RESUMO
An outbreak of Newcastle disease (ND) in poultry was reported in Belize in 2008. The characteristics of three virulent Newcastle disease virus (NDV) isolates from this outbreak (NDV-Belize-3/08, NDV-Belize-4/08, and NDV-Belize-12/08) were assessed by genomic analysis and by clinicopathological characterization in specific-pathogen-free (SPF) chickens. The results showed that all three strains belong to NDV genotype V and are virulent, as assessed by the intracerebral pathogenicity index and the polybasic amino acid sequence at the fusion protein cleavage site. In 4-week-old SPF chickens, NDV-Belize-3/08 behaved as a typical velogenic viscerotropic NDV strain, causing severe necrohemorrhagic lesions in the lymphoid organs, with systemic virus distribution. Phylogenetic analysis of multiple NDV genotype V representatives revealed that genotype V can be divided into three subgenotypes, namely, Va, Vb, and Vc, and that all tested Belizean isolates belong to subgenotype Vb. Furthermore, these isolates are nearly identical to a 2007 isolate from Honduras and appear to have evolved separately from other contemporary viruses circulating in Mexico, clustering into a new clade within NDV subgenotype Vb.
Assuntos
Doença de Newcastle/virologia , Vírus da Doença de Newcastle/genética , Virulência/genética , Animais , América Central , Galinhas/virologia , Análise por Conglomerados , Surtos de Doenças/veterinária , Genótipo , México , Filogenia , Doenças das Aves Domésticas/virologia , RNA Viral/genética , Análise de Sequência de DNA/métodos , Proteínas Virais de Fusão/genéticaRESUMO
Newcastle disease, one of the most important health problems that affects the poultry industry around the world, is caused by virulent strains of Newcastle disease virus. Newcastle disease virus is considered to be endemic in several countries in the Americas, including Mexico. In order to control Newcastle disease outbreaks and spread, intensive vaccination programs, which include vaccines formulated with strains isolated at least 60 years ago, have been established. These vaccines are dissimilar in genotype to the virulent Newcastle disease viruses that had been circulating in Mexico until 2008. Here, 28 isolates obtained between 2008 and 2011 from different regions of Mexico from free-living wild birds, captive wild birds, and poultry were phylogenetically and biologically characterized in order to study the recent epidemiology of Newcastle disease viruses in Mexico. Here we demonstrate that, until recently, virulent viruses from genotype V continued to circulate and evolve in the country. All of the Newcastle disease viruses of low virulence, mostly isolated from nonvaccinated free-living wild birds and captive wild birds, were highly similar to LaSota (genotype II) and PHY-LMV42 (genotype I) vaccine strains. These findings, together with the discovery of two virulent viruses at the Mexican zoo, suggest that Newcastle disease viruses may be escaping from poultry into the environment.
Assuntos
Aves , Galinhas , Doença de Newcastle/epidemiologia , Vírus da Doença de Newcastle/genética , Doenças das Aves Domésticas/epidemiologia , Animais , Aves/classificação , Genótipo , México/epidemiologia , Epidemiologia Molecular , Dados de Sequência Molecular , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/isolamento & purificação , Vírus da Doença de Newcastle/patogenicidade , Vírus da Doença de Newcastle/fisiologia , Filogenia , Reação em Cadeia da Polimerase , Doenças das Aves Domésticas/virologia , RNA Viral/genética , RNA Viral/metabolismo , Análise de Sequência de RNA/veterinária , Homologia de Sequência , VirulênciaRESUMO
A Newcastle disease virus (NDV) outbreak in chickens was reported in the Dominican Republic in 2008. The complete genome of this isolate, chicken/DominicanRepublic(JuanLopez)/499-31/2008 (NDV-DR499-31/08), and the fusion proteins of three other related viruses from the Dominican Republic and Mexico were sequenced and phylogenetically analyzed. Genetically, these four isolates were highly distinct from all other currently known isolates of NDV, and together, they fulfill the newly established criteria for inclusion as a novel genotype of NDV (genotype XVI). The lack of any reported isolation of viruses related to this group since 1986 suggests that virulent viruses of this genotype may have evolved unnoticed for 22 years. The NDV-DR499-31/08 isolate had an intracerebral pathogenicity index (ICPI) score of 1.88, and sequencing of the fusion cleavage site identified multiple basic amino acids and a phenylalanine at position 117, indicating this isolate to be virulent. These results were further confirmed by a clinicopathological assessment in vivo. In 4-week-old chickens, NDV-DR499-31/08 behaved as a velogenic viscerotropic strain with systemic virus distribution and severe necrohemorrhagic lesions targeting mainly the intestine and the lymphoid organs. The clear phylogenetic relationship between the 2008, 1986, and 1947 ancestral viruses suggests that virulent NDV strains may have evolved in unknown reservoirs in the Caribbean and surrounding regions and underlines the importance of continued and improved epidemiological surveillance strategies to detect NDV in wild-bird species and commercial poultry.
Assuntos
Evolução Molecular , Genótipo , Vírus da Doença de Newcastle/genética , Animais , Galinhas , Genoma Viral , Doença de Newcastle/patologia , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/classificação , Vírus da Doença de Newcastle/patogenicidade , Fenótipo , Filogenia , Doenças das Aves Domésticas/virologia , Proteínas Virais de Fusão/genética , Fatores de Virulência/genéticaRESUMO
Newcastle disease virus (NDV) was isolated from an outbreak in layer chickens in the Dominican Republic in 2008. Infections with this isolate led to a 100% apparent case fatality rate in birds. Complete genome sequencing revealed that the isolate does not belong to any of the previously described NDV genotypes. Similarly, large differences were observed in the amino acid sequence of the fusion and hemagglutinin-neuraminidase proteins in comparison with all known NDV genotypes, suggesting the existence of an unknown reservoir for NDV. The work presented here represents the first complete genome sequence of NDV in the Dominican Republic.
Assuntos
Genoma Viral , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/genética , Doenças das Aves Domésticas/virologia , Animais , Sequência de Bases , Galinhas , República Dominicana , Dados de Sequência Molecular , Vírus da Doença de Newcastle/classificação , Vírus da Doença de Newcastle/isolamento & purificaçãoRESUMO
Newcastle disease (ND) is one of the most important diseases of poultry, negatively affecting poultry production worldwide. The disease is caused by Newcastle disease virus (NDV) or avian paramyxovirus type 1 (APMV-1), a negative-sense single-stranded RNA virus of the genus Avulavirus, family Paramyxoviridae. Although all NDV isolates characterized to date belong to a single serotype of APMV-1, significant genetic diversity has been described between different NDV isolates. Here we present the complete genome sequence and the clinicopathological characterization of a virulent Newcastle disease virus isolate (NDV-Peru/08) obtained from poultry during an outbreak of ND in Peru in 2008. Phylogenetic reconstruction and analysis of the evolutionary distances between NDV-Peru/08 and other isolates representing established NDV genotypes revealed the existence of large genomic and amino differences that clearly distinguish this isolate from viruses of typical NDV genotypes. Although NDV-Peru/08 is a genetically distinct virus, pathogenesis studies conducted with chickens revealed that NDV-Peru/08 infection results in clinical signs characteristic of velogenic viscerotropic NDV strains. Additionally, vaccination studies have shown that an inactivated NDV-LaSota/46 vaccine conferred full protection from NDV-Peru/08-induced clinical disease and mortality. This represents the first complete characterization of a virulent NDV isolate from South America.