Climbing the steps of viral atomic force microscopy: visualization of Dengue virus particles.

In recent years, the application of atomic force microscopy (AFM) to biological systems has highlighted the potential of this technology. AFM provides insights into studies of biological structures and interactions and can also identify and characterize a large panel of pathogens, including viruses. The Flaviviridae family contains a number of viruses that are important human and animal pathogens. Among them, Dengue virus causes epidemics with fatal outcomes mainly in the tropics. In this study, Dengue virus is visualized for the first time using the in air AFM technique. Images were obtained from a potassium-tartrate gradient-purified virus. This study enhances the application of AFM as a novel tool for the visualization and characterization of virus particles. Because flavivirus members are closely related, studies of the morphologic structure of the Dengue virus can reveal strategies that may be useful to identify and study other important viruses in the family, including the West Nile virus.

Use of atomic force microscopy as a diagnostic tool to identify orthopoxvirus.

Atomic force microscopy (AFM) is a versatile technique that permits the imaging of surfaces and generates topographical images from a variety of materials. Due to the fact that AFM requires minimum sample manipulation, it is a valuable tool for studying biological materials such as cells, DNA, bacteria and viruses. The aim of the present study was to standardize the AFM technique as a diagnostic tool for detection of naturally occurring orthopoxviruses. The samples analyzed were collected during natural outbreaks of Vaccinia virus (VACV) in dairy cattle in Brazil. These viruses are zoonotic infections; and therefore safe manipulation of all samples is required. The AFM technique would provide a more secure way to diagnose infection. By using the "in air" AFM technique after purification and inactivation process, relatively crude preparations of viruses were visualized rapidly. Details for efficient sample preparation and AFM imaging are described. The AFM technique provides a rapid and biosecure tool for the diagnosis of emerging orthopoxviruses and has potential as a tool for screening bioterrorism samples.