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Avian Reovirus | 185

Table 6.1 Avian orthoreovirus genes, encoded proteins and their functions
Genome Encoded viral protein,
segment and location, and number Calculated
size (bp) of units per virion mol. wt. (kDa) Functions
L1 λA 142.2–142.3 A major core protein that forms the inner core shell (Guardado-Calvo et al., 2008)
3958 Inner core Serves as a scaffold during the early stages of viral morphogenesis (Benavente and
120
Martínez-Costas, 2007)
L2 λB 139.7–139.8 viral RNA dependent RNA polymerase (RdRp) enzyme/transcriptase (Xu and Coombs,
3830 Inner core 2008)
12
Allow template RNAs, nucleotides and divalent cations to access the interior catalytic site
(McDonald et al., 2009)
L3 λC 141.9–142.2 As a pentamer forms the turrets that extend from inner core through outer capsid (core
3907 Turrets turret protein) (Martínez-Costas et al., 1997; Zhang et al., 2005)
60
Guanylyltransferase/viral capping enzyme that replace a 5′ cap on extruded viral mRNA
(Martinez-Costas et al., 1995)
M1 µA 82–82.2 The co-factor for the enzyme RdRp (Benavente and Martínez-Costas, 2007)
2283 Inner core
24
M2 µB 73.1–73.3 A major outer capsid protein that form outer capsid with σB (Martínez-Costas et al., 1997;
2158 Outer capsid Zhang et al., 2005)
600
Penetration (virus entry to cytoplasm) (O’Hara et al., 2001)
(µBN and µBC
originated by post Transcriptase activation (O’Hara et al., 2001)
translational cleavage Cleavage and removal of µB associated with the endosomal membrane (O’Hara et al.,
of precursor µB, µBC is 2001)
further cleaved)
Interaction and conformational changes in the capsid required for delivery of the
transcriptionally active core particle to the cytoplasm (O’Hara et al., 2001)
M3 µNS 70.8–70.9 Forms viral factory scaffold (matrix) in infected cells and plays an important role
1996 Non-structural in the early steps of viral morphogenesis by temporally and selectively controlling
Conserved protein the recruitment of specific viral proteins to viral factories (Tourı́s-Otero et al., 2004;
Produce smaller µNS Brandariz-Nuñez et al., 2010)
isoforms µNSC and Mediate association of σNS and λA to inclusions during morphogenesis (Tourı́s-Otero et
µNSN
al., 2004; Brandariz-Nuñez et al., 2010)
S1 P10 10.3 Fusion associated small transmembrane (FAST) protein responsible for fusion of host
1643 Non-structural cells and syncytium formation (Shmulevitz and Duncan, 2000; Barry and Duncan, 2009)
A viroporin (Bodelón et al., 2002; Wu et al., 2016)
Increases plasma membrane permeability (Bodelón et al., 2002)
Induces apoptosis of host cell (Salsman et al., 2005; Wu et al., 2016)
P17 16.9 Causes host cell protein translation shutoff through activation of p53-dependent pathway
Membrane associated (Chulu et al., 2010)
non-structural protein
Cell cycle arrest (Chulu et al., 2010; Chiu et al., 2016)
A shuttle protein that moves between nucleus and cytoplasm continuously making it
available to participate in cellular nuclear processes such as host cell translation, cell
cycle and autophagosome formation benefiting virus replication (Costas et al., 2005; Liu
et al., 2005; Ji et al., 2009; Chi et al., 2013; Huang et al., 2015)
σC 34.9 An elongated homotrimer responsible for virus attachment to the host cell through its
A minor component of C-terminal globular domain while anchored in the λC pentamer via its N terminus to
outer capsid; the most protrude from the turret tops (Shapouri et al., 1996; Martínez-Costas et al., 1997; Grande
variable protein 36 et al., 2000; Grande et al., 2002; Guardado-Calvo et al., 2009)
Determines tissue tropism and contribute to host restriction (Bodelón et al., 2001)
Carries serological specificity. Induce type-specific neutralizing antibodies in virus
infection and protective antibodies after vaccination (Wickramasinghe et al., 1993;
Shapouri et al., 1996; Shih et al., 2004; Ping-Yuan et al., 2006)
Induces apoptosis of the host cell (Shih et al., 2004)
A viroporin
Determines tissue tropism and contribute to host restriction (Bodelón et al., 2001)
Carries serological specificity. Induce type-specific neutralizing antibodies in virus
infection and protective antibodies after vaccination (Wickramasinghe et al., 1993;
Shapouri et al., 1996; Shih et al., 2004; Ping-Yuan et al., 2006)
Induces apoptosis of the host cell (Shih et al., 2004)
A viroporin