Negative staining of Viruses


Viruses are microscopic infectious agents that can only replicate inside living cells. They have different shapes, sizes, and structures, and they can cause various diseases in humans, animals, and plants. To study viruses and understand their characteristics, scientists need to use special techniques that can make them visible under a microscope. One of these techniques is called negative staining.

Negative staining is a method of preparing virus samples for observation under an electron microscope. Electron microscopy is a type of microscopy that uses a beam of electrons instead of light to magnify and image the specimen. Electron microscopy can reveal details that are much smaller than what can be seen with a light microscope, such as the surface features and internal structures of viruses.

Negative staining works by coating the virus sample with a heavy metal salt solution, such as uranyl acetate, sodium silicotungstate, or ammonium molybdate. These solutions are called negative stains because they do not stain the virus itself, but rather the background around it. The negative stain fills the spaces between and around the virus particles, creating a dark contrast that outlines their shape and size. The virus particles remain unstained and appear light or transparent in the electron micrograph.

Negative staining is a simple and quick technique that does not require any fixation, dehydration, or embedding of the virus sample. It preserves the natural morphology and physiology of the virus without causing any distortion or damage. It also allows the visualization of surface antigens, spikes, filaments, and other features that are important for virus identification and classification.

In this article, we will explain the objectives, principle, procedure, advantages, limitations, and applications of negative staining of viruses. We will also discuss the transmission electron microscope and the preparation of viral samples for staining and visualization. We hope that this article will help you learn more about this useful technique in virology.