DNA-Launched Alphavirus Replicons Encoding a Fusion of Mycobacterial Antigens Acr and Ag85B Are Immunogenic and Protective in a Murine Model of TB Infection

There is an urgent need for effective prophylactic measures against Mycobacterium tuberculosis (Mtb) infection, particularly given the highly variable efficacy of Bacille Calmette-Guerin (BCG), the only licensed vaccine against tuberculosis (TB). Most studies indicate that cell-mediated immune responses involving both CD4+ and CD8+ T cells are necessary for effective immunity against Mtb. Genetic vaccination induces humoral and cellular immune responses, including CD4+ and CD8+ T-cell responses, against a variety of bacterial, viral, parasitic and tumor antigens, and this strategy may therefore hold promise for the development of more effective TB vaccines. Novel formulations and delivery strategies to improve the immunogenicity of DNA-based vaccines have recently been evaluated, and have shown varying degrees of success. In the present study, we evaluated DNA-launched Venezuelan equine encephalitis replicons (Vrep) encoding a novel fusion of the mycobacterial antigens α-crystallin (Acr) and antigen 85B (Ag85B), termed Vrep-Acr/Ag85B, for their immunogenicity and protective efficacy in a murine model of pulmonary TB. Vrep-Acr/Ag85B generated antigen-specific CD4+ and CD8+ T cell responses that persisted for at least 10 wk post-immunization. Interestingly, parenterally administered Vrep-Acr/Ag85B also induced T cell responses in the lung tissues, the primary site of infection, and inhibited bacterial growth in both the lungs and spleens following aerosol challenge with Mtb. DNA-launched Vrep may, therefore, represent an effective approach to the development of gene-based vaccines against TB, particularly as components of heterologous prime-boost strategies or as BCG boosters.     

Domain E of Bacillus macerans cyclodextrin glucanotransferase: An independent starch-binding domain

The starch-binding domains of glucoamylase I (SBD of GA-I) from Aspergillus awamori and of cyclodextrin glucanotransferase (domain E of CGTase) from Bacillus macerans were fused to the C-terminus of beta-galactosidase (beta-gal) The majority of the fusion proteins produced in Escherichia coli were found as inclusion bodies. Active fusion proteins were purified by partial solubilization of the inclusion bodies with 2 M urea followed by affinity chromatography. Adsorption isotherms of purified fusion proteins on corn starch and cross-linked amylose were generated. The beta-gal fusion proteins had similar affinities for cross-linked amylose and corn starch but significantly different saturation capacities on corn starch. The adsorption and elution data from the potato starch column as well as the adsorption isotherms of p-gal-domain E fusion protein (BDE109) on corn starch and cross-linked amylose demonstrated that domain E of CGTase is an independent domain, which retained its starch-binding activity when separated from the other four (A-D) domains in CGTase. (c) 1995 John Wiley & Sons Inc.     

Suppressed Deep Traps and Bandgap Fluctuations in Cu2CdSnS4 Solar Cells with ≈8% Efficiency

The identification of performance‐limiting factors is a crucial step in the development of solar cell technologies. Cu₂ZnSn(S,Se)₄‐based solar cells have shown promising power conversion efficiencies in recent years, but their performance remains inferior compared to other thin‐film solar cells. Moreover, the fundamental material characteristics that contribute to this inferior performance are unclear. In this paper, the performance‐limiting role of deep‐trap‐level‐inducing 2Cu_Zn+Sn_Zn defect clusters is revealed by comparing the defect formation energies and optoelectronic characteristics of Cu₂ZnSnS₄ and Cu₂CdSnS₄. It is shown that these deleterious defect clusters can be suppressed by substituting Zn with Cd in a Cu‐poor compositional region. The substitution of Zn with Cd also significantly reduces the bandgap fluctuations, despite the similarity in the formation energy of the Cu_Zn+Zn_Cu and Cu_Cd+Cd_Cu antisites. Detailed investigation of the Cu₂CdSnS₄ series with varying Cu/[Cd+Sn] ratios highlights the importance of Cu‐poor composition, presumably via the presence of V_Cu, in improving the optoelectronic properties of the cation‐substituted absorber. Finally, a 7.96% efficient Cu₂CdSnS₄ solar cell is demonstrated, which shows the highest efficiency among fully cation‐substituted absorbers based on Cu₂ZnSnS₄.     

Characterization of glucoamylase adsorption to raw starch

The adsorption of Aspergillus niger glucoamylase forms (GA-I and GA-II) to raw corn starch was studied as a function of pH, ionic strength, and temperature. A three-parameter model was developed to account for the specific and nonspecific adsorption of GA-I to starch. The adsorption of the GA-II form to raw starch was weak and independent of the pH and ionic strength of the mixture. GA-I was bound strongly to the starch surface, with association constant values ranging from 2 to 5 × 10⁶ M⁻¹. Maximum adsorption capacities (saturation concentrations) Q_max for GA-I were affected by pH, inonic strength, and temperature and varied between 1.6 and 4.3 mg protein g⁻¹ starch. The tightly bound GA-I could be specifically eluted from the starch surface with maltose, maltodextrin, or soluble starch. The adsorption of GA-II to starch in the presence of acarbose (glucoamylase activity inhibitor) indicated that the active site participates minimally in the adsorption process. The comparison of the distribution coefficients of GA-I and GA-II showed that the starch-binding domain, present only in GA-I, increases the affinity of GA-I for starch by two orders of magnitude.