| 1. |
- Wille, Michelle, et al.
(författare)
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Evaluation of seabirds in Newfoundland and Labrador, Canada, as hosts of influenza A viruses.
- 2014
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Ingår i: Journal of Wildlife Diseases. - : Wildlife Disease Association. - 0090-3558 .- 1943-3700. ; 50:1, s. 98-103
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Tidskriftsartikel (refereegranskat)abstract
- Influenza A viruses infect a wide range of hosts, including many species of birds. Avian influenza A virus (AIV) infection appears to be most common in Anseriformes (ducks, geese, and swans) and some Charadriiformes (shorebirds and gulls), but many other birds also serve as hosts of AIV. Here, we evaluated the role of seabirds as hosts for AIV. We tested 3,160 swab samples from 13 seabird species between May 2008 and December 2011 in Newfoundland and Labrador, Canada. We also tested 156 serum samples for evidence of previous infection of AIV in Common Murres (Uria aalge) and Atlantic Puffins (Fratercula arctica). Avian influenza A virus was detected in breeding Common Murres and nonbreeding Thick-billed Murres (Uria lomvia), and Common Murres also had high antibody prevalence (44%). From these findings, combined with other studies showing AIV infection in murres, we conclude that murres are important for the ecology of AIV. For other species (Razorbill, Alca torda; Leach's Storm-Petrel, Oceanodroma leucorhoa; Black-legged Kittiwake, Rissa tridactyla; Atlantic Puffin) with good coverage (>100 samples) we did not detect AIV. However, serology indicates infection does occur in Atlantic Puffins, with 22% antibody prevalence found. The possibility of virus spread through dense breeding colonies and the long distance movements of these hosts make a more thorough evaluation of the role for seabirds as hosts of AIV important.
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| 2. |
- Huang, Yanyan, et al.
(författare)
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A 4-year study of avian influenza virus prevalence and subtype diversity in ducks of Newfoundland, Canada.
- 2013
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Ingår i: Canadian journal of microbiology (Print). - : Canadian Science Publishing. - 0008-4166 .- 1480-3275. ; 59:10, s. 701-708
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Tidskriftsartikel (refereegranskat)abstract
- The island of Newfoundland, Canada, is at the eastern edge of North America and has migratory bird connections with the continental mainland as well as across the North Atlantic Ocean. Here, we report a 4-year avian influenza virus (AIV) epidemiological study in ducks in the St. John's region of Newfoundland. The overall prevalence of AIV detection in ducks during this study was 7.2%, with American Black Ducks contributing the vast majority of the collected samples and the AIV positives. The juvenile ducks showed a significantly higher AIV detection rate (10.6%) compared with adults (3.4%). Seasonally, AIV prevalence rates were higher in the autumn (8.4%), but positives were still detected in the winter (4.6%). Preliminary serology tests showed a high incidence of previous AIV infection (20/38, 52.6%). A total of 43 viruses were characterized for their HA-NA or HA subtypes, which revealed a large diversity of AIV subtypes and little recurrence of subtypes from year to year. Investigation of the movement patterns of ducks in this region showed that it is a largely non-migratory duck population, which may contribute to the observed pattern of high AIV subtype turnover. Phylogenetic analysis of 4 H1N1 and one H5N4 AIVs showed these viruses were highly similar to other low pathogenic AIV sequences from waterfowl in North America and assigned all gene segments into American-avian clades. Notably, the H1N1 viruses, which were identified in consecutive years, possessed homologous genomes. Such detection of homologous AIV genomes across years is rare, but indicates the role of the environmental reservoir in viral perpetuation.
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| 3. |
- Huang, Yanyan, et al.
(författare)
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Genetic structure of avian influenza viruses from ducks of the Atlantic flyway of North America.
