Target Molecular Weight of Foot-and-Mouth Disease Virus and Poliovirus

This study determined the target molecular weight of the RNA genome in foot-and-mouth disease virus and poliovirus using gamma-irradiation. Researchers exposed viral suspensions to ionizing radiation doses ranging from 10^4 to 10^6 rads and measured survival rates. Both viruses followed single exponential inactivation curves. Foot-and-mouth disease virus had a D37 value of 16 × 10^4 rads, corresponding to an RNA target molecular weight of 4.18 × 10^6 daltons, while poliovirus had a D37 of 28.8 × 10^4 rads, equivalent to 2.23 × 10^6 daltons. The larger genome size of foot-and-mouth disease virus compared to other enteroviruses may explain its unusual thermal and acid instability properties. The addition of 10% horse serum protected against indirect radiation effects, ensuring measurements reflected direct damage to viral RNA. These findings provide important biophysical characterization of picornavirus genomes.

Key findings

• Foot-and-mouth disease virus RNA has a target molecular weight of approximately 4.18 × 10^6 daltons, larger than other enteroviruses
• Poliovirus RNA target molecular weight of 2.23 × 10^6 daltons aligns well with electron microscopy measurements of 2 × 10^6 daltons
• Both viruses showed single exponential inactivation curves when exposed to gamma-radiation, following target theory predictions
• The larger genome size of foot-and-mouth disease virus may explain its distinctive thermal and acid instability characteristics