West Nile Virus (WNV)- An Overview


West Nile Virus (WNV) is a member of the Flaviviridae family, which includes other viruses that cause diseases such as Zika, dengue, and yellow fever. WNV is an enveloped virus, meaning that it has a lipid membrane derived from the host cell that surrounds its protein shell. The protein shell, or capsid, has an icosahedral symmetry and contains the viral genome. The genome of WNV is a single-stranded, positive-sense RNA molecule that is about 11,000 nucleotides long. The RNA genome has a 5` cap and a 3` poly(A) tail, and it encodes for 10 proteins: three structural proteins and seven nonstructural proteins. The structural proteins are the capsid (C), the envelope (E), and the pre-membrane (prM) proteins. The nonstructural proteins are NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5. The structural proteins are involved in the formation and entry of new viral particles, while the nonstructural proteins are involved in the replication and processing of the viral genome.

The structure and genome of WNV are similar to other flaviviruses, but they also have some distinctive features. For example, WNV has a relatively smooth protein shell compared to other flaviviruses, which have more prominent spikes on their surface. The spikes are formed by the E protein, which mediates the attachment and fusion of the virus with the host cell membrane. The E protein also undergoes conformational changes in response to pH changes during viral entry and maturation. Another feature of WNV is that its genome has two noncoding regions at both ends, called the untranslated regions (UTRs). These regions form stem-loop structures that play important roles in the initiation and regulation of viral transcription, translation, replication, and packaging.

The structure and genome of WNV determine its biological properties and interactions with the host cell. Understanding how WNV infects and replicates in different cell types and tissues can help us develop better diagnostic tools and preventive measures against this virus.