1 NBU J. Anim. Sc. 2 (1):1-13 (2008) Human Polyomaviruses: Clinical, Evolutionary and Anthropological Implications Soumen Bhattacharjee Cell and Molecular Biology Laboratory, Department of Zoology, University of North Bengal, District Darjeeling, West Bengal 734 013, India ABSTRACT Human polyomaviruses BK and JC, members of the Polyomaviridae virus family, are clinically important resident viruses in humans. The prototype viruses are ~ 5000 base pair double stranded circular DNA viruses of small sizes (~ 45 nm), which are thought to be acquired in childhood. Polyomavirus infection is almost ubiquitous in human populations. Following infection, both the viruses remain in a latent sub-clinical state within the body life-long, only to be reactivated under conditions of immunosuppression, when the viruses are shed in urine. Reactivation of both these viruses has been associated with several human pathological conditions including neoplasia. This review discusses the current state of knowledge regarding biology, prevalence, detection, reactivation and PCR-based genomic typing of natural isolates of these viruses. Key Words: BKV, JCV, polyomavirus, reactivation, Non-Coding Control Regions Introduction The Polyomaviruses were the first mammalian viruses to be analyzed molecularly and hence extensive information exists concerning their genomic and physical structures. The prototype member of the genus polyomavirus, the murine Polyomavirus (PyV) was discovered in 1953 (Gross, 1953) and the simian polyomavirus SV40 was discovered as the contaminating agent in rhesus monkey kidney cell line in 1960 (Sweet and Hilleman, 1960). The human polyomaviruses were first suspected to be present in human organs in 1965 (Zu Rhein and Chou, 1965; Silverman and Rubeinstein, 1965) and were later isolated from human samples in 1972. BK virus (BKV), the human polyomavirus, was first isolated from the urine of a kidney transplant patient (Gardner et al., 1971) and the name BK was derived from the initials of a 39 year old male Sudanese. Whereas JC virus (JCV), another human polyomavirus that frequently causes a rare fatal brain infection known as Progressive Multifocal Leucoencephalopathy (PML), was isolated from brain tissue of a 38 year old man of initial – JC, who was suffering from Hodgkin’s disease for quite a long time (Padgett et al., 1971). Both the human polyomaviruses have been associated with several human neoplasias. Comparison of viral genomes gene by gene and especially around the viral replication origins, indicate that SV40, murine Polyomavirus (PyV), BK and JC virus, all may have evolved from a common ancestor and then diverged with their host organisms (Soeda et al., 1980). Table I enumerates a list of several polyomaviruses and their natural hosts.