control. A better understanding of the basic immunobiology of pertinent host–parasite interactions in avian coccidiosis will facilitate the development of effective anti-Eimeria strategies to mitigate the negative effects of coccidiosis.

Reduction of macrophages by carrageenan decreases oocyst output and modifies local immune reaction in chick cecum with Eimeria tenella

This study aimed to evaluate the disease severity and local immune responses in macrophage-depleted chicks with Eimeria tenella. Macrophages were reduced by intraperitoneal injection of a carrageenan solution at 12, 13, and 16 days old, whereas the control group received intraperitoneal phosphate-buffered saline. Both chick groups were orally inoculated with E. tenella sporulated oocysts at 14 days old. Feces were collected daily, which were then quantified for oocysts. The chicks were sacrificed on day 5, and the ceca were collected for histopathological observation. The gene expression levels were measured using real-time quantitative reverse transcription-polymerase chain reaction. Macrophage-depleted chicks have been observed to shed a significantly reduced number of fecal oocysts compared to the infected control group. The parasite burden score in cecum specimens of macrophage-depleted chicks was significantly lower than those of infected control on day 5 after infection. Furthermore, macrophage reduction yielded significantly lower cecum histopathological scores and CD4 expression than those of the infected control group. The expression of interleukin (IL)-18, IL-22, interferon-γ, and inducible nitric oxide synthase was also noted to be significantly upregulated in both infected control and macrophage-depleted chicks compared to uninfected chicks. IL-4, IL-13, IL-17, and perforin expressions were also higher with macrophage depletion than in both control groups. These results suggest that macrophages serve as an invasive gate or a transporting vehicle to the site of first merogony. Furthermore, mononuclear phagocytes may play an important role in local immune responses, thus contributing to parasite development during early E. tenella infection.

In Vitro Anticoccidial Activity of Olive Pulp (Olea europaea L. var. Chemlal) Extract Against Eimeria Oocysts in Broiler Chickens

AIM

The objective of the present study was to investigate in vitro anticoccidial effect of olive pulp (Olea europaea L var. Chemlal) extract on the destruction of Eimeria spp. oocysts isolated from infected chickens naturally.

MATERIALS AND METHODS

The olive pulp (OP) powder was stirred manually in aqueous ethanol in preparation for extraction using the microwave-assisted extraction system. The identification of the phenolic compounds was obtained by ultra-high-performance liquid chromatography-mass spectrometry with electrospray ionisation (HPLC-ESI-MS). The treatment of Eimeria oocyst with OP extract and standard compounds (quercetin and oleuropein) leads to their lysis as shown by the release of substances absorbing at 273 nm.

RESULTS

Our results showed that the maximum number of reduced oocysts was recorded after 8 h of incubation of optimum OP extract, quercetin and oleuropein for different periods of time. Also, the number of Eimeria oocysts decreased considerably with increase concentrations after adding the optimum of OP extract in concentration ranging from 0.023 to 0.371 mg/ml. Positive correlation between the optimum OP extract concentrations and the number of Eimeria oocysts reduced was R² = 0.959. From this in vitro experiment, it can be concluded that the OP extract possesses an anti-Eimeria spp activity.

CONCLUSION

To our knowledge, this is the first time that quercetin and oleuropein were tested to evaluate their anticoccidial activity. The findings of this study showed that phenolic compound of OP extract tested separately possesses anti-Eimeria spp. effect. Further studies should be carried out to test its in vivo efficacy of the OP bioactive compounds in broiler chickens.

A Salmonella typhimurium ghost vaccine induces cytokine expression in vitro and immune responses in vivo and protects rats against homologous and heterologous challenges

