[Show abstract][Hide abstract] ABSTRACT: Infections of poultry species with virulent strains of Newcastle disease virus (NDV) cause Newcastle disease (ND), one of the most economically significant and devastating diseases for poultry producers worldwide. Biological engagement programs between the Southeast Poultry Research Laboratory (SEPRL) of the United States Department of Agriculture and laboratories from Russia, Pakistan, Ukraine, Kazakhstan, and Indonesia collectively have produced a better understanding of the genetic diversity and evolution of the viruses responsible for ND, which is crucial for the control of the disease. The data from Kazakhstan, Russia, and Ukraine identified possible migratory routes for birds that may carry both virulent NDV (vNDV) and NDV of low virulence into Europe. In addition, related NDV strains were isolated from wild birds in Ukraine and Nigeria, and from birds in continental USA, Alaska, Russia, and Japan, identifying wild birds as a possible mechanism of intercontinental spread of NDV of low virulence. More recently, the detection of new sub-genotypes of vNDV suggests that a new, fifth, panzootic of ND has already originated in Southeast Asia, extended to the Middle East, and is now entering into Eastern Europe. Despite expected challenges when multiple independent laboratories interact, many scientists from the collaborating countries have successfully been trained by SEPRL on molecular diagnostics, best laboratory practices, and critical biosecurity protocols, providing our partners the capacity to further train other employes and to identify locally the viruses that cause this OIE listed disease. These and other collaborations with partners in Mexico, Bulgaria, Israel, and Tanzania have allowed SEPRL scientists to engage in field studies, to elucidate more aspects of ND epidemiology in endemic countries, and to understand the challenges that the scientists and field veterinarians in these countries face on a daily basis. Finally, new viral characterization tools have been developed and are now available to the scientific community.
Frontiers in Public Health 11/2015; 3(235). DOI:10.3389/fpubh.2015.00235
[Show abstract][Hide abstract] ABSTRACT: Newcastle disease is an important health issue of poultry causing major economic losses and inhibits trade worldwide. Vaccination is used as a control measure, but it is unknown whether vaccination will prevent virus contamination of eggs. In this study, hens were sham-vaccinated or received one or two doses of inactivated LaSota vaccine, followed three weeks later by virulent Newcastle disease virus challenge. Eggs were collected daily and shell, albumen, and yolk were subjected to virus isolation, as were oral and cloacal swabs at 2 and 4 days post-challenge (dpc). A second experiment evaluated the distribution of the virus in the reproductive tract of non-vaccinates. All vaccinated chickens survived challenge, and the levels of virus shed from cloacal swabs were decreased significantly when compared to shams. In non-vaccinated hens, virus was detected in the ovary and all segments of the oviduct. Yolk, albumen and eggshell surface from eggs laid at day 4 and 5 post-infection by sham-vaccinated hens were positive for NDV, but eggs from LaSota vaccinated hens lacked virus in internal egg components (i.e. yolk and albumen) and had reduction in the number of positive eggshell surfaces. These results indicate virulent NDV can replicate in the reproductive tract of hens and contaminate internal components of eggs and eggshell surface, but vaccination was able to prevent internal egg contamination, reducing eggshell surface contamination, and reducing shedding from digestive and respiratory tracts in virulent NDV challenged hens.
[Show abstract][Hide abstract] ABSTRACT: Highly pathogenic avian influenza virus (HPAIV) and Newcastle disease virus (NDV) are two of the most important viruses affecting poultry worldwide and produce co-infections especially in areas of the world where both viruses are endemic; but little is known about the interactions between these two viruses. The objective of this study was to determine if co-infection with NDV affects HPAIV replication in chickens. Only infections with virulent NDV strains (mesogenic Pigeon/1984 or velogenic CA/2002), and not a lentogenic NDV strain (LaSota), interfered with the replication of HPAIV A/chicken/Queretaro/14588-19/95 (H5N2) when the H5N2 was given at a high dose (106.9 EID50) two days after the NDV inoculation, but despite this interference, mortality was still observed. However, chickens infected with the less virulent mesogenic NDV Pigeon/1984 strain three days prior to being infected with a lower dose (105.3–5.5 EID50) of the same or a different HPAIV, A/chicken/Jalisco/CPA-12283-12/2012 (H7N3), had reduced HPAIV replication and increased survival rates. In conclusion, previous infection of chickens with virulent NDV strains can reduce HPAIV replication, and consequently disease and mortality. This interference depends on the titer of the viruses used, the virulence of the NDV, and the timing of the infections. The information obtained from these studies helps to understand the possible interactions and outcomes of infection (disease and virus shedding) when HPAIV and NDV co-infect chickens in the field.
