title: Evaluation of the efficacy of a recombinant subunit West Nile vaccine in Syrian golden hamsters.
abstract: The efficacy of a recombinant subunit West Nile (WN) vaccine candidate was determined in a hamster model of encephalitis. Animals included young, aged, and immunocompromised animals in an effort to simulate key groups at risk of WN virus-induced disease. Groups of aged (12 month old), weanling, and adult hamsters rendered leukopenic after immunization were immunized subcutaneously with a WN virus recombinant envelope protein (WN-80E) with or without WN virus non-structural protein 1 (NS1) mixed with adjuvant or adjuvant alone. A challenge dose of wild-type WN virus was administered to produce 40-100% mortality in the control hamsters. The recombinant antigen preparations containing WN-80E with or without WN NS1 gave similar results. Hamsters in both groups had a strong antibody response after immunization, and none of the aged or weanling animals became ill or developed detectable viremia after challenge with WN virus at 2 weeks after booster vaccination. However, mortality among the control animals (administered adjuvant without antigen) at 2 weeks after booster challenge was 40-60%. In hamsters rendered leukopenic after immunization, survival rates up to 80% were observed, and a low-level viremia was detected in the vaccinated and challenged hamsters. The survival rate was significantly (P<0.05) higher in animals vaccinated with a higher dose of WN-80E than a lower dose. The addition of NS1 did not significantly affect survival after challenge. In contrast, all of the control animals that received adjuvant only developed a very high level of viremia, and the mortality rate was 100%. These findings indicate that the recombinant WN vaccines induced antibody in and afforded protection to young and aged hamsters and immunosuppressed hamsters.
authors.affiliation: University of Texas Medical Branch, Galveston, Texas 77555, USA.
authors.forename: Marina T
authors.initials: MT
authors.lastname: Siirin
authors.forename: Amelia P A
authors.initials: AP
authors.lastname: Travassos da Rosa
authors.forename: Patrick
authors.initials: P
authors.lastname: Newman
authors.forename: Carolyn
authors.initials: C
authors.lastname: Weeks-Levy
authors.forename: Beth-Ann
authors.initials: BA
authors.lastname: Coller
authors.forename: Shu-Yuan
authors.initials: SY
authors.lastname: Xiao
authors.forename: Michael M
authors.initials: MM
authors.lastname: Lieberman
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Watts
mesh_terms: D000375:Aging; D000818:Animals; D006224:Cricetinae; D003520:Cyclophosphamide / Q000494:pharmacology; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D016867:Immunocompromised Host; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008647:Mesocricetus; D021122:Protein Subunits / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology*; D013997:Time Factors; D014765:Viral Vaccines / Q000276:immunology*; D014766:Viremia; D014886:Weaning; D014901:West Nile Fever / Q000473:pathology / Q000517:prevention & control*
chemical_list: D007166:Immunosuppressive Agents; D021122:Protein Subunits; D011994:Recombinant Proteins; D014765:Viral Vaccines; D003520:Cyclophosphamide