Salmonella enteritidis and Salmonella typhimurium are important food-borne bacterial pathogens, which are responsible for diarrhea and gastroenteritis in humans and animals. In this study, S. typhimurium bacterial ghost (STG) was generated based on minimum inhibitory concentration (MIC) of sodium hydroxide (NaOH). Experimental studies performed using in vitro and in vivo experimental model systems to characterize effects of STG as a vaccine candidate. When compared with murine macrophages (RAW 264.7) exposed to PBS buffer (98.1%), the macrophages exposed to formalin-killed inactivated cells (FKC), live wild-type bacterial cells and NaOH-induced STG at 1 × 108 CFU/mL showed 85.6%, 66.5% and 84.6% cell viability, respectively. It suggests that STG significantly reduces the cytotoxic effect of wild-type bacterial cells. Furthermore, STG is an excellent inducer for mRNAs of pro-inflammatory cytokine (TNF-α, IL-1β) and factor (iNOS), anti-inflammatory cytokine (IL-10) and dual activities (IL-6) in the stimulated macrophage cells. In vivo, STG vaccine induced humoral and cellular immune responses and protection against homologous and heterologous challenges in rats. Furthermore, the immunogenicity and protective efficacy of STG vaccine were compared with those of FKC and non-vaccinated PBS control groups. The vaccinated rats from STG group exhibited higher levels of serum IgG antibody responses, serum bactericidal antibodies, and CD4+ and CD8+ T-cell populations than those of the FKC and PBS control groups. Most importantly, after challenge with homologous and heterologous strains, the bacterial loads in the STG group were markedly lower than the FKC and PBS control groups. In conclusion, these findings suggest that the STG vaccine induces protective immunity against homologous and heterologous challenges.

Metabolic alterations in broiler chickens experimentally infected with sporulated oocysts of Eimeria maxima

Metabolic and morphometric alterations of the duodenal villi caused by parasitism of chickens by Eimeria maxima were evaluated, using 100 male Cobb birds, randomly distributed into two groups (control and infected). The infected group was inoculated with 0.5 ml of a solution containing 5 × 10³ sporulated oocysts of Eimeria maxima. Ten birds per sample were sacrificed on the 6th, 11th, 22nd and 41st days post-infection (dpi). In order to evaluate the alterations, samples of duodenum, jejunum and ileum fragments were collected after necropsy for histological analysis. Villus biometry was determined by means of a slide graduated in microns that was attached to a binocular microscope. To evaluate the biochemical data, 5 ml of blood were sampled from the birds before sacrifice. The statistical analyses were performed using the GraphPad 5 statistical software for Windows. Tukey's multiple comparison test (p <0.05) was performed for the different dpi's and the unpaired t test for the difference between the groups. Infection by E. maxima causes both qualitative and quantitative alterations to the structure of the intestinal villi, thereby interfering with the absorption of nutrients such as calcium, phosphorus, magnesium, protein and lipids, with consequent reductions in the birds' weights.

Evaluation of novel adjuvant Eimeria profilin complex on intestinal host immune responses against live E. acervulina challenge infection

The effects against avian coccidiosis of two novel adjuvants, Quil A/cholesterol/dimethyl dioctadecyl ammonium bromide/Carbopol (QCDC) and QCDC/Bay R1005 (R)/cytosine-phosphate-guanosine (CpG) oligodeoxynucleotides (CpG ODN [T]) (QCDCRT) emulsified with profilin, a conserved Eimeria recombinant protein, were determined in broiler chickens. Chickens were subcutaneously immunized with isotonic saline (control group), profilin (P), profilin emulsified with QCDC (P-Q), or profilin with QCDCRT (P-QR) at 2 and 9 days post-hatch and orally challenged with 1.0 x 10(4) sporulated oocysts of Eimeria acervulina (EA) at 7 days postimmunization. All profilin-immunized groups showed increased body weight gain when compared to the control group, and the P-QR group had significantly higher body weight gain than did those of the P and P-Q groups following EA challenge infection. All groups immunized with profilin showed significantly decreased intestinal lesions compared with the control group, with the P-QR group showing the lowest intestinal lesions among the profilin-treated groups. Finally, the P-QR group showed greater CD4+/CD8+ and TCR1+/TCR2+ splenocytes and higher antiprofilin serum antibody titers compared with the P and P-Q (or both) groups following EA challenge infection. These results further suggest that vaccination of chickens with profilin, in combination with the QCDCRT adjuvant, may provide a novel control strategy against EA infection in commercial flocks.

