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Minor differences in body condition and immune status between avian influenza virus-infected and noninfected mallards: a sign of coevolution?
Dijk, J.G.B. van; Fouchier, R.A.M. ; Klaassen, M. ; Matson, K.D. - \ 2015
Ecology and Evolution 5 (2015)2. - ISSN 2045-7758 - p. 436 - 449.
a virus - anas-platyrhynchos - natural antibodies - stable hydrogen - wild birds - vice-versa - ducks - patterns - migration - isotopes
Wildlife pathogens can alter host fitness. Low pathogenic avian influenza virus (LPAIV) infection is thought to have negligible impacts on wild birds; however, effects of infection in free-living birds are largely unstudied. We investigated the extent to which LPAIV infection and shedding were associated with body condition and immune status in free-living mallards (Anas platyrhynchos), a partially migratory key LPAIV host species. We sampled mallards throughout the species' annual autumn LPAIV infection peak, and we classified individuals according to age, sex, and migratory strategy (based on stable hydrogen isotope analysis) when analyzing data on body mass and five indices of immune status. Body mass was similar for LPAIV-infected and noninfected birds. The degree of virus shedding from the cloaca and oropharynx was not associated with body mass. LPAIV infection and shedding were not associated with natural antibody (NAbs) and complement titers (first lines of defense against infections), concentrations of the acute phase protein haptoglobin (Hp), ratios of heterophils to lymphocytes (H:L ratio), and avian influenza virus (AIV)-specific antibody concentrations. NAbs titers were higher in LPAIV-infected males and local (i.e., short distance) migrants than in infected females and distant (i.e., long distance) migrants. Hp concentrations were higher in LPAIV-infected juveniles and females compared to infected adults and males. NAbs, complement, and Hp levels were lower in LPAIV-infected mallards in early autumn. Our study demonstrates weak associations between infection with and shedding of LPAIV and the body condition and immune status of free-living mallards. These results may support the role of mallards as asymptomatic carriers of LPAIV and raise questions about possible coevolution between virus and host.
Molecular Epidemiological Analysis of the Transboundary Transmission of 2003 Highly Pathogenic Avian Influenza H7N7 Outbreaks Between The Netherlands and Belgium
Borm, S. van; Jonges, M. ; Lambrecht, B. ; Koch, G. ; Houdart, P. ; Berg, T. van den - \ 2014
Transboundary and Emerging Diseases 61 (2014)1. - ISSN 1865-1674 - p. 86 - 90.
a virus - poultry
The 2003 outbreak of Highly pathogenic avian influenza (HPAI) A(H7N7) in the Netherlands, Belgium and Germany resulted in significant genetic diversification that proved informative for tracing transmission events. Building on previous investigations on the Dutch outbreak, we focused on the potential transnational transmissions between the Netherlands and Belgium. Although no clear epidemiological links could be identified from the tracing data, the transmission network based on concatenated HA-NA-PB2 sequences supports at least three independent introductions from the Netherlands to Belgium and suggests one possible introduction form Belgium back to the Netherlands. Two introductions in the Belgian province of Limburg occurred from nearby farms in the Dutch province of Limburg. One introduction resulted in three secondary infected farms, while a second introduction did not cause secondary infections. The third introduction into Belgium occurred in the north of the Antwerp province, very close to the national border, and originated from the North of the Dutch province Brabant (long distance transmission, >65 km). The virus spread to two additional Belgian farms, one of which may be the source of a secondarily infected farm in the Netherlands. One infected turkey farm in the province of Antwerp (Westmalle) was geographically close to the latter introduction, but genetically clustered with the first introduction event in the Limburg province. Epidemiological tracing data could neither confirm nor exclude whether this outbreak was a result from long distance contacts within Belgium or whether this farm presented a fourth independent transboundary introduction. These multiple transnational transmissions of HPAI in spite of reinforced biosecurity measures and trade restrictions illustrate the importance of international cooperation, legislation and standardization of tools to combat transboundary diseases.
