Document Detail


Comparative analysis of antigen-targeting sequences used in DNA vaccines.
MedLine Citation:
PMID:  20013075     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Plasmid vectors can be optimized by including specific signals that promote antigen targeting to the major antigen presentation and processing pathways, increasing the immunogenicity and potency of DNA vaccines. A pVAX1-based backbone was used to encode the Green Fluorescence Protein (GFP) reporter gene fused either to ISG (Invariant Surface Glycoprotein) or to TSA (trans-sialidase) Trypanosoma brucei genes. The plasmids were further engineered to carry antigen-targeting sequences, which promote protein transport to the extracellular space (secretion signal), lysosomes (LAMP-1) and to the endoplasmic reticulum (adenovirus e1a). Transfection efficiency was not affected by differences in the size between each construct as no differences in the plasmid copy number per cell were found. This finding also suggests that the addition of both ISG gene and targeting sequences did not add sensitive regions prone to nuclease attack to the plasmid. Cells transfected with pVAX1GFP had a significant higher number of transcripts. This could be a result of lower mRNA stability and/or a lower transcription rate associated with the bigger transcripts. On the other hand, no differences were found between transcript levels of each ISG-GFP plasmids. Therefore, the addition of these targeting sequences does not affect the maturation/stability of the transcripts. Microscopy analysis showed differences in protein localization and fluorescent levels of cells transfected with pVAX1GFP and ISG constructs. Moreover, cells transfected with the lamp and secretory sequences presented a distinct distribution pattern when compared with ISG protein. Protein expression was quantified by flow cytometry. Higher cell fluorescence was observed in cells expressing the cytoplasmic fusion protein (ISG-GFP or TSA-GFP) compared with cells where the protein was transported to the lysosomal pathway. Protein transport to the endoplasmic reticulum does not lead to a decrease in the mean fluorescence values. The secretion signal was only effective when used in conjunction with TSA gene. Therefore, the characteristics of each protein (e.g., presence of transmembrane domains) might influence the efficacy of its cellular transport. This analysis constitutes a useful tool for the optimization of the design of DNA vaccines.
Authors:
Joana A Carvalho; Adriano R Azzoni; Duarte M F Prazeres; Gabriel A Monteiro
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular biotechnology     Volume:  44     ISSN:  1559-0305     ISO Abbreviation:  Mol. Biotechnol.     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-02-04     Completed Date:  2010-05-24     Revised Date:  2011-01-04    
Medline Journal Info:
Nlm Unique ID:  9423533     Medline TA:  Mol Biotechnol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  204-12     Citation Subset:  IM    
Affiliation:
IBB-Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Instituto Superior Técnico, Lisbon, Portugal.
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MeSH Terms
Descriptor/Qualifier:
Antigens / genetics*
Artificial Gene Fusion / methods
Base Sequence
Endoplasmic Reticulum / metabolism
Escherichia coli / genetics
Extracellular Space / metabolism
Genes, Reporter
Genetic Vectors
Glycoproteins / genetics,  metabolism
Green Fluorescent Proteins / metabolism
Lysosomes / metabolism
Membrane Glycoproteins / genetics,  metabolism
Molecular Sequence Data
Neuraminidase / genetics,  metabolism
Plasmids / genetics
Protein Transport
Sequence Analysis, DNA*
Vaccines, DNA / genetics,  immunology*
Chemical
Reg. No./Substance:
0/Antigens; 0/Glycoproteins; 0/Membrane Glycoproteins; 0/Vaccines, DNA; 147336-22-9/Green Fluorescent Proteins; EC 3.2.1.-/trans-sialidase; EC 3.2.1.18/Neuraminidase
Comments/Corrections
Erratum In:
Mol Biotechnol. 2011 Jan;47(1):94

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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