REASON FOR PERFORMING STUDY: West Nile virus (WNF) is a Flavivirus responsible for a life-threatening neurological disease in man and horses. Development of improved vaccines against Flavivirus infections is therefore important. OBJECTIVES: To establish that a single immunogenicity dose of live Flavivirus chimera (WN-FV) vaccine protects horses from the disease and it induces a protective immune response, and to determine the duration of the protective immunity. METHODS: Clinical signs were compared between vaccinated (VACC) and control (CTRL) horses after an intrathecal WNV challenge given at 10 or 28 days, or 12 months post vaccination. RESULTS: Challenge of horses in the immunogenicity study at Day 28 post vaccination resulted in severe clinical signs of WNV infection in 10/10 control (CTRL) compared to 1/20 vaccinated (VACC) horses (P<0.01). None of the VACC horses developed viraemia and minimal histopathology was noted. Duration of immunity (DPI) was established at 12 months post vaccination. Eight of 10 CTRL exhibited severe clinical signs of infection compared to 1 of 9 VACC horses (P<0.05). There was a significant reduction in the occurrence of viraemia and histopathology lesion in VACC horses relative to CTRL horses. Horses challenged at Day 10 post vaccination experienced moderate or severe clinical signs of WNV infection in 3/3 CTRL compared to 5/6 VACC horses (P<0.05). CONCLUSIONS: This novel WN-FV chimera vaccine generates a protective immune response to WNV infection in horses that is demonstrated 10 days after a single vaccination and lasts for up to one year. POTENTIAL RELEVANCE: This is the first USDA licensed equine WNV vaccine to utilise a severe challenge model that produces the same WNV disease observed under field conditions to obtain a label claim for prevention of viraemia and aid in the prevention of WNV disease and encephalitis with a duration of immunity of 12 months.
REASON FOR PERFORMING STUDY: West Nile virus (WNF) is a Flavivirus responsible for a life-threatening neurological disease in man and horses. Development of improved vaccines against Flavivirus infections is therefore important. OBJECTIVES: To establish that a single immunogenicity dose of live Flavivirus chimera (WN-FV) vaccine protects horses from the disease and it induces a protective immune response, and to determine the duration of the protective immunity. METHODS: Clinical signs were compared between vaccinated (VACC) and control (CTRL) horses after an intrathecal WNV challenge given at 10 or 28 days, or 12 months post vaccination. RESULTS: Challenge of horses in the immunogenicity study at Day 28 post vaccination resulted in severe clinical signs of WNV infection in 10/10 control (CTRL) compared to 1/20 vaccinated (VACC) horses (P<0.01). None of the VACC horses developed viraemia and minimal histopathology was noted. Duration of immunity (DPI) was established at 12 months post vaccination. Eight of 10 CTRL exhibited severe clinical signs of infection compared to 1 of 9 VACC horses (P<0.05). There was a significant reduction in the occurrence of viraemia and histopathology lesion in VACC horses relative to CTRL horses. Horses challenged at Day 10 post vaccination experienced moderate or severe clinical signs of WNV infection in 3/3 CTRL compared to 5/6 VACC horses (P<0.05). CONCLUSIONS: This novel WN-FV chimera vaccine generates a protective immune response to WNV infection in horses that is demonstrated 10 days after a single vaccination and lasts for up to one year. POTENTIAL RELEVANCE: This is the first USDA licensed equine WNV vaccine to utilise a severe challenge model that produces the same WNV disease observed under field conditions to obtain a label claim for prevention of viraemia and aid in the prevention of WNV disease and encephalitis with a duration of immunity of 12 months.
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Authors: Nikolai Petrovsky; Maximilian Larena; Venkatraman Siddharthan; Natalie A Prow; Roy A Hall; Mario Lobigs; John Morrey Journal: J Virol Date: 2013-07-17 Impact factor: 5.103
Authors: K K Seino; M T Long; E P J Gibbs; R A Bowen; S E Beachboard; P P Humphrey; M A Dixon; M A Bourgeois Journal: Clin Vaccine Immunol Date: 2007-08-08
Authors: Marina De Filette; Silke Soehle; Sebastian Ulbert; Justin Richner; Michael S Diamond; Alessandro Sinigaglia; Luisa Barzon; Stefan Roels; Julianna Lisziewicz; Orsolya Lorincz; Niek N Sanders Journal: PLoS One Date: 2014-02-04 Impact factor: 3.240
Authors: Helle Bielefeldt-Ohmann; Natalie A Prow; Wenqi Wang; Cindy S E Tan; Mitchell Coyle; Alysha Douma; Jody Hobson-Peters; Lisa Kidd; Roy A Hall; Nikolai Petrovsky Journal: Vet Res Date: 2014-12-17 Impact factor: 3.683
Authors: Neal Van Hoeven; Sharvari Waghmare Joshi; Ghislain Ismael Nana; Angela Bosco-Lauth; Christopher Fox; Richard A Bowen; David E Clements; Timothy Martyak; D Elliot Parks; Susan Baldwin; Steven G Reed; Rhea N Coler Journal: PLoS One Date: 2016-02-22 Impact factor: 3.240