JC-Virus
JC virus (human polyomavirus 2, JC polyomavirus ) is grouped with the SV -40 and BK virus in the family of Polyomaviridae and therein to the genus polyomavirus. He is considered an opportunistic pathogen brain disorder characterized by demyelination, the so-called Progressive multifocal leukoencephalopathy ( PML).
Naming
The term " JC virus " is composed of the initials of John Cunningham, the patient in which the virus was first isolated in 1971, together.
Transmission
A long time been assumed that the transmission of the virus occurs via the respiratory tract, as viral DNA could be detected in tonsillar lymphocytes. Meanwhile, there is also evidence of a fecal- oral transmission of virus detection in the stool.
Infection
The infection usually occurs during childhood. About 85% of adults worldwide show antibodies to the JC virus as an indication made by the disease. There are usually no clinical symptoms and the viral genome remains latent in epithelial cells of the kidney. Under defensive weakness of the immune system can lead to reactivation of the virus come with immigration in oligodendrocytes of the CNS, where it can then come to the development of PML.
Construction
The JC virus genome consists of 5130 base pairs ( bp) and is divided into three sections. On the one hand, a non-coding region with origin of replication, a region for the large and small T antigen, as well as a region of the envelope proteins VP-1, VP-2 and VP -3 and the associated Agnoprotein. Different arrangements of the noncoding region produce different JC virus variants. Most commonly found in healthy individuals, the CY- trunk with a 98 -bp sequence consisting of two 23 and 66 bp inserts, while in PML patients is the Mad -1 strain of two 98 bp tandem repeats and TATA boxes. In particular, the Mad -4 strain has oncogenic potential, since the second TATA box is missing here.
In an animal model strain Mad- 4 offers numerous brain tumors, especially astrocytomas, medulloblastomas and PNET are caused by infection with the JC virus, was observed. It is also occasionally detected in surgical specimens of human CNS tumors JC virus DNA. In particular, the 80 - kDa protein of the large T antigen can bind and inactivate certain key proteins for the development of tumors ( p53 and pRb ).