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Virus inactivation at moderately low pH varies with virus and buffer properties
Pratik U Joshi1,2, Christa L Meingast2,3, Xuankuo Xu4
1Department of Chemical Engineering, Michigan Technological University, Houghton, Michigan, USA.
Background:
Virus inactivation is a critical operation in therapeutic protein manufacturing. Low pH buffers are a widely used strategy to ensure robust enveloped virus clearance. However, the choice of model virus can give varying results in viral clearance studies. Pseudorabies virus (SuHV) or herpes simplex virus-1 (HSV-1) are frequently chosen as model viruses to demonstrate the inactivation for the herpes family.
Results:
In this study, SuHV, HSV-1, and equine arteritis virus (EAV) were used to compare the inactivation susceptibility at pH 4.0 and 4°C. SuHV and HSV-1 are from the same family, and EAV was chosen as a small, enveloped virus. Glycine, acetate, and citrate buffers at pH 4.0 and varying buffer strengths were studied. The inactivation susceptibility was found to be in the order of SuHV > HSV > EAV. The buffer effectiveness was found to be in the order of citrate > acetate > glycine. The smaller virus, EAV, remained stable and infectious in all the buffer types and compositions studied.
Conclusion:
The variation in inactivation susceptibility of herpes viruses indicated that SuHV and HSV cannot be interchangeably used as a virus model for inactivation studies. Smaller viruses might remain adventitiously infective at moderately low pH.
Insights
Pseudorabies virus (SuHV) and herpes simplex virus-1 (HSV-1) show different inactivation rates in low pH buffers, impacting their use as interchangeable models in therapeutic protein manufacturing. Equine arteritis virus (EAV) remained infectious.
Area of Science:
- Biotechnology
- Virology
- Process Chemistry
Background:
- Virus inactivation is crucial for therapeutic protein manufacturing.
- Low pH buffers are standard for enveloped virus clearance.
- Model virus selection impacts viral clearance study outcomes.
Purpose of the Study:
- Compare inactivation susceptibility of Pseudorabies virus (SuHV), herpes simplex virus-1 (HSV-1), and equine arteritis virus (EAV) at low pH.
- Evaluate the efficacy of glycine, acetate, and citrate buffers.
- Determine the impact of buffer strength on virus inactivation.
Main Methods:
- Tested SuHV, HSV-1, and EAV inactivation at pH 4.0 and 4°C.
- Utilized glycine, acetate, and citrate buffers at varying strengths.
- Assessed viral infectivity post-treatment.
Main Results:
- Inactivation susceptibility order: SuHV > HSV > EAV.
- Buffer effectiveness order: citrate > acetate > glycine.
- Equine arteritis virus (EAV) showed stability and infectivity across all tested conditions.
Conclusions:
- Pseudorabies virus (SuHV) and herpes simplex virus-1 (HSV-1) exhibit differential inactivation, precluding their interchangeable use as virus models.
- Smaller enveloped viruses like EAV may retain infectivity under moderately low pH conditions.
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