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Wild birds, including waterfowl such as ducks, are reservoir hosts of influenza A viruses. Despite the increased number of avian influenza virus (AIV) genome sequences available, our understanding of AIV genetic structure and transmission through space and time in waterfowl in North America is still limited. In particular, AIVs in ducks of the Atlantic flyway of North America have not been thoroughly investigated. To begin to address this gap, we analyzed 109 AIV genome sequences from ducks in the Atlantic flyway to determine their genetic structure and to document the extent of gene flow in the context of sequences from other locations and other avian and mammalian host groups. The analyses included 25 AIVs from ducks from Newfoundland, Canada, from 2008-2011 and 84 available reference duck AIVs from the Atlantic flyway from 2006-2011. A vast diversity of viral genes and genomes was identified in the 109 viruses. The genetic structure differed amongst the 8 viral segments with predominant single lineages found for the PB2, PB1 and M segments, increased diversity found for the PA, NP and NS segments (2, 3 and 3 lineages, respectively), and the highest diversity found for the HA and NA segments (12 and 9 lineages, respectively). Identification of inter-hemispheric transmissions was rare with only 2% of the genes of Eurasian origin. Virus transmission between ducks and other bird groups was investigated, with 57.3% of the genes having highly similar (≥99% nucleotide identity) genes detected in birds other than ducks. Transmission between North American flyways has been frequent and 75.8% of the genes were highly similar to genes found in other North American flyways. However, the duck AIV genes did display spatial distribution bias, which was demonstrated by the different population sizes of specific viral genes in one or two neighbouring flyways compared to more distant flyways.
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| 4. |
- Huang, Yanyan, et al.
(författare)
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Perpetuation and reassortment of gull influenza A viruses in Atlantic North America
- 2014
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Ingår i: Virology. - : Elsevier BV. - 0042-6822 .- 1096-0341. ; 456-457, s. 353-363
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Tidskriftsartikel (refereegranskat)abstract
- Gulls are important hosts of avian influenza A viruses (AIVs) and gull AIVs often contain gene segments of mixed geographic and host lineage origins. In this study, the prevalence of AIV in gulls of Newfoundland, Canada from 2008 to 2011 was analyzed. Overall prevalence was low (30/1645, 1.8%) but there was a distinct peak of infection in the fall. AIV seroprevalence was high in Newfoundland gulls, with 50% of sampled gulls showing evidence of previous infection. Sequences of 16 gull AIVs were determined and analyzed to shed light on the transmission, reassortment and persistence dynamics of gull AIVs in Atlantic North America. Intercontinental and waterfowl lineage reassortment was prevalent. Of particular note were a wholly Eurasian AIV and another with an intercontinental reassortant waterfowl lineage virus. These patterns of geographic and inter-host group transmission highlight the importance of characterization of gull AIVs as part of attempts to understand global AIV dynamics.
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| 5. |
- Latorre-Margalef, Neus, et al.
(författare)
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Long-term variation in influenza A virus prevalence and subtype diversity in migratory mallards in northern Europe.
- 2014
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 281:1781, s. 20140098-
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Tidskriftsartikel (refereegranskat)abstract
- Data on long-term circulation of pathogens in wildlife populations are seldom collected, and hence understanding of spatial-temporal variation in prevalence and genotypes is limited. Here, we analysed a long-term surveillance series on influenza A virus (IAV) in mallards collected at an important migratory stopover site from 2002 to 2010, and characterized seasonal dynamics in virus prevalence and subtype diversity. Prevalence dynamics were influenced by year, but retained a common pattern for all years whereby prevalence was low in spring and summer, but increased in early autumn with a first peak in August, and a second more pronounced peak during October-November. A total of 74 haemagglutinin (HA)/neuraminidase (NA) combinations were isolated, including all NA and most HA (H1-H12) subtypes. The most common subtype combinations were H4N6, H1N1, H2N3, H5N2, H6N2 and H11N9, and showed a clear linkage between specific HA and NA subtypes. Furthermore, there was a temporal structuring of subtypes within seasons based on HA phylogenetic relatedness. Dissimilar HA subtypes tended to have different temporal occurrence within seasons, where the subtypes that dominated in early autumn were rare in late autumn, and vice versa. This suggests that build-up of herd immunity affected IAV dynamics in this system.
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| 6. |
- Tolf, Conny, et al.
