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1.
Three major epidemics of Newcastle disease (ND) occurred in Taiwan over the past three decades (in 1969, 1984, and 1995). In order to gain a better understanding of the relationships between past ND epizootics in Taiwan, 36 ND viruses (NDVs) isolated between 1969 and 1996 were characterized antigenically and genotypically. The antigenicity of these viruses was analysed by their ability to cause binding of mouse monoclonal antibodies (mAbs) to cell cultures infected with the isolate. Using a panel of 22 mAbs to divide NDVs into subgroups, a total of 18 binding patterns were revealed. The sequences covering the cleavage site of the fusion protein gene of these isolates were also determined. The results of the phylogenetic analysis placed 36 NDVs into I, II, VIb, VIIa, VIII and two novel genotypes (provisionally termed X and VIh). The 1969 velogenic isolates were of genotypes X and VIh; the 1984-1985 velogenic isolates were genotyped VIb, VIh, VIIa, and X; while the 1995-1996 velogenic isolates were genotyped VIIa or VIII. Some 1969 and 1984 velogenic isolates were of the same mAbs binding pattern and genotype, and the mAbs binding patterns of the 1995-1996 isolates have not been seen before. It is concluded that velogenic NDVs of different genotype and antigenic type have co-circulated in Taiwan at least since 1969. Also there were epizootiological links between strains isolated in 1969 and 1984, whereas the 1995-1996 epidemic was caused by new antigenic variants.  相似文献   

2.
3.
Yin Y  Cortey M  Zhang Y  Cui S  Dolz R  Wang J  Gong Z 《Veterinary microbiology》2011,149(3-4):324-329
Newcastle disease virus (NDV) strains isolated from ostriches have been genotyped for the first time by partial sequencing of the F gene to determine the epidemiologic role that this species can play within ND outbreaks. Fifteen additional NDV strains, mostly isolated from chickens but also from pigeons and penguins, were also included in the study to determine genetic relationships with ostriches NDV isolates. High genetic diversity was demonstrated in ostrich NDV isolates, as the 10 isolates were grouped in four distinct NDV genotypes. In agreement with the results obtained when chicken isolates have been molecularly characterized, the predominant genotype in ostriches was the genotype VII. More interestingly, evidences of recombination between genotype II and VII were observed in one ostrich isolate and in two further chicken isolates. Therefore, it seems that ostriches may play a relevant role in the ecology and epidemiology of ND particularly in those regions where they have an increasing farming importance as minor poultry species.  相似文献   

4.
Liu H  Wang Z  Wang Y  Sun C  Zheng D  Wu Y 《Avian diseases》2008,52(1):150-155
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5.
Twelve Newcastle disease virus (NDV) strains were isolated from chickens involved in outbreaks of Newcastle disease (ND) in western China (Shaanxi, Gansu, Xinjiang, Qinghai and Guangxi provinces) between 1979 and 1999. All strains were determined to be velogenic by plaque formation, the mean death time (MDT) of embryonated eggs, and the intracerebral pathogenicity index (ICPI). For preparation of virus RNA, the acid guanidinium-thiocyanate method was used. A 908bp fragment of nucleotide was amplified by RT-PCR starting from the N terminal of the F gene and the PCR segments were cloned into the PGEM-T vector and sequenced. The similarities of the nucleotide sequences (1-519bp) and predicted amino acid sequences of the F gene (1-125) were analyzed by comparing the 12 NDV isolates with the NDV vaccine strains Lasota, B1, H1 and V4, with classical NDV strains and recent epizootic strains. Phylogenetic analysis demonstrated that all strains were of two novel genotypes; the NDV strains that caused the outbreak of ND in western China during 1998-1999 was of the genotype VIIa, whereas the strains from the Qinghai province (1979-1985) were of genotype VIII, which has been found predominately in southern Africa.  相似文献   

