COINFECTION WITH 2 JC VIRUS GENOTYPES IN BRAIN, CEREBROSPINAL-FLUID OR URINARY-TRACT DETECTED BY DIRECT CYCLE SEQUENCING OF PCR PRODUCTS

The human polyomavirus TC (TCV), which exists in different geographica lly based genotypes, causes the central demyelinating disease known as progressive multifocal leukoencephalopathy (PML). A coding region rec ombinant ICV Type 1/Type 3 (Type 4) is excreted in the urine of some 1 6% of individuals in the USA. In addition, occasional 'crossovers' in viral DNA sequence at type-specific sites in the coding region occur b etween TCV genotypes amplified from PML brain. For recombination to oc cur requires the existence of two different genotypes in the same host . Here we provide evidence from direct cycle sequencing of PCR product s that different genotypes of TCV can be found in a single tissue samp le. After non-type-specific PCR amplification, cycle sequencing produc ed 'split bands' at type determining sites which were resolved into ty pe or subtype-specific sequences by subcloning of the PCR products, PC R products with split bands at typing sites were found in two brain sa mples and in one cerebrospinal fluid (CSF) from AIDS patients with PML and in the urine of four immunocompetent individuals. This indicates that co-infection with two viral types does not depend on severe immun ocompromise. Combinations of genotypes found were Types 1A & 1B, 1A & 2, 1B & 2 and 2 & 3. In one doubly infected patient the major TCV type excreted in the urine changed within 1 week.