Evolution of Salmonella nomenclature: a critical note

Salmonellae are widely distributed but nomenclaturally controversial pathogens of both humans and animals. Despite elaborate studies, much still remain to be discovered about these organisms. Although Salmonella nomenclature has proved to be rather complex, in 2005, Salmonella enterica finally gained official approval as the type species of the genus Salmonella. In addition, one other species has been approved and recognised in the genus Salmonella, namely, Salmonella bongori. New serovars (serotypes) are continually being discovered each year and reported in the journal Research in Microbiology. Salmonella serovars and their antigenic formulae are listed in the White-Kauffmann-Le Minor scheme and updated by the World Health Organization's Collaborating Centre for Reference and Research on Salmonella at the Pasteur Institute, Paris, France.

Effects of dietary supplementation with phytonutrients on vaccine-stimulated immunity against infection with Eimeria tenella

Two phytonutrient mixtures, VAC (carvacrol, cinnamaldehyde, and Capsicum oleoresin), and MC (Capsicum oleoresin and turmeric oleoresin), were evaluated for their effects on chicken immune responses following immunization with an Eimeria profilin protein. Chickens were fed with a non-supplemented diet, or with VAC- or MC-supplemented diets, immunized with profilin, and orally challenged with virulent oocysts of Eimeria tenella. Immunity against infection was evaluated by body weight, fecal oocyst shedding, profilin antibody levels, lymphocyte recall responses, cytokine expression, and lymphocyte subpopulations. Following immunization and infection, chickens fed the VAC- or MC-supplemented diets showed increased body weights, greater profilin antibody levels, and/or greater lymphocyte proliferation compared with non-supplemented controls. Prior to Eimeria infection, immunized chickens on the MC-supplemented diet showed reduced IFN-γ and IL-6 levels, but increased expression of TNFSF15, compared with non-supplemented controls. Post-infection levels of IFN-γ and IL-6 were increased, while IL-17F transcripts were decreased, with MC-supplementation. For VAC-supplemented diets, decreased IL-17F and TNFSF15 levels were observed only in infected chickens. Finally, immunized chickens fed the MC-supplemented diet exhibited increased MHC class II(+), CD4(+), CD8(+), TCR1+, or TCR2(+) T cells compared with nonsupplemented controls. Animals on the VAC-containing diet only displayed an increase in K1(+) macrophages. In conclusion, dietary supplementation with VAC or MC alters immune parameters following recombinant protein vaccination against avian coccidiosis.

Salmonella enteritidis ghost vaccine induces effective protection against lethal challenge in specific-pathogen-free chicks

Bacterial ghosts (BGs) are empty bacterial envelopes generated by expulsion of the bacterial genome and cytoplasmic contents from bacterial cells, and the process is mediated by lysis protein E encoded on bacteriophage PhiX174. BGs represent a new approach in vaccine development and have been applied to a variety of gram-negative bacterial vaccine candidates. In this study, a BG vaccine generated from Salmonella enteritidis (S. enteritidis) strain DH091 was prepared using the highly efficient plasmid, pBV-mE. The efficacy of the BG vaccine was tested using 75 chicks (Gallus gallus) kept under specific pathogen-free (SPF) conditions. A comprehensive evaluation of the immune response, including humoral and cellular immune responses, interferon-γ (IFN-γ) and interleukin-4 (IL-4) production, and histopathology of various tissues, was performed in BG-vaccinated animals subsequently challenged with S. enteritidis. The results were compared with animals that were immunized with the inactivated vaccine. S. enteritidis ghosts not only promoted the generation of high titer antibodies and IFN-γ and IL-4 production but also stimulated a significant increase in CD8(+) and CD4(+) T lymphocytes. In particular, the dramatic increase in CD8(+) T cells indicated that the vaccine was able to induce clearance of intracellular Salmonella. The protective effects of BG vaccination in SPF chicks against 5×10(9) colony forming units of S. enteritidis were a result of the induction of a more effective immune response than that observed with the inactivated vaccine. These findings demonstrate the potential of S. enteritidis ghosts to be used as effective vaccines.

