Life Cycle of West Nile Virus

Fig.4 The West Nile Virus Life cycle. (Suthar, Nat Rev Microbiol, 2013)

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).