Search

A multiplex PCR protocol was established to simultaneously detect major bacterial pathogens in olive flounder (Paralichthys olivaceus) including Edwardsiella (E.) tarda, Streptococcus (S.) parauberis, and S. iniae. The PCR assay was able to detect 0.01 ng of E. tarda, 0.1 ng of S. parauberis, and 1 ng of S. iniae genomic DNA. Furthermore, this technique was found to have high specificity when tested with related bacterial species. This method represents a cheaper, faster, and reliable alternative for identifying major bacterial pathogens in olive flounder, the most important farmed fish in Korea.

Edwardsiella (E.) ictaluri is a major bacterial pathogen that affects commercially farmed striped catfish (Pangasius hypothalamus) in Vietnam. In a previous study, 19 strains of E. ictaluri collected from striped catfish were biochemically identified with an API-20E system. Here, the same 19 strains were used to assess the ability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS; applied using a MALDI Biotyper) to conduct rapid, easy and accurate identification of E. ictaluri. MALDI-TOF MS could directly detect the specific peptide patterns of cultured E. ictaluri colonies with high (＞ 2.0, indicating species-level identification) scores. MALDI Biotyper 3.0 software revealed that all of the strains examined in this study possessed highly similar peptide peak patterns. In addition, electrophoresis (SDS-PAGE) and subsequent immuno-blotting using a specific chicken antibody (IgY) against E. ictaluri revealed that the isolates had highly similar protein profiles and antigenic banding profiles. The results of this study suggest that E. ictaluri isolated from striped catfish in Vietnam have homologous protein compositions. This is important, because it indicates that MALDI-TOF MS analysis could potentially outperform the conventional methods of identifying E. ictaluri.

Identification of expressed protein profiles and antigenic determination are some of the most challenging aspects of proteomics. Two-dimensional gel electrophoresis (2-DE) combined with immunoblot analysis were employed to study the N. caninum proteome. Protein sample preparation was carried out by first conducting sonication, followed by adding lysis buffer containing 7M urea plus 2M thiourea to the purified tachyzoites in order to complete disruption. A total of 335 differentially expressed protein spots were detected using pH 4-7 IPG strip (7 cm) that were run in a 56 kVh isoelectric focusing (IEF) system. Of the spots analyzed, 64 were identified as antigenic spots on immunoblot profile. Major antigenic spots appeared at 65 kDa (pI 5.2-5.3), 51 kDa (pI 5.5), 38 kDa (pI 5.1), 33 kDa (pI 4.4), 29 kDa (pI 5.6) and 15.5 kDa (pI 5.0) were observed to be significantly distinct compared to the rest of the antigenic spots. The results indicate that combination of 2-DE and immunoblotting methods were thought as very useful tools in defining both proteins and antigens of N. caninum tachyzoites. Additionally, present 2-DE profiles may be valuable in further proteomic approaches and study of the pathogen.

Protein identification by peptide mass fingerprinting using matrix-assisted laser desorption ionization time of fight (MALDI-TOF) mass spectrometry (MS) can analyze unambiguously identity of the spots from a 2-dimensional electrophoresis (2-DE) gel. This study developed a technique for 2-DE of Salmonella enterica serovar Enteritidis (8. enteritidis) by improving the dissolution conditions by 2-DE using a pH 4 - 7 immobilized pH gradient (IPG) strip. This report examines the protein components from the patterns of the S. enteritidis protein. The most abundant protein displayed a great number of clusters within the pH 4.5 - 7 range with a molecular mass ranging from 35-80 kDa. Some of these spots were identified as metabolic related enzymes. The protein fraction was also analyzed using an immobilized pH gradient strip. Different proteins were identified on the spot according to the elongation factors. In addition, this study showed that the 2-DE analysis of S. enteritidis provides useful information regarding the S. enteritidis proteome, and this approach might provide a strategy for identifying bacterial proteins using a proteome technology.

Monoclonal anti-enrofloxacin antibody was prepared for a direct competitive enzyme-linked immunosorbent assay (ELISA) and purification system using monoclonal antibody (mAb) coupled magnetic nanoparticles (MNPs). The IC50 values of the developed mAb for enrofloxacin (ENR), ciprofloxacin, difloxacin, sarafloxacin, pefloxacin, and norfloxacin were 5.0, 8.3, 9.7, 21.7, 36.0, and 63.7 ng/mL, respectively. The lowest detectable level of ENR was 0.7 ng/mL in the prepared ELISA system. To validate the developed ELISA in the food matrix, known amounts of ENR were spiked in meat and egg samples at 10, 20 and 30 ng/mL. Recoveries for ENR ranged from 72.9 to 113.16% with a coefficient of variation (CV) of 2.42 to 10.11%. The applicability of the mAb-MNP system was verified by testing the recoveries for ENR residue in three different matrices. Recoveries for ENR ranged from 75.16 to 86.36%, while the CV ranged from 5.08 to 11.53%. Overall, ENR-specific monoclonal antibody was prepared and developed for use in competitive to ELISAs for the detection of ENR in animal meat samples. Furthermore, we suggest that a purification system for ENR using mAb-coupled MNPs could be useful for determination of ENR residue in food.

The present study was undertaken to produce monoclonal antibodies (MAbs) against immunoglobulin (Ig) purified from black rockfish (Sebastes schlegeli Higendorf) serum using protein A, mannan binding protein, and goat IgG affinity columns. These three different ligands were found to possess high affinity for black rockfish serum Ig. All of the Igs purified eluted at only 0.46 M NaCl concentration in anion exchange column chromatography and consisted of two bands at 70 kDa and 25 kDa in SDS-PAGE; they also had similar antigenicity for MAbs to Ig heavy chain in immunoblot assays. Therefore, black rockfish Ig is believed to exist as a single isotype within serum. The MAbs produced against Ig heavy chain reacted specifically with spots distributed over the pI range from 4.8 to 5.6 with a molecular weight of 70 kDa on two dimensional gel electrophoresis immunoblot profiles.

The present study was attempted to compare the Neospora caninum (N. caninum) antigenic bands recognized by different bovine immunoglobulin classes. A total 10, 5, 2, and 6 antigenic bands were exhibited on immunoblot profiles against bovine IgM, IgE, IgA, and IgG, respectively. A 46 kDa band was probed as a common antigenic band except IgA; 69 kDa band was bovine IgM and IgE; 33, 37, 55, and 79 kDa bands were bovine IgM and IgG; 72 kDa band was found IgM and IgA profiles. Based on the analysis, it appeared that different immunoglobulin classes recognizing different antigenic molecules were cooperating to cope with neosporosis.

Black rockfish (Sebastes schlegeli) is an important mariculture species in Korea. The production of this fish is drastically declined due to bacterial diseases, particularly streptococcosis caused by Lactococcus garvieae. The bacterial surface characteristics of SJ7 and TY6 were found to have capsule but not NB13 and YS18. The experiential evaluation of L. garvieae pathogenicity, the capsular isolates showed high cumulative mortality i.e. SJ7 (100%) and TY6 (60%) compared to non-capsular isolates. Based on this result the capsular isolates L. garvieae were highly suspected as the causative agent of streptococcosis in rockfish.