Aflatoxicosis: Lessons from Toxicity and Responses to Aflatoxin B 1 in Poultry

This review is a comprehensive introduction to the effects of poultry exposure to the toxic and carcinogenic mycotoxin aflatoxin B 1 (AFB 1 ). The relationship between AFB 1 sensitivity and metabolism, major direct and indirect effects of AFB 1 , recent studies of gene expression and transcriptome responses to exposure, and mitigation strategies to reduce toxicity are discussed. Exposure to AFB 1 primarily occurs by consumption of contaminated corn, grain or other feed components. Low levels of residual AFB 1 in poultry feeds can cause reduction in growth, feed conversion, egg production, and compromised immune functions, resulting in significant economic costs to producers. Thus, AFB 1 acts as a “force multiplier” synergizing the adverse effects of microbial pathogens and other agents, and factors detrimental to poultry health. Domestic turkeys ( Meleagris gallopavo ) are one of the most sensitive animals known to AFB 1 due, in large part, to a combination of efficient hepatic bioactivation by cytochromes P450 1A5 and 3A37, and deficient hepatic glutathione- S -transferase (GST)-mediated detoxification. Because of their sensitivity, turkeys are a good model to investigate chemopreventive treatments and feed additives for their ability to reduce AFB 1 toxicity. Transcriptome analysis (RNA-seq) of turkey poults (liver and spleen) has identified AFB 1 -induced gene expression changes in pathways of apoptosis, carcinogenesis, lipid regulation, antimicrobial activity, cytotoxicity and antigen presentation. Current research focuses on further identifying the molecular mechanisms underlying AFB 1 toxicity with the goal of reducing aflatoxicosis and improving poultry health.