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Avian Paramyxoviruses | 91

single-stranded, non-segmented RNA genome which is encap- has the RNA-dependent RNA transcriptase activity and is the
sidated with nucleocapsid protein (N) and associated with large
Figure 1 minimum infectious unit of the virus. A schematic of the avian
paramyxovirus virion is given in Fig. 3.2.
polymerase (L) and phosphoprotein (P). The nucleocapsid core

Figure 3.1 Negative-contrast electron micrograph of an avian paramyxovirus. The electron micrograph of APMV-13 is shown. Bar: 100 nm.
This figure is reproduced with permission of the Japanese Society of Veterinary Science from Yamamoto E, et al.: JVet Med Sci 2015; 77(9):
1079–1085.

Fusion protein

Haemagglutinin-neuraminidase
protein
Nucleocapsid protein

Matrix protein

Large polymerase Virion envelope
protein

Phosphoprotein

Figure 3.2 A schematic diagram of an avian paramyxovirus (not drawn to scale). Like APMV-1 or Newcastle disease virus, all other
APMVs contain six major proteins in their virion, namely, nucleocapsid protein (N), phosphoprotein (P), matrix protein (M), fusion protein
(F), haemagglutinin-neuraminidase protein (HN) and large polymerase protein (L). The P, F, and HN are shown as tetramer, trimer, and
tetramer, respectively. An integral membrane protein called small hydrophobic protein (SH), which is only present in APMV-6, is not shown.