Enzyme histochemical and serological inves- tigations on the immune system from chickens treated in ovo with aflatoxin B 1 (AFB 1 )

In this study, the detrimental effects of in ova administrated antitoxin B-1 (AFB(1)) on the immune system of chickens in the post-hatching period were investigated by enzyme histochemical and serological methods. For this purpose, 730 laying hen eggs were divided into 7 groups [3 control groups (not-treated, drilled-sealed and 30% ethanol (solvent)-injected groups) and 4 assay groups in which eggs were injected with increasing AFB(1) doses (2.5, 7.5, 12.5 and 17.5 ng/egg)] then conventionally incubated. The chickens were vaccinated against the Newcastle Disease (ND) and the Infectious Bursal Disease (I BE)) viruses on days 2, 5, 20 and on days 10 and 15 post-hatching, respectively. The serum antibody titres were assayed at the 1(st) and 28(th) days using Haemagglutination-Inhibition Test and ELISA respectively. The proportions of the peripheral blood lymphocytes (PBL) and the ANAE (alphanaphtyl acetate esterase) or ACP-ase (acid phosphatase) positive lymphocytes/PBL ratios were determined on the days 1, 10,20 and 28. The AFB(1)-treatment caused significant decreases in both the ANAE and ACP-ase positivity ratios of PBL., depending on the AFB(1) dose, during the post-hatching period, but the PBL counts were significantly depressed at the end of the experimental period only in chickens treated in ovo by the highest AFB(1) close (17.5 ng/egg). The anti-IBD antibody titres measured on the hatching day (maternal antibodies) and the anti-ND and IBD antibody titres measured on the day 28 post-hatching were significantly reduced in chicks treated with 12.5 and 17.5 ng AFB(1)/egg compared to the controls and have also gradually declined according to the AFB(1) dose. The results clearly evidenced that AFB(1) transferred into the fertilised eggs has caused deficiency in cellular and Immoral immunity and particularly in the embryo transfer of the maternal antibodies, that can partially explain the observed immunosuppressive AFB(1) effects in poultry.