Background: In prokaryotes, the ureases are multi-subunit, nickel-containing enzymes that catalyze the hydrolysis of urea to carbon dioxide and ammonia. The Brucella genomes contain two urease operons designated as ure1 and ure2. We investigated the role of the two Brucella suis urease operons on the infection, intracellular persistence, growth, and resistance to low-pH killing.

Standardized ethanol extracts of Allium sativum (garlic), Glycyrrhiza glabra (licorice), Plantago major (plantain) and Hippophae rhamnoides (sea buckthorn) were assessed for their effects on cellular immunity in laying hens. Birds (n = 25) had blood samples taken and both specific and non-specific immune cell responsiveness were evaluated by a leukocyte proliferation assay, carbon clearance test and SRBC phagocytosis in monocyte-derived macrophage cultures. Licorice and sea buckthorn (50 microg/mL) clearly enhanced the macrophage membrane function (p < 0.05 and p < 0.01, respectively). Dual effects on circulating phagocytes were revealed for plantain and sea buckthorn, while garlic at 200 microg/mL impaired the phagocytic capacity of blood cells. None of the tested extracts showed mitogenic properties, but high concentrations of sea buckthorn (400 microg/mL) inhibited leukocyte proliferation. Small concentrations (20 microg/mL) of licorice proved the co-mitogenic potential for both T and B avian lymphocytes (p < 0.05). Certain extracts definitely enhanced the fowl innate and/or specific cell immunity and may therefore improve host resistance in poultry. Considering the chicken as an important non-mammalian model that also serves as an available laboratory approach for some human diseases, herbs exerting immunomodulatory properties may find relevant clinical applications.

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