A quantitative method for detection of three polyomaviruses
in patients
Amal Elfaitouri
JC virus (JCV), BK virus (BKV), and simian virus 40 (SV40) are species of the genus
polyomavirus within the Polyomaviridae family. Polyomaviruses are small viruses
(45 nm in diameter) with a DNA chromosome that only contains a few genes. The
DNA is surrounded only by a protein capsid. The three polyomaviruses JCV, BKV,
and SV40 are quite similar; about 70-72% of their DNA is identical. The name
polyoma refers to the viruses' ability to produce multiple (poly-) tumors (-oma). T.
Humans are natural hosts for BKV and JCV. The viruses often persist in what is
known as latent infections, where they stau in the body without causing disease.
They may produce disease in persons with an ineffective immune system, however.
If a latent BK virus is reactivated it may cause bleeding urinary tract infections in
patients with bone marrow transplants, and cause damage to or disease of the kidney
in patients who have received kidney transplants. Reactivation of latent JC virus has
been found to cause progressive damage or inflammation of the white matter of the
brain at multiple locations. SV40 is suspected to cause tumours in humans. It may
have been transferred to humans via contaminated polio vaccines in the 1950´s. The
polyomavirus genome has been detected in human tumors in several studies.
I developed a very sensitive and accurate method to detect the DNA of the three
polyomaviruses BKV, JCV, and SV40 in clinical samples. The method, quantitative
polymerase chain reaction (QPCR), involves copying small parts of the DNA and
measuring when the numer of copies exceed a certain predettermined threshold value.
the time when this threshold value is reached is a very accurate measure of how much
DNA there was to start with. I chose a small part of the DNA in one gene where the
three viruses have very similar DNA. The QPCR method was more sensitive than a
previously used method to detect viral DNA in patient samples, and should provide a
reliable and sensitive diagnostic method for screening and quantification of BKV,
JCV, and SV40 DNA in clinical samples. It should also be useful for studies on the
relation of polyomaviruses to tumours.
Degree project in Biology
Examensarbete i biologi, 20p, spring 2005
Biology Education Center and Department of Medical Sciences, Section of Virology,
Uppsala University
Supervisor: Jonas Blomberg