Effect of T-2 toxin and fermented wheat germ extract on the immune response of weaned pigs

The authors examined the dose dependent immunosuppressive effect of T-2 toxin, and the immunomodulating effect of a fermented wheat germ extract (FBK) feed supplement in pigs. Weaned castrated pigs of identical genotype, and of approximately 10-12 kg body weight were divided into 9 groups (n=6 in each group). The control (C) group received toxin free diet. Diet of groups T0.5, T1.0, T1.5 and T3.0 was contaminated with 0.5, 1.0, 1.5 and 3.0 ppm T-2 toxin, respectively. To the toxin containing diet of groups TFB0.5, TFB1.0, TFB1.5 and TFB3.0 FBK (Immunovet-HBM(R)) was added in a concentration of 1 g/kg. Immune response was measured after vaccinating the animals against Aujeszky's disease (day 1 and 5). Specific and non specific in vitro cellular immune response was measured on days 0, 7, 14 and 21 by the lymphocyte stimulation test (LST) induced by inactivated suspension of the Aujeszky virus, and phytohaemagglutinine (PHA-P), concanavalin-A (ConA), pokeweed mitogen (PWM), respectively. Humoral immune response, e.g. specific antibody titre was measured by an Aujeszky specific ELISA. The most expressed humoral immune response was observed on day 21, although antibody levels were significantly higher in group C than in the T-2 treated animals already on day 14. Immunoglobulin production in T0.5, T1.0, T1.5 and T3.0 was 44, 7, 45 and 27%, respectively, compared to controls (taken as 100%) on day 21. This decrease was compensated to 74, 44, 66 and 61%, respectively, using the feed additive (TFB0.5, TFB1.0, TFB1.5 and TFB3.0 groups). Changes in the cellular response due to treatments measured by LST could be observed also on days 14 and 21, on day 21 was the most expressed. The tendency was similar in case of specific (Aujeszky virus) and not specific (ConA, PHA, PWM) mitogens: 0.5-3.0 ppm T-2 toxin significantly decreased the rate of proliferation of the lymphocytes, the decrease was dose dependent and moderated by adding FBK to the diet. Cellular immune response of T-2 treated animals measured on day 21 compared to the response of the controls' (taken as 100%) concerning the specific mitogen was 78 (T0.5),71 (T1.0), 55 (T1.5) and 48% (T3.0), which was compensated to 86 (TFB0.5), 78 (TFB1.0), 70 (TFB1.5) and 52% (TFB3.0), respectively. In case of non specific mitogens (PHA, ConA and PWM) the results were the following: 95-98 (T0.5), 92-97 (T1.0), 81-87 (T1.5), 62-77 (T3.0) in T-2 treated animals, and 102-107 (TFB0.5), 96-100 (TFB1.0), 86-93 (TFB1.5), 72-87 (TFB3.0) in the T-2+FBK groups. It could be established, that all the measured parameters were significantly and dose dependently lower in pigs fed T-2 containing diet than in the controls. The fermented wheat germ extract supplementation induced a better immune response compared to pigs exposed to T-2.