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Bonilla-Aldana DK, Calle-Hernández DM, Ulloque-Badaracco JR, Alarcón-Braga EA, Hernández-Bustamante EA, Cabrera-Guzmán JC, Quispe-Vasquez SM, Huayta-Cortez MA, Benites-Zapata VA, Rodriguez-Morales AJ. Highly pathogenic avian influenza A(H5N1) in animals: A systematic review and meta-analysis. New Microbes New Infect 2024; 60-61:101439. [PMID: 38911488 PMCID: PMC11192795 DOI: 10.1016/j.nmni.2024.101439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 05/28/2024] [Accepted: 05/30/2024] [Indexed: 06/25/2024] Open
Abstract
Introduction Avian influenza A H5N1 is a significant global public health threat. Although relevant, systematic reviews about its prevalence in animals are lacking. Methods We performed a systematic literature review in bibliographic databases to assess the prevalence of H5N1 in animals. A meta-analysis with a random-effects model was performed to calculate the pooled prevalence and 95 % confidence intervals (95%CI). In addition, measures of heterogeneity (Cochran's Q statistic and I2 test) were reported. Results The literature search yielded 1359 articles, of which 33 studies were fully valid for analysis, including 96,909 animals. The pooled prevalence for H5N1 in birds (n = 90,045, 24 studies) was 5.0 % (95%CI: 4.0-6.0 %; I2 = 99.21); in pigs (n = 3,178, 4 studies) was 1.0 % (95%CI: 0.0-1.0 %); in cats (n = 2,911, 4 studies) was 0.0 % (95%CI: 0.0-1.0 %); and in dogs (n = 479, 3 studies) was 0.0 % (95%CI: 0.0-2.0 %). Conclusions While the occurrence of H5N1 in animals might be comparatively limited compared to other influenza viruses, its impact on public health can be substantial when it transmits to humans. This virus can potentially induce severe illness and has been linked to previous outbreaks. Therefore, it is essential to closely monitor and comprehend the factors influencing the prevalence of H5N1 in both avian and human populations to develop effective disease control and prevention strategies.
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Affiliation(s)
| | | | | | | | - Enrique A. Hernández-Bustamante
- Grupo Peruano de Investigación Epidemiológica, Unidad para la Generación y Síntesis de Evidencias en Salud, Universidad San Ignacio de Loyola, Lima, Peru
- Sociedad Científica de Estudiantes de Medicina de la Universidad Nacional de Trujillo, Trujillo, Peru
| | | | | | | | | | - Alfonso J. Rodriguez-Morales
- Faculty of Health Sciences, Universidad Cientifica del Sur, Lima, Peru
- Gilbert and Rose-Marie Chagoury School of Medicine, Lebanese American University, Beirut, Lebanon
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2
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Graziosi G, Lupini C, Gobbo F, Zecchin B, Quaglia G, Pedrazzoli S, Lizzi G, Dosa G, Martini G, Terregino C, Catelli E. Genetic Diversity of Avian Influenza Viruses Detected in Waterbirds in Northeast Italy Using Two Different Sampling Strategies. Animals (Basel) 2024; 14:1018. [PMID: 38612257 PMCID: PMC11010841 DOI: 10.3390/ani14071018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/11/2024] [Accepted: 03/25/2024] [Indexed: 04/14/2024] Open
Abstract
Avian influenza viruses (AIVs), which circulate endemically in wild aquatic birds, pose a significant threat to poultry and raise concerns for their zoonotic potential. From August 2021 to April 2022, a multi-site cross-sectional study involving active AIV epidemiological monitoring was conducted in wetlands of the Emilia-Romagna region, northern Italy, adjacent to densely populated poultry areas. A total of 129 cloacal swab samples (CSs) and 407 avian faecal droppings samples (FDs) were collected, with 7 CSs (5.4%) and 4 FDs (1%) testing positive for the AIV matrix gene through rRT-PCR. A COI-barcoding protocol was applied to recognize the species of origin of AIV-positive FDs. Multiple low-pathogenic AIV subtypes were identified, and five of these were isolated, including an H5N3, an H1N1, and three H9N2 in wild ducks. Following whole-genome sequencing, phylogenetic analyses of the hereby obtained strains showed close genetic relationships with AIVs detected in countries along the Black Sea/Mediterranean migratory flyway. Notably, none of the analyzed gene segments were genetically related to HPAI H5N1 viruses of clade 2.3.4.4b isolated from Italian poultry during the concurrent 2021-2022 epidemic. Overall, the detected AIV genetic diversity emphasizes the necessity for ongoing monitoring in wild hosts using diverse sampling strategies and whole-genome sequencing.
