Oral vitamin A supplementation of porcine epidemic diarrhea virus infected gilts enhances IgA and lactogenic immune protection of nursing piglets

Vitamin A (VA) has pleiotropic effects on the immune system and is critical for mucosal immune function and intestinal lymphocyte trafficking. We hypothesized that oral VA supplementation of porcine epidemic diarrhea virus (PEDV)-infected pregnant gilts would enhance the gut-mammary gland-secretory IgA axis to boost lactogenic immunity and passive protection of nursing piglets against PEDV challenge. Gilts received daily oral retinyl acetate (30 000 IU) starting at gestation day 76 throughout lactation. At 3–4 weeks pre-partum, VA-supplemented (PEDV + VA) and non-supplemented (PEDV) gilts were PEDV or mock inoculated (mock + VA and mock, respectively). PEDV + VA gilts had decreased mean PEDV RNA shedding titers and diarrhea scores. To determine if lactogenic immunity correlated with protection, all piglets were PEDV-challenged at 3–5 days post-partum. The survival rate of PEDV + VA litters was 74.2% compared with 55.9% in PEDV litters. Mock and mock + VA litter survival rates were 5.7% and 8.3%, respectively. PEDV + VA gilts had increased PEDV IgA antibody secreting cells and PEDV IgA antibodies in serum pre-partum and IgA+β7+ (gut homing) cells in milk post piglet challenge compared with PEDV gilts. Our findings suggest that oral VA supplementation may act as an adjuvant during pregnancy, enhancing maternal IgA and lactogenic immune protection in nursing piglets.

Effect of lignin supplementation of a diet contaminated with Fusarium mycotoxins on blood and intestinal lymphocyte subpopulations in chickens

The objective of the study was to investigate the effects of lignin supplementation of a diet contaminated with the Fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZEA) on peripheral blood leukocytes and duodenal immunocompetent cells in broiler chickens. From day 1 after hatching, all chickens were fed an identical control diet for two weeks. Then chickens of Group 1 continued to be fed the control diet, whereas Group 2 was fed the same diet supplemented with lignin at 0.5% level. Simultaneously, Group 3 started to receive a diet contaminated with DON (2.95 mg kg−1) and ZEA (1.59 mg kg−1), while Group 4 received an identical contaminated diet supplemented with 0.5% lignin for further two weeks. Samples of blood and duodenal tissue were collected from 6 birds of each group at 4 weeks of age. Neither counts of white blood cells nor phagocytic function in the peripheral blood were significantly affected in the mycotoxin- and/or lignin-treated birds. As compared to the control, increased numbers of IgM-bearing cells were found in the peripheral blood in Group 3 fed the contaminated diet (P < 0.05) and in Group 4 given the contaminated diet supplemented with lignin (P < 0.01). While the contaminated diet led to reduced numbers of duodenal CD4+ cells, in Group 2 treated only with lignin the number of duodenal CD4+ cells was increased. Lignin enrichment of the contaminated diet did not eliminate the mycotoxin-induced reduction in the number of duodenal CD4+ cells. The results suggest that dietary supplementation of lignin as an indigestible compound to poultry feed may increase the density of some intestinal immunocompetent cells without exerting effects on that in the peripheral blood. However, when added to a diet contaminated with Fusarium mycotoxins, lignin did not prevent the mycotoxin-induced changes in the numbers of blood and intestinal immunocompetent cells.