The Ebola and Marburg viruses are some of the deadliest viruses in the world. In 
this study a series of G-rich DNA sequences derived from these types of viruses 
which possess the potential to form G-quadruplex structures are analyzed. A set 
of DNA oligonucleotides derived from original viral isolates was used as a 
representative modeling sequence with which to demonstrate the influence of 
thiazole orange on circular dichroism (CD) spectral profiles. The results show 
the unique profile of the induced CD (ICD) signal in the visible region caused 
by interactions between the ligand and G-quadruplexes. This ligand was found to 
stabilize the G-quadruplex structure and can also induce topological changes and 
facilitate G-quadruplex multimerization. Thus, the ICD signatures can be used to 
determine whether specific unknown sequences can form G-quadruplex motifs. The 
viral sequences were analyzed using standard spectral and electrophoretic 
methods. In addition, the ability to target G-quadruplexes located in 
filoviruses offers researchers attractive therapeutic targets which would be of 
particular use in the development of novel antiviral therapies. This article is 
part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta 
Giancola and Dr. Daniela Montesarchio.