Embryo vaccination of chickens using a novel adjuvant formulation stimulates protective immunity against Eimeria maxima infection

Our previous study demonstrated that chickens immunized subcutaneously with an Eimeria recombinant profilin protein vaccine emulsified in a Quil A/cholesterol/DDA/Carbopol (QCDC) adjuvant developed partial protection against experimental avian coccidiosis compared with animals immunized with profilin alone. Because in ovo vaccination is presently used in commercial applications worldwide throughout the poultry industry, the current study was undertaken to investigate chicken embryo vaccination with profilin plus QCDC adjuvant. Eighteen day-old embryos were immunized with isotonic saline (control), profilin alone, QCDC alone, or profilin plus QCDC, and orally challenged with live Eimeria maxima at 7 days post-hatch. Body weight gain, fecal oocyst output, and intestinal cytokine transcript levels were assessed as measures of protective immunity. While immunization with profilin alone or QCDC alone did not alter body weight gain of infected chickens compared with the saline control group, vaccination with profilin plus QCDC increased body weight gain such that it was equal to the uninfected controls. Immunization with profilin plus QCDC also reduced fecal oocyst shedding compared with unimmunized controls, although in this case QCDC failed to provide an adjuvant effect since no difference was observed between the profilin-only and profilin/QCDC groups. Finally, increased levels of transcripts encoding IL-1β, IL-15, and IFN-γ were seen in the intestinal tissues of animals given profilin plus QCDC compared with the profilin-only or QCDC-only groups. In summary, this study demonstrates an adjuvant effect of QCDC on body weight gain and intestinal cytokine responses following in ovo vaccination of chickens with an Eimeria profilin vaccine.

The effects of a novel adjuvant complex/Eimeria profilin vaccine on the intestinal host immune response against live E. acervulina challenge infection

The effects of a novel adjuvant composed of Quil A, cholesterol, dimethyl dioctadecyl ammonium bromide, and Carbopol (QCDC) on protective immunity against avian coccidiosis following immunization with an Eimeria recombinant protein were determined. Broiler chickens were subcutaneously immunized with isotonic saline (control), Eimeria recombinant profilin alone, or profilin emulsified with QCDC at 1 and 7 days post-hatch, and orally challenged with live Eimeria acervulina at 7 days following the last immunization. Body weight gains, gut lesion scores, fecal oocyst outputs, profilin serum antibody titers, lymphocyte proliferation, and intestinal cytokine transcript levels were assessed as measures of protective immunity. Chickens immunized with profilin plus QCDC showed increased body weight gains and decreased intestinal lesion scores compared with the profilin only or control groups. However, no differences were found in fecal oocyst shedding among the three groups. Profilin serum antibody titers and antigen-induced peripheral blood lymphocyte proliferation in the profilin/QCDC group were higher compared with the profilin only and control groups. Finally, while immunization with profilin alone or profilin plus QCDC uniformly increased the levels of intestinal transcripts encoding all cytokines examined (IL-1β, IL-10, IL-12, IL-15, IL-17F, and IFN-γ) compared with the control group, transcripts for IL-10 and IL-17F were further increased in the profilin/QCDC group compared with the profilin only group. In summary, this study provides the first evidence of the immunoenhancing activities of QCDC adjuvant in poultry.

Construction of EGFP-tagged rBCG of E.tenella and distribution in chickens

Chicken coccidiosis is a major parasitic disease with substantial economic burden to the poultry industry. Enhanced green fluorescent protein (EGFP) tagged recombinant Bacille Calmette-Guerin (rBCG), as a fusion protein with coccidian rhomboid antigen was constructed to track rBCG in vivo in chickens in this study. Immunization of chickens with one dose of rBCG pMV361-Rho/EGFP induced humoral immune response. The colonization of rBCG in liver, spleen, lung, kidney and caecum was observed by laser confocal microscopy. Real-time quantitative RT-PCR showed a rise expression level of rhomboid protein on the 7th day and a peak on the 14th day and disappearance on the 28th day after immunization. These results have significant implications for the development of rBCG vaccines against avian coccidiosis.