Electronic supplementary material
The online version of this article (doi:10.1186/s13567-015-0237-5) contains supplementary material, which is available to authorized users.
Veterinary Research 09/2015; 46(1):97. DOI:10.1186/s13567-015-0237-5 · 2.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: H7N9 influenza A first caused human infections in early 2013 in China. Virus genetics, histories of patient exposures to poultry, and previous experimental studies suggest the source of the virus is a domestic avian species, such as chickens. In order to better understand the ecology of this H7N9 in chickens, we evaluated the infectious dose and pathogenesis of A/Anhui/1/2013 H7N9 in two common breeds of chickens, White Leghorns (table-egg layers) and White Plymouth Rocks (meat chickens). No morbidity or mortality were observed with doses of 106 or 108 EID50/bird when administered by the upper-respiratory route, and the mean infectious dose (106 EID50) was higher than expected, suggesting that the virus is poorly adapted to chickens. Virus was shed at higher titers and spread to the kidneys in chickens inoculated by the intravenous route. Challenge experiments with three other human-origin H7N9 viruses showed a similar pattern of virus replication.
[Show abstract][Hide abstract] ABSTRACT: Infections with avian influenza viruses (AIV) of low and high pathogenicity (LP and HP) and Newcastle disease virus (NDV) are commonly reported in domestic ducks in many parts of the world. However, it is not clear if co-infections with these viruses affect the severity of the diseases they produce, the amount of virus shed, and transmission of the viruses. In this study we infected domestic ducks with a virulent NDV virus (vNDV) and either a LPAIV or a HPAIV by giving the viruses individually, simultaneously, or sequentially two days apart. No clinical signs were observed in ducks infected or co-infected with vNDV and LPAIV, but co-infection decreased the number of ducks shedding vNDV and the amount of virus shed (P<0.01) at 4 days post inoculation (dpi). Co-infection did not affect the number of birds shedding LPAIV, but more LPAIV was shed at 2dpi (P<0.0001) from ducks inoculated with only LPAIV compared to ducks co-infected with vNDV. Ducks that received the HPAIV with the vNDV simultaneously survived fewer days (P<0.05) compared to the ducks that received the vNDV two days before the HPAIV. Co-infection also reduced transmission of vNDV to naïve contact ducks housed with the inoculated ducks. In conclusion, domestic ducks can become co-infected with vNDV and LPAIV with no effect on clinical signs but with reduction of virus shedding and transmission. These findings indicate that infection with one virus can interfere with replication of another, modifying the pathogenesis and transmission of the viruses.
Published by Elsevier B.V.
[Show abstract][Hide abstract] ABSTRACT: Inactivated and fowlpox virus (FP)-vectored vaccines have been used to control H5 avian influenza (AI) in poultry. In H5 AI endemic countries, breeder flocks are vaccinated and therefore, maternally-derived antibodies (MDA) are transferred to their progeny. Results of three immunogenicity and one efficacy studies performed in birds with or without MDA indicated that the immunogenicity of an inactivated vaccine based on a H5N9 AI isolate (inH5N9) was severely impaired in chicks hatched from inH5N9-vaccinated breeders. This MDA interference was lower when breeders received only one administration of the same vaccine and could be overcome by priming the chicks at day-of-age with a live recombinant FP-vectored vaccine with H5 avian influenza gene insert (FP-AI). The interference of anti-FP MDA was of lower intensity than the interference of anti-AI MDA. The highest interference observed on the prime-boost immunogenicity was in chicks hatched from breeders vaccinated with the same prime-boost scheme. The level of protection against an antigenic variant H5N1 highly pathogenic AI isolate from Indonesia against which the FP-AI or inH5N9 alone was poorly protective could be circumvented by the prime-boost regimen in birds with either FP or AI MDA. Thus, the immunogenicity of vaccines in young chicks with MDA depends on the vaccination scheme and the type of vaccine used in their parent flocks. The heterologous prime-boost in birds with MDA may at least partially overcome MDA interference on inactivated vaccine.
