Hepatitis A virus antibodies in immunoglobulin preparations

Abstract

Persons with primary immune deficiency receive intravenous immunoglobulin (IVIG) as antibody replacement therapy. These patients depend on the presence of protective antibody levels against circulating pathogens in IVIG. The incidence of hepatitis A virus (HAV) infections has been decreasing globally. We investigated whether this decrease in HAV incidence is reflected in human plasma pools and evaluated whether HAV antibody titers in IVIG preparations are still adequate for antibody replacement. By using ELISA, the HAV antibody titer of 3,953 plasma pools sourced from March 2003 through September 2008 in the European Union (EU) or United States (US) and of 169 IVIG lots manufactured from 2005 through 2007 was determined. The functionality of the HAV antibodies contained in IVIG was assessed by using a microneutralization assay. The results confirm a decrease in HAV antibody titers in EU (-28%) and US (-41%) plasma. Furthermore, the mean HAV antibody content in EU (1.70 +/- 0.12 IU/mL) and US (0.82 +/- 0.09 IU/mL [mean +/- SEM]) plasma was significantly different (P = .0001). A significant difference (P < .0001) was also evident in the IVIG preparations KIOVIG (22.91 +/- 0.68 IU/mL) and Gammagard Liquid (14.60 +/- 0.48 IU/mL), respectively, made from EU or US plasma. In accordance with the ELISA results, there was a significant difference (P < .0001) in HAV neutralization titer 50% (NT(50)) values between IVIG produced from EU-sourced (2,477 +/- 265 NT(50) [1:X]) or US-sourced (844 +/- 82 NT(50) [1:X]) plasma. Although HAV antibody seroprevalence continues to decrease in Europe and the US, HAV antibody titers in IVIG lots appear to remain adequate for antibody replacement therapy.