Chanpen WiwatWatanalai PanbangredSkorn MongkolsukSomsak PantuwatanaAmaret BhumiratanaMahidol University2018-07-042018-07-041995-02-01Current Microbiology. Vol.30, No.2 (1995), 69-7514320991034386512-s2.0-0028931295https://repository.li.mahidol.ac.th/handle/20.500.14594/17295Extraction of the S-layer protein by treatment with 6 m urea revealed a high-molecularweight protein in the extracts obtained from Bacillus thuringiensis subsp. israelensis (B.t.i) strain 4Q2. This protein band was found to be absent in partially cured (4Q2-72) and completely cured (c4Q2-72) strains. The antibody toward this S-layer protein was prepared and used to locate its antigenic protein on B.t.i cells by using indirect immunofluorescence. Immunodiffusion reactions and Western blot analysis confirmed the specificity of the anti-S-layer protein antibody. It was found that the antibody against 4Q2 S-layer protein, inhibited plasmid transfer via a conjugationlike process between, B.t.i. strains 4Q2-16 and c4Q2-72. That is, the frequency of transfer of plasmid pBC16 was reduced from 9.7×10-6 in the absence of the antibody to less than 1.0×10-8 in the presence of the antibody. The antibody was also found to reduce the frequency of pBC16 plasmid transfer via a conjugation-like process between B.t.i. strains A084-16-194 and c4Q2-72 from 2.2×10-5 in the absence of the antibody to 1.2×10-6 in the presence of the antibody. © 1995 Springer-Verlag.Mahidol UniversityImmunology and MicrobiologyArticleSCOPUS10.1007/BF00294185