Negative contrast electron microscopic techniques for diagnosis of viruses of veterinary importance.

The study presents how Negative contrast electron microscopy (NCEM) is used as a common tool in identifying different types of viruses affecting various domestic and wild animals based on their size, form, and structure. The technique has also been used to serotype, or determine the specific types of, viruses present within the examined specimens.

Negative Contrast Electron Microscopy as a Diagnostic Tool

• The research applied negative contrast electron microscopy (NCEM) as a standard method in diagnosing viral infections in domestic and wild animals. NCEM allows scientists to see the tiny structures like viruses by staining them against a lighter background, helping them to stand out and be more easily identified.
• The viruses were identified by the technique in samples collected either from infected culture systems or clinical specimens from different animal species such as horses, cattle, sheep, dogs, cats, pigs, deer, Rocky Mountain bighorn sheep, antelope, and several avian species.
• Using NCEM, viruses were identified by evaluating their size, morphology (shape and structural features), and symmetry. The technique proved effective in recognizing a substantial array of viruses, such as adenoviruses, herpesviruses, paramyxoviruses, myxoviruses, picornaviruses, parvoviruses, coronaviruses, reoviruses, rotaviruses, and poxviruses.

Detection of Mixed Viral Populations

• In addition to identifying individual viral species, NCEM also proved efficient in demonstrating mixed populations of viruses. These are instances where an animal is infected with more than one type of virus at the same time.
• The most frequently seen mixed infections included combinations of coronaviruses and rotaviruses, and picorna- or parvoviruses with coronaviruses, rotaviruses, herpesviruses, or adenoviruses.

Use of Immunoelectron Microscopy for Virus Serotype Identification

• Further, the research used a technique known as immunoelectron microscopy to serotype the viral agents found in the specimens. Serotyping is a method used to identify a microorganism based on its reaction to antibodies.
• Through this method, the study identified multiple serotypes of bovine rotaviruses, coronaviruses, and herpesviruses, as well as bovine and equine adenoviruses.