Aflatoxin B1 dihydrodiol antibody: production and specificity

Glycation reduces the binding dynamics of aflatoxin B1 to human serum albumin: a comprehensive spectroscopic and computational investigation

Aflatoxin B1 (AFB1), a potent mutagen, is synthesized by Aspergillus parasiticus and Aspergillus flavus. Human serum albumin (HSA) is a globular protein with diverse roles. As AFB1 is ingested with food and is transported in the body via blood, it becomes pertinent to comprehend the effect of the binding of this toxin on the structure and conformation of HSA, which may help to get insight into the toxic effect of the exposure of the mycotoxin. In this study, multi-spectroscopic approaches have been used to evaluate the binding efficiency of AFB1 with both the native HSA (nHSA) and the glycated HSA (gHSA). Steady-state fluorescence spectroscopy reveals the static type of fluorescence quenching in the fluorescence emission spectra of nHSA and gHSA in the presence of AFB1. The binding constant (Kb) is calculated to be 6.88 × 104 M-1 for nHSA, while a reduced Kb value of 2.95 × 104 M-1 has been obtained for gHSA. The circular dichroism study confirms the change in the secondary structure of nHSA and gHSA in the presence of AFB1, followed by alterations in the melting temperature (Tm) of nHSA and gHSA. In silico computational findings envisaged the amino acid residues and bonds involved in the binding of nHSA and gHSA with AFB1. The comprehensive study analyzes the binding effectiveness of AFB1 with nHSA and gHSA and shows reduced binding of AFB1 to gHSA.Communicated by Ramaswamy H. Sarma.

Vomitoxin-induced dysregulation of serum IgA, IgM and IgG reactive with gut bacterial and self antigens

The effect of dietary vomitoxin exposure on immunoglobulins that react with naturally occurring gut bacterial and self antigens was assessed in the B6C3F1 mouse. Ingestion of 25 ppm vomitoxin for 4 and 8 wk resulted in significantly elevated total IgA but depressed total IgG and IgM in serum when compared with control mice fed semi-purified diet only. IgA specific for phosphorylcholine (PC) and inulin (haptens associated with intestinal bacteria) increased significantly in mice fed vomitoxin whereas IgM with the identical specificity decreased. When sera were assessed for autoantibodies recognizing DNA and bromelated mouse red blood cells (MRBC), vomitoxin-exposed mice exhibited elevated specific IgA as compared with controls. This occurred together with decreases in DNA-specific IgG and IgM, and decreases in MRBC-specific IgM. Additionally, vomitoxin exposure did not enhance the specific serum IgA response to orally administered trinitrophenylated sheep red blood cells (TNP-SRBC), but significantly depressed TNP-specific serum IgG. The results suggest that hyperelevation of total and specific serum IgA for oral and self antigens occurs during vomitoxin feeding and that may be coupled with down-regulation of total and specific IgM or IgG. These effects could be contributory to the capacity of vomitoxin to induce IgA immune complex glomerulonephritis.

Application of immunochemical assays to food analysis

Immunochemical assays are powerful bioanalytical techniques with application to several areas in food science, including food analysis, microbiology, nutrition, food safety, food quality, and process control. In principle, immunochemical techniques can be applied to the analysis of any compound, with only one specific antibody needed that can be obtained either from laboratory animals or, when available, from commercial sources. A well-designed immunochemical assay can detect targeted compounds at levels as low as 10(-12) M. Immunochemical techniques require little or no sample pretreatment, making these analytical procedures relatively rapid. The initial cost of developing an immunoanalytical assay may be high, but when the procedure is well established, the cost per test is often a fraction of that for other analytical methods. For these reasons, immunoanalytical assays provide an attractive alternative for the food analyst who requires either inexpensive qualitative screening tests or reliable quantitative methods with a high degree of sensitivity. This review concentrates on the use of enzyme immunoassay to address analytical problems in food chemistry and the analysis of various food components.

Application of immunoassay in the food industry

Immunoassay techniques using the highly specific and sensitive nature of immunological reactions have been developed and applied in the food industry for detecting the naturally occurring constituents, antibiotics, pesticide residues, microorganisms, and fragments of microbial constituents related to food analysis, food production, food processing, and food safety. Both polyclonal and monoclonal antibodies are employed for the development of the various immunoassay systems, including enzyme-linked immunoassay (ELISA) and radioimmunoassay (RIA). Immunoassay techniques provide complementary and/or alternate approaches in reducing the use of costly, sophisticated equipment and analysis time, but still maintaining reliability and improved sensitivity. Immunoassay techniques in their most simple forms provide excellent screening tools to detect adulteration and contaminations qualitatively. The application of immunoassay techniques contributes tremendously to the quality control and safety of our food supply.

Immunochemical assay applied to mycotoxin biosynthesis: ELISA comparison of sterigmatocystin production by Aspergillus versicolor and Aspergillus nidulans

Conventional thin layer and instrumental methods for analyzing mycotoxins and their precursors are time-consuming and make the investigation of mycotoxin biosynthesis particularly difficult. As an alternative, sensitive enzyme-liked immunosorbent assays (ELISAs) can be utilized to analyze for these compounds. In this report, sterigmatocystin production in test tube cultures of Aspergillus versicolor ATCC 18643 and Aspergillus nidulans ATCC 32610 were compared using competitive ELISA. Polyclonal antiserum that was prepared against a sterigmatocystin hemiacetal-bovine serum albumin conjugate exhibited greatest specificity for sterigmatocystin hemiacetal and sterigmatocystin with less reactivity for O-methylsterigmatocystin. The antiserum could be used to detect as little as 50 ng/ml sterigmatocystin in ELISA. Direct ELISA could be performed on diluted culture broth and on mycelial extracts solubilized with N,N-dimethylformamide. Aspergillus versicolor ATCC 18643 produced more sterigmatocystin in SLS medium than in YES medium, and showed maximal levels at between 9 to 12 days incubation. Approximately 75% of sterigmatocystin was detectable in mycelium (254 micrograms/ml culture) compared to the extracellular fraction (87 micrograms/ml culture). Aspergillus nidulans exhibited qualitatively similar patterns of growth and toxigenesis in SLS medium but accumulated maximal levels of only 15 micrograms mycelial sterigmatocystin/ml culture and 5 micrograms extracellular sterigmatocystin/ml broth, respectively.