(författare)
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Birds and viruses at a crossroad : surveillance of influenza a virus in portuguese waterfowl
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:11
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Tidskriftsartikel (refereegranskat)abstract
- During recent years, extensive amounts of data have become available regarding influenza A virus (IAV) in wild birds in northern Europe, while information from southern Europe is more limited. Here, we present an IAV surveillance study conducted in western Portugal 2008-2009, analyzing 1653 samples from six different species of waterfowl, with the majority of samples taken from Mallards (Anas platyrhynchos). Overall 4.4% of sampled birds were infected. The sampling results revealed a significant temporal variation in the IAV prevalence, including a pronounced peak among predominantly young birds in June, indicating that IAV circulate within breeding populations in the wetlands of western Portugal. The H10N7 and H9N2 subtypes were predominant among isolated viruses. Phylogenetic analyses of the hemagglutinin and neuraminidase sequences of H10N7, H9N2 and H11N3 virus showed that sequences from Portugal were closely related to viral sequences from Central Europe as well as to IAVs isolated in the southern parts of Africa, reflecting Portugal's position on the European-African bird migratory flyway. This study highlights the importance of Portugal as a migratory crossroad for IAV, connecting breeding stationary waterfowl with birds migrating between continents which enable transmission and spread of IAV.
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| 7. |
- Tolf, Conny, et al.
(författare)
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Individual variation in influenza A virus infection histories and long-term immune responses in mallards
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:4, s. e61201-
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Tidskriftsartikel (refereegranskat)abstract
- Wild dabbling ducks (genus Anas) are the main reservoir for influenza A virus (IAV) in the Northern Hemisphere. Current understanding of disease dynamics and epidemiology in this virus-host system has primarily been based on populationlevel ,surveillance studies and infection experiments conducted in laboratory settings. Using a combined experimentalnatural approach with wild-strain captive mallards (Anas platyrhynchos), we monitored individual IAV infection histories and immunological responses of 10 birds over the course of 15 months. This is the first detailed study to track natural IAV infection histories over several seasons amongst the same individuals growing from juvenile to adults. The general trends in the infection histories of the monitored birds reflected seasonal variation in prevalence at the population level. However, within the study group there were significant differences between individuals in infection frequency as well as in short and long term anti-IAV antibody response. Further observations included individual variation in the number of infecting virus subtypes, and a strong tendency for long-lasting hemagglutinin-related homosubtypic immunity. Specifically, all infections in the second autumn, except one, were of different subtypes compared to the first autumn. The variation among birds concerning these epidemiologically important traits illustrates the necessity for IAV studies to move from the level of populations to examine individuals in order to further our understanding of IAV disease and epidemiology.
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| 8. |
- Tolf, Conny, et al.
(författare)
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Individual variation in influenza a virus infection histories and long-term immune responses in mallards
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:4, s. e61201-
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Tidskriftsartikel (refereegranskat)abstract
- Wild dabbling ducks (genus Anas) are the main reservoir for influenza A virus (IAV) in the Northern Hemisphere. Current understanding of disease dynamics and epidemiology in this virus-host system has primarily been based on population-level surveillance studies and infection experiments conducted in laboratory settings. Using a combined experimental-natural approach with wild-strain captive mallards (Anas platyrhynchos), we monitored individual IAV infection histories and immunological responses of 10 birds over the course of 15 months. This is the first detailed study to track natural IAV infection histories over several seasons amongst the same individuals growing from juvenile to adults. The general trends in the infection histories of the monitored birds reflected seasonal variation in prevalence at the population level. However, within the study group there were significant differences between individuals in infection frequency as well as in short and long term anti-IAV antibody response. Further observations included individual variation in the number of infecting virus subtypes, and a strong tendency for long-lasting hemagglutinin-related homosubtypic immunity. Specifically, all infections in the second autumn, except one, were of different subtypes compared to the first autumn. The variation among birds concerning these epidemiologically important traits illustrates the necessity for IAV studies to move from the level of populations to examine individuals in order to further our understanding of IAV disease and epidemiology.
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| 9. |
- Tolf, Conny, et al.
