Table 4

Positive SV40 DNA results in paired replicates of 25 mesothelioma tumor samples (A–Y) by type of assay in each laboratory

LaboratoryAssayABCDEFGHIJKLMNOPQRSTUVWXY
Lab 1aCommon1b111211111
Lab 2Common
Assay 2.1
Lab 3Common1
Assay 3.1
Assay 3.2
Lab 4Common1c?
Lab 5Common
Assay 5.1
Assay 5.2
Lab 6Common111121
Lab 7Common
Assay 7.1
Lab 8Common?··¿
Assay 8.1
Lab 9Southern1
  • a Lab 1 reported detecting contamination of their PCR primers (see text). Samples in Lab 1 were unavailable for DNA sequencing. However, positive results in all other laboratories were confirmed by sequencing unless indicated (see footnote c, below.)

  • b 1, one of the two paired replicate aliquots from the denoted specimen was positive; 2, both paired replicate aliquots from the denoted specimen were positive; ?, questionable weak band on Southern blot in one of the two aliquots, but the amplification product could not be sequenced because of insufficient material; ·, the amplification product in one of the two aliquots appeared as a broad smear on ethidium bromide gel and hybridized faintly with probe for SV40. The sample was not further analyzed because no specific fragment could be identified for cloning and sequencing. Thus, the sample was considered uninterpretable by the laboratory; ¿, amplification product of wrong size (600 bp) was observed on ethidium bromide gel in one of the two aliquots. It was considered a negative result by the laboratory and not further tested, although signal was present on Southern blot; ▪, insufficient amount of DNA for unamplified Southern blot testing in one of the two aliquots, as indicated by the inability to detect β-globin without amplification or underloading of the SV40 DNA test. All other samples were positive for β-globin on unamplified Southern blot and had adequate amounts of DNA for testing in this laboratory.

  • c One of the two paired aliquots was positive on Southern blot. However, the amplification product could not be sequenced because of insufficient material.