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104 | Paldurai and Samal

contains the preferred recognition site for furin (RX[K/R]R), antigenic analysis showed that APMV-9 is more closely related
which is an intracellular protease in most cells and tissues (basic to APMV-1, -12, -14, and -21 than to other APMV serotypes.
residues are underlined and the arrow indicates the cleavage site). The MDT in embryonated chicken eggs was found to be more
Hence, the F protein of virulent strains can be cleaved in most than 120 hours indicating APMV-9 to be avirulent for chickens
tissues, allowing the virulent strains to spread systemically. In (Samuel et al., 2009).
contrast, avirulent APMV-1 strains typically have mono or diba- A comparison of F and HN sequences of four Italian APMV-9
sic residues in the cleavage site ([G/E][K/R]Q[G/E]RL) and isolates among themselves and with the prototype strain revealed
depend on secretory protease. This restricts the avirulent virus significant sequence variation suggesting the existence of differ-
replication only to respiratory and enteric tracts, where the secre- ent lineages among APMV-9 viruses (Dundon et al., 2010). There
tory protease is found. All other APMV serotypes are avirulent was 41 aa carboxyl-terminus extension of the HN protein in all
to chickens, which is consistent with mono or dibasic residues the Italian isolates resulting in a HN protein of 620 aa compared
at their F protein cleavage site except APMV-5 (Fig. 3.5), which with 579 aa for the prototype strain. The biological significance of
is avirulent to chickens but contains a multibasic cleavage site this extension is not known. A phylogenetic analysis of APMV-9
(K-R-K-K-RF) in its F protein (Samuel et al., 2010). Therefore, strains is shown in Fig. 3.11.
the F protein cleavage site sequence may not be a diagnostic
feature to determine the virulence of other APMV serotypes in APMV-12
chickens. However, the F protein cleavage site sequence is an APMV-12 (AOAvV-12) was isolated from an apparently healthy
important sequence for infectivity of the virus and is perfectly Eurasian wigeon (A. penelope) trapped in 2005 in Rovigo prov-
conserved in each APMV serotype, except APMV-1, APMV-2, ince, northeastern Italy during AIV surveillance (Terregino et al.,
APMV-3 and APMV-6. Each of these APMV serotypes have at 2013). The virus showed a low-level antigenic relationship only
least two different F protein cleavage site sequences, indicating to APMV-1 by HI test. The genome of APMV-12 is 15,132 nt
that they may represent different subgroups. These results also and contains six genes. The leader and trailer regions are 55 nt
suggest that the F protein cleavage site sequence can be used as a and 204 nt, respectively. The only strain APMV-12/wigeon/
quick method to serotype an APMV isolate. Italy/3920-1/05 (Italy/3920-1) is considered the prototype for
the APMV-12. APMV-12 has the closest nt identity (62.2%) with
APMV-13. The other closer nt identities (55.1 and 55%, respec-
APMVs from genus Orthoavulavirus tively) are with APMV-1 and -16. The putative F protein cleavage
The species AOAvV-1 is the type species for the genus Orthoavu- site of strain Italy/3920-1 (G-R-E-P-RL) lacks multiple basic
lavirus which encompasses all strains of APMV-1, including NDV residues. The virus is avirulent to chickens based on ICPI values
and pigeon paramyxovirus 1 (PPMV-1). For detailed information (Terregino et al., 2013).
on APMV-1, refer to Chapter 2 on Newcastle disease virus.
APMV-13
APMV-9 Three novel APMVs were isolated during AIV surveillance in
APMV-9 (AOAvV-9) was first isolated from a domestic duck three separate regions of Eurasia: from a wild migratory goose
(Anas platyrhynchos domesticus) during routine surveillance in faeces sample collected in Japan in 2000 (Yamamoto et al., 2015),
New York in 1978 (Sandhu and Hinshaw, 1981; Alexander et al., from a white-fronted goose in Kazakhstan in 2013 (Karamendin
1983a). Since then APMV-9 strains have been isolated from feral et al., 2016b), and from a white-fronted goose in Ukraine in
ducks in Italy indicating worldwide distribution (Capua et al., 2011 (Goraichuk et al., 2016). The F genes of all three strains
2004; Dundon et al., 2010). Isolation of APMV-9 is less frequent share > 97% nt identity and belong to APMV-13 (AOAvV-13)
than some of the other APMV serotypes. APMV-9 does not cause (Amarasinghe et al., 2017). The APMV-13 strain goose/Shi-
clinical disease in birds. Strain domestic duck/New York/22/78 mane/67/2000 (Shimane/67) from Japan is the prototype strain
is the prototype strain for the serotype. and has the genome of 16,146 nt. The strain Shimane/67 grows in
The full genome sequence of APMV-9 strain domestic duck/ most cell lines in the presence of exogenous protease and causes
New York/22/78 has been published (Samuel et al., 2009). The syncytia formation (Yamamoto et al., 2015). The aa sequence at
genome of APMV-9 is 15,438 nt long and encodes six genes with the F protein cleavage site of strain Shimane/67 is V-R-E-N-RL,
intergenic regions of 0–30 nt. The genome contains a 55 nt leader which resembles the motif of lentogenic NDV. The virus is aviru-
sequence at the 3′ end and a 47 nt trailer sequence at the 5′ end. lent to chickens based on the ICPI value. The virus showed some
The cleavage site sequence of the F protein is R-I-R-E-G-RI, cross-reaction by HI test with APMV-1, APMV-4 and APMV-7.
which resembles the cleavage site sequence of lentogenic NDV. Complete genome sequences are also available for the strains from
Exogenous protease is required for in vitro virus replication. The Kazakhstan and Ukraine (Goraichuk et al., 2016; Karamendin et
virus grows only in a few established cell lines, such as Vero, DF-1 al., 2016b). The genome of Kazakhstan strain is 15,996 nt. How-
and BHK-21. It is necessary to include 10% allantoic fluid for ever, the genome of Ukraine strain is 16,146 nt, which is 150 nt
replication of the virus in cell culture, which cannot be met by longer than that of the Kazakhstan strain. The genome sequence
chymotrypsin or by trypsin. The virus grew efficiently in primary of Ukraine strain showed 97% nt identity to that of Kazakhstan
CEK cells but not in CEF cells. The CPE observed was rounding, strain. Phylogenetic analysis of the aa sequences showed that
detachment of cells and no syncytia formation. Phylogenetic and APMV-13 is most closely related to APMV-12.