Tracing enteric viruses in the European berry fruit supply chain
Maunula, L. ; Kaupke, A. ; Vasickova, P. ; Soderberg, K. ; Kozyra, I. ; Lazic, S. ; Poel, W.H.M. van der; Bouwknegt, M. ; Rutjes, S. ; Willems, K.A. ; Moloney, R. ; Agostino, M. D'; Husman, A.M.D. ; Bonsdorff, C.H. ; Rzezutka, A. ; Pavlik, I. ; Petrovic, T. ; Cook, N. - \ 2013
International Journal of Food Microbiology 167 (2013)2. - ISSN 0168-1605 - p. 177 - 185.
hepatitis-e virus - reverse transcription-pcr - time rt-pcr - waste-water - norovirus outbreaks - frozen raspberries - food safety - a virus - transmission - infection
In recent years, numerous foodborne outbreaks due to consumption of berry fruit contaminated by human enteric viruses have been reported. This European multinational study investigated possible contamination routes by monitoring the entire food chain for a panel of human and animal enteric viruses. A total of 785 samples were collected throughout the food production chain of four European countries (Czech Republic, Finland, Poland and Serbia) during two growing seasons. Samples were taken during the production phase, the processing phase, and at point-of-sale. Samples included irrigation water, animal faeces, food handlers' hand swabs, swabs from toilets on farms, from conveyor belts at processing plants, and of raspberries or strawberries at points-of-sale; all were subjected to virus analysis. The samples were analysed by real-time (reverse transcription, RT)-PCR, primarily for human adenoviruses (hAdV) to demonstrate that a route of contamination existed from infected persons to the food supply chain. The analyses also included testing for the presence of selected human (norovirus, NoV GI, NoV GII and hepatitis A virus, HAV), animal (porcine adenovirus, pAdV and bovine polyomavirus, bPyV) and zoonotic (hepatitis E virus, HEV) viruses. At berry production, hAdV was found in 9.5%, 5.8% and 9.1% of samples of irrigation water, food handlers' hands and toilets, respectively. At the processing plants, hAdV was detected in one (2.0%) swab from a food handler's hand. At point-of-sale, the prevalence of hAdV in fresh raspberries, frozen raspberries and fresh strawberries, was 0.7%, 3.2% and 2.0%, respectively. Of the human pathogenic viruses, NoV GII was detected in two (3.6%) water samples at berry production, but no HAV was detected in any of the samples. HEV-contaminated frozen raspberries were found once (2.6%). Animal faecal contamination was evidenced by positive pAdV and bPyV assay results. At berry production, one water sample contained both viruses, and at point-of-sale 5.7% and 13% of fresh and frozen berries tested positive for pAdV. At berry production hAdV was found both in irrigation water and on food handler's hands, which indicated that these may be important vehicles by which human pathogenic viruses enter the berry fruit chain. Moreover, both zoonotic and animal enteric viruses could be detected on the end products. This study gives insight into viral sources and transmission routes and emphasizes the necessity for thorough compliance with good agricultural and hygienic practice at the farms to help protect the public from viral infections. (C) 2013 Elsevier B.V. All rights reserved.
Contribution of the NS1 Gene of H7 Avian Influenza Virus Strains to Pathogenicity in Chickens
Post, J. ; Peeters, B.P.H. ; Cornelissen, J.B.W.J. ; Vervelde, L. ; Rebel, J.M.J. - \ 2013
Viral Immunology 26 (2013)6. - ISSN 0882-8245 - p. 396 - 403.
a virus - nonstructural protein-1 - cytokine responses - interferon - h5n1 - infection - virulence - cells - ducks - beta
Using reverse genetics (rg), we generated two reassortant viruses carrying the NS1 gene of two closely related HPAIV and LPAIV H7N1 variants (designated rgH7N7 HPHPNS1 and rgH7N7 HPLPNS1, respectively) in the backbone of the HP H7N7 strain A/Chicken/Netherlands/621557/03 (rgH7N7 HP). Comparison of these reassortants allowed us to determine the effect of amino acid differences in the nuclear export and nucleolar localization sequences of NS1 on pathogenesis in chickens. Compared to rgH7N7 HPLPNS1, a delay in weight gain and an increase in mortality were observed for rgH7N7 HPHPNS1. Furthermore, an increase in viral load in brains, lungs, and cloacal swabs, as well as an increased induction of mRNA for type I interferons and proinflammatory cytokines in brains, were observed for rgH7N7 HPHPNS1. Comparison of rgH7N7 HPLPNS1 with the backbone strain rgH7N7 HP allowed us to examine differences in pathogenesis due to differences in NS1 alleles. rgH7N7 HP, which contained allele A of NS1 showed a higher in vitro replication rate and proved to be more virulent than the isogenic virus carrying allele B of NS1(rgH7N7 HPLPNS1). In addition, higher virus accumulation in the lungs and brains, and an increased induction of host gene responses, especially in the brains, were found for rgH7N7 HP compared to rgH7N7 HPLPNS1. No large differences were observed in type I interferon expression in the lungs of chickens infected with any of the viruses, suggesting that differences in virulence due to differences in NS1 could be related to differences in the induction of pro-inflammatory cytokines in vital organs such as the brains.
