Usha Antony

Protective immune responses of recombinant VP2 subunit antigen of infectious bursal disease virus in chickens.

Infectious bursal disease virus (IBDV) is the causative agent of Gumboro disease and poses a huge threat to poultry industry. The risks associated with conventional attenuated viral vaccines make it indispensable to probe into the development of novel and rationally designed subunit vaccines which are safer as well as effective. VP2 is the major host-protective antigen found in IBDV capsid. It encompasses different independent epitopes responsible for the induction of neutralizing antibody. Here, we report the efficacy of the immunodominant fragment of VP2 which induces both humoral and cellular immunity against infectious bursal disease. A 366 bp fragment (52-417 bp) of the VP2 gene from an IBDV field isolate was amplified and expressed in Escherichia coli as a 21 kDa recombinant protein. The efficacy of rVP2(52-417) antigen was compared with two commercial IBDV whole virus vaccine strains. The rVP2(52-417) induced significantly high antibody titres in chicken compared to commercial vaccines and the anti-rVP2(52-417) sera showed reactivity with viral antigens from both commercial strains (P<0.0001) and field isolates. Also, the chicken splenocytes from rVP2(52-417) immunized group showed a significantly high proliferation (P<0.01) compared to other groups, which implies that the rVP2(52-417) fragment contains immunogenic epitopes capable of eliciting both B and T cell responses. Further, rVP2(52-417) conferred 100% protection against vIBDV challenge in the immunized chickens which was significantly higher (P<0.001) compared to 55-60% protection by commercial vaccine strains. Hence, the study confirms the efficacy of the immunodominant VP2 fragment that could be used as a potent vaccine against IBDV infection in chicken.

DNA vaccination with VP2 gene fragment confers protection against Infectious Bursal Disease Virus in chickens.

Infectious Bursal Disease Virus (IBDV) causes immunosuppression in young chickens by destruction of antibody producing B cells in the Bursa of Fabricius and poses a potential threat to the poultry industry. We have examined the protective efficacy of a subunit DNA vaccine against IBDV infection in chickens in this study. An immunodominant VP2 gene fragment (VP252-417) was cloned into CMV promoter based DNA vaccine vector pVAX1 and in vitro expression of the DNA encoded antigens was confirmed by transfection of CHO cells with vaccine constructs followed by RT-PCR and western blot analysis using IBDV-antiserum. Two weeks old chickens were immunized intramuscularly with pVAXVP252-417 and the in vivo transcription of the plasmid DNA was confirmed by RT-PCR analysis of DNA injected muscle tissue at different intervals of post immunization. Tissue distribution analysis revealed that the plasmid DNA was extensively distributed in muscle, spleen, kidney, liver, and bursa tissues. Chickens immunized with pVAXVP252-417 developed high titer (1:12,000) of anti-VP252-417 antibodies. Further, chicken splenocytes from pVAXVP252-417 immunized group showed a significantly high proliferation to the whole viral and recombinant antigen (P<0.01) compared to control groups, which implies that pVAXVP252-417 codes for immunogenic fragment which has epitopes capable of eliciting both B and T cell responses. This is evident by the fact that, pVAXVP252-417 immunized chicken conferred 75% protection against virulent IBDV (vIBDV) challenge compared to the control group. Thus, the present study confirms that the immunodominant VP2 fragment can be used as a potential DNA vaccine against IBDV infection in chickens.

Evaluation of antimicrobial activity and probiotic properties of wild strain Pichia kudriavzevii isolated from frozen Idli batter

The present research was undertaken to study the probiotic characteristics of Pichia kudriavzevii isolated from frozen idli batter. Polymerase chain reaction amplification with 18S rRNA primers confirmed Pichia kudriavzevii, a xylose‐utilizing probiotic strain. It was resistant to physiological concentrations of bile salts, pepsin and pancreatic enzyme. It also showed efficient auto‐aggregation as well as co‐aggregation ability with four commercial probiotic yeasts and exhibited good hydrophobicity in xylene and toluene. The strain inhibited the growth of 13 enteropathogens and showed a commensal relationship with four commercial probiotic yeast and bacteria. Moreover, it was resistant to 30 antibiotics with different modes of action. The yeast exhibited thermotolerance up to 95 °C for 2 h. The cell‐free supernatants were also found to be heat stable, indicating the presence of thermostable secondary metabolites. Hence it could be exploited as starter culture, co‐culture or probiotic in the preparation of fermented products or incorporated in heatable foods as well. Copyright

