The Influence of the Time and Temperature of Heat Treatment on the Allergenicity of Egg White Proteins

PURPOSE: The present study was performed to determine the factor, either duration or the temperature of heat treatment, exerting maximal and significant influence on the composition and allergenicity of egg white (EW) proteins. METHODS: Raw EW and 4 kinds of heated EW (fried EW, boiled EW for 10 minutes, boiled EW for 30 minutes, and baked EW for 20 minutes at 170degrees C) were prepared, and subsequently protein extraction was carried out. The proteins were separated by SDS-PAGE, and then immunoglobulin E (IgE) immunoblots were performed with the sera of 7 egg-allergic patients. Furthermore, the antigenic activities of ovalbumin (OVA), ovomucoid (OM), and ovotransferrin (OT) in different EW samples were measured by inhibition enzyme-linked Immuno-sorbent assay (ELISA). RESULTS: In SDS-PAGE analysis, the intensity of the protein band at 45 kD (corresponding to OVA) decreased significantly in boiled EW (30 minutes) and baked EW, but no change was observed in the case of boiled EW for 10 minutes. In IgE immunoblots, the IgE response to 34-50 kD (OM and OVA) in boiled EW for 30 minutes decreased significantly, when compared with raw EW and other heated EWs. In inhibition ELISA, a significant decrease in the OVA antigenic activity was observed in boiled EW for 30 minutes amongst other heated EW samples. However, OM antigenic activity in all kinds of heated EW including boiled EW for 30 minutes did not reduce after heat treatment. The OT antigenic activity nearly disappeared in heated EWs except in the case of boiled EW for 10 minutes. CONCLUSIONS: Amongst 4 kinds of heated EWs, the boiled EW for 30 minutes showed the most significant changes both in composition and reduction in allergenicity. Our results revealed that the duration of heat treatment had more influence on the composition and allergenicity of EW proteins than the temperature.

Proteomic Analysis of the Serum from Chicken Infected by Avian Influenza Virus

Avian influenza (AI) is an infectious, low pathogenic virus that is endemic all over the world and poses a potential threat to the poultry industry. Vaccination is a widely used effective method to prevent avian influenza virus. Here we employed a comparative proteomics approach [two-dimensional electrophoresis (2-DE) and matrix assisted laser desorption ionization-time of flight (MALDI-TOF)] to characterize proteome in the sera from the specific pathogen free (SPF) chickens, the vaccinated chickens, and the naturally infected chickens. We identified total 58 proteins that were differentially expressed in the sera of three groups. Among them ovotransferrin and vitamin D-binding protein were more expressed in the sera of naturally infected chickens compare with other groups. Our results suggested that the level of these two proteins in the serum may help to discriminate the naturally infected chicken from the vaccinated chicken.

Reduced allergenicities of irradiated egg white ovalbumin determined by skin prick test and ELISA inhibition test / 천식및알레르기

BACKGROUND: Hen's egg is the most frequent cause of food hypersensitivity in infants and young children. The major egg white(EW) proteins are ovalbumin(OVA), ovomucoid(OM), ovotransferrine, and lysozyme. OVA and OM have been generally considered to be the most allergic EW proteins. Food irradiation has been permitted in the fields of agriculture and food handling. Currently, it was suggested that the binding ability of specific IgE to gamma-irradiated OVA was rapidly decreased depending upon the irradiation dose. OBJECTIVE: The purpose of this study is to evaluate the application of food irradiation technology as a method for reducing the allergenicities of EW proteins. METHODS: A total of 10 egg-allergic patients less than 24 months of age were enrolled in this study. OVA was gamma-irradiated at 10 kGy in an aqueous state(2.0 mg/mL). Skin prick test and ELISA inhibition test were done to compare the IgE binding capacities before and after irradiation of OVA. RESULTS: One hundred percent of patients showed positive skin reactions with EW and native-OVA. Negative skin reactions to irradiated-OVA were observed in 7 of 10 patients and remainder 3 showed reduced skin reactions(p=0.001). In IgE-ELISA inhibition test, the IgE-binding capacities of irradiated-OVA reduced 1/80 (50% inhibition concentration: native-OVA-0.1 microgram/mL, irradiated-OVA-8 microgram/mL), respectively. CONCLUSION: We suggest that the allergenicity of OVA can be reduced by the treatment with gamma irradiation.

Efeito do íon ferro e da conalbumina no desenvolvimento e produçäo de proteínas extracelulares na linhagem Staphylococcus aureus S-6 / Effect of iron and conalbumin on the development and production of extracellular proteins by Staphylococcus aureus S-6 strain

O efeito da concentraçäo do íon ferro assim como da proteína conalbumina foi estudado na linhagem Staphylococcus aureus S-6 desenvolvida num meio contendo hidrolizado de caseína, meio NAK, e no mesmo após a remoçäo dos íons, meio NAKSA. Outras propriedades estudadas foram a produçäo de proteínas extracelulares coagulase, nuclease e as enterotoxinas A (EEA) e B (EEB). A adiçäo de ferro em concentraçöes superiores a 1,19microng/ml ao meio NAKSA contendo 1,11microng/ml de Mg2+ teve como consequência efeitos adversos, tanto para o desenvolvimento do microrganismo, quanto na produçäo de DNAse e EEB. A adiçäo de conalbumina ao meio NAKSA com 1,11microng/ml de Mg2+ näo teve efeito inibitório nas propriedades estudadas, ocorrendo inclusive um ligeiro estímulo na produçäo de proteínas extracelulares. A adiçäo de ferro näo afetou a retençäo de DNAse ligada à superfície celular, indicando que a açäo inibitória foi a nível de produçäo e näo de liberaçäo da enzima