Guiding outbreak management by the use of influenza A(H7Nx) virus sequence analysis
Jonges, M. ; Meijer, A. ; Fouchier, R.A.M. ; Koch, G. ; Li, J. ; Pan, J.C. ; Shu, Y.L. ; Koopmans, M.P.G. ; Chen, H. - \ 2013
EuroSurveillance 18 (2013)16. - ISSN 1025-496X - 8 p.
avian influenza - a virus - transmission - replication - poultry - ferrets - humans - mice
The recently identified human infections with avian influenza A(H7N9) viruses in China raise important questions regarding possible source and risk to humans. Sequence comparison with an influenza A(H7N7) outbreak in the Netherlands in 2003 and an A(H7N1) epidemic in Italy in 1999–2000 suggests that widespread circulation of A(H7N9) viruses must have occurred in China. The emergence of human adaptation marker PB2 E627K in human A(H7N9) cases parallels that of the fatal A(H7N7) human case in the Netherlands.
Rapid emergence of a virulent PB2 E627K variant during adaptation of highly pathogenic avian influenza H7N7 virus to mice
Jong, M.C. de; Stockhofe-Zurwieden, N. ; Verheij, E.S. ; Boer-Luijtze, E.A. de; Ruiter, S.J.M. ; Leeuw, O.S. de; Cornelissen, A.H.M. - \ 2013
Virology journal 10 (2013). - ISSN 1743-422X
a virus - amino-acid - viral polymerase - molecular-basis - h5n1 viruses - host-range - mouse lung - humans - determinants - transmission
Background Highly pathogenic avian influenza (HPAI) viruses pose a potential human health threat as they can be transmitted directly from infected poultry to humans. During a large outbreak of HPAI H7N7 virus among poultry in The Netherlands in 2003, bird to human transmission was confirmed in 89 cases, of which one had a fatal outcome. Methods To identify genetic determinants of virulence in a mammalian host, we passaged an avian H7N7/03 outbreak isolate in mouse lungs and evaluated the phenotype of the mouse-adapted variant in animal models and in vitro. Results Three passages in mouse lungs were sufficient to select a variant that was highly virulent in mice. The virus had a MLD50 that was >4.3 logs lower than that of its non-lethal parental virus. Sequence analysis revealed a single mutation at position 627 in PB2, where the glutamic acid was changed to a lysine (E627K). The mouse-adapted virus has this mutation in common with the fatal human case isolate. The virus remained highly pathogenic for chickens after its passage in mice. In ferrets, the mouse-adapted virus induced more severe disease, replicated to higher titers in the lower respiratory tract and spread more efficiently to systemic organs compared with the parental virus. In vitro, the PB2 E627K mutation had a promoting effect on virus propagation in mammalian, but not in avian cells. Conclusions Our results show that the E627K mutation in PB2 alone can be sufficient to convert an HPAI H7N7 virus of low virulence to a variant causing severe disease in mice and ferrets. The rapid emergence of the PB2 E627K mutant during mouse adaptation and its pathogenicity in ferrets emphasize the potential risk of HPAI H7N7 viruses for human health.
The duck genome and transcriptome provide insight into an avian influenza virus reservoir species
Huang, Y. ; Li, Y. ; Burt, D.W. ; Chen, H. ; Groenen, M.A.M. ; Crooijmans, R.P.M.A. ; Kraus, R.H.S. - \ 2013
Nature Genetics 45 (2013). - ISSN 1061-4036 - p. 776 - 783.
gene family evolution - positive selection - a virus - maximum-likelihood - phylogenetic trees - protein - transmission - duplication - expression - defensins
The duck (Anas platyrhynchos) is one of the principal natural hosts of influenza A viruses. We present the duck genome sequence and perform deep transcriptome analyses to investigate immune-related genes. Our data indicate that the duck possesses a contractive immune gene repertoire, as in chicken and zebra finch, and this repertoire has been shaped through lineage-specific duplications. We identify genes that are responsive to influenza A viruses using the lung transcriptomes of control ducks and ones that were infected with either a highly pathogenic (A/duck/Hubei/49/05) or a weakly pathogenic (A/goose/Hubei/65/05) H5N1 1 virus. Further, we show how the duck’s defense mechanisms against influenza infection have been optimized through the diversification of its b-defensin and butyrophilin-like repertoires. These analyses, in combination with the genomic and transcriptomic data, provide a resource for characterizing the interaction between host and influenza viruses.
