Besides retroviruses, late domain motifs have also been identified in other enveloped viruses like rhabdoviruses (vesicular stomatitis virus, rabies virus) [15–17], filoviruses (ebola, marburg) [18–22], arenaviruses (lymphocytic choriomeningitis virus, lassa virus) SCH727965 concentration [23, 24], paramyxoviruses (Nipah virus, Sendai virus) [25, 26] and DNA viruses like hepatitis B virus, vaccinia virus, herpes simplex virus-1 and Epstein Barr virus [27–33]. Amongst flaviviruses, the NS3 of Japanese encephalitis virus (JEV) has been shown to associate with Tsg101 [34] while the yellow fever virus (YFV) NS3 has been shown to interact with Alix [35] assisting in virus release.

However, currently there is no information on the presence of late domains in WNV proteins. The process of WNV budding into the lumen of the ER is topologically similar to the process of MVB biogenesis in that both occur in a direction that is away from the cytosol. MVB biogenesis is mediated by the family of ESCRT proteins namely ESCRT-0, -I, -II and -III and other associated proteins like Alix/AIP1. The membrane associated ESCRT-III complexes are finally disassembled and recycled by the Ku 0059436 ATPase Vps4. A number

of enveloped viruses via the conserved late (L) domain motifs that mimic similar motifs in cellular proteins are able to recruit the ESCRT machinery to the site of virus budding [36]. Disruption of L domain motifs or their function leads to defects in the final (late) stages of virus budding characterized by the tethering of virions to the cell surface [9, 14, 36, 37]. Most Vorinostat nmr data on the role of ESCRT proteins and viral late domain motifs has come from research on retroviruses that primarily bud from the plasma membrane. Although there are reports that NS3 of other Flaviviruses can interact with ESCRT components [34, 35] there are no such reports for WNV. Furthermore, it is not known whether any late domain like motifs are present in WNV structural proteins especially E protein that is essential for assembly into virus like

particles [38]. Results and discussion Identification of conserved motifs in the WNV E protein In case of Flaviviruses, the structural E protein is necessary for virus assembly and release and the production of recombinant VLPs. Hence, using sequence analysis and information based on work with other viruses we undertook this study to identify the presence of conserved motifs (a vital indicator of the functional importance) in the Flavivirus structural E proteins and determine whether they play a role in virus assembly and release. Sequence analysis of different Flavivirus structural proteins and different WNV isolates revealed the presence of conserved 461PXAP464 and 349YCYL352 motifs in the E protein (Figure 1A and B).