Surveillance and characterization of Newcastle disease viruses isolated from northern pintail (Anas acuta) in Japan during 2006-09

Stability and Detection Limit of Avian Influenza, Newcastle Disease Virus, and African Horse Sickness Virus on Flinders Technology Associates Card by Conventional Polymerase Chain Reaction

The Flinders Technology Associates (FTA) card, a cotton-based cellulose membrane impregnated with a chaotropic agent, effectively inactivates infectious microorganisms, lyses cellular material, and fixes nucleic acid. The aim of this study is to assess the stability and detection limit of various RNA viruses, especially the avian influenza virus (AIV), Newcastle disease virus (NDV), and African horse sickness virus (AHSV), on the FTA card, which could significantly impact virus storage and transport practices. To achieve this, each virus dilution was inoculated onto an FTA card and stored at room temperature in plastic bags for durations ranging from 1 week to 6 months. Following storage, the target genome was detected using conventional reverse transcription polymerase chain reaction. The present study demonstrated that the detection limit of AIV ranged from 1.17 to 6.17 EID50 values over durations ranging from 1 week to 5 months, while for NDV, it ranged from 2.83 to 5.83 ELD50 over the same duration. Additionally, the detection limit of AHSV was determined as 4.01 PFU for both 1 and 2 weeks, respectively. Based on the demonstrated effectiveness, stability, and safety implications observed in the study, FTA cards are recommended for virus storage and transport, thus facilitating the molecular detection and identification of RNA viral pathogens.

Avian paramyxovirus serotype-1 isolation from migratory birds and environmental water in southern Japan: An epidemiological survey during the 2018/19-2021/2022 winter seasons

Newcastle disease caused by highly pathogenic viruses of avian paramyxovirus serotype-1 (APMV-1) is a highly contagious poultry disease. Although a large-scale epidemic of Newcastle disease had occurred in Japan between the 1950s and the 2000s, there have been no outbreaks anywhere since 2010. In addition, there are no reports of epidemiological surveys of APMV-1 in wild birds in Japan in the last 10 years. We conducted the first epidemiological survey of APMV-1 in the Izumi plain, Kagoshima prefecture of southern Japan from the winter of 2018 to 2022. A total of 15 APMV-1 strains were isolated, and isolation rates from roosting water and duck fecal samples were 2.51% and 0.10%, respectively. These results indicate that the isolation method from environmental water may be useful for efficient surveillance of APMV-1 in wild birds. Furthermore, this is the first report on the success of APMV-1 isolation from environmental water samples. Genetic analysis of the Fusion (F) gene showed that all APMV-1 isolates were closely related to virus strains circulating among waterfowl in Far East Asian countries. All isolates have avirulent motifs in their cleavage site of F genes, all of which were presumed to be low pathogenic viruses in poultry. However, pathogenicity test using embryonated chicken eggs demonstrated that some isolates killed all chicken embryos regardless of viral doses inoculated (10² -10⁶ 50% egg infectious dose). These results indicated that APMV-1 strains, which are potentially pathogenic to chickens, are continuously brought into the Izumi plain by migrating wild birds.

Sensitivity of RNA viral nucleic acid-based detection of avian influenza virus, Newcastle disease virus, and African horse sickness virus on flinders technology associates card using conventional reverse-transcription polymerase chain reaction

Background and Aim

The flinders technology associates (FTA) card is a cotton-based cellulose membrane impregnated with a chaotropic agent that inactivates infectious microorganisms, lyses cellular material, and fixes DNA and/or RNA within the fiber matrix. However, little is known about the effectiveness of these cards for detecting RNA viruses in animals. This study aimed to evaluate the sensitivity of RNA virus detection using conventional reverse-transcription polymerase chain reaction (RT-PCR) on FTA cards.

Materials and Methods

A highly virulent Newcastle disease virus (NDV) and an avian influenza virus (AIV) with low pathogenicity were propagated using chicken embryonic eggs. Three days after inoculation, the allantoic fluid was harvested, stored at -80°C, and the stock virus was tested for virus titration. African horse sickness virus (AHSV) was obtained from a live attenuated vaccine that was dissolved and stored at -80°C. For sample preparation, each stock virus was 10-fold serially diluted and each dilution was inoculated onto an FTA card, followed by drying in a Class II safety cabinet. Both the stock virus and infected FTA card were genomically isolated using an extraction kit, FTA purification kit, and extraction kit with Tris-EDTA (TE) buffer. The target genome was then detected by one-step RT-PCR for NDV and AIV, and two-step RT-PCR for African horse sickness, including gel electrophoresis for the detection of specific nucleic acids.