Chicken dendritic cells are susceptible to highly pathogenic avian influenza viruses which induce strong cytokine responses
Vervelde, L. ; Reemens, S.S. ; Haarlem, D.A. van; Post, J. ; Claassen, E.A.W. ; Rebel, J.M.J. ; Jansen, C.A. - \ 2013
Developmental and Comparative Immunology 39 (2013)3. - ISSN 0145-305X - p. 198 - 206.
ns1 protein - a virus - swine influenza - gene-expression - infection - interferon - activation - pathobiology - recognition - inhibition
Infection with highly pathogenic avian influenza (HPAI) in birds and mammals is associated with severe pathology and increased mortality. We hypothesize that in contrast to low pathogenicity avian influenza (LPAI) infection, HPAI infection of chicken dendritic cells (DC) induces a cytokine deregulation which may contribute to their highly pathogenic nature. Infection of DC with LPAI H7N1 and H5N2 resulted in viral RNA and NP expression without increase in time, in contrast to HPAI H7N1 and H5N2 mRNA expression. No increase in IFN mRNA was detected after infection with LPAI, but after LPAI H5N2, and not LPAI H7N1, infection the level of bioactive IFNa/ß significantly increased. After HPAI H7N1 and H5N2 infection, significant increases in IL-8, IFN-a, IFN-¿ mRNA expression and in TLR1, 3, and 21 mRNA were observed. This enhanced activation of DC after HPAI infection may trigger deregulation of the immune response as seen during HPAI infection in chickens.
New DIVA vaccine for the protection of poultry against H5 highly pathogenic avian influenza viruses irrespective of the N-subtype
Peeters, B.P.H. ; Boer, S.M. de; Tjeerdsma-de Bruin, G. ; Moormann, R.J.M. ; Koch, G. - \ 2012
Vaccine 30 (2012)49. - ISSN 0264-410X - p. 7078 - 7083.
newcastle-disease virus - a virus - heterologous neuraminidase - reverse genetics - animals strategy - cleavage site - hong-kong - b virus - hemagglutinin - transmission
Most human cases of highly pathogenic H5N1 avian influenza virus (HPAIV) infection are the result of direct contact with infected poultry. Therefore, infection of poultry should be prevented to avoid human exposure. One method to combat HPAIV outbreaks relies on depopulation. An alternative or supplementary method is the use of DIVA (discriminating infected from vaccinated animals) vaccines to prevent infection of animals on holdings surrounding an outbreak. Discrimination between infected and vaccinated animals is often based on the ‘heterologous neuraminidase’ strategy. This implies that a suitable vaccine can only be selected when the N-subtype of the outbreak strain is known. Thus, at least two vaccines with different N-subtypes must be available, allowing a switch of vaccine in the event that one of them matches the outbreak strain. However, such vaccines cannot be used preventively in situations in which the N-subtype of the outbreak strain is unknown. In order to circumvent these drawbacks we generated a recombinant influenza virus containing the HA gene of a contemporary H5N1 HPAIV strain in combination with the NA gene of a human type B influenza virus. An inactivated vaccine based on this virus protected chickens against clinical disease, and completely prevented virus shedding after H5N1 HPAIV challenge infection. Serological analyses confirmed that the vaccine complied with the DIVA principle. Since NA of type B does not occur in avian influenza strains, this vaccine is suitable as a DIVA vaccine against any H5 HPAIV, and may be used preventively without compromising the DIVA principle.
Modelling the wind-borne spread of highly pathogenic avian influenza virus between farms
Ssematimba, A. ; Hagenaars, T.H.J. ; Jong, M. de - \ 2012
PLoS One 7 (2012)2. - ISSN 1932-6203
mouth-disease virus - swine-fever virus - livestock buildings - commercial poultry - airborne spread - great-britain - risk-factors - a virus - epidemic - foot
A quantitative understanding of the spread of contaminated farm dust between locations is a prerequisite for obtaining much-needed insight into one of the possible mechanisms of disease spread between farms. Here, we develop a model to calculate the quantity of contaminated farm-dust particles deposited at various locations downwind of a source farm and apply the model to assess the possible contribution of the wind-borne route to the transmission of Highly Pathogenic Avian Influenza virus (HPAI) during the 2003 epidemic in the Netherlands. The model is obtained from a Gaussian Plume Model by incorporating the dust deposition process, pathogen decay, and a model for the infection process on exposed farms. Using poultry- and avian influenza-specific parameter values we calculate the distance-dependent probability of between-farm transmission by this route. A comparison between the transmission risk pattern predicted by the model and the pattern observed during the 2003 epidemic reveals that the wind-borne route alone is insufficient to explain the observations although it could contribute substantially to the spread over short distance ranges, for example, explaining 24% of the transmission over distances up to 25 km.
