Negri

Negri bodies are eosinophilic, often found in the cytoplasm of nerve cells, and are pathognomonic (disease-defining) for rabies. They were discovered by and named after Adelchi Negri.

History

Adelchi Negri, an Italian pathologist, discovered Negri bodies in 1903. He found these inclusions in the nerve cells while studying the brains of animals infected with rabies. Negri bodies are considered a hallmark of rabies infection.

Characteristics

Negri bodies are intracytoplasmic inclusions, which means they are located within the cytoplasm of a cell. They are eosinophilic, meaning they have an affinity for eosin, a red dye used in staining procedures in microscopy. Negri bodies are round or oval in shape and can vary in size. They are composed of viral nucleocapsid aggregates, which are collections of viruses.

Association with Rabies

Negri bodies are pathognomonic for rabies, meaning their presence is definitive proof of a rabies infection. They are found in around 90% of cases of rabies in humans. Negri bodies are most commonly found in the Purkinje cells of the cerebellum and the pyramidal cells of the hippocampus, but they can also be found in other parts of the brain and occasionally in other tissues.

Detection

The detection of Negri bodies is a key part of diagnosing rabies. This is usually done through a direct fluorescent antibody test (dFA), which uses antibodies to bind to the rabies virus in a tissue sample and then uses fluorescence microscopy to visualize the virus.

See Also

• Rabies
• Adelchi Negri
• Purkinje cells
• Hippocampus

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