Inactivated West Nile Virus Lineage 2 (1986)

West Nile virus (WNV) is a single-stranded, positive-sense RNA virus belonging to the genus Flavivirus in the family Flaviviridae. It is part of the Japanese encephalitis virus serocomplex, which also includes other medically significant arboviruses such as St. Louis encephalitis virus and Murray Valley encephalitis virus. The viral genome is approximately 11 kilobases in length and encodes three structural proteins (capsid [C], premembrane/membrane [prM/M], and envelope [E]) and seven nonstructural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) that are essential for viral replication, assembly, and immune evasion.

The E protein is crucial for viral attachment and entry into host cells, mediating receptor binding and membrane fusion. The NS3 and NS5 proteins function as a protease and RNA-dependent RNA polymerase, respectively, to facilitate viral replication. West Nile virus (WNV) exhibits genetic diversity, with two major lineages: lineage 1 (widespread and associated with outbreaks) and lineage 2 (traditionally restricted to Africa but now also occurring in Europe).

WNV is primarily transmitted through the bites of infected mosquitoes, primarily Culex pipiens, which serve as both vectors and reservoirs. Birds are the primary amplification hosts, while humans and horses serve as occasional dead-end hosts. The virus replicates in the mosquito''s salivary glands and is injected into the vertebrate host during a blood meal. In humans, WNV can cross the blood-brain barrier, causing severe neurological symptoms such as encephalitis, meningitis, or acute flaccid paralysis in approximately 1% of cases.