1. ➢ WNV infects a wide range of target cells. Virion entry is initiated after
the envelope protein, E, engages an cellular receptor (step 1),
followed by receptor-mediated endocytosis of the virus (step 2).
➢ The low-pH environment within the endosomal vesicle triggers viral
fusion with the endosomal membrane (step 3), leading to virion
uncoating and release of the viral (+)ssRNA genome (step 4). The viral
(+)ssRNA is translated into a single polyprotein at the ER and cleaved
into mature proteins by the viral NS2B–NS3 and cellular proteases
(step 5). The NS proteins form the replication complex for the
synthesis of full-length (–)ssRNA intermediates (step 6). These serve
as templates for the synthesis of full-length (+)ssRNAs (step 7).
➢ The viral capsid protein, C, is responsible for encapsidating viral
genomic RNA, with assembly occurring on rough ER membranes
(step 8). Immature virions are transported through the host secretory
pathway, resulting in glycosylation of the viral E protein and host cell
furin mediated-cleavage of the protein prM to the mature membrane
protein, M (step 9). Mature virions are transported to the plasma
membrane and released by exocytosis (step 10).
Fig.4 The West Nile Virus Life cycle.
(Suthar, Nat Rev Microbiol, 2013)
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Life cycle of West Nile Virus