| |
|
 |
Polyomavirus is the sole genus in the family Polyomaviridae. These viruses have a 5-kbp double-stranded DNA genome surrounded by a 40- to 50-nm icosahedral capsid. Human polyomaviruses (HPyVs) (JC virus [JCV] and BK virus [BKV]) are unique to humans and are widespread throughout the population. High titers of these viruses have been documented in municipal sewage. Both viruses are excreted in the urine either simultaneously or individually. Consequently, human polyomaviruses can be used as an indicator of human fecal pollution. JC virus (JCV) and BK virus (BKV) are human viruses classified in the genus Polyomavirus of the family Papovaviridae.
Asymptomatic primary infection usually occurs during childhood, followed by establishment of latent infections in the renal tissue, which can allow the viruses to persist indefinitely. Asymptomatic viruria can occur occasionally or continuously in infected individuals, and high titers of viral particles can be shed in urine from a healthy individual.
HPyVs are shed by more than 50% of immunocompetent individuals. It has been documented that individuals experiencing asymptomatic viruria can shed up to 1.5 X109 virus particles in a day, and therefore, high titers of HPyVs are generally found in urban sewage.
Polyomaviruses can be detected through a DNA analytical technique called quantitative polymerase chain reaction (qPCR). qPCR allows quantities of DNA from the polyomavirus to be amplified into large number of small copies of DNA sequences. This is accomplished with small pieces of DNA called primers that are complementary and specific to the polymaviruses to be detected.
Through a heating process called thermal cycling, the double stranded DNA is denatured and inserted with complementary primers to create exact copies of the DNA fragment desired. This process is repeated rapidly many times ensuring an exponential progression in the number of copied DNA. If the primers are successful in finding a site on the DNA fragment that is specific to the virus or genome to be studied, then billions of copies of the DNA fragment will be available and detected in real-time. The accumulation of DNA product is plotted as an amplification curve. The absence of an amplification curve indicates that the Polyomavirus is not present.
.
To strengthen the validity of the results, the Human Urine Virus ID™ service should be combined with other DNA analytical services such as the Human Bacteroidetes ID™ and Human Enterococcus ID™ services. Negative results should also be analyzed further for the presence of other human enteric viruses such as enteroviruses and adenoviruses.
|
