BK virus (Hemorrhagic cystitis)

00:00 / 00:00


BK virus (Hemorrhagic cystitis)


0 / 8 complete

USMLE® Step 1 questions

0 / 1 complete

High Yield Notes

3 pages


BK virus (Hemorrhagic cystitis)

of complete


USMLE® Step 1 style questions USMLE

of complete

A patient with a recent allogeneic stem cell transplant for treatment of chronic lymphocytic leukemia presents to his physician for evaluation of painful urination in addition to passing blood clots in his urine. The physician suspects a viral infection caused by the patient’s immunocompromised state. A virus from which of the following families is most likely the cause of this patient’s condition?  

Memory Anchors and Partner Content

External References

First Aid







BK virus p. 161

External Links



BK virus, or BKV, is a mosquito borne virus that’s named after the initials of the patient in whom the virus was first identified.

BK virus typically infects the urinary system of immunocompromised individuals, or those with a weakened immune system, especially those receiving immunosuppressive medications following organ transplants.

Major clinical manifestations of BKV infection include hemorrhagic cystitis, which is inflammation of the urinary bladder associated with bloody urine, in bone marrow transplant recipients; ureteral stenosis, or narrowing, and nephropathy in kidney transplant recipients.

BK virus belongs to the polyomavirus family along with the JC virus. These contain a circular double-stranded DNA genome which is surrounded by an icosahedral capsid, which is a spherical protein shell made up of 20 equilateral triangular faces.

They are also called non-enveloped viruses since the capsid isn’t covered by a lipid membrane.

It turns out that the vast majority of the population is infected with BK virus during their childhood.

The virus is thought to be transmitted from person to person through respiratory droplets when someone coughs or sneezes and by ingesting contaminated food and water.

Once inside, the virus moves through the bloodstream and eventually reaches the kidneys, specifically the renal tubular epithelial cells, where it starts to replicate.

But, the cytotoxic CD8+ T cells of our immune system keep the virus in check by killing any cell that has replicating BK virus inside it.

However, the sneaky little viruses are not eliminated, but instead they hit the snooze button, and go into a latent phase within the kidney epithelial cells.

In other words, they’re not dividing or causing disease.

Most people with a healthy immune system are able to keep BK virus in the latent phase in the kidney epithelial cells for their entire life.


The BK virus is a double-stranded DNA virus that infects the kidney epithelial cells, causing life-threatening hemorrhagic cystitis in immunocompromised people, especially in bone marrow transplant recipients. It can also cause nephropathy and ureteral stenosis in kidney transplant recipients. Symptoms include suprapubic pain, hematuria, symptoms of chronic kidney disease such as edema; fatigue, and breathlessness due to anemia.


Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.