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Affiliation(s)
- Giulia Graziosi
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano dell’Emilia, BO, Italy; (C.L.); (G.Q.); (S.P.); (G.L.); (E.C.)
| | - Caterina Lupini
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano dell’Emilia, BO, Italy; (C.L.); (G.Q.); (S.P.); (G.L.); (E.C.)
| | - Federica Gobbo
- Comparative Biomedical Sciences Division, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro, PD, Italy; (F.G.); (B.Z.); (C.T.)
| | - Bianca Zecchin
- Comparative Biomedical Sciences Division, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro, PD, Italy; (F.G.); (B.Z.); (C.T.)
| | - Giulia Quaglia
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano dell’Emilia, BO, Italy; (C.L.); (G.Q.); (S.P.); (G.L.); (E.C.)
| | - Sara Pedrazzoli
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano dell’Emilia, BO, Italy; (C.L.); (G.Q.); (S.P.); (G.L.); (E.C.)
| | - Gabriele Lizzi
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano dell’Emilia, BO, Italy; (C.L.); (G.Q.); (S.P.); (G.L.); (E.C.)
| | - Geremia Dosa
- Veterinary Services, Local Health Unit of Imola (A.U.S.L. di Imola), 40026 Imola, BO, Italy; (G.D.); (G.M.)
| | - Gabriella Martini
- Veterinary Services, Local Health Unit of Imola (A.U.S.L. di Imola), 40026 Imola, BO, Italy; (G.D.); (G.M.)
| | - Calogero Terregino
- Comparative Biomedical Sciences Division, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro, PD, Italy; (F.G.); (B.Z.); (C.T.)
| | - Elena Catelli
- Department of Veterinary Medical Sciences, University of Bologna, 40064 Ozzano dell’Emilia, BO, Italy; (C.L.); (G.Q.); (S.P.); (G.L.); (E.C.)
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3
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Birds and viruses at a crossroad--surveillance of influenza A virus in Portuguese waterfowl. PLoS One 2012; 7:e49002. [PMID: 23145046 PMCID: PMC3492218 DOI: 10.1371/journal.pone.0049002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 10/03/2012] [Indexed: 11/19/2022] Open
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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Vittecoq M, Grandhomme V, Champagnon J, Guillemain M, Crescenzo-Chaigne B, Renaud F, Thomas F, Gauthier-Clerc M, van der Werf S. High influenza a virus infection rates in Mallards bred for hunting in the Camargue, South of France. PLoS One 2012; 7:e43974. [PMID: 22952832 PMCID: PMC3428329 DOI: 10.1371/journal.pone.0043974] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 07/27/2012] [Indexed: 11/19/2022] Open
Abstract
During the last decade, the role of wildlife in emerging pathogen transmission to domestic animals has often been pointed out. Conversely, far less attention has been paid to pathogen transmission from domestic animals to wildlife. Here, we focus on the case of game restocking, which implies the release of millions of animals worldwide each year. We conducted a 2-year study in the Camargue (Southern France) to investigate the influence of hand-reared Mallard releases on avian influenza virus dynamics in surrounding wildlife. We sampled Mallards (cloacal swabs) from several game duck facilities in 2009 and 2010 before their release. A very high (99%) infection rate caused by an H10N7 strain was detected in the game bird facility we sampled in 2009. We did not detect this strain in shot ducks we sampled, neither during the 2008/2009 nor the 2009/2010 hunting seasons. In 2010 infection rates ranged from 0 to 24% in hand-reared ducks. The 2009 H10N7 strain was fully sequenced. It results from multiple reassortment events between Eurasian low pathogenic strains. Interestingly, H10N7 strains had previously caused human infections in Egypt and Australia. The H10 and N7 segments we sequenced were clearly distinct from the Australian ones but they belonged to the same large cluster as the Egyptian ones. We did not observe any mutation linked to increased virulence, transmission to mammals, or antiviral resistance in the H10N7 strain we identified. Our results indicate that the potential role of hand-reared Mallards in influenza virus epizootics must be taken into account given the likely risk of viral exchange between game bird facilities and wild habitats, owing to duck rearing conditions. Measures implemented to limit transmission from wildlife to domestic animals as well as measures to control transmission from domestic animals to wild ones need to be equally reinforced.