Estimating the per-contact probability of infection by highly pathogenic avian influenza (H7N7) virus during the 2003 epidemic in the Netherlands.
Ssematimba, A. ; Elbers, A.R.W. ; Hagenaars, T.H.J. ; Jong, M.C.M. de - \ 2012
PLoS One 7 (2012)7. - ISSN 1932-6203 - 1 p.
h5n1 infection - poultry farms - a virus - transmission - outbreaks - history
Estimates of the per-contact probability of transmission between farms of Highly Pathogenic Avian Influenza virus of H7N7 subtype during the 2003 epidemic in the Netherlands are important for the design of better control and biosecurity strategies. We used standardized data collected during the epidemic and a model to extract data for untraced contacts based on the daily number of infectious farms within a given distance of a susceptible farm. With these data, we used a maximum likelihood estimation approach to estimate the transmission probabilities by the individual contact types, both traced and untraced. The estimated conditional probabilities, conditional on the contact originating from an infectious farm, of virus transmission were: 0.000057 per infectious farm within 1 km per day, 0.000413 per infectious farm between 1 and 3 km per day, 0.0000895 per infectious farm between 3 and 10 km per day, 0.0011 per crisis organisation contact, 0.0414 per feed delivery contact, 0.308 per egg transport contact, 0.133 per other-professional contact and, 0.246 per rendering contact. We validate these outcomes against literature data on virus genetic sequences for outbreak farms. These estimates can be used to inform further studies on the role that improved biosecurity between contacts and/or contact frequency reduction can play in eliminating between-farm spread of the virus during future epidemics. The findings also highlight the need to; 1) understand the routes underlying the infections without traced contacts and, 2) to review whether the contact-tracing protocol is exhaustive in relation to all the farm’s day-to-day activities and practices.
Evolutionary Analysis of Inter-Farm Transmission Dynamics in a Highly Pathogenic Avian Influenza Epidemic
Bataille, A. ; Meer, F. van der; Stegeman, A. ; Koch, G. - \ 2011
PLoS Pathogens 7 (2011)6. - ISSN 1553-7366
amino-acid sites - virus h7n7 - a virus - phylogenetic analysis - maximum-likelihood - poultry farms - netherlands - selection - h5n1 - recombination
Phylogenetic studies have largely contributed to better understand the emergence, spread and evolution of highly pathogenic avian influenza during epidemics, but sampling of genetic data has never been detailed enough to allow mapping of the spatiotemporal spread of avian influenza viruses during a single epidemic. Here, we present genetic data of H7N7 viruses produced from 72% of the poultry farms infected during the 2003 epidemic in the Netherlands. We use phylogenetic analyses to unravel the pathways of virus transmission between farms and between infected areas. In addition, we investigated the evolutionary processes shaping viral genetic diversity, and assess how they could have affected our phylogenetic analyses. Our results show that the H7N7 virus was characterized by a high level of genetic diversity driven mainly by a high neutral substitution rate, purifying selection and limited positive selection. We also identified potential reassortment in the three genes that we have tested, but they had only a limited effect on the resolution of the inter-farm transmission network. Clonal sequencing analyses performed on six farm samples showed that at least one farm sample presented very complex virus diversity and was probably at the origin of chronological anomalies in the transmission network. However, most virus sequences could be grouped within clearly defined and chronologically sound clusters of infection and some likely transmission events between farms located 0.8-13 Km apart were identified. In addition, three farms were found as most likely source of virus introduction in distantly located new areas. These long distance transmission events were likely facilitated by human-mediated transport, underlining the need for strict enforcement of biosafety measures during outbreaks. This study shows that in-depth genetic analysis of virus outbreaks at multiple scales can provide critical information on virus transmission dynamics and can be used to increase our capacity to efficiently control epidemics.
MDCK cell line with inducible allele B NS1 expression propagates deINS1 inflenza virus to high titres
Wielink, R. van; Harmsen, M.M. ; Martens, D.E. ; Peeters, B.P.H. ; Wijffels, R.H. ; Moormann, R.J.M. - \ 2011
Vaccine 29 (2011)40. - ISSN 0264-410X - p. 6976 - 6985.