Veterinary Research 10/2014; 45(1):107. DOI:10.1186/PREACCEPT-3462105181282326 · 2.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Highly pathogenic (HP) H5N1 avian influenza virus (AIV) was introduced to Egyptian poultry in 2006 and has since become enzootic. Vaccination has been utilized as a control tool combined with other control methods, but for a variety of reasons, the disease has not been eradicated. In 2007, an antigenically divergent hemagglutinin subclade, 18.104.22.168, emerged from the original clade 2.2.1 viruses.Objectives
The objective was to evaluate four diverse AIV isolates for use as vaccines in chickens, including two commercial vaccines and two additional contemporary isolates, against challenge with numerous clade 2.2.1 and clade 22.214.171.124 H5N1 HPAIV Egyptian isolates to assess the variation in protection among different vaccine and challenge virus combinations.Methods
Vaccination-challenge studies with four vaccines and up to eight challenge strains with each vaccine for a total of 25 vaccination-challenge groups were conducted with chickens. An additional eight groups served as sham-vaccinated controls. Mortality, mean death time, morbidity, virus, and pre-challenge antibodies were evaluated as metrics of protection. Hemagglutination inhibition data were used to visualize the antigenic relatedness of the isolates.Results and conclusionsAlthough all but one vaccine-challenge virus combination significantly reduced shed and mortality as compared to sham vaccinates, there were differences in protection among the vaccines relative to one another based on challenge virus. This emphasizes the difficulty in vaccinating against diverse, evolving virus populations, and the importance of selecting optimal vaccine seed strains for successful HPAIV control.
Influenza and Other Respiratory Viruses 10/2014; 8(6). DOI:10.1111/irv.12290 · 2.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the spring of 2012 an outbreak of H7N3 highly pathogenic (HP) avian influenza virus (AIV) occurred in poultry in Mexico. Vaccination was implemented as a control measure, along with increased biosecurity and surveillance. At that time there was no commercially available H7 AIV vaccine in North America; therefore, a recent H7N3 wild bird isolate of low pathogenicity from Mexico (A/cinnamon teal/Mexico/2817/2006 H7N3) was selected and utilized as the vaccine seed strain. In these studies, the potency and efficacy of this vaccine strain was evaluated in chickens against challenge with the 2012 Jalisco H7N3 HPAIV. Although vaccine doses of 256 and 102 hemagglutinating units (HAU) per bird decreased morbidity and mortality significantly compared to sham vaccinates, a dose of 512 HAU per bird was required to prevent mortality and morbidity completely. Additionally, the efficacy of 11 other H7 AIV vaccines and an antigenic map of hemagglutination inhibition assay data with all the vaccines and challenge viruses were evaluated, both to identify other potential vaccine strains and to characterize the relationship between genetic and antigenic distance with protection against this HPAIV. Several other isolates provided adequate protection against the 2012 Jalisco H7N3 lineage, but antigenic and genetic differences were not clear indicators of protection because the immunogenicity of the vaccine seed strain was also a critical factor.
