Absence of simian virus 40 in human brain tumors from northern India

Abstract

Simian virus 40 (SV40), a monkey polyomavirus, was a contaminant of early poliovirus vaccines administered to millions of individuals in the 1950s and early 1960s. SV40 causes brain tumors in laboratory animals, and SV40 DNA sequences have been variably identified in human choroid plexus tumors and ependymomas. We studied the possible association between SV40 and human brain tumors in northern India, where humans have frequent contact with SV40-infected rhesus macaques. DNA from pathologic specimens from 33 ependymomas, 14 choroid plexus tumors and 18 control brain tissues (contused brain, brain metastases) was extracted and analyzed under masked conditions. We used real-time PCR to detect and quantify SV40 (T antigen) and human (GAPDH) DNA sequences. The SV40 PCR assay detected as few as 10 copies of SV40 DNA and had a linear range from 1 ؋ 10 2 to 1 ؋ 10 6 copies. SV40 DNA was detected in 1 specimen (an ependymoma). However, few SV40 DNA copies were detected in this sample (<10 copies, equivalent to <1 copy/350 cells, based on simultaneous GAPDH quantification), and SV40 was not detected when this sample was retested. The monkey polyomavirus simian virus 40 (SV40) was a contaminant of early poliovirus vaccines, which were produced in kidney tissue from rhesus macaques. 1 Following the discovery of SV40 in 1960, 2 changes in vaccine preparation were soon implemented; poliovirus vaccines have been required to be free of SV40 since 1963. However, during the period of vaccine contamination (1955)(1956)(1957)(1958)(1959)(1960)(1961)(1962), millions of persons, mostly children, were exposed to SV40 through large-scale poliovirus vaccination campaigns. 1 This contamination has caused concern because SV40 induces malignancies in laboratory animals, notably brain tumors (ependymoma and choroid plexus tumor), 3,4 mesothelioma and osteosarcoma. SV40 DNA sequences have been detected in human brain tumors, including ependymomas and choroid plexus tumors, as well as other cancers. [5][6][7][8] The finding of SV40 DNA sequences in tumors from individuals too young to have received SV40-contaminated poliovirus vaccines 5-7 raises the question, so far unanswered, of whether SV40 is presently being transmitted asymptomatically in the human population. Creating further uncertainty, other laboratory studies of SV40 in human brain tumors have been largely negative. 9 -12 Humans living in northern India may be uniquely exposed to SV40 through contact with infected monkeys. SV40 infection is endemic in rhesus macaques living in this region, 13 and humans live in close contact with them. If SV40 can be transmitted among humans, as implied by the detection of SV40 DNA sequences in childhood brain tumors, then it appears likely that SV40 can be transmitted from monkeys to humans. SV40 is present in infected monkey urine, 14 and transmission to humans might occur through ingestion of contaminated food or water.Because people living in northern India might acquire SV40 from infected rhesus macaques, we hypothesized that an association ...

SV40 and human brain tumors

“…We disagree with the interpretation of the results presented in the article by Engels et al, 1 and we believe that statements in the text are unsubstantiated and misleading.…”

Human retinoblastoma is not caused by known pRb‐inactivating human DNA tumor viruses

“…52 In vitro, repression of SV40 T-antigen function results in cellular senescence and loss of the transformed phenotype, 53 suggesting that a clonal-association with one or more copies of the SV40 Tantigen per tumor cell would be causally necessary. Previous studies that used quantitative PCR for detection of SV40 sequences in human tumors reported SV40 copy numbers substantially less than one viral copy per cell (1-100 copies per 0.5 lg of tumor DNA) 54 ; 0.12 in 14,000 cells, 55,56 or have been negative. 57,58 Although it has been argued that low SV40 copy numbers in human tumors are still compatible with an etiologic role, such low copy numbers, in combination with the uniform absence of sequences found in native SV40, argue against a hit and run mechanism.…”

New developments about the association of SV40 with human mesothelioma

“…Briefly, Engels et al (2002) used quantitative PCR (Q-PCR) to test for SV40 and to determine the amount of SV40 actually present in tumors. However, the sensitivity of their assay was so low that they estimated at 'less than 10' the total number of SV40 genomes present in six mouse tumors formed by the CRL-2162 SV40-positive mouse cell line (ATCC).…”

“…Unfortunately, the GAPDH estimates were incorrect, leading to an error in their calculations of SV40 copy number in the cells. Engels et al (2002), stated that GAPDH is a single-copy gene. In fact, human cells contain 25 copies of highly homologous GAPDH sequences, 12 of which share extensive nucleotide identity with the universally known cDNA sequence (Hanauer and Mandel, 1984).…”