Background: Control and eradication of intestinal infections caused by protozoa are important biomedical challenges worldwide. Prophylactic control of coccidiosis has been achieved with the use of anticoccidial drugs; however, the increase in anticoccidial resistance has raised concerns about the need for new alternatives for the control of coccidial infections. In fact, new strategies are needed to induce potent protective immune responses in neonatal individuals. Methods: The effects of a dietary supplementation of mannan-oligosaccharide (yeast cell wall; YCW) on the local, humoral and cell-mediated immune responses, and intestinal replication of coccidia were evaluated in a neonatal animal model during natural exposure to Eimeria spp. A total of 840 one-day-old chicks were distributed among four dietary regimens: A) Control diet (no YCW) plus anticoccidial vaccine); B) Control diet plus coccidiostat; C) YCW diet plus anticoccidial vaccination; and D) YCW diet plus coccidiostat. Weight gain, feed consumption and immunological parameters were examined within the first seven weeks of life. Results: Dietary supplementation of 0.05% of YCW increased local mucosal IgA secretions, humoral and cell-mediated immune responses, and reduced parasite excretion in feces. Conclusion: Dietary supplementation of yeast cell wall in neonatal animals can enhance the immune response against coccidial infections. The present study reveals the potential of YCW as adjuvant for modulating mucosal immune responses.

This study was conducted to evaluate the effect of Saccharomyces cerevisiae yeast cell walls (YCWs) in diets with low doses of aflatoxin B1 (AFB1) and ochratoxin A (OTA), alone or in combination, on broiler performance and immune response. A total of 210 male broilers aged 1–21 days were used. Broilers were completely randomized into seven treatments with five replicates of six broilers each, as follows: 1) control diet; 2) control + 350 µg/kg AFB1; 3) Control + 350 µg/kg OTA; 4) Control + 350 µg/kg AFB1 and 350 µg/kg OTA; 5) Control + 350 µg/kg AFB1 and 1.5 kg/ton YCW; 6) control + 350 µg/kg OTA and 1.5 kg/ton YCW; 7) control + 350 µg/kg AFB1, 350 µg/kg OTA, and 1.5 kg/ton YCW. The broilers were housed under environmentally controlled conditions in Petersime battery cages. Weight gain, feed intake, and feed conversion index were measured. The relative weights of the thymus, spleen, and bursa of Fabricius (BF) were evaluated. The local immune response was assessed by quantifying the level of intestinal immunoglobulin A (IgA). The cellular immune response was evaluated using a delayed hypersensitivity test. Hemograms and blood cell counts were also performed. The results showed that mycotoxins decreased performance and reduced the immune response (p<0.05) of broilers. Weight gain and feed conversion improved in the groups receiving YCWs. The YCWs increased (p<0.05) intestinal IgAs and the cellular immune response (p<0.05). The addition of YCWs also affected the relative weight of the thymus, spleen, and BF (p<0.05), and the leukocyte, lymphocyte, and heterophil counts (p<0.05). The addition of YCWs can be an alternative to counterage the negative effect of low doses of AFB1 and OTA in broilers diets.

Considering that glycyrrhizic acid (GRA) has been shown to have in-vitro and in-vivo antiviral activity against a wide range of viruses as well as immunostimulating activity, a trial to evaluate its effects on the performance and the immune response against Newcastle disease of broiler chickens was carried out. The study was performed with one-day-old Ross x Ross broiler chickens. GRA was added to the drinking water throughout the 49-d production cycle at a dose of 0.03%. Sample size of the trial was established in a pilot assay. Results showed that broiler chickens treated with GRA presented better weight gain, final body weight, feed conversion ratio, and lower mortality rate than the non-treated controls. In addition, GRA-treated birds presented higher antibody titers against Newcastle disease virus and more efficient cellular immune response, as demonstrated by the late-hypersensitivity response test. Blood lymphocyte and thrombocyte counts also increased in this group. The histopathological examination of the bursa, spleen, and thymus revealed that only the thymus of the GRA-treated group had a clearly defined increase in cortex thickness on day 49. The bursa showed a higher number of lymphoid lesions in CG on days 21 and 49 compared with the GRA group. These results suggest that GRA has growth promotion properties, which are possibly linked to immune-based effects.

Aspergillosis affects all types of birds; it causes the loss of specimens with high ecologic value and also leads to significant economic losses within the poultry industry. The main etiologic agent is Aspergillus fumigatus, a filamentary fungus with multiple virulence factors, such as gliotoxin (GT), which is an immunosuppressive epipolythiodioxopiperazine molecule. Necropsy was performed on 73 poultry from different provenances, all of which presented with a respiratory semiology compatible with aspergillosis. A mycological culture was performed on the injured lungs of diseased birds, as was chloroform extraction of the GT, a thin-layer chromatography analysis (TLC), and a histopathology analysis with hematoxylin-eosin and Grocott stainings. The A. fumigatus identification was confirmed by PCR, where the ITS 1 5.1-5.8S-ITS 2 fragment of the rDNA complex was amplified. The in vitro GT production was studied by TLC in the recovered isolates from A. fumigatus. Seven isolates of A. fumigatus were obtained and in six of them, GT-like compounds were detected. In a lung sample, a compound with the same retention time (RF) as the reference GT was detected; whereas RF compounds different from the GT standard were observed in three lung samples. Aspergilosis, una infección natural en la avicultura: caracterización micológica y molecular y determinación de la producción de gliotoxina de aislamientos de Aspergillus fumigatus. La aspergilosis afecta a todos los tipos de aves; provoca la pérdida de especímenes con alto valor ecológico y también puede producir pérdidas económicas significativas dentro de la industria avícola. El principal agente etiológico es Aspergillus fumigatus, que es un hongo filamentoso con múltiples factores de virulencia, como la gliotoxina (GT), que es una molécula de epipolitiodioxopiperazina con propiedades inmunodepresoras. Se realizó la necropsia de 73 aves de diferente procedencia, todas presentaron signos respiratorios compatibles con aspergilosis. Se realizó el cultivo micológico en los pulmones dañados de las aves enfermas, como la extracción de gliotoxina con cloroformo, el análisis de cromatografía en capa fina (TLC), e histopatología con tinciones de hematoxilina-eosina y Grocott. La identificación de A. fumigatus se confirmó por PCR, donde se amplificó el fragmento ITS 1 5.1-5.8S-ITS 2 del complejo de rDNA. La producción de gliotoxina in vitro se estudió mediante el análisis de cromatografía en capa fina de los aislamientos de A. fumigatus recuperados. Se obtuvieron siete aislamientos de A. fumigatus y se detectaron compuestos similares a la gliotoxina en seis de ellos. En una muestra de pulmón, se detectó un compuesto con el mismo tiempo de retención (RF) que la gliotoxina de referencia, mientras que se observaron en tres muestras de pulmón, compuestos con diferentes tiempos de retención al de la gliotoxina estándar.