[Show abstract][Hide abstract] ABSTRACT: Aquatic habitats play a critical role in the transmission and maintenance of low-pathogenic avian influenza (LPAI) viruses in wild waterfowl; however, the importance of these environments in the ecology of H5N1 highly pathogenic avian influenza (HPAI) viruses is unknown. In laboratory-based studies, LPAI viruses can remain infective for extended durations (months) in water, but the persistence is strongly dependent on water conditions (temperature, salinity, pH) and virus strain. Little is known about the stability of H5N1 HPAI viruses in water. With the use of an established laboratory model system, the persistence of 11 strains of H5N1 HPAI virus was measured in buffered distilled water (pH 7.2) at two temperatures (17 and 28 C) and three salinities (0, 15,000, and 30,000 ppm). There was extensive variation between the 11 H5N1 HPAI virus strains in the overall stability in water, with a range similar to that which has been reported for wild-bird-origin LPAI viruses. The H5N1 HPAI virus strains responded similarly to different water temperatures and salinities, with all viruses being most stable at colder temperatures and fresh to brackish salinities. These results indicate that the overall stability and response of H5N1 HPAI viruses in water is similar to LPAI viruses, and suggest there has been no increase or loss of environmental survivability in H5N1 HPAI viruses.
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Modulating the host response is a promising approach to treating influenza, caused by a virus whose pathogenesis is determined in part by the reaction it elicits within the host. Though the pathogenicity of emerging H7N9 influenza virus in several animal models has been reported, these studies have not included a detailed characterization of the host response following infection. Therefore, we characterized the transcriptomic response of BALB/c mice infected with H7N9 (A/Anhui/01/2013) virus and compared it to the responses induced by H5N1 (A/Vietnam/1203/2004), H7N7 (A/Netherlands/219/2003), and pandemic 2009 H1N1 (A/Mexico/4482/2009) influenza viruses. We found that responses to the H7 subtype viruses were intermediate to those elicited by H5N1 and pdm09H1N1 early in infection but that they evolved to resemble the H5N1 response as infection progressed. H5N1, H7N7, and H7N9 viruses were pathogenic in mice, and this pathogenicity correlated with increased transcription of cytokine response genes and decreased transcription of lipid metabolism and coagulation signaling genes. This three-pronged transcriptomic signature was observed in mice infected with pathogenic H1N1 strains such as the 1918 virus, indicating that it may be predictive of pathogenicity across multiple influenza virus strains. Finally, we used host transcriptomic profiling to computationally predict drugs that reverse the host response to H7N9 infection, and we identified six FDA-approved drugs that could potentially be repurposed to treat H7N9 and other pathogenic influenza viruses.
Emerging avian influenza viruses are of global concern because the human population is immunologically naive to them. Current influenza drugs target viral molecules, but the high mutation rate of influenza viruses eventually leads to the development of antiviral resistance. As the host evolves far more slowly than the virus, and influenza pathogenesis is determined in part by the host response, targeting the host response is a promising approach to treating influenza. Here we characterize the host transcriptomic response to emerging H7N9 influenza virus and compare it with the responses to H7N7, H5N1, and pdm09H1N1. All three avian viruses were pathogenic in mice and elicited a transcriptomic signature that also occurs in response to the legendary 1918 influenza virus. Our work identifies host responses that could be targeted to treat severe H7N9 influenza and identifies six FDA-approved drugs that could potentially be repurposed as H7N9 influenza therapeutics.
Journal of Virology 07/2014; 88(18). DOI:10.1128/JVI.00570-14 · 4.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Avian influenza vaccines for poultry are based on hemagglutinin proteins, and protection is specific to the vaccine subtype. Over 113 billion doses have been used between 2002 and 2010 for high pathogenicity avian influenza control. No universal vaccines are currently available. The majority of avian influenza vaccines are inactivated whole influenza viruses that are grown in embryonating eggs, inactivated, emulsified in oil adjuvant systems, and injected into chickens. Live virus-vectored vaccines such as recombinant viruses of fowl pox, Newcastle disease, herpesvirus of turkeys and duck enteritis containing inserts of avian influenza virus hemagglutinin genes have been used on a more limited basis. In studies to evaluate vaccine efficacy and potency, the protocol design and its implementation should address the biosafety level needed for the work, provide information required for approval by Institutional Biosafety and Animal Care Committees, contain information on seed strain selection, provide needed information on animal subjects and their relevant parameters, and address the selection and use of challenge viruses. Various metrics have been used to directly measure vaccine induced protection. These include prevention of death, clinical signs, and lesions; prevention of decreases in egg production and alterations in egg quality; quantification of the reduction in virus replication and shedding from the respiratory tract and gastrointestinal tracts; and prevention of contact transmission in in vivo poultry experiments. In addition, indirect measures of vaccine potency and protection can be developed and validated against the direct measures and include serological assays in vaccinated poultry and assessment of the content of hemagglutinin antigen in the vaccine. These indirect assessments of protection are useful in determining if vaccine batches have a consistent ability to protect. For adequate potency, vaccines should contain 50 mean protective doses of antigen, which corresponds to 0.3-7.8 μg of hemagglutinin protein, depending on immunogenicity of individual seed strains.
