Muraki Yuko, Fujita Takeshi, Matsuura Masaaki, Fuke Isao, Manabe Sadao, Ishikawa Toyokazu, Okuno Yoshinobu, Morita Kouichi
Kanonji Institute, The Research Foundation for Microbial diseases of Osaka University, Yahata-cho 2-9-41, Kannonnji City, Kagawa, 768-0061, Japan.
Department of Virology, Institute of Tropical Medicine, Nagasaki University, Sakamoto-machi 1-12-4, Nagasaki City, Nagasaki, 852-8523, Japan.
Virol J. 2015 Apr 9;12:54. doi: 10.1186/s12985-015-0282-8.
West Nile virus (WNV) belonging to the genus Flavivirus of the family Flaviviridae causes nervous system disorder in humans, horses and birds. Licensed WNV vaccines are available for use in horses but not for humans. We previously developed an inactivated West Nile virus vaccine (WN-VAX) using a seed virus from West Nile virus (WNV NY99) that was originally isolated in New York City in 1999. In this study, we report the immunogenicity of WN-VAX in both mice and non-human primates.
The WN-VAX immunized mice showed protection against lethal infection with WNV NY99. The challenge test performed on mice passively immunized with serum from other mice that were previously immunized with WN-VAX confirmed that the neutralizing antibody titers of more than 1log10 protected the passively immunized mice from WNV lethal infection. Furthermore, monkeys (Macaca fascicularis) immunized three times with 2.5 μg, 5 μg or 10 μg/dose of WN-VAX exhibited neutralizing antibodies in their sera with titers of more than 2log10 after the second immunization.
The WN-VAX was protective in mice both by active and passive immunizations and was immunogenic in monkeys. These results suggest that the vaccine developed in this study may be a potential WNV vaccine candidate for human use.
西尼罗河病毒（WNV）属于黄病毒科黄病毒属，可导致人类、马匹和鸟类出现神经系统疾病。有许可的西尼罗河病毒疫苗可用于马匹，但不适用于人类。我们之前使用1999年最初在纽约市分离出的西尼罗河病毒（WNV NY99）的种子病毒开发了一种灭活西尼罗河病毒疫苗（WN-VAX）。在本研究中，我们报告了WN-VAX在小鼠和非人灵长类动物中的免疫原性。
用WN-VAX免疫的小鼠对WNV NY99的致死性感染具有保护作用。对用先前用WN-VAX免疫的其他小鼠的血清进行被动免疫的小鼠进行的攻毒试验证实，中和抗体滴度超过1log10可保护被动免疫的小鼠免受WNV致死性感染。此外，用2.5μg、5μg或10μg/剂量的WN-VAX免疫三次的猴子（食蟹猴）在第二次免疫后血清中出现了中和抗体，滴度超过2log10。
WN-VAX通过主动免疫和被动免疫在小鼠中均具有保护作用，并且在猴子中具有免疫原性。这些结果表明，本研究中开发的疫苗可能是一种潜在的可供人类使用的西尼罗河病毒疫苗候选物。
