Negri's bodies

Cytoplasmatic Inclusion bodies found in the purkinje cells of the brain in cases of rabies. Negri's bodies are important becuse their presence make possible a positive diagnosis of rabies.

In 1903, most of the histopathologic signs of rabies were recognized, but rabies inclusions had not yet been detected. At this time, Dr. Adelchi Negri reported the identification of what he believed to be the etiologic agent of rabies, the Negri body. In his report, he described Negri bodies as round or oval inclusions within the cytoplasm of nerve cells of animals infected with rabies. Negri bodies may vary in size from 0.25 to 27 µm. They are found most frequently in the pyramidal cells of Ammon's horn, and the Purkinje cells of the cerebellum. They are also found in the cells of the medulla and various other ganglia. Negri bodies can also be found in the neurons of the salivary glands, tongue, or other organs. Staining with Mann's, giemsa, or Sellers stains can permit differentiation of rabies inclusions from other intracellular inclusions. With these stains, Negri bodies appear magenta in color and have small (0.2 µm to 0.5 µm), dark-blue interior basophilic granules.

The American bacteriologist Anna Wessels Williams (1863-1954) in 1896 brought to the U.S. from the Pasteur Institute in Paris a culture of the rabies virus. The culture made possible large scale production of the rabies vaccine. Following this, she worked on developing quicker methods to diagnose rabies. At the time, rabies was diagnosed by injecting rabbits with brain tissue of dogs suspected of having the disease and waiting for the rabbits to develop rabies. The results of this test were available in several days, a long time to wait before treating a sick patient. She noticed distinctive cell structures in brain tissues of animals infected with the virus. While she was repeating her experiments which proved that these structures were indicative of the rabies infection, Adelchi Negri published his findings. In 1905 Williams published her own method of preparing and staining the tissue, which became a standard test for rabies and it made possible to get test results in less than half hour.

We thank Miroslav J. Novak, Research Scientist with the Shearwater Corporation, Huntsville, Alabama, for information.

• A. Negri:
  Contributo allo studio dell'eziologia della rabia.
  Bollettino della Societa medico-chirurgica, Pavia, 1903, 88, 229.
  Bollettino della Societa medico-chirurgica, Pavia, 1904, 22.
  Bollettino della Societa medico-chirurgica, Pavia, 1905, 321. Beitrag zum Studium de Aetiologie der Tollwuth.
  Zeitschrift für Hygiene und Infektionskrankheiten, Leipzig, 1903, 43: 507-528.