Studies on thermostable antigens, production of species-specific antiadrenal sera and comparison of immunological techniques in meat speciation

Detección inmunoquímica de la adulteración de chorizo de cerdo con proteínas de soja

Rabbit polyclonal antisera were produced against soy flour proteins extracted with 0.5 M NaCl solution and purified by affinity chromatography to detect adulteration in pork chorizo (sausage) with an enzyme-linked immunoabsorbent assay (ELISA). To detect adulteration the following saline extracts were prepared: 100% pork and 100% soy chorizo and mixtures of these two pro ducts (90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90), and extracts of two commercial chorizos labeled as pork. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that the salt solution was the most suitable for protein extraction compared to water and a 1% SDS solution. The commercial chorizos did not have the characteristic electrophoretic pattern for pork chorizos. The antibodies were specific for soy and its products, as there was no response to other vegetable and animal proteins by gel immunodiffusion assay or ELISA. The standard curve obtained with the ELISA results of the chorizo mixtures gave a correlation coefficient of r2 = 0.988. The two commercial chorizo values resulted in a 32 and 40% soy substitution. Total time for ELISA was optimized to 4 h, and 2 h if the plates were previously activated with the antigen. Variation coefficients of ELISA readings for replicates of the same extract in one plate and variation of different assays on different days were 2.3 and 8% respectively.

A rapid method for authentication of Buffalo (Bubalus bubalis) meat by Alkaline Lysis method of DNA extraction and species specific polymerase chain reaction

Buffalo (Bubalus bubalis) meat is a major item of export from India but export of beef i.e. meat from cattle (Bos indicus) is prohibited. Also, adulteration of buffalo meat with that of beef (meat from cattle) is a common fraudulent practice because of prohibition on cow slaughter in most states of India. Food analysts require precise identification techniques to implement such regulations. In the present study, a method of DNA extraction by Alkaline lysis from meat samples and speciation of buffalo meat using species specific Polymerase Chain Reaction (PCR) has been reported. Alkaline lysis technique is a rapid method which involves triturating meat with four volumes of 0.2N NaOH, dilution of resultant liquid extract with eight volumes of 0.2N NaOH, heating the mix 75 °C for 20 min followed by neutralization with eight volumes of 0.04N Tris HCl. Entire procedure of DNA extraction takes less than 30 min and it is economical as it involves less expensive chemicals. Method was successfully applied in animal byproducts also viz., liver, heart and kidney. For authentication of buffalo meat, pair of primers was designed based on mitochondrial D loop gene nucleotide sequence. PCR amplification using the designed primers gave amplicon of size 482 bp in buffalo and no amplification was detected in closely related species viz., cattle, sheep and goat meat samples. Results of the assay were highly repetitive and reliable. An export sample referred by export regulation authorities was also analyzed by using the Alkaline lysis method of DNA extraction and species specific PCR which enabled authentication of meat within 5 h.

Identification of species in animal feedstuffs by polymerase chain reaction--restriction fragment length polymorphism analysis of mitochondrial DNA

Restriction site analysis of Polymerase Chain Reaction (PCR) products of cytochrome b mitochondrial DNA was applied to identify species in meat meal and animal feedstuffs. PCR was used to amplify a variable region of cytochrome b mitochondrial DNA gene. Species differentiation was determined by digestion of the obtained 359 bp amplicon with restriction enzymes, which generated species-specific electrophoresis patterns; the sequencing of PCR products was used as confirming analysis. PCR-RFLP analysis revealed the presence of meat meal in animal feedstuffs and distinguished species of interest. The results supported the application of the method in control measures which should be adopted for meat-meal-based animal feed, as suggested by EU law. As a technical improvement, to simplify the analysis, the number of enzymes presented in this study for the detection of different species was smaller than others described in the literature; discrimination between ruminant and nonruminant species and between mammalian and poultry species was possible with few digestions.

Generation and applications of monoclonal antibodies for livestock production

Monoclonal antibodies (MCAs) have found widespread applications in livestock production. Although the generation of murine MCAs is at present a routine, the production of homologous MCAs, especially important for in vivo applications, is still hampered by the lack of efficient homologous fusion partners for immortalization of antibody producing lymphocytes of livestock species. At present, MCAs are used in immunodiagnostic tests e.g. to monitor livestock reproduction and quality of livestock products. In the future MCAs will also be used in immunosensors for real-time and on-site applications in the same areas. The commercial application of MCAs for the immunomodulation of (pharmacologically induced) physiological processes underlying important (re)production traits is at present limited to the use of anti-PMSG MCAs in PMSG-induced superovulation. However, many potentially interesting applications are under investigation (e.g. immunopotentiation of growth hormone to enhance growth; immunocytolysis of adipocytes to increase lean meat production; immunoneutralization of GnRH for immunocastration; immunoimitation of hormone activity with anti-idiotype antibodies). Attempts to use specific MCAs for the sexing of embryos have been disappointing, mainly because of the relatively low accuracy. In the future, MCAs against membrane proteins which are specific for X- or Y-chromosome bearing spermatozoa might be used for bulk separation of livestock sperm. In general, it is expected that engineered (homologous) recombinant MCAs will largely contribute to the development of a new generation of rapid immunodiagnostic tests and effective immunomodulation applications. They will further increase the use of MCAs in livestock production.