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Staphylococcal enterotoxins (SEs) are the second most common causal agents of food poisoning throughout the world. Staphylococcal enterotoxin B (SEB) is one of the most potent and a listed biological warfare agent. Therefore, its quick, accurate and sensitive detection is of paramount importance. But availability of sensitive and specific antibodies against SEB is the major bottleneck in the development of an immunodetection system. Therefore, in the present study seb gene was cloned and expressed in a heterologous host resulting in a yield of 92 mg pure toxin per litre of culture broth after Ni-NTA affinity purification. Antibodies raised against the recombinant toxin did not cross react with related enterotoxins and organisms that can gain access in the food. Further, a sandwich ELISA was developed to detect SEB after extraction from artificially spiked food samples like milk, orange juice, skim milk and khoya. The sandwich ELISA was able to detect SEB in the range of 0.25 to 0.49 ng/ml or g of food. The detection system developed in the present study is at least as specific and sensitive as other commercially available kits which use monoclonal antibodies. [ABSTRACT FROM AUTHOR]

Staphylococcal food poisoning (SFP) is one of the most prevalent causes of food-borne illness throughout the world. SFP is caused by 21 different types of staphylococcal enterotoxins produced by Staphylococcus aureus. Among these, staphylococcal enterotoxin B (SEB) is the most potent toxin and is a listed biological warfare (BW) agent. Therefore, development of immunological reagents for detection of SEB is of the utmost importance. High-affinity and specific monoclonal antibodies are being used for detection of SEB, but hybridoma clones tend to lose their antibody-secreting ability over time. This problem can be overcome by the use of recombinant antibodies produced in a bacterial system. In the present investigation, genes from a hybridoma clone encoding monoclonal antibody against SEB were immortalized using antibody phage display technology. A murine phage display library containing single-chain variable-fragment (ScFv) antibody genes was constructed in a pCANTAB 5E phagemid vector. Phage particles displaying ScFv were rescued by reinfection of helper phage followed by four rounds of biopanning for selection of SEB binding ScFv antibody fragments by using phage enzyme-linked immunosorbent assay (ELISA). Soluble SEB-ScFv antibodies were characterized from one of the clones showing high affinity for SEB. The anti-SEB ScFv antibody was highly specific, and its affinity constant was 3.16 nM as determined by surface plasmon resonance (SPR). These results demonstrate that the recombinant antibody constructed by immortalizing the antibody genes from a hybridoma clone is useful for immunodetection of SEB. [ABSTRACT FROM AUTHOR]

Abstract: Outbreaks of staphylococcal food poisoning (SFP) are very common across the world, however, there is hardly any report of SFP from the Indian subcontinent. An outbreak occurred in the state of Madhya Pradesh (India) after the consumption of a snack called “Bhalla” made up of potato balls fried in vegetable oil. More than 100 children and adults who ate the snack suffered from the typical symptoms of SFP and required hospitalization. Food and clinical samples were found to contain a large number of enterotoxigenic Staphylococcus aureus. All enterotoxigenic isolates produced a combination of SEB and SED enterotoxins and were sensitive to oxacillin and vancomycin. Isolates were characterized by molecular biology tools, viz., SDS-PAGE, amplified ribosomal DNA restriction analysis (ARDRA), randomly amplified polymorphic DNA (RAPD) and nucleotide sequencing of seb, sed, and 16S rDNA genes. Results of these studies suggested that the isolates, irrespective of their isolation from food or clinical samples, were clonal in origin. Further, seb gene sequence of isolates showed nucleotide variations at multiple sites when compared with other sequences available in the database. Representative isolates, one each from food and clinical samples, were found to be highly heat resistant (D 60 ∼15–16 min). Isolates obtained in the current outbreak need to be further studied to find out the impact on food safety guidelines with respect to thermal processing. [Copyright &y& Elsevier]

In the present study, a simple molecular imprinting technique for the quantitative measurement of lysophosphatidic acid (LPA) is reported for the first time through colorimetry. LPA is a phospholipid bioactive involved in many physiological and pathological processes like stimulating DNA synthesis, proliferating ovarian cancer and inducing cell migration. It is reported that the concentration of LPA in patients with gynecological cancers like ovarian cancer is considerably higher than in the control. The early diagnosis of ovarian cancer may exceed the survival rate of patients. There is a need for an analytical tool for point of care detection of ovarian cancer at an early stage. Herein, molecular imprinting technique is used to develop an imprinted β‐Cyclodextrin (β‐CD) polymer using LPA as a template. This MIP prepared was imprinted with an LPA cavity, which has been extended for colorimetry assay. The colorimetric LPA assay was conducted in the spiked blood serum sample. The detection limit of LPA in spiked serum samples is calculated as 0.078 μmol/L. [ABSTRACT FROM AUTHOR]