A real time genotyping PCR assay for polyomavirus BK.

BACKGROUND

Polyomavirus BK (BKV) may cause nephropathy in renal transplant recipients and hemorrhagic cystitis in bone marrow recipients. We developed real-time PCRs (RT-PCR) to determine easily and rapidly the different BKV genotypes (BKGT) (I-IV).

METHODS

On the VP1 gene a duplex of RT-PCRs was developed and validated to differentiate the four main BKGT. 212 BKV positive samples (21 plasma, 191 urine) were tested with these specific PCRs. Of these 212 samples, 55 PCR results were additionally confirmed by sequencing a VP1 gene fragment (nucleotide 1630-1956).

RESULTS

For every genotype, a highly specific, precise and internally controlled assay was developed with a limit of detection of log 3 copies per ml. In 18 (8.5%) of these samples genotyping was not successful due to a low viral load. By sequence analysis, the genotype of 46 out of 55 and 2 out of 4 samples with double infection could be confirmed.

CONCLUSIONS

This study describes RT-PCRs for detection of the main BKGT. It proved to be rapid, cheap and sensitive compared to sequencing. Double infections can also be detected. This method will be of value to investigate the role of BKV infection in relation to the genotype.