protein induces apoptosis - airway epithelial-cells - a virus - gene-expression - infected-cells - interferon - vaccine - rna - systems - ability
Influenza A viruses lacking the gene encoding the non-structural NS1 protein (delNS1) have potential use as live attenuated vaccines. However, due to the lack of NS1, virus replication in cell culture is considerably reduced, prohibiting commercial vaccine production. We therefore established two stable MDCK cell lines that show inducible expression of the allele B NS1 protein. Upon induction, both cell lines expressed NS1 to about 1000-fold lower levels than influenza virus-infected cells. Nevertheless, expression of NS1 increased delNS1 virus titres to levels comparable to those obtained with an isogenic virus strain containing an intact NS1 gene. Recombinant NS1 expression increased the infectious virus titres 244 to 544-fold and inhibited virus induced apoptosis. However, NS1 expression resulted in only slightly, statistically not significant, reduced levels of interferon-ß production. Thus, the low amount of recombinant NS1 is sufficient to restore delNS1 virus replication in MDCK cells, but it remains unclear whether this occurs in an interferon dependent manner. In contrast to previous findings, recombinant NS1 expression did not induce apoptosis, nor did it affect cell growth. These cell lines thus show potential to improve the yield of delNS1 virus for vaccine production.
Highly pathogenic or low pathogenic avian influenza virus subtype H7N1 infection in chicken lungs: small differences in general acute responses.
Rebel, J.M.J. ; Peeters, B.P.H. ; Fijten, H.P.D. ; Post, J. ; Cornelissen, J.B.W.J. ; Vervelde, L. - \ 2011
Veterinary Research 42 (2011). - ISSN 0928-4249 - 11 p.
cytokine responses - respiratory-tract - a virus - immune-responses - host-responses - h5n1 virus - cells - expression - deposition - h9n2
Avian influenza virus can be divided into two groups, highly pathogenic avian influenza virus (HPAI) and low pathogenic avian influenza virus (LPAI) based on their difference in virulence. To investigate if the difference in clinical outcome between LPAI and HPAI in chickens is due to immunological host responses in the lung within the first 24 hours post infection (hpi), chickens were infected with LPAI or HPAI of subtype H7N1. Virus was found in the caudal and cranial part of the lung. With LPAI, virus was localised around the intrapulmonary bronchus and secondary bronchi. In sharp contrast, HPAI was detected throughout the whole lung. However, based on viral RNA levels, no quantitative difference was observed between LPAI and HPAI infected birds. In infected areas of the lungs, an influx of CD8a+ cells as well as KUL01+ macrophages and dendritic cells (DC) occurred as fast as 8 hpi in both infected groups. No major difference between LPAI and HPAI infected birds in the induction of cytokines and interferons at mRNA level in lung tissue was found. In conclusion, the differences in lethality for chickens infected with LPAI or HPAI could be ascribed to difference in location of the virus. However similar amounts of viral RNA, similar cytokine mRNA levels, and similar influxes of CD8a+ and KUL01+ macrophages and DC were found between HPAI and LPAI in the lungs. A cytokine storm at mRNA level as described for mammals was not observed in the lungs of HPAI infected birds within 24 hpi.
Base-pairing promotes leader selection to prime in vitro influenza genome transcription
Geerts-Dimitriadou, C. ; Zwart, M.P. ; Goldbach, R.W. ; Kormelink, R.J.M. - \ 2011
Virology 409 (2011)1. - ISSN 0042-6822 - p. 17 - 26.
messenger-rna synthesis - cap-snatching mechanism - mosaic-virus rnas - viral-rna - 5' ends - complementary rna - a virus - polymerase - endonuclease - sequences
The requirements for alignment of capped leader sequences along the viral genome during influenza transcription initiation (cap-snatching) have long been an enigma. In this study, competition experiments using an in vitro transcription assay revealed that influenza virus transcriptase prefers leader sequences with base complementarity to the 3'-ultimate residues of the viral template, 10 or 11 nt from the 5' cap. Internal priming at the 3'-penultimate residue, as well as prime-and-realign was observed. The nucleotide identity immediately 5' of the base-pairing residues also affected cap donor usage. Application to the in vitro system of RNA molecules with increased base complementarity to the viral RNA template showed stronger reduction of globin RNA leader initiated influenza transcription compared to those with a single base-pairing possibility. Altogether the results indicated an optimal cap donor consensus sequence of 7mG-(N)7–8-(A/U/G)-(A/U)-AGC-3'.
