Human cytomegalovirus replicates in gamma-irradiated fibroblasts

Modulation of Radiation-Induced Genetic Damage by HCMV in Peripheral Blood Lymphocytes from a Brain Tumor Case-Control Study

Human cytomegalovirus (HCMV) infection occurs early in life and viral persistence remains through life. An association between HCMV infection and malignant gliomas has been reported, suggesting that HCMV may play a role in glioma pathogenesis and could facilitate an accrual of genotoxic damage in the presence of g-radiation; an established risk factor for gliomas. We tested the hypothesis that HCMV infection modifies the sensitivity of cells to γ-radiation-induced genetic damage. We used peripheral blood lymphocytes (PBLs) from 110 glioma patients and 100 controls to measure the level of chromosome damage and cell death. We evaluated baseline, HCMV-, γ-radiation and HCMV + γ-radiation induced genetic instability with the comprehensive Cytokinesis-Blocked Micronucleus Cytome (CBMN-CYT). HCMV, similar to radiation, induced a significant increase in aberration frequency among cases and controls. PBLs infected with HCMV prior to challenge with γ-radiation led to a significant increase in aberrations as compared to baseline, γ-radiation and HCMV alone. With regards to apoptosis, glioma cases showed a lower percentage of induction following in vitro exposure to γ-radiation and HCMV infection as compared to controls. This strongly suggests that, HCMV infection enhances the sensitivity of PBLs to γ-radiation-induced genetic damage possibly through an increase in chromosome damage and decrease in apoptosis.

Induction of latent human cytomegalovirus by conventional gamma irradiation and prevention by treatment with INACTINE PEN110

BACKGROUND AND OBJECTIVES

Two different leucocyte-inactivation technologies--gamma irradiation and INACTINE PEN110--were evaluated for their effects on cell-associated human cytomegalovirus (CMV).

MATERIALS AND METHODS

In vitro CMV-infected cells were spiked into leucoreduced red blood cell concentrates (RCC) or medium at a final concentration of 0.5 - 1 x 10(7) cells/ml to mimic non-leucoreduced levels of leucocytes. The spiked RCC/medium was divided into three equal units and treated with gamma irradiation at the US Food and Drug Administration (FDA)-approved dose of 25 Gy, with 0.1% v/v PEN110 at 22 degrees C for 24 h, or stored at 4 degrees C as a control. The treated and control cells were recovered and tested using infectivity, viability and polymerase chain reaction (PCR) assays.

RESULTS

Gamma-irradiated CMV-infected cells produced active virus, as shown by both infectivity assays and PCR quantification of viral DNA. PCR analysis demonstrated higher CMV DNA levels in gamma-irradiated, latently infected monocytic THP-1 cells than untreated control cells. The increased virus production in gamma-irradiated cells was paralleled by an increased metabolic rate and the development of enlarged multinuclear cells. In contrast, PEN110 treatment terminated virus replication and completely inactivated the infected cell.

CONCLUSIONS

These results demonstrate that gamma irradiation, at levels currently used to treat RCC, has the capacity to induce expression of CMV, whereas PEN110 inhibits CMV replication and efficiently inactivates the infected cells.

Role of proliferation for intercellular induction of apoptosis

We have recently described induction of apoptosis of transformed target cells by TGF-beta-treated nontransformed effector cells as a potential novel control step in oncogenesis. Here we study the role of proliferation of both cell types for the efficiency of induction of apoptosis. Inhibition of proliferation of transformed target cells by gamma irradiation or colchicine treatment did not affect their sensitivity to induction of apoptosis by TGF-beta-treated nontransformed effector cells. This finding indicates that sensitivity to intercellular induction of apoptosis is not related to cell cycle control. In contrast, the ability of nontransformed effector cells to induce apoptosis was dependent on their proliferation. Nontransformed cells blocked by gamma irradiation, colchicine treatment, or thymidine treatment were no longer able to induce apoptosis of transformed target cells. This inability seems to be partially due to substances that are released from proliferation-inhibited nontransformed effector cells and that interfere with induction of apoptosis.