Characterization of monoclonal antibodies that recognize the Eimeria tenella microneme protein MIC2

The apicomplexan pathogens of Eimeria cause coccidiosis, an intestinal disease of chickens, which has a major economic impact on the poultry industry. Members of the Apicomplexa share an assortment of unique secretory organelles (rhoptries, micronemes and dense granules) that mediate invasion of host cells and formation and modification of the parasitophorous vacuole. Among these, microneme protein 2 from Eimeria tenella(EtMIC2) has a putative function in parasite adhesion to the host cell to initiate the invasion process. To investigate the role of EtMIC2 in host parasite interactions, the production and characterization of 12 monoclonal antibodies (mabs) produced against recombinant EtMIC2 proteins is described. All mabs reacted with molecules belonging to the apical complex of sporozoites and merozoites of E. tenella, E. acervulina and E. maxima in an immunofluorescence assay. By Western blot analysis, the mabs identified a developmentally regulated protein of 42 kDa corresponding to EtMIC 2 and cross-reacted with proteins in developmental stages of E. acervulina. Collectively, these mabs are useful tools for the detailed investigation of the characterization of EtMIC2 related proteins in Eimeria species.

Changes in the localization of antigen presenting cells and T cells in the utero-vaginal junction after repeated artificial insemination in laying hens

The goal of our present study was to observe whether the populations of antigen presenting cells (Ia+ cells) and T cell subsets (CD4+ and CD8+ T cells) change in the utero-vaginal junction (UVJ) of Rhode Island Red laying hens that showed dramatic declines in fertility after repeated artificial insemination (AI). Rhode Island Red laying hens were divided into two groups: a virgin group (R-V) and artificial inseminated group (R-AI), which was exposed to weekly AI for a period of 3 mo. Undiluted fresh semen collected from healthy Tosa-Jidori roosters, a native Japanese breed maintained in Kochi Prefecture, was used for AI. The UVJ tissues were processed for frozen sections, and Ia+ cells and CD4+ and CD8+ T cells were identified by immunohistochemistry. The Ia+ cells and CD4+ and CD8+ T cells were observed in the stroma and mucosal epithelium of UVJ in both the R-AI and R-V birds. The frequencies of them in the stroma were significantly higher in R-AI than R-V. The higher frequency of Ia+ cells in the UVJ of R-AI group indicated a greater potential capability for antigen presentation to CD4+ cells. The significant increase in CD8+ and CD4+ T cells in the UVJ of R-AI birds might be the result of a homing process of lymphocytes, which may affect sperm survivability and fertility.

Effects of Age and Gonadal Steroids on the Localization of Antigen Presenting Cells in the Epididymis of the Male Chicken, Gallus domesticus

The goal of this study was to localize antigen presenting cells (APC), which may play roles in defense against pathogens and fertility, and examine the effects of age and gonadal steroids on their population in the rooster epididymis. Healthy White Leghorn male birds (immature 60-day-old birds; matured 150-, 330-, and 550-day-old), and immature birds treated with testosterone propionate (TP) or estradiol benzoate (EB) for 3 or 6 days were used. Cryostat sections of the epididymis and ductus deference were immunostained for Ia to identify APC. RT-PCR was performed to confirm the expression of major histocompatibility complex class II (MHC class II) mRNA in the epididymis. Ia+ cells were localized in the surface epithelium and subepithelial layer of the ductules and occasionally in the luminal content of the epididymis and ductus deference. RT-PCR analysis confirmed expression of MHC class II mRNA in the epididymis, ductus deferens, testis, and spleen. The frequency of Ia+ cells in the subepithelial layer was significantly greater in the proximal efferent ductules than in the other two types of ductules in the epididymis of 550-day-old birds. Although there were no significant differences in the frequencies in the subepithelial layer of the proximal efferent ductules between 60- and 150-day-old birds, the frequencies were significantly greater in 330- and 550-day-old birds than in 60-day-old birds. The frequencies of Ia+ cells in the ductus deferences was increased in the 150-day-old birds compared with the 60-day-old birds, with a larger increase in 330- and 550-day-old birds. The Ia+ cell frequency was significantly increased by EB-injection, but not by TP-injection, on Days 3 and 6 of injection compared with Day 0. These results suggest that the population of APC in the epididymis increases with age after sexual maturation, and estrogen may be one of the factors involved in induction of Ia+ cells.

