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Published on: June 16, 2011
Studies on the stability of foot-and-mouth disease virus using absorbance - temperature profiles
Abstract:
The main immunogenic component of FMD virus harvests is the intact 140S virus particle. For the production of stable vaccines it is important to ensure that virus strains having a stable capsid should be used. The method of measuring the heat stability of FMD virus by following the increase in optical density of purified virus during capsid breakdown as the temperature is increased was described in 1964 (P. Bachrach, 1964, J. Mol. Biol 8. 348). We have investigated this technique in the hope that it might provide a means of screening virus isolates rapidly to eliminate unstable strains. Using this method we have been unable to follow the course of virus breakdown from the absorbance profile alone. A much more precise indication has been obtained by including ribonuclease in the virus sample. This enhances the optical density rise which occurs when the capsid disintegrates and the RNA becomes accessible. A sigmoid curve is obtained from which 50% breakdown temperature can be calculated. The presence of RNase does not appear to alter the temperature at which breakdown occurs since parallel samples heated in the absence of RNase showed the same behaviour when virus breakdown was measured by sucrose gradient analysis. With a given virus preparation the method gives highly reproducible results. Typical standard deviations for the 50% breakdown point were about 0.5 degrees C. However, the results are influenced by the method of purification of the virus. Virus purified by CsCl gradient centrifugation was less stable than virus purified on sucrose gradients. Thus the environmental conditions through which the virus passes during processing may affect its stability.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
This study refines a method to assess Foot-and-Mouth Disease virus (FMDV) capsid stability by incorporating ribonuclease (RNase). This improves the accuracy of determining the 50% breakdown temperature, crucial for stable vaccine production.
Area of Science:
- Virology
- Biochemistry
- Vaccine Development
Background:
- The intact 140S virus particle is the primary immunogen in Foot-and-Mouth Disease virus (FMDV) vaccines.
- Ensuring the use of virus strains with stable capsids is critical for producing effective and stable FMDV vaccines.
Purpose of the Study:
- To investigate and refine a heat stability assay for FMDV.
- To develop a rapid screening method for identifying unstable FMDV strains for vaccine production.
Main Methods:
- Utilized an optical density-based assay to measure FMDV capsid breakdown upon heating.
- Incorporated ribonuclease (RNase) to enhance the optical density signal during capsid disintegration.
- Calculated the 50% breakdown temperature from the resulting sigmoid curve.
- Validated RNase-enhanced results using sucrose gradient analysis.
Main Results:
- The addition of RNase significantly improved the precision of measuring FMDV capsid breakdown.
- A reproducible sigmoid curve allowed for accurate calculation of the 50% breakdown temperature.
- RNase did not alter the intrinsic thermal stability of the FMDV capsid.
- Virus purification methods, specifically CsCl vs. sucrose gradients, influenced measured capsid stability.
Conclusions:
- The RNase-enhanced heat stability assay provides a precise and reproducible method for screening FMDV strains.
- The findings highlight the importance of considering purification methods' impact on virus stability for vaccine formulation.
- This technique can aid in selecting stable FMDV strains, contributing to improved vaccine efficacy.
