Amotosalen photochemical inactivation of severe acute respiratory syndrome coronavirus in human platelet concentrates

Abstract

A novel human coronavirus causing severe acute respiratory syndrome (SARS) emerged in epidemic form in early 2003 in China and spread worldwide in a few months. Every newly emerging human pathogen is of concern for the safety of the blood supply during and after an epidemic crisis. For this purpose, we have evaluated the inactivation of SARS-coronavirus (CoV) in platelet concentrates using an approved pathogen inactivation device, the INTERCEPT Blood System. Apheresis platelet concentrates (APCs) were inoculated with approximately 10(6) pfu mL(-1) of either Urbani or HSR1 isolates of SARS-CoV. The inoculated units were mixed with 150 microm amotosalen and illuminated with 3 J cm(-2) UV-A light. The viral titres were determined by plaque formation in Vero E6 cells. Mixing SARS-CoV with APC in the absence of any treatment decreased viral infectivity by approximately 0.5-1 log10. Following photochemical treatment, SARS-CoV was consistently inactivated to the limit of detection in seven independent APC units. No infectious virus was detected after treatment when up to one-third of the APC unit was assayed, demonstrating a mean log10-reduction of >6.2. Potent inactivation of SARS-CoV therefore extends the capability of the INTERCEPT Blood System in inactivating a broad spectrum of human pathogens including recently emerging respiratory viruses.

Figure 1

Photochemical Treatment System – INTERCEPT Blood System for Platelets. The photochemical treatment system consists of an illumination device and a series of plastic containers. The disposable set provides a single‐use, closed, integrated system for pathogen inactivation treatment of a platelet product (300 mL). The platelet product in a mixture of 35% plasma and 65% InterSol (also known as PAS III) is connected via a sterile connection device (SCD) and passed through a container of amotosalen HCl (also known as S‐59) into an illumination container (Step 1). The integrated set is placed in the UV‐A illumination device that provides a three J cm⁻² dose of UV‐A light to the mixture (Step 2). After illumination for 3–6 min, the platelets are transferred to a second container for treatment with a compound adsorption device (CAD) to lower the levels of residual amotosalen and free photoproducts (Step 3). After a minimum of 4 h of CAD treatment, the photochemical treatment platelets are transferred to a PL 2410 plastic container for storage up to 5 days (Step 4). The CAD step was not used in the viral inactivation experiments described in this report.