Implications of Biosecurity in Food Safety

Owing to growing population of world, efforts are being made to maximise food production. Food safety should not be compromised to meet the food requirement of increasing population. Biosecurity is the imperative approach to ensure food safety. This is a holistic approach that interlinks health, environment, security and trade. Increased incidents of foodborne diseases led to promotion of biosecurity as a major priority policy worldwide to curtail such incidents and ensure food safety. Microbial risk management is an essential component of food safety. National biosecurity programmes are essentially required to identify the prospective modes of introduction and spread of a disease in a country or region and to specify the control measures to curtail the risk associated with the disease. International standards for various biosecurity sectors are set mainly by Codex Alimentarius Commission, the World Organisation for Animal Health and Commission on Phytosanitary Measures, which are implemented through the Sanitary and Phytosanitary Agreement, 1995 of World Trade Organisation. Agricultural biosecurity is of utmost importance in the countries that are large crop and animal producers, and these countries are at risk from alien pests and pathogens. Adequate biosecurity programmes are essential in all the countries to protect global environment, agriculture and biodiversity. Developing countries, particularly with large populations aiming maximised food production require stringent biosecurity approaches to provide safe and nutritious food to the people

Biological Warfare Agents

There is a long historic record of use of biological warfare (BW) agents by warring countriesagainst their enemies. However, the frequency of their use has increased since the beginningof the twentieth century. World war I witnessed the use of anthrax agent against human beingsand animals by Germans, followed by large-scale field trials by Japanese against war prisonersand Chinese population during world war II. Ironically, research and development in biologicalwarfare agents increased tremendously after the Geneva Protocol, signed in 1925, because ofits drawbacks which were overcome by Biological and Toxin Weapons Convention (BTWC) in1972. Biological warfare programme took back seat after the 1972 convention but biologicalagents regained their importance after the bioterrorist attacks of anthrax powder in 2001. In thelight of these attacks, many of which turned out to be hoax, general awareness is required aboutbiological warfare agents that can be used against them. This review has been written highlightingimportant biological warfare agents, diseases caused by them, possible therapies and otherprotection measures

Enhanced Production of Protective Antigen, a Potent Diagnostic Protein of Bacillus anthracis, the Causative Agent of Anthrax

Protective antigen (PA) produced by Bacillus anthracis is a highly immunogenic protein. Therefore, it has significant importance in serodiagnosis as well as a vaccine candidate for anthrax. In the present study, codons for PA gene were optimised and synthesised for its expression in Escherichia coli. Various expression conditions were optimised for scaled up production of rPA. The final yield of affinity chromatography purified protein was 40.8 mg/l during batch fermentation. For further purification, affinity purified protein was diafiltered and subjected to anion exchange chromatography. SDS-PAGE and Western blot was used to characterise the purified rPA protein. The diagnostic potential of purified rPA was evaluated in Western blot using standards reference serum AVR 801 and cutaneous anthrax clinical sera. The results of the present study established the optimum production of rPA in E. coli after codon optimisation for its subsequent use in diagnosis of anthrax infection

Probiotics: Microbial Therapy for Health Modulation

The human gastrointestinal tract is a complex ecosystem that harbours a rich and diversemicroflora. These microbes live in harmony with the host and exert various beneficial effects onhuman health by their metabolic activities. However, in our modern life style, frequent andindiscriminate use of antibiotics has disturbed this microbial ecosystem, resulting in occurrenceof various bowel diseases. Some live microbial food supplements can re-establish this microbialecosystem. Such a group of microorganisms, which positively influences the intestinal microbiotaby stimulating the growth of beneficial bacteria and suppressing the harmful ones, is collectivelyknown as probiotics. These have been consumed in the form of fermented milk products forcenturies. However, scientific interest in their use for health maintenance and disease preventionhas emerged over the past few years only.Various scientific evidences show that probiotics help to reduce several disorders includingdiarrhea, inflammatory bowel diseases, urinary tract infections, hypertension, allergies, and cancer.Besides, probiotics exert several other benefits also to human beings and animals. Importantissues in the probiotic therapy include selection of appropriate strain, its viability during storage,gut persistence potential and functional properties. Another category involved in gut health isprebiotics. These are non-digestible food ingredients, which beneficially affect the host byselectively stimulating the growth or activity of one or a limited number of beneficial bacteriain the colon. This review paper highlights the major health benefits of probiotic organisms,mechanisms of their action, criteria of selection, enumeration, and safety of their use for humanhealth

Visual Field Mapping by Tangent Screen and Humphrey Perimetry: A Comparative Study