6.
Newcastle disease (ND) is a highly contagious viral disease and is a continuous threat to the poultry industry worldwide. In the early months of 2011, several devastating ND outbreaks occurred in Jordan affecting broilers, layers and breeders. The fusion gene of the isolated Newcastle disease virus (NDV) was partially amplified by RT-PCR, then directly sequenced. The NDV isolates were found to have the motif(112)RRQKRF(117). This motif and a mean death time (MDT) of 46h are indicative of the velogenic nature of these NDV isolates. Phylogenetic analysis showed that the new NDV strain belongs to the lineage 5d (Aldous et al., 2003) and is closely related to the Chinese strain SG/Liaoning/2009. NDV outbreaks in 2010 and 2011 have been noted in neighboring countries. Based on the high nucleotide similarity between our isolated NDV isolates and the Chinese NDV strain, the origin of these recent NDV isolates might be from China.  相似文献   

7.
Seventy-nine velogenic Newcastle disease virus (NDV) isolates were obtained from infected chicken flocks during the outbreaks of Newcastle disease (ND) in various regions of the mainland of China in 2006. The F gene fragment (535 bp, from nt 47 to 581 of the F gene) which codes the main functional region of the F protein was obtained by RT-PCR and sequenced. All sequences obtained in this study have been submitted to GenBank. All the isolates have the motif 112R-R-Q/R-K/R-R-F117 at the cleavage site of the fusion protein, which is typical of velogenic NDV isolates. For genotyping, a phylogenetic tree based on nucleotides 47–435 of the F gene was constructed, and the 79 isolates could be divided into two genotypes, namely VIId and III. Most of the isolates proved to be of genotype VIId; only two isolates were of genotype III. Genotype VIId NDV has been the predominant pathogen responsible for most Newcastle disease outbreaks in China. The proportion of isolates of genotype VIId NDV shows an increasing trend, according to studies on the molecular epidemiology of NDV in China from 2002 to 2006.  相似文献   

8.
Seventy-nine velogenic Newcastle disease virus (NDV) isolates were obtained from infected chicken flocks during the outbreaks of Newcastle disease (ND) in various regions of the mainland of China in 2006. The F gene fragment (535 bp, from nt 47 to 581 of the F gene) which codes the main functional region of the F protein was obtained by RT-PCR and sequenced. All sequences obtained in this study have been submitted to GenBank. All the isolates have the motif 112R-R-Q/R-K/R-R-F117 at the cleavage site of the fusion protein, which is typical of velogenic NDV isolates. For genotyping, a phylogenetic tree based on nucleotides 47–435 of the F gene was constructed, and the 79 isolates could be divided into two genotypes, namely VIId and III. Most of the isolates proved to be of genotype VIId; only two isolates were of genotype III. Genotype VIId NDV has been the predominant pathogen responsible for most Newcastle disease outbreaks in China. The proportion of isolates of genotype VIId NDV shows an increasing trend, according to studies on the molecular epidemiology of NDV in China from 2002 to 2006.  相似文献   

9.
To expand the epidemiological understanding of Newcastle disease virus (NDV) found in domestic ducks in Korea, 14 NDV isolates from apparently healthy domestic ducks were biologically and genetically characterized. Thirteen and 1 isolates of NDV were categorized into lentogenic and velogenic viruses, respectively, based on in vivo pathogenicity tests. Twelve lentogenic viruses showed HA activity to horse RBCs, while 1 lentogenic virus and the velogenic virus were negative. Lentogenic viruses (n=13) had sequence motifs of (112)ERQERL(117) (n=1) or (112)GRQGRL(117) (n=12) at the F0 cleavage site, while the velogenic virus (n=1) had a sequence motif of (112)RRQKRF(117) at the same site. Phylogenetic analysis revealed that at least three distinct genotypes may exist in domestic ducks in Korea; one class I genotype (genotype 2), and two class II (genotypes I and VII) genotypes. The class I virus was most closely related to strains of genotype 2 which were isolated in birds from the USA, Germany and Denmark. Twelve lentogenic class II viruses were grouped together in genotype I, and were then divided into at least three clusters, namely Aomori-like, Ulster2C-like, and V4-like. The velogenic class II virus was assigned to genotype VII which represents viruses responsible for recent epidemics in many Asian countries including Korea. The epidemiological importance of domestic duck isolates of NDV in Korea is discussed.  相似文献   

