Hepatitis E virus is effectively inactivated by methylene blue plus light treatment

Area of Science:

• Biomedical Science
• Transfusion Medicine
• Virology

Background:

• Photodynamic treatment with methylene blue (MB) and visible light is a validated pathogen inactivation method for human plasma.
• This technique is widely adopted globally for ensuring blood product safety.
• The efficacy of MB/light treatment against transfusion-transmittable viruses is known, but its effect on hepatitis E virus (HEV) remained uninvestigated.

Purpose of the Study:

• To evaluate the efficiency of the THERAFLEX MB-Plasma system in inactivating hepatitis E virus (HEV) in human plasma.
• To determine the optimal light dose for HEV inactivation using this photodynamic method.

Main Methods:

• Human plasma units were intentionally contaminated with cell culture-derived HEV.
• Plasma samples underwent treatment with the THERAFLEX MB-Plasma system at varying light doses (30, 60, 90, and 120 J/cm²).
• HEV titers were quantified pre- and post-treatment using virus titration and a sensitive large-volume plating assay.

Main Results:

• The THERAFLEX MB-Plasma system demonstrated efficient inactivation of HEV in human plasma across all tested light doses.
• A minimum light dose of 30 J/cm² was sufficient to reduce HEV levels to the limit of detection.
• The overall process achieved a mean log reduction factor exceeding 2.4 for HEV.

Conclusions:

• The THERAFLEX MB-Plasma system is highly effective for inactivating hepatitis E virus in human plasma.
• This finding supports the use of MB/light treatment as a robust method for mitigating HEV transmission risk in blood transfusions.