Abstract
We report here the complete genomic sequence of a novel Newcastle disease virus (NDV) strain, egret/China/Guangxi/2011, isolated from an egret in Guangxi Province, southern China. A phylogenetic analysis based on a fusion gene comparison with different NDV strains revealed that egret/China/Guangxi/2011 was phylogenetically close to genotype VIIa NDV, and the deduced amino acid sequence was 112R-R-R-K-R-F117 at the fusion protein cleavage site. The whole nucleotide sequence had the highest homology (93.3%) with the sequence of strain chicken/Sukorejo/019/10 (GenBank accession number HQ697255). This study will help us to understand the epidemiology and molecular characteristics of Newcastle disease virus in a migratory egret.
GENOME ANNOUNCEMENT
Newcastle disease virus (NDV), synonymous with avian paramyxovirus-1, is the causative agent of Newcastle disease, which is a highly contagious and fatal viral disease that affects all species of birds (1, 3, 5).
NDV has a nonsegmented, negative-sense RNA genome consisting of six transcriptional units (3′-NP-P-M-F-HN-L-5′) (4, 8). NDV strains have been classified into classes I (9 genotypes) and II (11 genotypes): class I strains are generally avirulent and have been isolated mainly from wild birds, whereas class II strains are virulent and avirulent and have been isolated from wild and domestic birds (2, 6).
In May 2011, NDV was isolated from a wild egret in Guangxi Province, southern China. The isolate's virus was named egret/China/Guangxi/2011. Nucleotide sequences of egret/China/Guangxi/2011 were amplified through reverse transcription-PCR (RT-PCR). The amplified products were purified and cloned into the pMD18-T vector (TaKaRa) and then sequenced (TaKaRa, Dalian, China). Sequences were assembled and manually edited to generate the final genome sequence.
Sequence analysis showed that the full genomic length of egret/China/Guangxi/2011 is 1 5,192 nucleotides (nt). A phylogenetic analysis classified this strain into class II, genotype VIIa. The whole nucleotide sequence had the highest homology (93.3%) with the sequence of strain chicken/Sukorejo/019/10 (GenBank accession number HQ697255, class II, genotype VIIa). The amino acid sequence identities of the NP, P, M, F, HN, and L proteins between egret/China/Guangxi/2011 and Sukorejo01910 are 97.6%, 96.7%, 97.8%, 98%, 96%, and 97.3%, respectively. The amino acid sequence identities of the NP, P, M, F, HN, and L proteins between egret/China/Guangxi/2011 and strain La Sota (GenBank accession number JF950510, class II, genotype II) are 84.2%, 81.8%, 83.7%, 84.2%, 81.9%, and 85.8%, respectively.
The homology of the 374-bp partial F gene (positions 4550 to 4923) of egret/China/Guangxi/2011 with the sequences of Que-66 (GenBank accession number M24693, class II, genotype I), La Sota (GenBank accession number JF950510, class II, genotype II), Aus-32 (GenBank accession number M24700, class II, genotype III), Herts-33 (GenBank accession number AY741404, class II, genotype IV), CA1085-71 (GenBank accession number JQ247691, class II, genotype V), ISreal70-1 (GenBank accession number AF001111, class II, genotype VI), chicken/Sukorejo/019/10 (GenBank accession number HQ697255, class II, genotype VIIa), QH-4-48 (GenBank accession number AF378252, class II, genotype VIII), F48E9 (GenBank accession number AY508514, class II, genotype IX), US(NJ) (GenBank accession number EF565065, class I) were 79.7% 75.4%, 80.2%, 81.0%, 81.8%, 84.8%, 96.3%, 82.6%, 78.6%, and 58.3%, respectively.
The sequence at the fusion protein cleavage site is a major determinant of NDV pathogenicity (7). The cleavage sites of virulent NDV strains contain multiple basic residues, whereas avirulent strains have few basic residues. The egret/China/Guangxi/2011 strain has a virulent fusion protein cleavage site sequence (112R-R-R-K-R-F117), and it accorded with the detection of an intracerebral pathogenicity index of 1.846.
To our knowledge, this is the first report of a phylogenetic analysis of the whole nucleotide sequence of NDV isolated from a wild egret. Thus, it will help us to understand the epidemiology and molecular characteristics of Newcastle disease virus in wild birds.
Nucleotide sequence accession number.
The GenBank accession number of egret/China/Guangxi/2011 is JX193074.
ACKNOWLEDGMENTS
This work was supported by the Guangxi Science and Technology Bureau (grants 10100014-5 and 1222003-2-4) and by the Guangxi Government Senior Scientist Foundation (grant 2011B020).
REFERENCES
- 1. Alexander DJ. 2000. Newcastle disease and other avian paramyxoviruses. Rev. Sci. Tech. 19:443–462 [DOI] [PubMed] [Google Scholar]
- 2. Czeglédi A, et al. 2006. Third genome size category of avian paramyxovirus serotype 1 (Newcastle disease virus) and evolutionary implications. Virus Res. 120(1–2):36–48 [DOI] [PubMed] [Google Scholar]
- 3. de Leeuw OS, Koch G, Hartog L, Ravenshorst N, Peeters BP. 2005. Virulence of Newcastle disease virus is determined by the cleavage site of the fusion protein and by both the stem region and globular head of the haemagglutinin-neuraminidase protein. J. Gen. Virol. 86:1759–1769 [DOI] [PubMed] [Google Scholar]
- 4. Knipe DM, Lamb R, Parks G. 2007. Paramyxoviridae: the viruses and their replication, p 1449–1496 In Knipe DM, et al. (ed), Fields virology, 5th ed Lippincott Williams & Wilkins, Philadelphia, PA [Google Scholar]
- 5. Mast J, Nanbru C, van den Berg T, Meulemans G. 2005. Ultrastructural changes of the tracheal epithelium after vaccination of day-old chickens with the La Sota strain of Newcastle disease virus. Vet. Pathol. 42:559–565 [DOI] [PubMed] [Google Scholar]
- 6. Miller PJ, Decanini EL, Afonso CL. 2010. Newcastle disease: evolution of genotypes and the related diagnostic challenges. Infect. Genet. Evol. 10:26–35 [DOI] [PubMed] [Google Scholar]
- 7. Panda A, Huang Z, Elankumaran S, Rockemann DD, Samal SK. 2004. Role of fusion protein cleavage site in the virulence of Newcastle disease virus. Microb. Pathog. 36:1–10 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8. Yan Y, Samal S. 2008. Role of intergenic sequences in Newcastle disease virus RNA transcription and pathogenesis. J. Virol. 82:1323–1331 [DOI] [PMC free article] [PubMed] [Google Scholar]