The hypothesis of this project is that conditions of spaceflight – including solar radiation – damage the human immune system, leading to reactivation of latent viruses, increased viral infections and disease, and the possible development of cancer. Dr. Janet S. Butel’s laboratory is studying the immune system responses of mice in space-like conditions to determine the effect of space radiation on viral infections and virus-infected cells and to determine the ability of the mice to overcome viral infections and virus-induced cancers. This investigation will provide insights into the effects of spaceflight on infectious diseases and help develop methods for detecting, treating, and preventing virus reactivation.
Biology of Virus Infections: Radiation and Immunity
Janet S. Butel, Ph.D.
Baylor College of Medicine
The general hypothesis is that conditions of long-duration spaceflight, including radiation, stress, isolation, containment and sleep deprivation, will alter human immune responses, leading to reactivation of latent viruses, increased viral infections and viral disease, and possible development of malignancies. We focused on reactivation and shedding of human herpesvirus EBV and human polyomaviruses, agents known to establish persistent infections and to undergo reactivation and cause disease, including cancer, when the host immune system is compromised. Animal models were used to study radiation effects on viral infections and host responses to those infections.
Key findings of the project were from the mouse polyomavirus space radiation model we developed. A quantitative real-time polymerase chain reaction (RQ-PCR) assay was developed to measure murine polyomavirus (MuPyV) genome copies in infected animal tissues. This model showed that gamma-irradiation leads to immunosuppression, delayed clearance of primary virus infection, and reactivated latent viral infections. Both single high-dose and multiple low-doses of gamma-irradiation cause virus reactivation. HLU, which simulates aspects of weightlessness, was applied to the mouse model. HLU results in the loss of control of virus infection in a tissue-specific manner. Another finding was the identification of a herpesvirus EBV latent protein that might modulate the development of EBV-associated disease. In collaboration with Dr. Gerald Sonnenfeld, we carried out measurements of virus reactivations in volunteers participating in the NASA-sponsored Bed Rest and Immunity study, a model for the effects of spaceflight conditions on human physiology.