Dynamics and ecological consequences of avian influenza virus infection in greater white-fronted geese in their winter staging areas
Kleijn, D. ; Munster, V.J. ; Ebbinge, B.S. ; Jonkers, D.A. ; Müskens, G.J.D.M. ; Randen, Y. van; Fouchier, R.A.M. - \ 2010
Proceedings of the Royal Society. B: Biological Sciences 277 (2010)1690. - ISSN 0962-8452 - p. 2041 - 2048.
wild mallard ducks - affect body condition - a virus - migratory waterfowl - branta-canadensis - north-america - vice-versa - birds - h5n1 - paramyxoviruses
Recent outbreaks of highly pathogenic avian influenza (HPAI) in poultry have raised interest in the interplay between avian influenza (AI) viruses and their wild hosts. Studies linking virus ecology to host ecology are still scarce, particularly for non-duck species. Here, we link capture–resighting data of greater white-fronted geese Anser albifrons albifrons with the AI virus infection data collected during capture in The Netherlands in four consecutive winters. We ask what factors are related to AI virus prevalence and whether there are ecological consequences associated with AI virus infection in staging white-fronted geese. Mean seasonal (low pathogenic) AI virus prevalence ranged between 2.5 and 10.7 per cent, among the highest reported values for non-duck species, and occurred in distinct peaks with near-zero prevalence before and after. Throat samples had a 2.4 times higher detection frequency than cloacal samples. AI virus infection was significantly related to age and body mass in some but not other winters. AI virus infection was not related to resighting probability, nor to maximum distance travelled, which was at least 191 km during the short infectious lifespan of an AI virus. Our results suggest that transmission via the respiratory route could be an important transmission route of AI virus in this species. Near-zero prevalence upon arrival on their wintering grounds, in combination with the epidemic nature of AI virus infections in white-fronted geese, suggests that white-fronted geese are not likely to disperse Asian AI viruses from their Siberian breeding grounds to their European wintering areas.
Validation of diagnostic tests for detection of avian influenza in vaccinated chickens using Bayesian analysis
Goot, J.A. van der; Engel, B. ; Water, S.G.P. van de; Buist, W.G. ; Jong, M.C.M. de; Koch, G. ; Boven, M. van; Stegeman, J.A. - \ 2010
Vaccine 28 (2010)7. - ISSN 0264-410X - p. 1771 - 1777.
nonstructural protein ns1 - a virus - infected chickens - antibodies - poultry - transmission - disease - quantification - neuraminidase - distinction
Vaccination is an attractive tool for the prevention of outbreaks of highly pathogenic avian influenza in domestic birds. It is known, however, that under certain circumstances vaccination may fail to prevent infection, and that the detection of infection in vaccinated birds can be problematic. Here, we investigate the characteristics of three serological tests (immunofluorescent antibody test (iIFAT), neuraminidase inhibition (NI) assay, and NS1 ELISA) that are able to differentiate infected from vaccinated animals. To this end, data of H7N7 infection experiments are analyzed using Bayesian methods of inference. These Bayesian methods enable validation of the tests in the absence of a gold standard, and allow one to take into account that infected birds do not always develop antibodies after infection. The results show that the N7 iIFAT and the NI assay have sensitivities for detecting antibodies of 0.95 (95% CI: 0.89–0.98) and 0.93 (95% CI: 0.78–0.99), but substantially lower sensitivities for detecting infection: 0.64 (95% CI: 0.52–0.75) and 0.63 (95% CI: 0.49–0.75). The NS1 ELISA has a low sensitivity for both detecting antibodies 0.55 (95% CI: 0.34–0.74) and infection 0.42 (95% CI: 0.28–0.56). The estimated specificities of the N7 iIFAT and the NI assay are 0.92 (95% CI: 0.87–0.95) and 0.91 (95% CI: 0.85–0.95), and 0.82 (95% CI: 0.74–0.87) for the NS1 ELISA. Additionally, our analyses suggest a strong association between the duration of virus excretion of infected birds and the probability to develop antibodies
Validated RealTime reverse transcriptase PCR methods for the diagnosis and pathotyping of Eurasian H7 avian influenza viruses
Slomka, M.J. ; Pavlidis, T. ; Coward, V.J. ; Voermans, J. ; Koch, G. ; Hanna, A. ; Banks, J. ; Brown, I.H. - \ 2009
Influenza and Other Respiratory Viruses 3 (2009)4. - ISSN 1750-2640 - p. 151 - 164.