10.
Newcastle disease (ND) is a highly contagious disease that affects many species of birds and causes significant economic losses to the poultry industry worldwide. Fifteen Newcastle disease virus (NDV) isolates obtained from rural chickens in northwest Ethiopia in 2011 and 2012 were characterized genotypically. The main functional region of the F gene was amplified and sequenced (260 nucleotides). Among the Ethiopian NDV isolates, 2 isolates had the virulent motif 112R-R-Q-K-R-F117 at the cleavage site of the fusion protein while 13 isolates contained the lentogenic motif 112G-G/R-Q-G-R-L117. Phylogenetic analysis based on the variable region of the F gene indicated that the two isolates exhibiting the virulent motif belonged to lineage 5 (genotype VII) subgenotype d and the remaining 13 isolates were grouped into lineage 2 (genotype II). The nucleotide sequences of lineage 5 isolates were genetically related to the Sudanese NDV isolates, suggesting potential epidemiological link of ND outbreaks between neighbouring countries. The lentogenic strains shared similarities with La Sota vaccine strain and probably originated from the vaccine strain either through direct exposure of birds to the live vaccine or to infectious La Sota-like strains circulating in rural poultry. This study provides genetic evidence on the existence of different NDV genotypes circulating in the rural poultry in Ethiopia. The virulent NDV continues to be a problem in poultry sector in Ethiopia, and their continuous circulation in rural and commercial poultry calls for improved surveillance and intensified vaccination and other control measures.  相似文献   

11.
Newcastle disease (ND) is one of the most important diseases of poultry, and may cause devastating losses in the poultry industry worldwide. Its causative agent is Newcastle disease virus (NDV), also known as avian paramyxovirus type 1. Many countries maintain a stringent vaccination policy against ND, but there are indications that ND outbreaks can still occur despite intensive vaccination. It has been argued that this may be due to antigenic divergence between the vaccine strains and circulating field strains. Here we present the complete genome sequence of a highly virulent genotype VII virus (NL/93) obtained from vaccinated poultry during an outbreak of ND in the Netherlands in 1992-1993. Using this strain, we investigated whether the identified genetic evolution of NDV is accompanied by antigenic evolution. In this study we show that a live vaccine that is antigenically adapted to match the genotype VII NL/93 outbreak strain does not provide increased protection compared to a classic genotype II live vaccine. When challenged with the NL/93 strain, chickens vaccinated with a classic vaccine were completely protected against clinical disease and mortality and virus shedding was significantly reduced, even with a supposedly suboptimal vaccine dose. These results suggest that it is not antigenic variation but rather poor flock immunity due to inadequate vaccination practices that may be responsible for outbreaks and spreading of virulent NDV field strains.  相似文献   

12.
通过毒力测定、RT-PCR及F基因的序列测定与遗传进化分析,对2005-2008年从河北省部分地区的发病鸡群中分离到的10株新城疫病毒(NDV)进行了研究。各分离株经典毒力测定结果显示:MDT在37.6~54.4h之间,ICPI在1.71~2.0之间,IVPI值在2.16~2.8之间,均为新城疫病毒强毒株特征。F基因的序列测定表明,分离株之间的核苷酸序列具有77.4%~98.0%的同源性,与疫苗株Lasota的同源性为87.0%~98.9%,与国内标准强毒株F48E9同源性为89.7%~98.9%。推导其氨基酸序列分析表明,8个分离株的F蛋白的裂解位点氨基酸组成为112 R-R-Q-K-R-F117,具有NDV强毒株特征,与毒力测定结果相符,2个分离株的F蛋白的裂解位点氨基酸组成为112 G-R-Q-G-R-L117,与弱毒株特征相符。F基因分型和同源性比较显示:目前河北新城疫的流行以基因Ⅶ型为主(占70%),同时兼有基因Ⅱ型(占20%)和基因Ⅸ型(占10%)。  相似文献   

