X-ray inactivation of RNA viruses without loss of biological characteristics.

In the event of an unpredictable viral outbreak requiring high/maximum biosafety containment facilities (i.e. BSL3 and BSL4), X-ray irradiation has the potential to relieve pressures on conventional diagnostic bottlenecks and expediate work at lower containment. Guided by Monte Carlo modelling and in vitro 1-log10 decimal-reduction value (D-value) predictions, the X-ray photon energies required for the effective inactivation of zoonotic viruses belonging to the medically important families of Flaviviridae, Nairoviridae, Phenuiviridae and Togaviridae are demonstrated. Specifically, it is shown that an optimized irradiation approach is attractive for use in a multitude of downstream detection and functional assays, as it preserves key biochemical and immunological properties. This study provides evidence that X-ray irradiation can support emergency preparedness, outbreak response and front-line diagnostics in a safe, reproducible and scalable manner pertinent to operations that are otherwise restricted to higher containment BSL3 or BSL4 laboratories.

Inactivation of viral agents in bovine serum by gamma irradiation.

Cell culture origin or suckling mouse brain origin viruses of Akabane disease, Aino, bovine ephemeral fever, swine vesicular disease, hog cholera, bluetongue, and minute virus of mice were each suspended in bovine serum. Aliquots (1 mL) were exposed to various doses of gamma radiation from a 60Co source while at -68 degrees C. Aliquots (100-mL) of serum from a steer experimentally infected with foot-and-mouth disease virus were similarly irradiated. The samples were assayed for infectivity in cell culture systems before and after irradiation, and the data points were analyzed by linear regression. The irradiation doses (in megarads) necessary to inactivate one log10 of viral infectivity (D10) was calculated for each virus. D10 is otherwise known as the slope of the regression line. The r2 value, a measure of association with 1.0 = perfect fit, was also calculated for each regression line. The values (D10, r2) for each virus were as follows: Akabane, 0.25, 0.998; Aino, 0.35, 0.997; bovine ephemeral fever, 0.29, 0.961; swine vesicular disease, 0.50, 0.969; foot-and-mouth disease, 0.53, 0.978; hog cholera, 0.55, 0.974; bluetongue, 0.83, 0.958; and minute virus of mice, 1.07, 0.935.