polymerase-chain-reaction - cleavage site - a virus - low-pathogenicity - hemagglutinin - h5 - subtypes - surveillance - replication - genes
Background Avian influenza (AI) caused by H7 AI viruses (AIVs) of both low pathogenicity (LP) and high pathogenicity (HP) are notifiable poultry diseases. Objectives Design and validate two RealTime reverse transcriptase polymerase chain reactions (RRT PCRs) for Eurasian H7 AIV detection and pathotyping. Methods The H7 RRT PCRs amplified within the (i) HA2 and (ii) cleavage site CS regions of the haemagglutinin gene. Both were validated against 65 H7 AIVs, 57 non-H7 AIVs and 259 poultry swabs in comparison to M gene (AI generic) RRT PCR and virus isolation (VI). An additional 38 swabs and 20 tissue specimens extended validation against M gene RRT PCR. Results Both H7 RRT PCRs amplified all 61 Eurasian lineage H7 AIVs and none of 57 non-H7 AIVs. A total of 297 poultry swabs were used to determine diagnostic sensitivity and specificity relative to M gene RRT PCR, sensitivity was 95 center dot 4% and 64 center dot 6% for the HA2 and CS RRT PCRs respectively, and specificity 97 center dot 9% and 99 center dot 6% respectively. The H7 HA2 RRT PCR was more sensitive than VI. This was emphasized by analysis of 37 swabs from turkeys infected experimentally with HPAI H7N1 virus sampled at 24 hours post-inoculation and LPAI H7N1 chicken infections sampled at 40-64 hours. Although less sensitive, usefulness of the H7 CS RRT PCR was confirmed by the correct molecular pathotyping for all 61 Eurasian lineage H7 AIVs tested. Conclusions The high sensitivity of H7 HA2 RRT PCR confirms its suitability for use in poultry surveillance and disease diagnosis. H7 CS RRT PCR provides an opportunity for rapid pathotyping of H7 AIVs.
Intra- and interspecies transmission of H7N7 highly pathogenic avian influenza virus during the avian influenza epidemic in the Netherlands in 2003
Jong, M.C.M. de; Stegeman, J.A. ; Goot, J.A. van der; Koch, G. - \ 2009
Revue scientifique et technique / Office International des Epizooties 28 (2009)1. - ISSN 0253-1933 - p. 333 - 340.
a virus - poultry farms - risk-factors - outbreak - quantification - performance - vaccination - infection - virulence - mice
The poultry epidemic of H7N7 highly pathogenic avian influenza (HPAI) virus in the Netherlands in 2003 was probably the result of the introduction of an H7N7 low pathogenic avian influenza (LPAI) virus (by interspecies transmission from wild birds) and the subsequent intraspecies transmission of this virus in poultry. The intraspecies transmission of the ensuing H7N7 HPAI virus was very successful both within and between flocks. Consequently, in the two poultry-dense areas that were affected, the epidemic could only be stopped by eliminating all poultry in the region. According to the spatial models these are the only areas where this was the case in the Netherlands. There was also interspecies transmission to mammals, i.e. to pigs and to humans. For pigs it was shown that possible subsequent intraspecies transmission was negligible (R0 <1). With hindsight the same was probably also true for humans
Seroprevalence of H1N1, H3N2 and H1N2 influenza viruses in pigs in seven European countries in 2002-2003
Reeth, K. ; Brown, I.H. ; Durrwald, R. ; Foni, E. ; Labarque, G. ; Lenihan, P. ; Maldonado, J. ; Markowska-Daniel, I. ; Pensaert, M. ; Pospisil, Z. ; Koch, G. - \ 2008
Influenza and Other Respiratory Viruses 2 (2008)3. - ISSN 1750-2640 - p. 99 - 105.
swine influenza - a virus - genetic reassortment - emergence - evolution - subtype
Objectives Avian-like H1N1 and human-like H3N2 swine influenza viruses (SIV) have been considered widespread among pigs in Western Europe since the 1980s, and a novel H1N2 reassortant with a human-like H1 emerged in the mid 1990s. This study, which was part of the EC-funded 'European Surveillance Network for Influenza in Pigs I', aimed to determine the seroprevalence of the H1N2 virus in different European regions and to compare the relative prevalences of each SIV between regions. Design Laboratories from Belgium, the Czech Republic, Germany, Italy, Ireland, Poland and Spain participated in an international serosurvey. A total of 4190 sow sera from 651 farms were collected in 2002-2003 and examined in haemagglutination inhibition tests against H1N1, H3N2 and H1N2. Results In Belgium, Germany, Italy and Spain seroprevalence rates to each of the three SIV subtypes were high (>= 30% of the sows seropositive) to very high (>= 50%), except for a lower H1N2 seroprevalence rate in Italy (13.8%). Most sows in these countries with high pig populations had antibodies to two or three subtypes. In Ireland, the Czech Republic and Poland, where swine farming is less intensive, H1N1 was the dominant subtype (8.0-11.7% seropositives) and H1N2 and H3N2 antibodies were rare (0-4.2% seropositives). Conclusions Thus, SIV of H1N1, H3N2 and H1N2 subtype are enzootic in swine producing regions of Western Europe. In Central Europe, SIV activity is low and the circulation of H3N2 and H1N2 remains to be confirmed. The evolution and epidemiology of SIV throughout Europe is being further monitored through a second 'European Surveillance Network for Influenza in Pigs'.