Evaluating the Allergic Risk of Genetically Modified Soybean

Genetically modified (GM) soybean (carrying the EPSPS transgene) is the most common GM food in Korea. In order to assess whether genetic modification increases the allergenic risk of soybeans, the allergenicity and IgE-reactive components of wild-type and GM soybean extracts were compared in allergic adults who had been sensitized to soybeans. We enrolled 1,716 adult allergy patients and 40 healthy, non-atopic controls. Skin prick tests and IgE enzyme linked immunosorbent assays (ELISAs) were performed using wild-type and GM soybean extracts, along with other common inhaled allergens. The specificities of serum IgE antibodies from allergic patients and the identities of the IgE-reactive components of the soybean extracts were compared using ELISA inhibition testing, 2-dimensional gel electrophoresis, and IgE immunoblotting. To evaluate the effects of digestive enzymes and heat treatment, the soybean extracts were heated or pre- incubated with or without simulated gastric and intestinal fluids. The IgE sensitization rates to wild-type and GM soybeans were identical (3.8% of allergic adults), and circulating IgE antibodies specific for the two extracts were comparable. The results of the ELISA inhibition test, SDS-PAGE, and IgE immunoblotting showed a similar composition of IgE-binding components within the wild-type and GM extracts, which was confirmed using two-dimensional gel electrophoresis, IgE immunoblotting, and amino acid sequencing. None of the subjects had a positive response to purified EPSPS protein in the skin prick test, ELISA, or IgE immunoblot analysis. These findings suggest that the IgE sensitization rate to GM soybean extracts is identical to that of wild-type soybean extracts in adult allergy patients. In addition, based on both in vivo and in vitro methods, the allergenicity of wild type and GM soybean extracts was identical.

Isolation of Enterotoxin - positive Strains of Clostridium perfringens Type A in Korea

Clostridium perfringens is an anaerobe responsible for a wide range of diseases in animals and humans. Symptoms associated with C. perfringens food poisoning are caused by enterotoxin expressed only during sporulation of C. perfringens. It has been known that only 6% of global C. perfringens isolates carry the enterotoxin gene. We found 2 strains of enterotoxigenic C. perfringens out of 33 strains isolated from various sources in Korea using PCR. It was also found that these two strains were both type A that were strongly associated with food poisoning by checking the presence of four major lethal toxins (a-, B-, e-, l-toxin) using PCR. These results suggest that foodborne illness caused by C. perfringens may be common in Korea and that public education is necessary to prevent contamination of foods by this organism.

Rapid Diagnosis of Isoniazid Resistance by Detection of Mutations in katG and inhA of Mycobacterium tuberculosis from Korea

29 isoniazid (INH) resistant isolated strains and INH sensitive reference strain (H37Rv) of Mycobacterium tuberculosis were analysed by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and NciI restriction mapping for the detection of mutations in katG gene and inhA gene. The katG gene was divided into 3 parts (Akat, Bkat, Ckat; each part is about 800 bp) and amplified, inhA gene was amplified as a whole. Each of the amplified 800 bp DNA was digested into small fragments of less than 400 bp with restriction enzymes for the direct PCR-SSCP analysis. Firstly, 10 strains were analysed. All the 10 isolates showed clearly distinct SSCP patterns in Bkat from that of the reference strain, but only two isolates showed distinct SSCP patterns in Akat, and no isolated strain showed any distinct SSCP patterns in Ckat. 10 isolates also showed distinct SSCP patterns in inhA. NciI restriction mapping of Bkat showed mutation in codon 463 in 7 strains among 10 isolated strains. With these results an early detection strategy for the INH resistant M. tuberculosis was applied to the rest of 19 isolated INH resistant strains. Firstly, isolates were screened by Ncsl mapping in Bkat, and 13 strains showed mutations in codon 463. Secondly, the rest of 6 INH resistant isolates were analysed by PCR-SSCP with restriction enzyme digestion (PCR-SSCP-RE) in Bkat, and all the strains showed distinct SSCP patterns from that of the INH sensitive reference strain. This proved our strategy as effective and economic and time saving method in early detection of INH resistant M. tuberculosis.