Newcastle disease in wild water birds in western Canada, 1990

This report describes the investigation of mortality of double-crested cormorants (Phalacrocorax auritus), white pelicans (Pelecanus erythrorhynchos), and gulls (Larus spp.) in Alberta, Saskatchewan, and Manitoba during late summer 1990. Techniques used varied among areas, but virological and histopathological examination of birds was done in each area. The major clinical sign in cormorants was inability to fly, often with unilateral wing or leg paralysis. Focal nonsuppurative inflammation was present in the brain and spinal cord of cormorants and pelicans. Newcastle disease virus (NDV) was isolated from cormorants, a pelican, and a ring-billed gull (Larus delawarensls) from Saskatchewan. Cormorants from Alberta were positive for NDV in an immunofluorescent test. Most of the viruses were classed as velogenic and all had a similar monoclonal antibody profile to viruses from the 1970 to 1974 panzootic. Approximately half of cormorant, pelican, and gull eggs collected from affected colonies in the spring of 1991 had antibody to NDV. Antibody was also present in cormorant eggs from the Great Lakes. No unusual mortality was detected at any colony in 1991. Fledgling cormorants and gulls from colonies where mortality occurred in 1990 did not have antibody to NDV in June-July 1991. The overall extent of mortality among water birds and the source of the virus were not determined.     

Wintering of neurotropic velogenic Newcastle disease virus and West Nile virus in double-crested cormorants (Phalacrocorax auritus) from the Florida Keys

During November 2002, six double-crested cormorants (DCCs; Phalacrocorax auritus) were found moribund in Big Pine Key, FL, exhibiting clinical signs indicative of neurologic disease. Postmortem diagnostic evaluations were performed on two adult birds. Virulent Newcastle disease virus (NDV) was isolated from a cloacal swab from cormorant 1. West Nile virus (WNV) was isolated from the brain and lung of cormorant 2. Nucleotide sequence analysis of a portion of the fusion (F) protein gene of the NDV cormorant isolate revealed it shared a 100% deduced amino acid identity with only two viruses: the 1992 epizootic cormorant isolate from Minnesota and the 1992 turkey isolate from North Dakota. The epidemiologic significance of the recognition of virulent NDV on cormorant wintering grounds during a nonepizootic period, in addition to the potential implications of the concurrent isolation of NDV and WNV from cormorants, is discussed.     

Comparison of Newcastle disease viruses isolated from cormorants in Canada and the USA in 1975, 1990 and 1992.

Seventeen Newcastle disease virus (NDV) isolates obtained from cormorants, turkeys, a pelican, and a gull in Canada and the USA collected in 1975, 1990 and 1992 were analyzed for relatedness by monoclonal antibody profiling. In addition, nucleotide sequence analysis was performed in two areas of the fusion (F) gene for 5 of the isolates. No difference in the antigenicity of these 17 viruses, as determined by monoclonal antibody binding patterns, was seen. The amino acid sequences obtained via nucleotide sequencing at the cleavage site of the F protein showed that all the isolates tested had two pairs of basic amino acids immediately upstream of the cleavage site, and a phenylalanine residue at the N-terminus of the F1 protein, which is consistent with velogenic NDV. The deduced amino acid sequence obtained at the cleavage site of the F protein from 6 of the isolates was virtually identical regardless of the species, year of isolation, or location. However, the 1975 cormorant isolate showed marked differences from the 1990-1992 isolates in the nucleotide and deduced amino acid sequence of the F gene signal region. These data indicate that the 1990 and 1992 outbreaks were caused by the same epizootic virus and further suggest that the population of NDV in these wild birds may be very stable. The belief that the velogenic NDV circulating in cormorants in 1992 was transmitted into the free-ranging turkey flocks located near the cormorants in North Dakota is supported by the present study in which no distinction could be made between the viruses isolated from turkeys or wild birds.     

Molecular characterization of a recent Newcastle disease virus outbreak in Jordan

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.     