Results

The detection limit of stock AIV was compared on FTA cards, using the FTA purification kit, and with TE buffer with an extraction kit. The corresponding results were 1.47, 1.17, and 2.18 log₁₀ EID₅₀, respectively, while for NDV the results were 4.13, 4.83, and 4.84 log₁₀ ELD₅₀. Finally, detection limit of stock AHSV and AHSV on the FTA card extracted using TE buffer with an extraction kit were 4.30 and 4.01 log₁₀ plaque-forming units, respectively.

Conclusion

This study demonstrated that the detection limit or sensitivity of all tested RNA viruses on FTA cards did not differ when compared with those of the stock virus and in both methods for RNA isolation on FTA cards. These cards are suitable for collecting and transporting samples infected with RNA viruses, particularly AIV, NDV, and AHSV. Flinders technology associates cards also provide hazard-free samples, a reliable source of RNA for molecular characterization, and sufficient quantity for diagnostic applications based on nucleic acid-based detection.

Active Surveillance and Genetic Characterization of Prevalent Velogenic Newcastle Disease and Highly Pathogenic Avian Influenza H5N8 Viruses Among Migratory Wild Birds in Southern Egypt During 2015-2018

A total of 1007 samples (910 fecal droplets and 97 cloacal swabs) were collected from 14 species of migratory wild birds in most wetlands during 3 successive migration seasons from September to March (2015-2018) in Southern Egypt. The samples were propagated in embryonated chicken eggs and positive allantoic fluids by hemagglutination test were tested for Newcastle disease virus (NDV) and avian influenza virus (AIV) prevalence using RT-PCR and specific primers targeting the NDV fusion (F) and AIV matrix genes. Further subtyping of the AIV hemagglutinin (HA) and neuraminidase (NA) was conducted, and representative isolates were selected and sequenced for full F gene of NDVs and HA and NA genes of the AIV. Overall isolation rate of hemagglutinating viruses was 5.56% (56/1007), from them 5.36% (3/56) AIV, 85.71% (48/56) NDV and 8.93% (5/56) co-infection of NDV and AIV was detected. The sequences analysis of full F genes of 10 NDV isolates revealed that they have multi-basic amino acid motifs ¹¹¹E/GRRQKR/F¹¹⁷ as velogenic strains with nucleotides and amino acids similarities of 96-100%. In addition, they phylogenetically clustered into groups and subgroups within genotype VII.1.1 and sub-genotype VIIj with a close relation to NDVs isolated from chickens in Egypt. The AIV H5N8 subtype was in clade 2.3.4.4b with a highly pathogenic nature and close relation to Egyptian domesticated H5N8 viruses rather than those from wild birds. The current data showed the contribution of migratory birds to the continuous circulation of virulent NDV and AIV H5N8 among domesticated chickens in Southern Egypt.

Pathobiology of Avian avulavirus 1: special focus on waterfowl

Avian avulaviruses serotype 1 (abbreviated as APMV-1 for the historical name avian paramyxovirus 1) are capable of infecting a wide spectrum of avian species with variable clinical symptoms and outcomes. Ease of transmission has allowed the virus to spread worldwide with varying degrees of virulence depending upon the virus strain and host species. The emergence of new virulent genotypes from global epizootics, and the year-to-year genomic changes in low and high virulence APMV-1 imply that distinct genotypes of APMV-1 are simultaneously evolving at different geographic locations across the globe. This vast genomic diversity may be favoured by large variety of avian species susceptibility to APMV-1 infection, and by the availability of highly mobile wild birds. It has long been considered that waterfowls are not sensitive to APMV-1 and are unable to show any clinical signs, however, outbreaks from the 90's contradict these concepts. The APMV-1 isolates are increasingly reported from the waterfowl. Waterfowl have strong innate immune responses, which minimize the impact of virus infection, however, are unable to prevent the viral shedding. Numerous APMV-1 are carried by domestic waterfowl intermingling with terrestrial poultry. Therefore, commercial ducks and geese should be vaccinated against APMV-1 to minimize the virus shedding and for the prevention the transmission. Genetic diversity within APMV-1 demonstrates the need for continual monitoring of viral evolution and periodic updates of vaccine seed-strains to achieve efficient control and eradication of APMV-1 in waterfowls.