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Avian influenza viruses in wild birds at the Jeziorsko reservoir in Poland in 2008-2010. Pol J Vet Sci 2012; 15:323-8. [PMID: 22844711 DOI: 10.2478/v10181-011-0150-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
During a 3-year surveillance study for avian influenza virus (AIV) infections at the Jeziorsko reservoir in central Poland, 549 oropharyngeal or cloacal swabs from 366 birds of 14 species belonging to 3 orders (Anseriformes, Charadriiformes and Gruiformes) were tested. AIV was detected in 14 birds (3.8%): Common Teals (12x), Mallard (1x) and Garganey (1x). Three potentially dangerous H5 AIV were detected in Common Teals (2x) and Garganey (1x) but all of them revealed a low pathogenic pathotype. A unique cleavage site amino acid motif PQREIR*GLF was found in one H5 isolate from a Garganey.
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Study of influenza A virus in wild boars living in a major duck wintering site. INFECTION GENETICS AND EVOLUTION 2011; 12:483-6. [PMID: 22197763 DOI: 10.1016/j.meegid.2011.12.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 12/06/2011] [Accepted: 12/08/2011] [Indexed: 02/08/2023]
Abstract
Wild birds, which are reservoirs of influenza viruses, are believed to be the original source of new influenza viruses-including highly pathogenic ones-that can be transmitted to domestic animals as well as humans and represent a potential epizootic and/or pandemic threat. Despite increasing knowledge on influenza A virus dynamics in wild birds, the viral circulation in wild boars remains largely unknown. This is of particular interest since pigs can be infected with both human and avian viruses; upon co-infection, they can act as a mixing vessel through reassortment, a mechanism that resulted in the emergence of the pandemic H1N1 virus in 2009. The Camargue (Southern France) appears as an ideal study area to investigate inter-species transmission of influenza A viruses from wild birds and possibly humans to wild boars. Indeed, the important local wild boar population shares wetland use with humans and the largest concentration of wintering ducks in France, that are both susceptible to infection by influenza A viruses. Additionally, wild boars occasionally prey on ducks. We conducted a virological and serological survey on wild boars in the Camargue (Southern France) between September 2009 and November 2010. No influenza A virus was detected in the collected nasal swabs (n=315) and no influenza specific antibodies were observed in the serological samples (n=20). As the study was mainly focused on viral excretion, which is limited in time, we cannot exclude that low or occasional influenza A virus circulation took place during the study period. Although, wild boars did not seem to be a key element in the dynamics of influenza A virus circulation in the Camargue, wild boar influenza A virus infections should be more widely studied to determine if the pattern observed here represents the normal situation or an exceptional one.
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Hammouda A, Pearce-Duvet J, Chokri MA, Arnal A, Gauthier-Clerc M, Boulinier T, Selmi S. Prevalence of influenza A antibodies in yellow-legged gull (Larus michahellis) eggs and adults in southern Tunisia. Vector Borne Zoonotic Dis 2011; 11:1583-90. [PMID: 21919723 DOI: 10.1089/vbz.2011.0639] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Investigating the prevalence of anti-influenza A viruses (AIV) antibodies in wild birds can provide important information for the understanding of bird exposure to AIV, as well as for prevention purposes. We investigated AIV exposure in nature by measuring the prevalence of anti-AIV antibodies in the nests and adults of an abundant and anthropophilic waterbird species common around the Mediterranean sea, the yellow-legged gull (Larus michahellis). Sampling took place in two colonies located in the gulf of Gabès in southern Tunisia: Sfax and Djerba. Antibodies were detected in the two sites, with higher prevalence in adults, eggs, and nests at Sfax than Djerba. Across both colonies, clutches that were laid later in the season, and, thus, more likely by younger parents, showed lower prevalence. Using patch occupancy modeling applied to egg clutches, we found that it is unnecessary to sample all the eggs in a given nest; nest status (antibody positive or negative) can be reliably estimated from a single egg. Differences in the density of birds, notably Larids, between the two sites may explain the observed differences in prevalence. The higher concentration of Larids in the Sfax colony could favor the transmission of AIV to yellow-legged gulls. This study highlights the importance of further developing ecological-based approaches to the factors determining the circulation of infectious agents in species such as the yellow-legged gull, which exist at the interface between diverse biological communities and human activities.
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Affiliation(s)
- Abdessalem Hammouda
- Département des Sciences de la Vie, Faculté des Sciences de Gabès, Gabès, Tunisia.
