Transfection of infectious RNA and DNA/RNA layered vectors of semliki forest virus by the cell-penetrating peptide based reagent PepFect6

Comparative Analysis of Non-viral Transfection Methods in Mouse Embryonic Fibroblast Cells

Mouse embryonic fibroblast (MEF) cells are an important in vitro model for developmental biology, disease, and reprogramming studies. However, as with other primary cells, they are challenging to transfect. Although viral gene-delivery methods achieve high gene-delivery efficiency, challenges with cell mutagenesis and safety among others have led to the use and improvement of non-viral gene-delivery methods in MEF cells. Despite the importance of gene delivery in MEF cells, there is limited comparison of method/reagent efficacy. In this study, we compared the effectiveness of different gene-delivery methods and several reagents currently available in MEF cells by introducing a plasmid containing enhanced green fluorescent protein (EGFP). We analyze transfection efficiency by EGFP fluorescence. Our results suggest that two gene-delivery methods-electroporation and magnetofection in combination with a lipid reagent, are the most efficient transfection methods in MEF cells. This study provides a foundation for the selection of transfection methods or reagents when using MEF cells.

Alkaline hydrolysis to remove potentially infectious viral RNA contaminants from DNA

Background

Diagnostics and research of high-consequence animal disease agents is often limited to laboratories with a high level of biosecurity that restrict the transport of biological material. Often, sharing of DNA with external partners is needed to support diagnostics, forensics, or research. Even in the absence of virus, RNA from positive-sense single stranded RNA (+ssRNA) viruses that may contaminate otherwise purified DNA preparations continues to pose a threat due to its potential to be infectious via direct translation to yield viral proteins. While the risk of animal infection or accidental reconstitution and release of a virus from RNA is very low, the high impact of an animal disease event associated with the accidental release of some + ssRNA viruses, such as classical swine fever or foot-and-mouth disease viruses, necessitates the precaution of having procedures to ensure the complete inactivation of viruses and + ssRNA viral genomes. RNA and DNA are differentially susceptible to enzymatic degradations; however, such procedures are susceptible to unintended DNA damage and/or failure due to enzyme or cofactor instabilities. Therefore, we describe the development and verification of a robust and simple chemical and physical method to selectively degrade RNA from purified DNA preparations. The procedure employs incubation of DNA in 0.25 N sodium hydroxide at 65 °C for 1 h followed by neutralization and boiling for 10 min to hydrolyze contaminating RNA and inactivate animal disease viruses from DNA preparations. Additional critical quality control elements include use of a synthetic control RNA (SCR) and an SCR-specific real-time RT-PCR to track effectiveness of the procedure in a parallel treated control sample, and a pH check of reagents to ensure proper neutralization of alkaline conditions.

Results

The new procedure reduced intact RNA beyond the limit of detection by realtime RT-PCR and inactivated viruses by in vitro culture infectivity assays.

Conclusions

Treated DNA, while denatured, remains suitable for most common molecular biology procedures including PCR, transformation of E. coli, and molecular sequencing. The procedure ensures not only the inactivation of a variety of viruses but also the degradation through hydrolysis of potentially contaminating infectious + ssRNA viral genomes.

The Antimicrobial and Antiviral Applications of Cell-Penetrating Peptides

Over the past two decades, cell-penetrating peptides (CPPs) have become increasingly popular both in research and in application. There have been numerous studies on the physiochemical characteristics and behavior of CPPs in various environments; likewise, the mechanisms of entry and delivery capabilities of these peptides have also been extensively researched. Besides the fundamental issues, there is an enormous interest in the delivery capabilities of the peptides as the family of CPPs is a promising and mostly non-toxic delivery vector candidate for numerous medical applications such as gene silencing, transgene delivery, and splice correction. Lately, however, there has been an emerging field of study besides the high-profile gene therapy applications-the use of peptides and CPPs to combat various infections caused by harmful bacteria, fungi, and viruses.In this chapter, we aim to provide a short overview of the history and properties of CPPs which is followed by more thorough descriptions of antimicrobial and antiviral peptides. To achieve this, we analyze the origin of such peptides, give an overview of the mechanisms of action and discuss the various practical applications which are ongoing or have been suggested based on research.