Physicochemical properties of cookies enriched with xylooligosaccharides

The growing commercial importance of xylooligosaccharides is based on their beneficial health properties, particularly their ability to stimulate the growth and activity of intestinal bacteria such as Bifidobacterium and Lactobacillus species. Xylooligosaccharides are less sweet, acid, and heat stable, with low recommended levels of intake compared to other oligosaccharides. In view of the consumer demand for foods with low sugar, low fat, and high fiber contents, they are suitable for incorporation into bakery products. In this study, we have developed wheat-based cookies incorporated with xylooligosaccharides at 5%, 10%, and 15% levels. The nutritive value and physicochemical properties of the cookies changed with xylooligosaccharides incorporation; both crude fiber and dietary fiber contents increased by 14% and 35%, respectively, in the enriched cookies. The moisture levels increased with increase in the percentage of xylooligosaccharides incorporated. Cookies with 5% xylooligosaccharides were found most acceptable, although the color was slightly darker compared to the control, while cookies with 10% and 15% xylooligosaccharides were softer and darker and therefore less acceptable. Enrichment with xylooligosaccharides at 5% provided a product stable for 21 days at room temperature (25 ± 2℃). The storage stability of cookies with higher levels of xylooligosaccharides was less than the 5% xylooligosaccharides cookies and control. The retention of the prebiotic xylooligosaccharides in the products was relatively high (74%).

Chemical, microbial and antibiotic susceptibility analyses of groundwater after a major flood event in Chennai

During floods, human exposure to pathogens through contaminated water leads to the outbreak of epidemic diseases. This research presents the first extensive assessment of surface and groundwater samples collected immediately after a flood (December 2015) and post-flood (April 2016) from the Adyar River of Chennai, a major city in India, for major ions, trace metals, bacterial population, and pathogens. Severe rains in a short period of time resulted in flooding which inundated the wells, allowing the entry of sewage contaminated river water into the groundwater zone. This has led to bacterial counts and chemical ions exceeding Bureau of Indian Standard’s recommended limits in most flood affected areas. Pathogens isolated from the groundwater showed resistance to antibiotics, namely ceftriaxone, doxycycline and nalidixic acid. However, they were sensitive to chloramphenicol, ciprofloxacin, norfloxacin, and tetracycline. Determining the antibiotic susceptibility of pathogens will help in the treatment of humans affected by contaminated water through an appropriate selection of prescribed medication.

Microbial and physico-chemical changes in tomato juice subjected to pulsed electric field treatment

The possibility of microbial reduction by external pulsed electric field (PEF) offers a new application for pulsed power technology. Applying PEF technology to food pasteurization is a promising non-thermal method. One of such application is prevention of microbial growth, an effect that is based on irrreversible permiabilization of cell membranes. The objective of this study was to increase the shelf life of tomato juice using PEF method. It is reported that the microbes present in tomato juice were inactivated by PEF process using co-axial and co-field continuous treatment chambers. The samples were subjected to different electric field intensities (30 and 50 kVcm-1) with the same flow rate (100 mL min-1) and the same pulse number (150 pulses). After treatment, in both co-axial and co-linear chambers, greater reduction in microbial counts were seen at higher intensity of 50 kVcm-1. The co-axial treatment chamber at 150 pulses was more effective than co-linear treatment chamber (1.16 and 0.77 log reduction). Key words: Pulsed electric field, co-field continuous flow treatment chamber, co-axial continuous flow treatment chamber, tomato juice, microbial growth reduction.

Determination of forced convection heat transfer coefficients and development of empirical correlations for milk in vessel with mechanical agitators

Abstract Heating of milk is an important unit operation to produce many milk based products. This process is done either in heat exchangers or in agitated vessels, where the mode and type of heat transfer plays a significant role. Use of mechanical agitator with suitable impeller would result in uniform agitation of the liquid. Data for forced convection heat transfer coefficients for milk in agitated vessel have not been documented. In the present investigation, forced convection heat transfer coefficients for milk, using mechanical agitators in vessels have been determined. Experiments have been conducted in vessels (Baffled as well as Unbaffled vessel) that were designed and fabricated under standard procedure employing: (1) Flat Six Blade Turbine impeller, (2) Inclined Six Blade Turbine impeller, (3) Three Blade Propeller impeller and (4) Two Bladed Paddle. Heat transfer coefficients were determined for

Assessment of the microbiological quality of koozh, a fermented millet beverage

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