(författare)
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Prevalence of avian paramyxovirus type 1 in Mallards during autumn migration in the western Baltic Sea region
- 2013
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Ingår i: Virology Journal. - 1743-422X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Newcastle disease virus (NDV) is the causative agent of the Newcastle disease, a severe disease in birds associated with substantial economic losses to the poultry industry worldwide. Sweden is situated along the Western European waterfowl flyway and applies a non-vaccination policy combined with directives of immediate euthanisation of NDV infected flocks. During the last decades there have been several outbreaks with NDV in poultry in Sweden. However, less is known about the virus prevalence in the wild bird population including waterfowl, a well-established reservoir of avian paramyxovirus type 1 (APMV-1), the paramyxovirus serotype that include pathogenic NDV. Methods: The survey constituted of 2332 samples from Mallards (Anas platyrhynchos), trapped in the southern part of Sweden during autumn migration in 2010. These samples were screened for APMV-1 by real-time reverse transcription PCR, and viral strains from positive samples were isolated and characterized by sequence analysis of the fusion gene and by phylogenetic analysis. Conclusions: Twenty of these samples were positive for APMV-1, hence a virus prevalence of 0.9% (95% Confidence Interval [95% CI]=0.54%, 1.35%). The highest APMV-1 prevalence was detected in juvenile Mallards sampled in November (n=887, prevalence 1.24% ([95% CI])=0.67%, 2.24%). Sequence analysis and evaluation of phylogenetic relatedness indicated that isolated APMV-1 strains were lentogenic, and phylogenetically most closely related to genotype Ib strains within the clade of class II viruses. The sampling system employed enabled us to follow APMV-1 infections and the shedding of one particular viral strain in one individual bird over several days. Furthermore, combining previous screening results with the APMV-1 detections in this study showed that more than 50% of Mallards that tested positive for APMV-1 RNA were co-infected with influenza A virus.
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| 10. |
- Wille, Michelle, et al.
(författare)
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Frequency and patterns of reassortment in natural influenza A virus infection in a reservoir host
- 2013
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Ingår i: Virology. - : Elsevier BV. - 0042-6822 .- 1096-0341. ; 443:1, s. 150-160
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Tidskriftsartikel (refereegranskat)abstract
- Influenza A viruses (IAV) can dramatically alter both genotype and phenotype at a rapid rate as a product of co-infection and reassortment Avian IAV exhibit high levels of phylogenetic incongruence, suggesting high levels of reassortment in the virus reservoir. Using a natural-experimental system, we reconstructed relationships amongst 92 viruses across 15 subtypes from 10 Mallards in an autumn season. Phylogenetic analyses estimated that 56% of the isolated viruses were reassorted. Network analysis demonstrated different patterns of reassortment and limited exchange of segments between primary and secondary infections. No clear patterns of linkage between segments were found, and patterns within a season were likely the consequence of continued introduction of new constellations, high viral load and diversity in the wild bird reservoir, and co-infections. This is the first IAV study to implement multiple tools available for elucidating factors governing reassortment patterns in naturally infected Mallards.
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| 11. |
- Wille, Michelle, et al.
(författare)
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Infected or not : are PCR-positive oropharyngeal swabs indicative of low pathogenic influenza A virus infection in the respiratory tract of Mallard Anas platyrhynchos?
- 2014
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Ingår i: Veterinary research (Print). - : Springer Science and Business Media LLC. - 0928-4249 .- 1297-9716. ; 45, s. Article ID: 53-
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Tidskriftsartikel (refereegranskat)abstract
- Detection of influenza virus in oropharyngeal swabs collected during wild bird surveillance is assumed to representrespiratory infection, although intestine is the main site of infection. We tested this assumption by histologicalexamination of the respiratory tract of wild Mallards with virus-positive oropharyngeal swabs. Thirty-two of 125Mallards tested had viral-RNA positive oropharyngeal swabs. The respiratory tracts of four Mallards with the mostvirus were examined in detail by immunohistochemistry. None had detectable virus antigen in the respiratory tract,suggesting it was not infected. An alternative explanation is that the oropharynx was contaminated with virusthrough feeding in surface water or through preening.
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