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8
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Feare CJ. Role of wild birds in the spread of highly pathogenic avian influenza virus H5N1 and implications for global surveillance. Avian Dis 2010; 54:201-12. [PMID: 20521633 DOI: 10.1637/8766-033109-resnote.1] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This paper reviews outbreaks of Asian-lineage highly pathogenic avian influenza virus (HPAIV) H5N1 in wild birds since June 2006, surveillance strategies, and research on virus epidemiology in wild birds to summarize advances in understanding the role of wild birds in the spread of HPAIV H5N1 and the risk that infected wild birds pose for the poultry industry and for public health. Surveillance of apparently healthy wild birds ("active" surveillance) has not provided early warning of likely infection for the poultry industry, whereas searches for and reports of dead birds ("passive" surveillance) have provided evidence of environmental presence of the virus, but not necessarily its source. Most outbreaks in wild birds have occurred during periods when they are experiencing environmental, physiologic, and possibly psychological stress, including adverse winter weather and molt, but not, apparently, long-distance migration. Examination of carcasses of infected birds and experimental challenge with strains of HPAIV H5N1 have provided insight into the course of infection, the extent of virus shedding, and the relative importance of cloacal vs. oropharyngeal excretion. Satellite telemetry of migrating birds is now providing data on the routes taken by individual birds, their speed of migration, and the duration of stopovers. It is still not clear how virus shedding during the apparently clinically silent phase of infection relates to the distance travelled by infected birds. Mounting an immune response and undertaking strenuous exercise associated with long migratory flights may be competitive. This is an area where further research should be directed in order to discover whether wild birds infected with HPAIV H5N1 are able or willing to embark on migration.
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Affiliation(s)
- Chris J Feare
- WildWings Bird Management, 2 North View Cottages, Grayswood Common, Haslemere, Surrey GU27 2DN, United Kingdom.
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Lebarbenchon C, Chang CM, Grandhomme V, Dietrich M, Kayser Y, Elguero E, Renaud F, Thomas F, van der Werf S, Gauthier-Clerc M. Avian influenza circulation in the Camargue (south of France) during the 2006-07 season. Avian Dis 2010; 54:446-9. [PMID: 20521676 DOI: 10.1637/8665-022509-resnote.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Situated at the crossroads of numerous migratory routes of Palaearctic birds, the Camargue is considered a high-risk area for the introduction and transmission of numerous avian-borne pathogens. We investigated the epidemiologic cycles of avian influenza viruses (AIVs) in the local bird community by performing regular sampling on a large variety of bird species during 11 consecutive months in 2006-07. To detect the presence of AIV, SYBR green reverse transcriptase-PCR targeting the M gene was performed on 2901 samples from 66 bird species. A clear seasonal pattern of AIV circulation in ducks was observed during autumn and winter, with higher prevalence rates in early fall. Our results also support an absence of circulation of AIV in passerine birds during spring and the wintering periods. Finally, even if the prevalence of infection was very low, AIVs were found in gulls in breeding colonies, indicating a possible specific circulation in spring in these birds.
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Lebarbenchon C, Albespy F, Brochet AL, Grandhomme V, Renaud F, Fritz H, Green AJ, Thomas F, van der Werf S, Aubry P, Guillemain M, Gauthier-Clerc M. Spread of avian influenza viruses by common teal (Anas crecca) in Europe. PLoS One 2009; 4:e7289. [PMID: 19802387 PMCID: PMC2750755 DOI: 10.1371/journal.pone.0007289] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 09/10/2009] [Indexed: 11/18/2022] Open
Abstract
Since the recent spread of highly pathogenic (HP) H5N1 subtypes, avian influenza virus (AIV) dispersal has become an increasing focus of research. As for any other bird-borne pathogen, dispersal of these viruses is related to local and migratory movements of their hosts. In this study, we investigated potential AIV spread by Common Teal (Anas crecca) from the Camargue area, in the South of France, across Europe. Based on bird-ring recoveries, local duck population sizes and prevalence of infection with these viruses, we built an individual-based spatially explicit model describing bird movements, both locally (between wintering areas) and at the flyway scale. We investigated the effects of viral excretion duration and inactivation rate in water by simulating AIV spread with varying values for these two parameters. The results indicate that an efficient AIV dispersal in space is possible only for excretion durations longer than 7 days. Virus inactivation rate in the environment appears as a key parameter in the model because it allows local persistence of AIV over several months, the interval between two migratory periods. Virus persistence in water thus represents an important component of contamination risk as ducks migrate along their flyway. Based on the present modelling exercise, we also argue that HP H5N1 AIV is unlikely to be efficiently spread by Common Teal dispersal only.
