Improving detection of JC virus by ultrafiltration of cerebrospinal fluid before polymerase chain reaction for the diagnosis of progressive multifocal leukoencephalopathy

Table 1 PCR detection of JCV DNA in CSF specimens from patients suspected of having PML

	Standard procedure			Ultrafiltration procedure^a
Patient	Positive reaction^b	Copies / reaction^c	Copies/mL CSF^d	Positive reaction	Copies / reaction^e	Copies / mL CSF^f
1	3/3	207,033	5,175,825	3/3	1,030,133	3,219,166
2	3/3	766	19,150	3/3	2433	7603
3	3/3	321	8025	3/3	1383	4322
4	3/3	123	3075	3/3	568	1775
5	3/3	20	500	3/3	110	344
6	3/3	12	300	3/3	93	291
7	3/3	7	175	3/3	61	191
8	1/3	NA	NA	3/3	6	19
9	0/3	NA	NA	0/3	NA	NA
10	0/3	NA	NA	0/3	NA	NA
11	0/3	NA	NA	0/3	NA	NA
12	0/3	NA	NA	0/3	NA	NA
13	0/3	NA	NA	0/3	NA	NA
14	0/3	NA	NA	0/3	NA	NA
15	0/3	NA	NA	0/3	NA	NA
16	0/3	NA	NA	0/3	NA	NA
17	0/3	NA	NA	0/3	NA	NA
18	0/3	NA	NA	0/3	NA	NA
19	0/3	NA	NA	0/3	NA	NA
20	0/3	NA	NA	0/3	NA	NA

Abbreviations: CSF Cerebrospinal fluid, JCV JC virus, NA Not applicable, PCR Polymerase chain reaction, PML Progressive multifocal leukoencephalopathy
^aEach CSF specimen was concentrated from 4 mL to 500 μL by ultrafiltration before DNA extraction
^bThe PCR was repeated three times
^cThe mean copy numbers of JCV DNA in 2-μL PCR template of total 25-μL DNA extract from 500-μL CSF were determined, when all three PCRs were positive
^dThe copy numbers of JCV DNA per mL were calculated with respect to total volume of DNA extracts (12.5-fold) and the amounts of test samples (2-fold)
^eThe mean copy numbers of JCV DNA in 2-μL PCR template of total 25-μL DNA extract from 4-mL CSF were determined, when all three PCRs were positive
^fThe copy numbers of JCV DNA per mL were calculated with respect to total volume of DNA extracts (12.5-fold) and the amounts of test samples (0.25-fold)

ISSN: 1471-2377