Newcastle disease virus isolated from recent outbreaks in Taiwan phylogenetically related to viruses (genotype VII) from recent outbreaks in western Europe

Three major outbreaks of Newcastle disease (ND) occurred in Taiwan in the last three decades (in 1969, 1984, and 1995). Newcastle disease viruses (NDVs) isolated in the three outbreaks, together with those isolated in 1998, were sequenced between nucleotides 47 and 435 of the fusion gene. A phylogenetic tree based on sequences obtained showed that the NDV isolated in 1969 was similar to the genotype III viruses. In contrast, all isolates in 1984 and seven of the eight isolates in 1995, together with all isolates in 1998, fell into the genotype VII. These results suggest that the 1969 outbreak of ND in Taiwan was caused by the genotype III virus, whereas the 1984 and 1995 outbreaks were caused by the genotype VII viruses. To date, the genotype VII viruses have caused many outbreaks in east Asia and western Europe. We suspect that these outbreaks have constituted the fourth panzootic of ND, which is distinct from the third panzootic caused by the "pigeon PMV-1 viruses." NDV isolated in Taiwan in 1984 was the earliest isolation of the genotype VII virus.     

Phylogenetic analysis of Newcastle disease viruses isolated from wild birds in the Poyang Lake region of China

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.     

Newcastle disease--seroepidemiologic study of a highly contagious epizootic in poultry and in wild birds in Switzerland

Newcastle disease (ND) is a highly contagious viral disease particularly of domestic poultry. Switzerland is currently declared free from ND. A serosurvey using an ELISA was performed to investigate infections with ND-Virus (NDV) in 260 Swiss laying hen flocks, 169 backyard poultry flocks and 1576 wild birds. For laying hen flocks, a stochastic model was applied to analyse the results from serological testing. Four laying hen flocks were identified as NDV-seropositive, and the true NDV seroprevalence in this population was most likely between 1.3 and 1.5%. NDV antibodies were also detected in five of the 169 backyard poultry-flocks. ND-antibody positive birds were found in 10% of all wild birds examined, with the highest proportions among cormorants, grebes, birds of prey, owls, and swifts. The study indicated that positive flocks must have been in contact with NDV strains causing sub-clinical infection, since no clinical signs had been observed. Moreover, trade of poultry or poultry eggs was considered to be an important factor associated with seropositivity in backyard poultry flocks. Contact to wild birds did not seem to be of major importance.     

ClassⅠ新城疫病毒概述

新城疫病毒是影响养禽业健康发展的主要病原之一。新城疫病毒只有一个血清型,但根据亲源关系可以划分为ClassⅠ和ClassⅡ两大类。ClassⅠ新城疫病毒于2006年被证实存在,当前可被细分为9个基因型(1～9)。ClassⅠ所有自然分离株均为无毒株或弱毒株,但有经人工传代返强的报道,由于其分布广泛,数量庞大,对养禽业有巨大的潜在威胁。为了更好的了解ClassⅠ新城疫毒株的生物学特性,为研究ClassⅠ新城疫病毒提供参考,现将其基因组结构、分子流行病学及检测方法等综述如下。     

Molecular characterization of Newcastle disease viruses isolated from rural chicken in northwest Ethiopia reveals the circulation of three distinct genotypes in the country

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.     

Molecular characterization of Newcastle disease viruses in Ostriches (Struthio camelus L.): further evidences of recombination within avian paramyxovirus type 1

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.     

Molecular characterization and phylogenetic analysis of Newcastle disease virus isolates from healthy wild birds

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.     

Simultaneous detection and differentiation of Newcastle disease and avian influenza viruses using oligonucleotide microarrays

Newcastle disease (ND) and avian influenza (AI) are two of the most important zoonotic viral diseases of birds throughout the world. These two viruses often have a great impact upon the poultry industry. Both viruses are associated with transmission from wild to domestic birds, and often display similar signs that need to be differentiated. A rapid surveillance among wild and domestic birds is important for early disease detection and intervention, and is the basis for what measures should be taken. The surveillance, thus, should be able to differentiate the diseases and provide a detailed analysis of the virus strains. Here, we described a fast, simultaneous and inexpensive approach to the detection of Newcastle disease virus (NDV) and avian influenza virus (AIV) using oligonucleotide microarrays. The NDV pathotypes and the AIV haemagglutinin subtypes H5 and H7 were determined at the same time. Different probes on a microarray targeting the same gene were implemented in order to encompass the diversified virus strains or provide multiple confirmations of the genotype. This ensures good sensitivity and specificity among divergent viruses. Twenty-four virus isolates and twenty-four various combinations of the viruses were tested in this study. All viruses were successfully detected and typed. The hybridization results on microarrays were clearly identified with the naked eyes, with no further imaging equipment needed. The results demonstrate that the detection and typing of multiple viruses can be performed simultaneously and easily using oligonucleotide microarrays. The proposed method may provide potential for rapid surveillance and differential diagnosis of these two important zoonoses in both wild and domestic birds.     