Differential responses of macrophages to Salmonella enterica serovars Enteritidis and Typhimurium

Macrophages are major effectors against Salmonella infection, and also transport bacteria between host tissues and provide a protected site for intracellular bacterial replication. We hypothesized that differences in chicken macrophage responses to Salmonella enterica serovar Enteritidis (SE) and serovar Typhimurium (ST) played a role in preferential infection of eggs by SE compared with ST. To test this hypothesis, we determined bacterial phagocytosis and intracellular viability and macrophage nitric oxide (NO) production following in vitro infection with SE or ST in the presence or absence of interferon-gamma (IFN-gamma). The effects of bacterial components, lipopolysaccharide (LPS), outer membrane proteins (OMP) and flagella, on NO production were also assessed. Our results showed: (1) in the presence or absence of IFN-gamma, the percentage macrophages phagocytizing SE and ST was similar; (2) the number of intracellular viable SE was significantly reduced compared with ST in the presence or absence of IFN-gamma; (3) increased macrophage necrosis was seen in the presence of IFN-gamma and ST; (4) Salmonella infection acted synergistically with IFN-gamma in induction of nitric oxide production; and (5) in the absence of IFN-gamma, macrophages produced significantly greater NO following treatment with SE outer membrane protein or flagella compared with ST OMP or flagella, while in the presence of IFN-gamma significantly less NO was produced following treatment with SE-LPS compared with ST-LPS. These results suggest that differential responses of chicken macrophages to SE versus ST may result in increased macrophage death with ST, which could result in an increased inflammatory response as compared to SE.

Protective immunity against Eimeria acervulina following in ovo immunization with a recombinant subunit vaccine and cytokine genes

A purified recombinant protein from Eimeria acervulina (3-1E) was used to vaccinate chickens in ovo against coccidiosis both alone and in combination with expression plasmids encoding the interleukin 1 (IL-1), IL-2, IL-6, IL-8, IL-15, IL-16, IL-17, IL-18, or gamma interferon (IFN-gamma) gene. When used alone, vaccination with 100 or 500 mug of 3-1E resulted in significantly decreased oocyst shedding compared with that in nonvaccinated chickens. Simultaneous vaccination of the 3-1E protein with the IL-1, -15, -16, or -17 gene induced higher serum antibody responses than 3-1E alone. To evaluate protective intestinal immunity, vaccinated birds were challenged with live E. acervulina oocysts 14 days posthatch, and fecal-oocyst shedding and body weight gain were determined as parameters of coccidiosis. Chickens vaccinated with 3-1E protein showed significantly lower oocyst shedding and normal body weight gain than nonvaccinated and infected controls. Simultaneous immunization with 3-1E and the IL-2, -15, -17, or -18 or IFN-gamma gene further reduced oocyst shedding compared with that achieved with 3-1E alone. These results provide the first evidence that in ovo vaccination with the recombinant 3-1E Eimeria protein induces protective intestinal immunity against coccidiosis, and this effect was enhanced by coadministration of genes encoding immunity-related cytokines.

Salmonella enteritidis clearance and immune responses in chickens following Salmonella vaccination and challenge

Our previous work showed that the cell-mediated immunity (CMI) was enhanced by live Salmonella vaccine (LV). The objective of this study was to evaluate the impact of live and killed Salmonella vaccines on Salmonella enteritidis (SE) clearance and to determine if the clearance was mediated by cell-mediated and/or humoral immunity. Chickens were first immunized at 2 weeks of age followed by a booster dose at 4 weeks, challenged with live SE 2 weeks later (6-week-old) and tested for CMI, antibody response and SE clearance 1-week post SE-challenge (7-week-old). Spleen cell proliferation induced by SE-flagella and Concanavalin A (Con A) were significantly higher and SE shedding was significantly lower in the LV group. The splenic CD3 population was significantly lower and B cells were higher in the control group compared to all the SE-challenged groups (with and without vaccination). Serum antibody to SE-flagella and envelope were significantly higher in the KV group compared to all the other groups. These results suggest that LV protects against SE infection, probably by enhancing the CMI.

