Resistance of porcine circovirus and chicken anemia virus to virus inactivation procedures used for blood products.

BACKGROUND: Virus inactivation procedures are used to prevent contamination of plasma-derived blood products with viruses. Pasteurization or prolonged dry heat has proven effective against several enveloped and nonenveloped viruses and provides an additional layer of safety for plasma products.

STUDY DESIGN AND METHODS: The resistance of porcine circovirus 2 (PCV2) and chicken anemia virus (CAV), two small, nonenveloped viruses, to standard (pasteurization, 10 hr at 60 degrees C; dry heating, 80 degrees C for 72 hr) and more extreme heat inactivation procedures (temperatures up to 120 degrees C) was determined. The ability of these procedures to inactivate PCV2 and CAV was measured by comparison of in vitro infectivity before and after treatment.

RESULTS: Infectivity of PCV2 and CAV was reduced by approximately 1.6 and 1.4 log by pasteurization and by 0.75 and 1.25 log by dry-heat treatment, both substantially more resistant than other viruses previously investigated. PCV2 and CAV were additionally almost completely resistant to dry-heat treatment up to 120 degrees C for 30 minutes (mean log infectivity reductions, 1.25 and 0.6), although both were more effectively inactivated when the temperature of wet-heat treatment was increased to 80 degrees C (>3.2 and >3.6 log infectivity reduction).

CONCLUSION: Although neither PCV2 nor CAV are known to infect humans, their inactivation properties may represent those of other small DNA viruses known to be present (e.g., TT virus, small anellovirus) or potentially present in human plasma. Findings of extreme thermal resistance demonstrate that recipients of plasma-derived therapeutics may potentially still be exposed to small DNA viruses, despite the implementation of viral inactivation steps.