Newcastle disease virus outbreaks: Vaccine mismatch or inadequate application?

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.     

新城疫病毒通用型实时RT-PCR检测方法的建立与应用

采用TaqMan方法,经引物和探针的设计、筛选及反应条件优化,研究了检测活禽和禽产品中新城疫病毒的通用型实时RT-PCR(RRT-PCR)方法。结果显示,对12株分别为速发型、中发型、缓发型和疫苗株新城疫病毒的尿囊液倍比稀释液的检测极限在10-5~10-7之间;建立的方法与常见禽类病毒无交叉反应,特异性良好;在检测人工感染肉鸡的脏器组织、咽喉、泄殖腔拭子中病毒的灵敏度同鸡胚分离试验基本一致;弱毒疫苗免疫鸡群在免疫后14 d,应用本方法不能从咽喉、泄殖腔拭子中检测到病毒;临床样品检测表明,该方法不仅可以检出中强毒力新城疫毒株,也可检出缓发型野毒株和疫苗毒株。     

Gordon Memorial Lecture. Newcastle disease

1. In this paper several historical and contemporary aspects of Newcastle disease (ND) are reviewed, with particular reference to the greater understanding which modern techniques have allowed. 2. Virulent ND viruses were generally thought to have emerged in 1926 as a result of transfer from a wild bird host reservoir but there is evidence that the virulent virus may have existed in poultry before 1926. Recent findings suggest that the virulent virus may emerge in poultry as a result of mutations in viruses of low virulence. 3. The history of ND in Great Britain reflects the four known panzootics that have occurred and serves as a model for the impact this disease may have on poultry populations. 4. Attempts to control and eradicate ND are not as straightforward as it may appear; in particular vaccination, while preventing deaths and disease, on challenge may not prevent virus replication and could therefore lead to the virulent virus becoming endemic. 5. Village chickens are extremely important assets in most developing countries, representing a significant source of protein in the form of eggs and meat but endemic ND can cause mortality of up to 60% in village chickens.     

Newcastle disease and avian influenza A virus in wild waterfowl in South Africa

In an intensive ostrich farming area in South Africa with a history of ostrich influenza outbreaks, we conducted a survey of avian influenza virus (AIV) and Newcastle disease virus (NDV) in wild aquatic birds. During late autumn and winter 1998, the time of year when outbreaks in ostriches typically start to occur, 262 aquatic birds comprising 14 species were sampled and tested for both virus infections. From eight samples, AIV, serotype H10N9, could be isolated. All isolates were apathogenic as determined by the intravenous pathogenicity index (0.00). Conversely, none of 33 sera of these wild birds showed antibodies against H10. However, one bird was found serologically positive for H6 AIV. This AIV serotype was later isolated from ostriches during an avian influenza outbreak in this area. No NDV was isolated although 34 of 46 serum samples contained NDV-specific antibodies. This is the first H10N9 isolate to be reported from Africa. In addition, our data support the notion that wild aquatic birds may function as a reservoir for AIV and NDV in South Africa.     

The role of indigenous wild, semidomestic, and exotic birds in the epizootiology of velogenic viscerotropic Newcastle disease in southern California, 1972-1973.

During an epornitic of velogenic viscerotropic Newcastle disease (VVND) in southern California, free-flying wild birds, captive and free-ranging semidomestic birds, and exotic birds were collected from the quarantine area to determine their role in the epizootiology of the disease. The VVND virus was isolated from 0.04% of 9,446 free-flying wild birds, 0.76% of 4,367 semidomestic birds, and 1.01% of 3,780 exotic birds examined. Three house sparrows and 1 crow directly associated with infected poultry flocks were the only free-flying wild birds from which VVND virus was isolated. Among semidomestic species, ducks, quail, chukars, pheasants, peafowl, pigeons, and doves were found to be infected. Psttacines, pittas, and toucans accounted for 92% of the VVND virus isolations from exotic birds. In addition, domestic Newcastle disease virus (NDV) was isolated from 0.29% of the free-flying wild birds, from 1.65% of the semidomestic birds, and from 0.19% of the exotic birds collected. Hemagglutination-inhibition against domestic NDV was demonstrated in 0.24% of 3,796 wild bird serums, 8.28% of 2,004 semidomestic bird serums, and 3.90% of 231 exotic bird serums tested. Although few free-flying wild birds were infected with VVND virus in this epornitic, the isolation of domestic NDV strains from free-flying wild ducks and mourning doves suggests the potential for transportation of NDV over long distances by migratory birds.