Inactivation Of Hepatitis B Virus By Heat In Antithrombin III Stabilized With Citrate

The recent report that antithrombin III (AT-III) prepared in solution with 0.5 M sodium citrate can withstand heating at 60°C for 10 hours suggested that this method of preparation could permit the heat-inactivation of hepatitis B virus (HBV) which might be present. Although heating at 60°C for 10 hours will inactivate HBV in albumin, this will not inactivate HBV in whole plasma or in some purified hepatitis B surface antigen (HBsAg) preparations. HBV, subtype ayw, hepatitis B e antigen positive, containing 10^3.5 chimpanzee infectious doses per ml, was added to each of two vials containing 690 plasma units each of AT- III. One was kept at 4°C for 10 hours (unheated AT-III), the second was heated at 60°C for 10 hours. The contents of both vials were separately dialyzed and inoculated intravenously into chimpanzees with no prior exposure to hepatitis B virus and with no serologic evidence of prior hepatitis B infection. No evidence of hepatitis B was detected in the chimpanzee inoculated with the heated AT-III during six months of evaluation. Aspartate and alanine aminotransferase levels (AST, ALT) remained within or near the normal range. Neither HBsAg, antibody to hepatitis B core antigen (anti-HBc), nor antibody to HBsAg (anti-HBs) was detected in any of the weekly serum samples. The chimpanzee inoculated with the unheated AT-III developed hepatitis B. AST and ALT became elevated 13 weeks after inoculation; HBsAg (subtype ayw) was detected six weeks after inoculation and remained detectable; anti-HBc became detectable 12 weeks after inoculation. Liver biopsies obtained 20 and 23 weeks after inoculation showed histologic changes of acute hepatitis. This study shows that the application of heat at 60°C for 10 hours to AT-III stabilized with 0.5 M sodium citrate can inactivate > 1,000 chimpanzee infectious doses of HBV.