Intravenous immunoglobulin products contain neutralizing antibodies to vaccinia

Abstract

Individuals with primary or secondary immune-deficiency diseases may be at risk for vaccinia infection if widespread smallpox-immunization programmes are implemented in the United States of America (USA) for bioterrorism preparedness. The objective of this study was to determine whether commercial immune globulin (intravenous, human) products contain biologically active antibodies to vaccinia that have the potential to protect people, with immune deficiencies, from complications of vaccinia. Eight currently United States (US)-licensed and two European intravenous immunoglobulin (IVIG) products were tested in a vaccinia plaque-reduction neutralization assay. The in vivo activity of five of these lots was assessed in severely immune-deficient mice. All tested products contained neutralizing anti-vaccinia activity, in vitro and in vivo. The use of IVIG by individuals with inherited or acquired humoral immune deficiencies may provide some protection if they are inadvertently exposed to vaccinia.