13.
Newcastle disease (ND) epizootics in some European countries after the World War II were caused by ND virus (NDV) of multiple genotypes (IV-VIIa) occurring sequentially and/or simultaneously. This study was carried out to characterise the genetic composition of NDV strains during the outbreaks in the territory of the former Yugoslavia in order to enhance our understanding of the relationships of past epizootics in Europe. Sixty-eight NDV strains isolated between 1979 and 2002 were analysed by restriction enzyme digestion and partial sequencing of the fusion protein gene. All isolates were placed in genotype V, an exotic type, that was introduced to western Europe in 1970. Residue substitution analysis has allowed the recognition of four genetic variants, Vb1-Vb4, and the tracing of their movements. Vb1, a dominant variant in Bulgaria from the late 1970s, was also wide spread in the former Yugoslavia throughout the period under investigation. Vb2, a variant occurring in the neighbouring countries in the early 1970s could be the founder of the epidemic in Yugoslavia and it was present up to the late 1980s. Variants Vb3 and Vb4 could be found only after 1987. In conclusion, the ND outbreaks in Yugoslavia were part of the epizootic wave due to genotype V viruses that started in western Europe in 1970 and became endemic in the region. Inter-country transmission occurred for all variants, and Vb3 and Vb4 might have evolved during the endemic period.  相似文献   

14.
Newcastle disease virus (NDV) causes significant economic losses to the poultry industry in Southeast Asia. In the present study, 12 field isolates of NDV were recovered from dead village chickens in Vietnam between 2007 and 2012, and were characterized. All the field isolates were classified as velogenic. Based on the sequence analysis of the F variable region, two distinct genetic groups (Vietnam genetic groups G1 and G2) were recognized. Phylogenetic analysis revealed that all the 12 field isolates fell into the class II genotype VII cluster. Ten of the field isolates, classified as Vietnam genetic group G1, were closely related to VIIh viruses that had been isolated from Indonesia, Malaysia, and Cambodia since the mid-2000s, while the other two field isolates, of Vietnam genetic group G2, clustered with VIId viruses, which were predominantly circulating in China and Far East Asia. Our results indicate that genotype VII viruses, especially VIIh viruses, are predominantly responsible for the recent epizootic of the disease in Vietnam.  相似文献   

15.
一株鸡副粘病毒F基因重要片段的扩增、克隆与分析   总被引:7,自引:0,他引:7  
应用RT-PCR技术对新城疫病毒(NDV)Y98株的F基因重要功能区片段扩增、克隆后进行序列测定,并与多株已报道的NDV参考株相应片段进行序列比较,经遗传基因进行化树分析后,首次报道了VII型DNV分离株在中国大陆的存在。  相似文献   

16.
应用PCR技术扩增NDV贵州不同鸡源分离株,包括肉鸡源P1株与BY株、蛋鸡源H2株与FW株、七彩山鸡源N98株和越南斗鸡源DQ株的F蛋白基因,将该基因片段分别进行克隆和测序,并与国内外NDV参考株的对应序列进行比较分析。结果表明:6株NDV贵州不同鸡源分离株的F基因长度均为1 662 bp,编码553个氨基酸;分离株间核苷酸同源性为86.9%~99.7%,氨基酸同源性为91.0%~99.3%;与国内外NDV代表株(LaSota株、B1株、F48E9株、CH2000株和TW 2000株)的核苷酸同源性为84.0%~98.9%,氨基酸同源性为87.2%~98.6%;经系统发育进化树分析,DQ株、N98株、P1株和H2株为基因VIId型,而BY株和FW株为基因IX型。这些结果提示贵州省不同鸡群间存在相同NDV毒株感染的可能性,不同年份间NDV毒株发生基因型改变,而近年来贵州省流行的ND疫情主要是由NDV基因VII型引起。  相似文献   