Background and Objectives: (a) To compare manual tangent screen perimetry and automated Humphrey perimetry for visual field testing, and (b) to analyze whether manual tangent screen perimetry still has a role or it should be replaced by computerized automated Humphrey perimetry in physiology labs and clinical diagnostic settings.Methods: Study was done on 45 patients between 18 and 65 years of age that included 30 eyes of patients suffering from glaucoma/ other eye diseases giving rise to visual field defects, 5 eyes of patients suffering from neurological diseases and 10 eyes of normal subjects.All patients underwent perimetry examination by tangent screen at 1 meter distance (and 2 meter distance, if required) and automated Humphrey perimetry by Humphrey visual field analyzer (HFA) using 30-2 ‘white on white’ full threshold strategy. Tangent screen consists of black screen 2 meter square or 1 meter square. Accordingly, patient is seated at a distance of 2 meter or 1 meter respectively. A patient with organically constricted visual fields will show an increase in the size of the visual field when moved to a farther distance while a patient with functional visual field loss will often report the same absolute size of the field (tubular or gun-barrel field) to be consistent with their first field. This is clear evidence of functional visual field impairment.Results: Out of 45 patients, 29 were male and 16 were female. The age cases in the study ranged from 40-79 years with mean age of 60.70 years. Tangent screen perimetry was able to detect about 5 patients with early field defects and 15 patients with moderate/ advanced field defects. On the other hand, Humphrey automated perimetry was able to detect 10 patients with early field defects and 18 patients with moderate/ advanced field defects. While only 13.33% technicians preferred tangent screen perimetry, around three-fourths of the technicians found Humphrey automated perimetry more preferable. 91.11% technicians found HVF to be technically easier because the automated perimeter eliminates observer bias, is easier to perform and also overcomes the tedium of manual perimetry. Moreover, automated perimetry also uses quantified parameters while manual perimetry does not. On evaluating sensitivity and specificity of manual tangent screen perimeter using the Humphrey automated perimeter as the standard, the tests showed that the tangent screen perimeter had 75.75% sensitivity and 88.88% specificity. Since the mean time taken was more in automated perimetry: 474.5 sec, 474 sec and 459.9 sec versus 340.5 sec, 339.1 sec, and 339.1 sec in glaucoma, neurological and normal patients respectively; more patients-66% preferred tangent screen perimetry.Interpretation and Conclusions: Our results suggest that visual field testing with automated perimetry is superior to visual field testing with tangent screen perimetry. The automated perimeter picked up visual field defects in a larger number of eyes than the tangent screen perimeter. Visual field defects were more extensive on automated perimetry compared to tangent screen perimetry.The advantage of the HVF analyzer also lies in its ability to make use of quantified parameters like mean deviation and corrected pattern standard deviation to detect subtle worsening of visual field defect, with statistical level of confidence

One step Purification and Characterisation of Abrin Toxin from Abrus Precatorius Seeds

Abrin is a plant toxin obtained from Abrus precatorius seeds. It belongs to the type II ribosomal inactivating proteins (RIPs) consisting of two chains namely, catalytically active A chain and sugar binding B chain linked by a single disulphide bond.  Due to high toxicity of abrin, its exposure or consumption can lead to serious public health problems. In the present work, we have extracted and purified the abrin toxin from Abrus precatorius seeds. The toxin was purified using a single step anion exchange chromatography. The purified protein was characterized by SDS-PAGE and MALDI- TOF to confirm its purity. The toxicity of purified abrin toxin was also confirmed by injecting the toxin in mice.  The purified protein was further used to raise antibodies in mice and characterized by indirect Enzyme Linked Immunosorbent Assay. The results of present study established the use of single step ion exchange chromatography to purify abrin toxin for further development of its detection system

Production and Purification of Protective Antigen of Bacillus anthracis and Development of a Sandwich ELISA for its Detection

Anthrax, a zoonotic disease caused by Bacillus anthracis is important for biowarfare as well as public health point of view. The virulence factors of B. anthracis are encoded by the two plasmids, pXO1 and pXO2. Protective antigen (PA), an 83 kDa protein encoded by pXO1 along with lethal factor (LF, 90 kDa) or edema factor (EF, 89 kDa), makes the anthrax toxin responsible for causing the disease. Current detection and diagnostic systems for anthrax are mostly based on PA, a potential biomarker of B. anthracis. The objective of the present study was to produce and purify the PA for development of a sandwich ELISA for its detection. In this study, pYS5 plasmid containing the full PA gene was transformed into an 8 proteases deficient Bacillus anthracis host BH480. The PA was produced under shake flask conditions and purified using the gel filtration chromatography. The reactivity of PA with rabbit and mouse anti-PA antibodies was confirmed by Western blotting. The antibodies were purified and used for the development of a sandwich ELISA for detection of PA. The detection sensitivity of ELISA was found to be 3.9 ng/ mL PA

Heterologous expression of staphylococcal enterotoxin B (seb) gene for antibody production

Staphylococcal food poisoning (SFP) is caused by the members of superantigen family called staphylococcal enterotoxins (SEs). About 20 different types of SEs are produced by Staphylococcus aureus out of which type A (SEA), B (SEB), C (SEC) and D (SED) are commonly implicated in SFP. Among these, SEB is the most potent toxin and has also gained the status of biological warfare (BW) agent. Therefore, detection of SEB is of utmost importance. Any immunological detection system for SEB requires specific and sensitive antibodies which inturn depends on the purity of the SEB. In the present investigation, seb gene of S. aureus was cloned and expressed in E. coli along with biotin as fusion partner to facilitate the purification process. The yield of purified recombinant SEB was 13.1 mg/L of culture broth. Biotin tag from the biotinylated toxin was removed by protease cleavage, and both biotinylated and non-biotinylated toxin types were used for raising hyperimmune antiserum. Antisera were also specific for SEB amongst different kinds of food poisoning agents tested by indirect plate ELISA and western blot analysis. The quality of the antisera raised in this study was found superior to the commercially available antiserum. The investigation suggests that construction of recombinant staphylococcal enterotoxin B is a good alternative for production of pure enterotoxin to be used in antibody generation