Polyomavirus inactivation - a review.

Polyomavirus inactivation has been studied since the 1950s when it became apparent that certain polio vaccines were contaminated with SV40. Relatively high temperatures (≥70 °C) are required to effect thermal inactivation of the polyomaviruses. The chemical inactivants that are effective (ß-propiolactone, ethanol, sodium hydroxide, and formaldehyde) are those that have displayed efficacy for other small, non-enveloped viruses, such as the circoviruses. Low pH inactivation can be effective, especially at pH at or below 3 and at higher temperatures. Polyomaviruses are more resistant to UV-C irradiation than are other small non-enveloped viruses such as the parvoviruses and caliciviruses. The efficacy of photodynamic inactivation of polyomaviruses is very much dye-dependent, with toluidine blue, acridine orange, and methylene blue dyes being effective photosensitizers. Ionizing radiation can be effective, depending on the conditions employed and the inactivation matrix. Inactivation of the oncogenic properties of the polyomaviruses may require higher doses of inactivant than those required to inactivate infectivity. While the polyomaviruses are considered to be highly resistant to inactivation, the degree of resistance is dependent upon the specific approach under consideration. For certain approaches, such as UV-C and gamma-irradiation, the polyomaviruses appear to be more resistant than other small non-enveloped viruses.

General purpose lamps induce polyoma DNA replication in H3 cells.

We have previously demonstrated the ability of UVC (254 nm) radiation to induce asynchronous polyoma replication in rat fibroblast cells (H3 line) that contain an integrated copy of polyoma virus. In the present study we show that general purpose lamps can induce polyoma replication in these cells as well. The amount of UV radiation emitted by three different light sources was determined and the effects of each source on the replication of polyoma DNA was assessed. Our findings indicate that a 100 W incandescent lamp had a minimal effect on replication, whereas a 90 s exposure to a halogen lamp or a 160 W mercury vapor lamp induced replication 1.5-fold and 2-fold, respectively, in comparison with nontreated controls. We have previously shown that asynchronous polyoma replication in H3 cells involves UV-inducible cellular protein factors. Our present results indicate that these factors are also activated by exposure to commonly used lamps that emit comparable doses of UV radiation.

Functional role of the ultraviolet light responsive element (URE; TGACAACA) in the transcription and replication of polyoma DNA.

We have previously identified a novel 8 bp sequence (UV-responsive element, URE: TGACAACA) present in the regulatory region of polyoma DNA that interacts with protein factors induced in rat fibroblast cells by exposure to UV light. In the present study, we demonstrate through competitive binding assays that this sequence is distinct from the partially homologous AP1 and CRE target sequences. The proteins that bind to the URE appear to have transcriptional activity in UV-exposed rat fibroblasts. In addition, the URE appears to play a role in promoting the replication of polyoma DNA as determined through two different experimental approaches. Together, these findings suggest that the URE is a novel DNA binding element that interacts with proteins involved in the transcription and replication of polyoma sequences.

Differential adsorption of polyoma virions and capsids to mouse kidney cells and guinea pig erythrocytes.

Adsorption of 125I-labeled polyoma virions and capsids to the surface of mouse kidney cells (MKC) and guinea pig erythrocytes was examined. Purified polyoma capsids lack the ability to compete with polyoma virions for specific binding sites on the surface of MKC. These same capsids were, however, able to block virion adsorption to guinea pig erythrocytes. UV-inactivated virions blocked cellular receptors on MKC and thus inhibited infectious virions from infecting the cells. Capsids were unable to inhibit virion infection of MKC. Adsorption of polyoma virions to MKC and infection of these cells were found to be independent of the ability of the virions to agglutinate guinea pig erythrocytes.

[Different sensitivities to ultraviolet rays of various functions of the polyoma virus. Stimulation of the synthesis of cellular DNA]. / Sensibilité différentielle aux rayons ultraviolets de quelques fonctions du virus polyome. Stimulation de la synthèse d'ADN cellulaire

Peritoneal Mouse macrophage were used to study the stimulation of cell DNA synthesis by polyoma virus. Using ultraviolet-irradiated polyoma virus, it was possible to show a difference between the inactivations of infectivity and of induction of DNA synthesis. By statistically analysis of these two phenomena it was found that 39% of the viral genome is necessary for the induction of cell DNA synthesis.

Absence of a cell membrane alteration function in non-transforming mutants of polyoma virus.

A surface receptor for an agglutinin, exposed in transformed but not in normal cells, arises in normal mouse cells during lytic infection by polyoma virus. The structural change in the surface membrane characteristic of transformed cells and of cells productively infected by wild type virus fails to occur in normal mouse cells infected by mutants of the virus that are unable to cause transformation. The exposure of the receptor site by wild type virus is reversibly blocked by inhibitors of DNA synthesis.

Oncogenicity by DNA tumor viruses: enhancement after ultraviolet and cobalt-60 radiations.

Simian virus-40, polyoma, and LLE46 virus preparations were treated with ultraviolet or gamma radiations (cobalt-60) in a frozen state. Infectivity and induction of complement-fixing antigen and DNA synthesis declined as a logarithmic function of dose, the latter two properties being more resistant than infectivity to radiation by a factor of 2 to 5. Oncogenicity of all three viruses did not decrease with progressive amounts of both types of irradiation, but actually increased in absolute and relative terms (per infectious unit), even at the maximum dose of irradiation used (24,000 ergs per square millimeter per minute and 2.7 x 10(6) rads).