Generation of oligomers of subunit vaccine candidate glycoprotein D of Herpes Simplex Virus-2 expressed in fusion with IgM Fc domain(s) in Escherichia coli: A strategy to enhance the immunogenicity of the antigen

Glycoprotein D (gD) of Herpes Simplex Virus-2 is used as an antigen in various anti-herpes subunit vaccines owing to its involvement in binding the host cell receptors for host infectivity. However, most of these monomeric protein based candidates have shown low immunogenicity in animal models. To enhance the immunogenicity of gD, a fresh approach of fusing its ectodomain with the Fc domain(s) of IgM has been adopted to oligomerize the viral antigen and to exploite the immune-modulating potential of IgM Fc. Six vaccine constructs, generated by fusing three gD-ectodomain-length-variants with the Ig µ-chain domain 4 (µCH4) and µCH3-CH4 fragment, were cloned in Escherichia coli using pET28b( +) vector. The vaccine proteins were expressed in the form of inclusion bodies (IBs) and were in vitro refolded into protein oligomers of high stoichiometries of ~ 15–24, with 70–80% refolding yields. The conformations of gD and Fc components of the refolded oligomers were analyzed by ELISA and CD spectroscopy and were found to be native-like. The sizes and profiles of the size-distribution of oligomers were determined by dynamic light scattering (DLS). The candidate C2 (gD-μCH3-CH4), showing the most compact oligomer size and uniform distribution of its particles was chosen as the suitable candidate for mice immunization studies to assess the immunogenicity of the antigen gD. The C2 oligomer stimulated a strong anti-gD humoral response with an antibody titer of 102,400 and a strong, biased Th1 immune response in C57BL/6 mice, indicating its potential as a strong immunogen which may serve as an effective vaccine candidate.

Adsorptive removal of water poisons from contaminated water by adsorbents

Adsorptive removal of water poisons such as Pb(II), Cu(II), Mn(II), Hg(II), CN(-), microbes, nerve and blister agents (concentration range from 100 to 1000 mg/L) were studied by using adsorbents such as active carbon, impregnated carbon and bentonite loaded fabric strip. Removal of water poisons (99.5%) could be achieved with an optimum stirring time of 5-15 min and weight of adsorbent of 0.8-8.0 g/100mL contaminated water, respectively. However, 85% bentonite loading was found to be most effective for Pb(II) removal. Effect of contaminants concentration was also studied.

Development of an immunodetection test for a botulinum-like neurotoxin produced by Clostridium sp. RKD

BACKGROUND & OBJECTIVES

Clostridial neurotoxins are among the most toxic substances known and cause severe illnesses in both humans and animals. A neurotoxigenic Clostridium sp. (strain RKD) isolated from intestine of decaying fish produced a novel, botulinum type B like neurotoxin as suggested by mouse bioassay, protection with anti-botulinum antibodies and PCR. The aim of the present investigation was to develop a laboratory based detection assay as an alternative to the mouse bioassay without compromising sensitivity and specificity.

METHODS

Growth and toxin production were carried out in trypticase peptone yeast-extract glucose (TPYG) broth. Toxicity was estimated in terms of minimum lethal dose (MLD) by mouse bioassay. The toxin was partially purified by acid precipitation. It was used for toxoid preparation by formaldehyde treatment. This purified IgG was used for detection of neurotoxin using indirect ELISA. The culture supernatant was concentrated using a stirred cell with a 50 kDa cut-off membrane at 4 degrees C. Further purification was carried out using Prep cell. Fractions showing toxicity and sufficient purity were pooled, concentrated and analyzed on sodium dodecyl sulphatepolyacrylamide gel electrophoresis (SDS-PAGE).

RESULTS

The toxin was purified with a recovery of 8.56 per cent. Polyclonal antiserum was raised in mice using partially purified toxin with a titre of 1: 80000. A detection assay with sensitivity of approximately 15 and 300 ng/ml for partially purified and crude toxins, respectively were achieved using an indirect ELISA method.

INTERPRETATION & CONCLUSION

The Clostridium sp. RKD produced a potent neurotoxin earlier shown to have novelties. A specific detection assay for the neurotoxin has been developed that may be useful both from food safety and clinical point of view.

Isolation and characterization of Clostridium botulinum type E from soil of Gwalior, India

A strain of Clostridium botulinum type E has been isolated from soil samples of Gwalior, India. The isolated strain shows curved vegetative cells with oval, bulging, and terminal spores. The production of toxin was detected by immunodiffusion test, symptomatic death of mice and mouse protection assay with trivalent antitoxin (A+B+E). The culture supernatant gave 10(3) MLD (minimum lethal dose) per ml without any protease treatment. Group specific and serotype specific primers amplified the DNA fragments of 260 bp and 445 bp, respectively, indicating Clostridium botulinum type 'E.'