Gamma Irradiation as an Effective Method for Inactivation of Emerging Viral Pathogens.

Gamma irradiation using a cobalt-60 source is a commonly used method for the inactivation of infectious specimens to be handled safely in subsequent laboratory procedures. Here, we determined irradiation doses to safely inactivate liquid proteinaceous specimens harboring different emerging/reemerging viral pathogens known to cause neglected tropical and other diseases of regional or global public health importance. By using a representative arenavirus, bunyavirus, coronavirus, filovirus, flavivirus, orthomyxovirus, and paramyxovirus, we found that these enveloped viruses differed in their susceptibility to irradiation treatment with adsorbed doses for inactivation of a target dose of 1 × 106 50% tissue culture infectious dose (TCID50)/mL ranging from 1 to 5 MRads. This finding seemed generally inversely correlated with genome size. Our data may help to guide other facilities in testing and verifying safe inactivation procedures.

Modern dosimetric tools for (60)Co irradiation at high containment laboratories.

PURPOSE: To evaluate an innovative photo-fluorescent film as a routine dosimetric tool during (60)Co irradiations at a high containment biological research laboratory, and to investigate whether manufacturer-provided chamber exposure rates can be used to accurately administer a prescribed dose to biological specimens. MATERIALS AND METHODS: Photo-fluorescent, lithium fluoride film dosimeters and National Institutes of Standards and Technology (NIST) transfer dosimeters were co-located in a self-shielded (60)Co irradiator and exposed to γ-radiation with doses ranging from 5-85 kGy. Film dose-response relationships were developed for varying temperatures simulating conditions present when irradiating infectious biological specimens. Dose measurement results from NIST transfer dosimeters were compared to doses predicted using manufacturer-provided irradiator chamber exposure rates. RESULTS: The film dosimeter exhibited a photo-fluorescent response signal that was consistent and nearly linear in relationship to γ-radiation exposure over a wide dose range. The dosimeter response also showed negligible effects from dose fractionization and humidity. Significant disparities existed between manufacturer-provided chamber exposure rates and actual doses administered. CONCLUSION: This study demonstrates the merit of utilizing dosimetric tools to validate the process of exposing dangerous and exotic biological agents to γ-radiation at high containment laboratories. The film dosimeter used in this study can be utilized to eliminate potential for improperly administering γ-radiation doses.