ABSTRACT
Polyomaviruses are a group of nonenveloped, double-stranded DNA viruses with a ~5 kb genome that commonly occur in animal and human populations and show notable differences in tissue tropism. The first polyomavirus was discovered in the 1950s as the transmissible agent for causing multiple parotid gland tumors in neonatal or immunosuppressed rodents. Polyomavirus infection in permissive cells begins with the binding of the virion to a receptor on the outer cell membrane facilitating viral internalization. Primary infection appears to take place during early childhood and sustains throughout life as indicated by higher percentages of seropositivity in older people. In recent years, some changes in polyomavirus disease epidemiology are being noticed as a consequence of medical intervention.
