Genetic variation of Italian avian paramyxoviruses serotype 9 William G. Dundon • Alireza Heidari • Roberta De Nardi • Calogero Terregino • Ilaria Capua • Giovanni Cattoli Received: 12 January 2010 / Accepted: 31 March 2010 Ó Springer Science+Business Media, LLC 2010 Abstract The haemagglutinin-neuraminidase (HN) and fusion protein (F) gene of four avian paramyoviruses serotype 9 (APMV9) recently isolated from wild birds in Italy have been sequenced. A comparison between the sequences of these four isolates and the prototype virus PMV-9/domestic Duck/New York/22/78 revealed signifi- cant sequence variation that suggests that different lineages exist among APMV-9 viruses similar to that seen for APMV-1 (Newcastle disease). Avian paramyxoviruses (APMV) are classified into nine serotypes (1–9) and infect both domestic and wild birds. APMV-1 (Newcastle disease), APMV-2, APMV-3, APMV-6 and APMV-7 are known to cause disease in poultry although the severity differs between the serotypes [1]. Since it is not associated with clinical disease, APMV- 9 has not been studied in any great depth and, as such, there is a paucity of genetic information available for this virus. Indeed, in the literature, only two isolations of APMV-9 have been reported to date. The first was from a domestic duck isolated during routine surveillance in New York, USA (PMV-9/domestic Duck/New York/22/78) [2, 3] and the second, some 26 years later in Italy (PMV-9/pintail/ Italy/493/2004) following a wild bird surveillance pro- gramme [4]. The full genome of the prototype strain (PMV-9/domestic Duck/New York/22/78) has recently been published which has provided a first glimpse of the genetic makeup of APMV-9 [5]. The genome of avian paramyxovirus 9 encodes six proteins namely a nucleoprotein (N), a phosphoprotein (P), a matrix protein (M), a fusion protein (F), an attachment hemagglutinin-neuraminidase (HN) and a large polymerase protein (L). Transcription of each of the genes encoding these proteins begins at a conserved gene start (GS) sequence and ends with a conserved gene end (GE) sequence [6]. Between the GS and GE specific non-coding intergenic sequences (IGS) have been identified, whose length can vary [6]. Both the HN and F proteins are glycoproteins involved in virus penetration of the host cell. HN binds to sialic containing cell surface receptors facilitating virus entry, while the F protein induces fusion between the viral envelope and the plasma host cell membrane. Analysis of the HN and F genes of NDV have been used by several groups to categorise the different genotypes and pathotypes of NDV [7–10]. With this in mind and in order to increase the available genetic data for APMV-9 viruses, we have sequenced the complete F and HN gene and their flanking intergenic regions of four APMV-9 viruses isolated in Italy between 2004 and 2008 and have compared them to the prototype PMV-9/domestic Duck/New York/22/78 strain. PMV-9/pintail/Italy/493/2004 previously described by Capua et al. [4] was used in this study in addition to three other APMV9 viruses (e.g. PMV-9/Mallard/Italy/6226/08, PMV-9/Widgeon/Italy/6436/08 and PMV-9/Mallard/Italy/ 5709/07) isolated from cloacal swabs collected from hun- ted wild birds as part of a surveillance programme for avian influenza in North-Eastern Italy. Standard isolation in specific pathogen free (SPF) chicken eggs and character- ization using haemagglutination inhibition protocols and W. G. Dundon (&) Á A. Heidari Á R. De Nardi Á C. Terregino Á I. Capua Á G. Cattoli OIE, FAO and National Reference Laboratory for Avian Influenza and Newcastle Disease, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell’universita ` 10, 35020 Legnaro, Padova, Italy e-mail: wdundon@izsvenezie.it 123 Virus Genes DOI 10.1007/s11262-010-0479-2