RESUMO
Ideal immunogenicity in antigens is a prerequisite to eliciting a sufficiently strong immune and memory response via either DNA or protein vaccines. To improve immunogenicity, efforts have focused on high-level expression of target proteins and on maintaining their natural conformations. In the present work, two trimer motifs (MTQ and MTI) were designed and introduced into a plasmid vector with the tissue plasminogen activator signal peptide (tPA-SP). Next, we examined the efficacy and the efficiency of the two motifs as well as the introduction of tPA-SP and its mutant forms, 22P/A and 22P/G, in facilitating the secretory expression of trimeric proteins in mammalian cells. We found that both trimer motifs could produce the target protein in a trimeric form at a high level. Introduction of tPA-SP 22P/A markedly increased the secretory expression level. The combination of the trimer motif, MTQ, and the signal peptide, 22P/A, may serve as a universal mammalian vector for producing trimeric proteins in vaccine development.
Assuntos
Motivos de Aminoácidos/imunologia , Complexos Multiproteicos , Sinais Direcionadores de Proteínas/genética , Ativador de Plasminogênio Tecidual/genética , Sequência de Aminoácidos , Ensaio de Imunoadsorção Enzimática , Células HEK293 , HIV/genética , HIV/metabolismo , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/metabolismo , Humanos , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/metabolismo , Mutação , Estrutura Secundária de Proteína , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Ativador de Plasminogênio Tecidual/imunologia , Vacinas de DNA/imunologia , Vacinas de Subunidades Antigênicas/imunologia , Produtos do Gene gag do Vírus da Imunodeficiência Humana/genética , Produtos do Gene gag do Vírus da Imunodeficiência Humana/imunologia , Produtos do Gene gag do Vírus da Imunodeficiência Humana/metabolismoRESUMO
To evaluate the interaction between HIV-1 envelope glycoprotein (Env) and target cell receptors, various cell-cell-fusion assays have been developed. In the present study, we established a novel fusion system. In this system, the expression of the sensitive reporter gene, firefly luciferase (FL) gene, in the target cells was used to evaluate cell fusion event. Simultaneously, constitutively expressed Renilla luciferase (RL) gene was used to monitor effector cell number and viability. FL gave a wider dynamic range than other known reporters and the introduction of RL made the assay accurate and reproducible. This system is especially beneficial for investigation of potential entry-influencing agents, for its power of ruling out the false inhibition or enhancement caused by the artificial cell-number variation. As a case study, we applied this fusion system to observe the effect of a serine protease, thrombin, on HIV Env-mediated cell-cell fusion and have found the fusion enhancement activity of thrombin over two R5-tropic HIV strains.
Assuntos
Proteína gp160 do Envelope de HIV/metabolismo , HIV-1/fisiologia , Fusão de Membrana , Receptores de HIV/metabolismo , Trombina/metabolismo , Internalização do Vírus , Fusão Celular/métodos , Linhagem Celular , Inibidores da Fusão de HIV/farmacologia , HIV-1/efeitos dos fármacos , Humanos , Luciferases de Renilla/biossínteseRESUMO
The blending of aliphatic polyolefins and aromatic poly(ethylene terephthalate) (PET) based on different intrinsic viscosities (IV) was conducted in a torque rheometer. The comparison of blend components in terms of low density polythene (LDPE) and polypropylene (PP) in blending with PET was investigated, and the effects of the IV and proportion of PET on polymer blends are discussed in detail. Polymer blends with or without compatibilizer were examined by using a differential scanning calorimeter, thermogravimetric analyzer, rotary rheometer, field-emission scanning electron microscopy and a universal testing machine. It was found that the blending led to an increase in processability and a decrease in thermal stability for blends. The morphological analysis revealed that the incompatibility of blends was aggravated by a higher IV of PET, while this situation could be improved by the addition of compatibilizer. Results showed that there was an opposite effect for the tensile strength and the elongation at break of the polymer blend in the presence of a compatibilizer, wherein the influence of IV of PET was complicated.