Immune Response and Antibody Persistence against Hantaan Virus of Vaccinees with Hantavax(TM)

Chu, Yong Kyu; Woo, Young Dae; Lee, Ho Wang

Abstract

BACKGROUND
Hantavax(TM) was developed for preven-tion of hemorrhagic fever with renal syndrome caused by Hantaan or Seoul virus in 1990, and has been commer-cially available in Korea since then. Because Hantavax (TM) has such short usage history, the duration of antibody persistency in vaccinees has not been well studied.
METHODS
61 healthy people were immunized subcu-taneously with Hantavax (TM) twice at one month intervals as primary vaccination. 21 vaccinees were tested at 1 ~4 months after primary vaccination and 40 vaccinees were tested at one year after primary vaccination and then one month and 1 ~2 years after booster vaccination. Antibody titers were measured by immunofluorescent assay(IFA), Hantaan virus antigen-coated high density particle agglu-tination assay(HDPA), and plaque reduction neutralization test(PRNT).
RESULTS
Seroconversion rates of 21 vaccinees at 1 ~ 4 months after primay vaccination were 20/21(95.2%), 19/21(90.5%) and 14/21(66.7%); seropositivity of 40 vaccinees at one year after primary vaccination was 25/40 (62.5%), 18/40(45.0%), and 9/40(22.5%) by IFA, HDPA, and PRNT, respectively. Seroconversion rates of 8 vaccinees at one month after booster vaccination were 8/ 8(100 %), 8/ 8(100%); antibody persistence rate of 11 vaccinees at 20 months after booster vaccination were 11/ 12 (91.7%), 9/ 12(75.0%), and seroconversion rates of 7 vaccinees at 3 months after second booster vaccination were 7/7(100%) and 6/7(85.7%) by IFA and PRNT, respectively. Geometric mean antibody titers of 21 vaccinees at 1-4 months after primary basic vaccination were 262, 248, 120; and those of 40 vaccinees at one year after primary vaccination were 90, 56, and 24 by IFA, HDPA, and PRNT, respectively. Geometric mean antibody titers of 8 vaccinees at one month after booster vaccination were 852, 183, of 12 vaccinees at 20 months after booster vaccination were 296, 33, and of 7 vaccinees at 3 months after second booster vaccination were 549 and 46 by IFA and PRNT, respectively.
CONCLUSION
The booster vaccination is necessary at 12 months after primary vaccination to maintain high levels of antibodies which persist at least two years after booster vaccination.