Ready-to-use single tube quadruplex PCR for differential identification of mutton, chicken, pork and beef in processed meat samples.

A reliable and sensitive identification method is required to tackle food adulteration mainly in meat production. We developed a dry reagent based ready-to-use single tube quadruplex PCR assay for accurate identification of chicken, mutton, beef and pork. The assay was found to be specific and reproducible. Thermo-stability studies of lyophilized PCR master mix were conducted at different temperature and time intervals, which revealed significant stability for 75 days at 4°C and for 60 days at 25°C. The developed assay was shown to be sensitive down to 16 pg DNA per reaction and the detection limit was found to be 0.01% (w/w) of each species. Furthermore, this method has been applied to the analysis of 68 commercial meat products and the results indicated that nine samples contained non-declared meat components. This dry reagent-based quadruplex PCR assay can be utilized to monitor various processed food products and also to maintain quality control in food industries mainly in the resource-limited settings.

Oral immunization of mice with Lactococcus lactis expressing Shiga toxin truncate confers enhanced protection against Shiga toxins of Escherichia coli O157:H7 and Shigella dysenteriae.

Regardless of the communal impact of Shiga toxins, till today neither a specific treatment nor licensed vaccine is available. Lactococcus lactis (L. lactis), generally regarded as safe organism, is well known to provide a valuable approach regarding the oral delivery of vaccines. This study was undertaken to evaluate the protective efficacy of Stx2a1 expressed in nisin-inducible L. lactis, against Shiga toxins (Stx1, Stx2) in mouse model. Oral immunization of BALB/c mice with LL-Stx2a1 elicited significant serum antibody titer with elevated fecal and serum IgA, along with minimized intestinal and kidney damage resulting in survival of immunized animals at 84% and 100% when challenged with 10 × LD50 of Escherichia coli O157 and Shigella dysenteriae toxins, respectively. HeLa cells incubated with immune sera and toxin mixture revealed high neutralizing capacity with 90% cell survivability against both the toxins. Mice immunized passively with both toxins and antibody mixture survived the observation period of 15 days, and the controls administered with sham sera and toxins were succumbed to death within 3 days. Our results revealed protective efficacy and toxin neutralization ability of LL-Stx2a1, proposing it as an oral vaccine candidate against Shiga toxicity mediated by E. coli O157 and S. dysenteriae.