INCLUSION BODIES
Tavishi
An Arizona autumn is not marked by anything seasonally except the changing of the calendar page and scores of Halloween decorations. Maybe temperatures drop to 70 degrees in the morning rather than the usual 80, but honestly, there is nothing that feels like a transition.
London, however, has the fall of my dreams. It's cold enough to wear flannels and coats and actually be comfortable, but it's not quite cold enough to make enjoying the outside impossible. I definitely still struggle with the temperatures quite a bit, but a lot less than I would if I was somewhere like Boston.
Anyways, it's fall here, and I am making the most of it. I've been collecting all the pretty leaves whenever I go anywhere, and making fun fall syrups for my coffees. I even made a PUMPKIN PIE! Or. Well. My flatmate did the actual work, I just did the grunt work of whisking and the dishes. I did get to creme brulee the top with our BLOWTORCH!!
That's right, I have a blowtorch.
This is entirely unrelated to the post, I just wanted an excuse to brag about my blowtorch and my crunchy leaf piles. This blog is the only place anyone has to listen to my yapping.
Oh, sorry for the late post- I was afflicted by great illness (A Cold).
Anyways, I've been known to be a fan of inclusion bodies. My guilty pleasure are these fun little clinical pathology accounts on instagram that post slides and ask you to guess the disease. That, and shrimp-breeders.
On topic!
Inclusion bodies are aggregates of protein, and act as little clues that distinctively point to one disease or another. Some inclusion bodies are a clear tell for certain pathologies.
Below I've listed some of my favs:
NEGRI BODIES
Negri bodies are the most classic veterinary inclusion body. This inclusion body is typically found in cells of the nervous tissue, and indicates rabies infection.
Rabies is transmitted by exchange of infected fluid, and makes its way from the body up the nerves and towards the central nervous system. When rabies is inside a cell, it uses its machinery to produce its viral proteins in order to synthesize more rabies virions.
These inclusion bodies are typically found in nerve cells, especially in the pyramidal cells of the hippocampus.
Under an H+E stain, Negri bodies stain eosinophilic, or pink! They are typically round or oval, and occasionally have basophilic granules in the center. Those can be a little hard to identify.
Can you identify the Negri bodies in this nervous tissue? Go to the next slide to see if you got it right!
LENZ INCLUSION BODIES
We come now to Lenz inclusion bodies, or the hallmark of canine distemper virus and other morbiliviruses. (Including phocine distemper viruses! You can bet your buttons I'm going to bring up pinnipeds.) CDV is a virus spread by inhalation of virions, hence why quarantine of infected dogs in a shelter space is essential. CDV first colonizes the immune cells of the respiratory system, before spreading to the secondary lymphoid tissues like the tonsils. Viral replication within the nervous system eventually leads to dissemination through the body's systems, when viruses can be found in the GI tract, central nervous system, and urinary cells.
CDV enters cells through the receptor CD150 on immune cells, and PVRL-4 on epithelial cells.
Lenz inclusion bodies are most indicative in later stages of infection, after infection has spread throughout the body. These inclusions can be found in nervous, renal, and respiratory tissue. Cells where Lenz bodies are most typically found include astrocytes and renal and respiratory epithelium. Lenz bodies are eosinophilic, or pink-staining, and can be found in both the cytoplasm and nuclei of the cell (more common in nervous tissue.)
HEINZ BODIES
Whereas Lenz and Negri bodies indicate specific viruses, Heinz bodies indicate a specific cellular process. These inclusions are indicative of oxidation of exposed sulfhydryl groups on hemoglobin, resulting in clumping. These clumps of hemoglobin are insoluble and are typically caused by the ingestion of something toxic.
Ingestion of acetaminophen, garlic, and onions can cause the formation of Heinz bodies in dogs and cats. Cats are more sensitive to acetaminophen ingestion when it comes to the formation of Heinz bodies.
Heinz bodies are found only in red blood cells, and can be visualized using Wright's stain or new methylene blue. When stained with New Methylene blue, Heinz bodies can be mistaken for Howell-Jolly bodies.
Can you identify the Heinz bodies in these erythrocytes? Go to the next slide to see if you got it right!
RUSSELL BODIES
Hello, Russell! I see you reading this, and have identified you as an inclusion body!!! Just kidding.
Just like Heinz bodies, Russell bodies are not accumulations from a specific pathogen; rather, Russell bodies can indicate a variety of problems. Russell bodies are eosinophilic masses of immunoglobulins, or antibodies, contained inside the folds of the rough endoplasmic reticulum. These inclusions are typically found in B cells, and when they're found, are called Mott cells.
Mott cells are formed when B cells are too proactive in producing antibodies, which can be a symptom of a variety of diseases, including multiple myeloma, B cell lymphoma, and more. Mott cells were first identified in the brains of monkeys with sleeping sickness.
Mott cells are very, very distinctive, as you can see below:
Can you identify the Mott cell in this blood smear? Go to the next slide to see if you got it right!
BABESIA
Babesia is a tick-borne protozooan parasite that replicates within the erythrocytes of mammals. Babesia has two species that infect dogs: B. canis and gibsoni.
When a tick bites an animal, it releases Babesia into the bloodstream. The parasite is, at this point, in its sporozoite stage of life. The sporozoites invade the red blood cells, and using these cells, form the trophozoite stage of life, where they reproduce asexually and form merozoites. It is in these stages of life that Babesia makes its classic inclusion bodies- a ring and the Maltese cross.
Babesia inclusions can occasionally be mistaken for Plasmodium falciparum, or a similar protozooan parasite. The two can generally most easily be told apart by symptoms the animal is experiencing. The Maltese cross is also very distinctly Babesia!
These are only a few of my favorite inclusion bodies- but there is no end of little Easter eggs hidden in blood smears and tissues. I suppose this is one of the things I really enjoy about histopathology- it feels like exploring a whole new world.
see you next week! Email me at kradiganscience24@gmail.com OR drop a comment below if you have any thoughts or fancy a chat about this post/future posts!
Comments