RESUMO
BACKGROUND: Fowl adenovirus (FAdV) is an infectious agent that can cause jaundice, severe anaemia, dyspnoea and reproductive disorders in fowls. Since 2015, FAdV disease has been rapidly spreading among broiler chickens in China, where it has caused significant economic losses. In this study, a loop-mediated isothermal amplification (LAMP) real-time turbidity method with strong specificity to FAdV was established. RESULTS: The established assay was specific to FAdV-4, and the lower limit of detection was 75 copies/µL of extracted DNA. The positive detection rate for the suspected tissue samples was 33.3% (14/42), which was consistent with that of the real-time PCR. CONCLUSION: The proposed LAMP method can quickly and accurately detect prevalent FAdV via real-time turbidity assay, thereby providing a diagnostic platform for the prevention and control of the FAdV disease.
Assuntos
Infecções por Adenoviridae/veterinária , Adenoviridae/isolamento & purificação , Técnicas de Amplificação de Ácido Nucleico/veterinária , Doenças das Aves Domésticas/virologia , Adenoviridae/genética , Infecções por Adenoviridae/diagnóstico , Infecções por Adenoviridae/virologia , Animais , Galinhas , DNA Viral , Técnicas de Amplificação de Ácido Nucleico/métodos , Doenças das Aves Domésticas/diagnóstico , Sensibilidade e EspecificidadeRESUMO
Thirty Newcastle disease virus (NDV) strains isolated from outbreaks in China during 1996 to 2005 were characterized pathotypically and genotypically. All strains except one were velogenic. An analysis of the variable region (nucleotides 47 to 420) of the F gene indicated that 6 isolates belonged to genotype II, 3 to genotype III, 1 (isolated from a pigeon) to genotype VI, and 20 to genotype VII. Isolates belonging to genotype VII were further divided into five subtypes, VIIa, VIIb, VIIc, VIId, and VIIe, and subtype VIId was made up of VIId1 to VIId5. These results showed that genotype VII isolates might have been the most prevalent in China during the past two decades. Genotype VII isolates shared high homology, but the homology was less than that between genotype VII viruses and the vaccine virus LaSota. Among these NDV isolates, 25 isolates had the velogenic motif (112)R/K-R-Q-K/R-R-F(117) that is consistent with results of the biological tests. However, four of five LaSota-type isolates that contained the lentogenic motif (112)G-R-Q-G-R-L(117) were velogenic, except SY/03, in the view of the biological test. The majority of genotype VII isolates had lost one or two N-glycosylation sites. Finally, a cross-protection experiment in which specific-pathogen-free chickens vaccinated with LaSota were challenged by six NDV isolates showed that more than three isolates were antigenic variants that could be responsible for recent outbreaks of Newcastle disease.
Assuntos
Doenças das Aves/virologia , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/classificação , Vírus da Doença de Newcastle/isolamento & purificação , Motivos de Aminoácidos , Animais , Doenças das Aves/epidemiologia , Galinhas , China/epidemiologia , Análise por Conglomerados , Columbidae , Surtos de Doenças , Patos , Gansos , Genótipo , Epidemiologia Molecular , Dados de Sequência Molecular , Doença de Newcastle/epidemiologia , Doença de Newcastle/imunologia , Vírus da Doença de Newcastle/genética , Vírus da Doença de Newcastle/patogenicidade , Filogenia , Polimorfismo Genético , Análise de Sequência de DNA , Homologia de Sequência , Spheniscidae , Proteínas Virais de Fusão/genéticaRESUMO
Three cases of Newcastle disease virus (NDV) found in nature had the lentogenic motif (112)G-R-Q-G-R-L(117) in their fusion protein cleavage sites. However, both intracerebral pathogenicity and intravenous pathogenicity indexes showed that these NDV isolates were virulent. In comparison with the LaSota live virus vaccine, these viruses had significant genetic variations in the hemagglutinin-neuraminidase gene.
Assuntos
Proteína HN/genética , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/isolamento & purificação , Vírus da Doença de Newcastle/patogenicidade , Proteínas Virais de Fusão/genética , Motivos de Aminoácidos , Animais , Aves , China/epidemiologia , Análise por Conglomerados , Dados de Sequência Molecular , Doença de Newcastle/epidemiologia , Vírus da Doença de Newcastle/genética , Filogenia , Análise de Sequência de DNA , Homologia de Sequência , VirulênciaRESUMO
Prevailed Newcastle disease virus isolates were collected during 1999-2005 in China. These isolates were purified by CEF plaque assay and replicated in SPF embryos. The fusion protein (F) gene and hemagglutinin-neuraminidase (HN) gene of these isolated viruses were cloned and sequenced. Some of the F gene and HN gene sequences from GenBank were also used in this study. The homologies of nucleotide and amino acids were compared and correlations were analyzed by SPSS8.0 software among different length sequences of the F gene or HN gene. The nucleotide homologies and correlation among the F gene and HN gene were also analyzed. The results indicated there are good correlation among different length sequences of the F gene or HN gene and the F genome or HN genome (r > or = 0.973). There was also good correlations among different length amino acids of NDV F protein or HN protein (0.911< or = r < or = 0.968). But, there was only a less correlation between the whole F gene and HN gene (r = 0.312). The heredity mutation of HN genes had the character of geographical areas. The sequences of HN gene in Chinese isolates had an identity of more than 97%. But there was only 79.2% - 80.7% in HN nucleotide homology among the Chinese isolates and La Sota (vaccine).