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Necessary for efficient viral DNA replication

Source: Adapted from Fields et al. (1996, p. 2030) and additional data from Walker and Frisque (1986).

Source: Adapted from Fields et al. (1996, p. 2030) and additional data from Walker and Frisque (1986).

distribution. It is an infrequent complication of a wide variety of conditions, including Hodgkin's disease, chronic diseases such as tuberculosis, primary acquired immunodeficiency diseases such as AIDs, or immunosuppression following organ transplant. The frequency of PML has increased with the AIDS epidemic and PML is now recognized as one of the AIDS-defining illnesses—it occurs in 0.7% of all AIDS cases reported to the Centers for Disease Control and Prevention. PML may be more likely to occur when immunosuppression is due to infection by HIV because HIV-1 transactivates the JC late promoter. The disease progresses rapidly and can lead to mental deterioration and death within 3-6 months after onset.

Polyomaviruses cause tumors in laboratory animals and many attempts to associate BK or JC virus with human cancer have been made. Association of BK with certain human malignancies has been reported, but these associations are not consistent and no convincing evidence exists that the association is causative rather than adventitious.

Early lots of poliovirus vaccine were contaminated with SV40 virus, which shares 69% sequence identity with JC and BK viruses (Table 6.12), and many people were infected with this virus during the poliovirus vaccination campaigns. Extensive study of this cohort of people, both in the United States and in Europe, has not revealed any convincing evidence for tumors associated with SV40 infection. The fact that SV40 infects man is of interest because there are recent reports that an SV40-like virus of humans is circulating in the United States. There are suggestive data that this virus may be associated with certain brain tumors in children.

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