Identification of Avian Paramyxovirus Serotype-1 in Wild Birds in the USA

In the US, sampling for avian paramyxovirus serotype-1 (APMV-1) is generally conducted when morbidity or mortality events occur involving certain families of wild birds known to be affected by the virus, such as cormorants (Family Phalacrocoracidae), pigeons, doves (Family Columbidae), or pelicans (Family Pelecanidae). To quantify the prevalence of APMV-1 in apparently healthy wild birds and to determine its geographic distribution, we collected swab and serum samples from >3,500 wild birds, representing eight orders from 1 January 2013 to 30 September 2013. Antibody prevalence was highest in wild birds of Order Suliformes (44.9%), followed by Pelecaniformes (24.4%), Anseriformes (22.7%), and Columbiformes (11.7%), with a relatively high occurrence of virulent viruses in Columbiformes (100% of virulent viruses isolated). As expected, viral shedding was comparatively much lower, and positives were only identified in Orders Accipitriformes (1.4%), Columbiformes (1.0%), Anseriformes (0.8%), and Charadriiformes (0.4%). We also demonstrate circulating virulent APMV-1 viruses of genotype VI in apparently healthy Rock Pigeons ( Columba livia ) from March through September in three states.

Surveillance of avian paramyxovirus serotype-1 in migratory waterfowls in Japan between 2011 and 2013

To further understand the epidemiology of avian paramyxovirus serotype-1 (APMV-1) in migratory waterfowls in Japan, we conducted the surveillance of this virus from feces derived from the migratory waterfowls collected in 41 Japanese prefectures between October 2011 and March 2013. Six APMV-1 viruses were isolated from total 661 samples. All isolates were identified as the avirulent (lentogenic) type on the basis of intracerebral pathogenicity tests. Genetic analysis showed that these viruses possessed the deduced amino acid sequence of ¹¹²GKQGR-L¹¹⁷ or ¹¹²ERQER-L¹¹⁷ at the cleavage site of the F0 protein, which was identical to the motif in the avirulent type. Phylogenetic analysis based on the partial fusion protein gene classified these APMV-1 isolates into 2 major genetic groups. Four isolates were classified as class II genotype I, and they were genetically closely related to strains isolated in Asian countries, including Japan. In contrast, two isolates were classified as class I, and they were genetically closely related to strains mainly isolated in the U.S.A.

Characterization of newcastle disease viruses in wild and domestic birds in Luxembourg from 2006 to 2008

Newcastle disease virus (NDV) is one of the most important viral diseases of birds. Wild birds constitute a natural reservoir of low-virulence viruses, while poultry are the main reservoir of virulent strains. Exchange of virus between these reservoirs represents a risk for both bird populations. Samples from wild and domestic birds collected between 2006 and 2010 in Luxembourg were analyzed for NDV. Three similar avirulent genotype I strains were found in ducks during consecutive years, suggesting that the virus may have survived and spread locally. However, separate introductions cannot be excluded, because no recent complete F gene sequences of genotype I from other European countries are available. Detection of vaccine-like strains in wild waterbirds suggested the spread of vaccine strains, despite the nonvaccination policy in Luxembourg. Among domestic birds, only one chicken was positive for a genotype II strain differing from the LaSota vaccine and exhibiting a so-far-unrecognized fusion protein cleavage site of predicted low virulence. Three genotype VI strains from pigeons were the only virulent strains found. The circulation of NDV in wild and free-ranging domestic birds warrants continuous surveillance because of increased concern that low-virulence wild-bird viruses could become more virulent in domestic populations.

Situation of serum antibodies against Newcastle disease virus in slaughter-age ostriches after vaccination campaign in Japan

A total of 516 slaughter-age ostrich sera were collected in Japan during 2006-2009. Sixty-one of five hundred and sixteen were positive by virus neutralization (VN) test and the titer of most positive samples was low level. Within the 61 positive sera, 35 sera were collected from unvaccinated ostriches. This result implies that these ostriches might have been infected naturally with low-virulent Newcastle disease virus (NDV). Within the 455 negative samples, 125 samples were from vaccinated ostriches. Since ostrich farmers use live attenuated vaccines, it is reasonable that the titer decreased to below detection level by 1 or 1.5 year-old. The above data indicate that NDV has infiltrated into ostrich farms in Japan, and that the efficacy of ostrich ND vaccination is often time-limited.