17.
Newcastle disease virus (NDV) causes a highly contagious viral disease in poultry and wild birds, and it can cause significant economic loss worldwide. Eight viral strains were isolated by inoculating embryonated chicken eggs from the Poyang Lake region of China with swab samples. All eight of the NDV isolates were identified as class I genotype 3 strains, but they diverged notablely from class II viruses. Further analysis revealed that all eight NDV isolates were lentogenic strains containing the 112ERQER↓L117 motif at the F protein cleavage site. The strains were highly identical and were more species specific (chicken and waterfowl) than site specific (Nanchang and Duchang regions). The close phylogenetic proximity of these isolates indicates that viral transmission may happen between poultry and wild birds. Our study demonstrates that lentogenic class I NDVs exist in clinically healthy wild waterfowl and poultry within the Poyang Lake region. Active surveillance of these viruses to determine their evolution and origin is one of the most realistic strategies for preventing and controlling NDV outbreaks.  相似文献   

18.
In 2002-2003, velogenic Newcastle Disease Virus outbreaks, closely related to the Mexican isolates, were confirmed in the United States (U.S.) in southern California, Arizona, Nevada, and Texas. In this report, virulent NDVs isolated in Mexico between 1998 and 2006 were subjected to biologic characterization, using standard pathogenicity tests, and to phylogenetic analysis. Chicken embryo mean death time (MDT) test results ranged from 39.7 to 61.5 hours, and intracerebral pathogenicity index (ICPI) values were between 1.59 and 1.94, compared to a possible maximum value of 2.0. These isolates showed a dibasic amino acid motif at the fusion protein cleavage site sequence required for host systemic replication. Phylogenetic analysis indicated that the Mexican virulent NDVs belong to the class II, genotype V viruses and can be clearly divided in two groups as follows: isolates from 1998 to 2001 with close epidemiologic relationship with the latest U.S. NDV outbreaks, and phylogenetically distinct viruses, isolated from 2004 to 2006, which showed higher virulence. The assessment of the evolution of viruses from Mexico and other neighboring countries will aid in the U.S surveillance efforts for early detection of highly virulent NDV.  相似文献   

19.
Wild waterfowl is considered a natural reservoir of potentially infectious agents and a source of pathogenic viruses like avian paramyxoviruses type 1 (APMV 1). In 1997, commercial poultry in Argentina had reached the status of being free from virulent Newcastle disease virus (NDV) infections. Vaccination and biosecurity measures are actively performed to maintain this preferential sanitary condition. However, the risk of reintroduction of pathogenic viruses is always present. In this context, we conducted a study to describe the status of wild healthy birds in a geographic region relevant for the poultry industry. The presence of anti-NDV antibodies was determined in different species in all areas sampled suggesting previous contact with NDV. Seven ND viruses were isolated and characterized as apathogenic strains by biological and molecular methods. The phylogenetic analysis revealed that the majority of the Argentinian isolates form a subgroup related to viruses of genotype II. The results presented here highlight the importance of maintaining strict biosecurity measures and vaccination programs in poultry industries in order to preserve the virulent NDV-free status for commercial flocks in the country.  相似文献   

20.
Chen JP  Wang CH 《Avian diseases》2002,46(2):461-465
Sporadic outbreaks of Newcastle disease (ND) occurred in Taiwan during 1998-2000. In some cases, the disease occurred in broilers less than 2 wk old that originated in a broiler breeder farm, so spread of the ND virus (NDV) from the infected breeder farm to broiler ranches was suspected. The purpose of the present study was to examine the possibility of the transmission of NDV through eggs. Both clinical and experimental evidence were used to prove that this is possible. From epidemiological investigation, the possibility of transmission through eggs was suggested in two separate ND cases from a breeder farm and its progeny because two identical NDVs were isolated from both cases. In order to clarify the possibility of the transmission through eggs, one mean egg lethal dose (ELD50) of NDV was inoculated into the allantoic cavity of 155 9-to-11-day-old specific-pathogen-free (SPF) chicken embryos. Seventy-one hatching chicks from the inoculated embryos were raised for 14 days. The cloacal swabs from those chicks at the ages of 1, 4, and 7 days and the tissues after necropsy at the ages of 14 days were taken for virus isolation. The same NDV was reisolated from three hatching chicks. This experiment confirms that a few chicken embryos infected in ovo with a low titer of NDV can hatch and contain NDV after hatching, which results in NDV spreading through eggs.  相似文献   

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