[Show abstract][Hide abstract] ABSTRACT: High pathogenicity avian influenza viruses (HPAIV) have caused fatal infections in mammals through consumption of infected bird carcasses or meat, but scarce information exists on the dose of virus required and the diversity of HPAIV subtypes involved. Ferrets were exposed to different HPAIV (H5 and H7 subtypes) through consumption of infected chicken meat. The dose of virus needed to infect ferrets through consumption was much higher than via respiratory exposure and varied with the virus strain. In addition, H5N1 HPAIV produced higher titers in the meat of infected chickens and more easily infected ferrets than the H7N3 or H7N7 HPAIV.
Veterinary Research 06/2014; 45(1):60. DOI:10.1186/1297-9716-45-60 · 2.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Double reassortant H13N8 influenza A virus was isolated from gull in Mongolia. The basic virological characteristics were studied. Complete genome sequence analysis indicated the complicated evolutionary history. The PA gene belongs to classical Avian-like lineage and more likely originated from non-gull avian virus pool. Data confirm the state of extensive geographic mosaicism in AIV from gulls in the Northern Hemisphere.
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The recent outbreak of H7N9 influenza in China has resulted in many human cases with a high fatality rate. Poultry are the likely source of infection for humans on the basis of sequence analysis and virus isolations from live bird markets, but it is not clear which species of birds are most likely to be infected and shedding levels of virus sufficient to infect humans. Intranasal inoculation of chickens, Japanese quail, pigeons, Pekin ducks, Mallard ducks, Muscovy ducks, and Embden geese with 10(6) 50% egg infective doses of the A/Anhui/1/2013 virus resulted in infection but no clinical disease signs. Virus shedding was much higher and prolonged in quail and chickens than in the other species. Quail effectively transmitted the virus to direct contacts, but pigeons and Pekin ducks did not. In all species, virus was detected at much higher titers from oropharyngeal swabs than cloacal swabs. The hemagglutinin gene from samples collected from selected experimentally infected birds was sequenced, and three amino acid differences were commonly observed when the sequence was compared to the sequence of A/Anhui/1/2013: N123D, N149D, and L217Q. Leucine at position 217 is highly conserved for human isolates and is associated with α2,6-sialic acid binding. Different amino acid combinations were observed, suggesting that the inoculum had viral subpopulations that were selected after passage in birds. These experimental studies corroborate the finding that certain poultry species are reservoirs of the H7N9 influenza virus and that the virus is highly tropic for the upper respiratory tract, so testing of bird species should preferentially be conducted with oropharyngeal swabs for the best sensitivity.
The recent outbreak of H7N9 influenza in China has resulted in a number of human infections with a high case fatality rate. The source of the viral outbreak is suspected to be poultry, but definitive data on the source of the infection are not available. This study provides experimental data to show that quail and chickens are susceptible to infection, shed large amounts of virus, and are likely important in the spread of the virus to humans. Other poultry species can be infected and shed virus but are less likely to play a role of transmitting the virus to humans. Pigeons were previously suggested to be a possible source of the virus because of isolation of the virus from several pigeons in poultry markets in China, but experimental studies show that they are generally resistant to infection and are unlikely to play a role in the spread of the virus.
Journal of Virology 02/2014; 88(10). DOI:10.1128/JVI.03689-13 · 4.44 Impact Factor