Recent progress in West Nile virus diagnosis and vaccination

1. Introduction2. West Nile virus3. Epidemiology4. Pathogenesis5. Diagnosis5.1. Nucleic acid based tests for WNV5.2. Serologic diagnosis of WNV infections5.3. WNV antigen detection6. Vaccination6.1. Licensed West Nile virus vaccines for animals6.2. WNV vaccines under development6.3. Clinical trials with West Nile virus vaccines in humans7. Conclusions8. Competing interests9. Authors' contributions10. Acknowledgments11. ReferencesWest Nile virus (WNV) is a zoonotic mosquito-transmitted arbovirus belonging to the genus Flavivirus in the family Flaviviridae. WNV is maintained in a mosquito-bird-mosquito transmission cycle [1], whereas humans and horses are considered dead-end hosts. WNV is transmitted primarily by the bite of infected mosquitoes, themselves acquiring the virus by feeding on infected birds.The West Nile virus has been reported in dead or dying birds of at least 326 species [2]. The clinical outcome of infection is variable e.g. chickens and turkeys are resistant to disease while some species are particularly susceptible, e.g. crows, Carolina chickadees, tufted titmice, blue jays, American robins, and eastern bluebirds.WNV has a wide geographical range that includes portions of Europe, Asia, Africa, Australia (Kunjin virus) and North, Central and South America [3]. Migratory birds are thought to be primarily responsible for virus dispersal, including reintroduction of WNV from endemic areas into regions that experience sporadic outbreaks [3].In humans, it was first isolated in the West Nile province of Uganda in 1937 from the blood of a woman suffering from a mild febrile illness [4]. Until the mid 1990's, West Nile (WN) disease was considered as a minor risk for humans and horses because it only appeared sporadically. The first cases of West Nile virus in its lethal encephalitic form were reported in Algeria in 1994. Since the first large outbreak in Romania in 1996, which was characterized by a high number of neuroinvasive cases, and the huge epidemics