Ovarian Cell-Mediated Immune Response to Salmonella enteritidis Infection in Laying Hens (Gallus Domesticus)

The aim of this study was to examine the response of cell-mediated ovarian immunity against Salmonella infection in hens. Laying hens were injected intraperitoneally with PBS (control) or Salmonella enteritidis (SE). Ovarian stroma containing stromal follicles, small white follicles (SWF), and third largest (F3) and the largest (F1) follicles were collected 12 or 24 h after inoculation and fixed in periodate-lysine-paraformaldehyde. Frozen sections were stained first for CD3+, CD4+, or CD8+ T cells and then for SE by a double immunostaining method. Immunoreaction products for SE were detected in the ovarian stroma, theca of stromal follicles, SWF, F3, and F1 at 12 and 24 h after inoculation. Immunopositive T-cell subsets were localized in the stroma and theca of follicles in birds inoculated with or without SE. The populations of CD3+, CD4+, and CD8+ T cells were significantly greater in the stroma and the theca of follicles 12 h after SE inoculation than in those of control birds (P < 0.01). Their frequencies were further increased in those tissues 24 h after inoculation (P < 0.01). Injection of SE did not cause significant differences in the CD4+:CD8+ T-cell ratio as both subsets increased proportionately. The current results indicate that the population of T-cell subsets increases in the ovarian stroma and the follicular tissues in response to SE invasion within 12 h of inoculation. Thus, cell-mediated immune response against SE, their products, or both may be induced in the hen ovary.

Immune modulation of the pulmonary hypertensive response to bacterial lipopolysaccharide (endotoxin) in broilers

The lungs of broilers are constantly challenged with lipopolysaccharide (LPS, endotoxin) that can activate leukocytes and trigger thromboxane A2 (TxA2)- and serotonin (5HT)-mediated pulmonary vasoconstriction leading to pulmonary hypertension. Among broilers from a single genetic line, some individuals respond to LPS with large increases in pulmonary arterial pressure, whereas others fail to exhibit any response to the same supramaximal dose of LPS. This extreme variability in the pulmonary hypertensive response to LPS appears to reflect variability in the types or proportions of chemical mediators released by leukocytes. Our research has confirmed that TxA2 and 5HT are potent pulmonary vasoconstrictors in broilers and that broilers hatched and reared together consistently exhibit pulmonary hypertension after i.v. injections of TxA2 or 5HT. Previous in vitro studies conducted using macrophages from different lines of chickens demonstrated innate variability in the LPS-stimulated induction of nitric oxide synthase (iNOS) followed by the onset of an LPS-refractory state. The NOS enzyme converts arginine to citrulline and nitric oxide (NO). It is known that NO produced by endothelial NOS serves as a key modulator of flow-dependent pulmonary vasodilation, and it is likely that NO generated by iNOS also contributes to the pulmonary vasodilator response. Accordingly, it is our hypothesis that the pulmonary hypertensive response to LPS in broilers is minimal when more vasodilators (NO, prostacyclin) than vasoconstrictors (TxA2, 5HT) are generated during an LPS challenge. Indeed, inhibiting NO production through pharmacological blockade of NOS with the inhibitor Nomega-nitro-L-arginine methyl ester modestly increased the baseline pulmonary arterial pressure and dramatically increased the pulmonary hypertensive response to LPS in all broilers evaluated. Innate differences in the effect of LPS on the pulmonary vasculature may contribute to differences in susceptibility of broilers to pulmonary hypertension syndrome (ascites).

Characterization of Stage-Specific and Cross-Reactive Antigens from Eimeria acervulina by Chicken Monoclonal Antibodies

The characterization of five chicken monoclonal antibodies (mAbs) that were developed against apical complex antigens of Eimeria acervulina sporozoites is realized and the mAbs reactivity to merozoites belonging to this species is tested. Using immuno-fluorescence assay (IFA), one mAb (HE-4) that recognized apical antigens common to sporozoites of E. acervulina and E. brunetti bound antigens localized on the apical tip of merozoites from all stages of development examined. The mAb 8E-1, reactive with antigens found on the apical tip of all chicken Eimeria sporozoites, also showed binding to antigens common to merozoites from all generations. Another mAb, 8C-3, which identified an antigen shared by sporozoites apical tip and sporocysts wall of E. acervulina reacted very weak and inconstantly with the merozoites from all generations whereas the mAbs 5D-11 and 8D-2 that recognized antigens shared by the sporozoites of E. acervulina and E. maxima (mAb 5D-11) and E. acervulina and E. brunetti (mAb 8D-2) did not react with the merozoites from any generation. Collectively, these results showed that the invasive stages of chicken Eimeria share cross reactive apical complex antigens which are inter-species and inter-generation-specific that might be components of a potential recombinant vaccine.