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Brochet AL, Guillemain M, Lebarbenchon C, Simon G, Fritz H, Green AJ, Renaud F, Thomas F, Gauthier-Clerc M. The potential distance of highly pathogenic avian influenza virus dispersal by mallard, common teal and Eurasian pochard. ECOHEALTH 2009; 6:449-57. [PMID: 20112048 DOI: 10.1007/s10393-010-0275-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 11/30/2009] [Accepted: 11/30/2009] [Indexed: 05/04/2023]
Abstract
Waterbirds represent the major natural reservoir for low pathogenic (LP) avian influenza viruses (AIV). Among the wide diversity of subtypes that have been described, two of them (H5 and H7) may become highly pathogenic (HP) after their introduction into domestic bird populations and cause severe outbreaks, as is the case for HP H5N1 in South-Eastern Asia. Recent experimental studies demonstrated that HP H5N1 AIV infection in ducks does not necessarily have significant pathological effects. These results suggest that wild migratory ducks may asymptomatically carry HP AIV and potentially spread viruses over large geographical distances. In this study, we investigated the potential spreading distance of HP AIV by common teal (Anas crecca), mallard (A. platyrhynchos), and Eurasian pochard (Aythya ferina). Based on capture-mark-recapture method, we characterized their wintering movements from a western Mediterranean wetland (Camargue, South of France) and identified the potential distance and direction of virus dispersal. Such data may be crucial in determining higher-risk areas in the case of HP AIV infection detection in this major wintering quarter, and may serve as a valuable reference for virus outbreaks elsewhere.
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Affiliation(s)
- Anne-Laure Brochet
- Centre de Recherche de La Tour du Valat, Le Sambuc, 13200, Arles, France.
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Zohari S, Gyarmati P, Ejdersund A, Berglöf U, Thorén P, Ehrenberg M, Czifra G, Belák S, Waldenström J, Olsen B, Berg M. Phylogenetic analysis of the non-structural (NS) gene of influenza A viruses isolated from mallards in Northern Europe in 2005. Virol J 2008; 5:147. [PMID: 19077274 PMCID: PMC2625346 DOI: 10.1186/1743-422x-5-147] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Accepted: 12/12/2008] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Although the important role of the non-structural 1 (NS) gene of influenza A in virulence of the virus is well established, our knowledge about the extent of variation in the NS gene pool of influenza A viruses in their natural reservoirs in Europe is incomplete. In this study we determined the subtypes and prevalence of influenza A viruses present in mallards in Northern Europe and further analysed the NS gene of these isolates in order to obtain a more detailed knowledge about the genetic variation of NS gene of influenza A virus in their natural hosts. RESULTS A total number of 45 influenza A viruses of different subtypes were studied. Eleven haemagglutinin- and nine neuraminidase subtypes in twelve combinations were found among the isolated viruses. Each NS gene reported here consisted of 890 nucleotides; there were no deletions or insertions. Phylogenetic analysis clearly shows that two distinct gene pools, corresponding to both NS allele A and B, were present at the same time in the same geographic location in the mallard populations in Northern Europe. A comparison of nucleotide sequences of isolated viruses revealed a substantial number of silent mutations, which results in high degree of homology in amino acid sequences. The degree of variation within the alleles is very low. In our study allele A viruses displays a maximum of 5% amino acid divergence while allele B viruses display only 2% amino acid divergence. All the viruses isolated from mallards in Northern Europe possessed the typical avian ESEV amino acid sequence at the C-terminal end of the NS1 protein. CONCLUSION Our finding indicates the existence of a large reservoir of different influenza A viruses in mallards population in Northern Europe. Although our phylogenetic analysis clearly shows that two distinct gene pools, corresponding to both NS allele A and B, were present in the mallards populations in Northern Europe, allele B viruses appear to be less common in natural host species than allele A, comprising only about 13% of the isolates sequenced in this study.
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Affiliation(s)
- Siamak Zohari
- Joint Research and Development Unit for Virology, Immunobiology, and Parasitology, of the National Veterinary Institute (SVA) and Swedish University of Agricultural Sciences (SLU), and Department of Biomedical Sciences and Public Health, Section of Parasitology and Virology, SLU, Ulls väg 2B, SE-751 89 Uppsala, Sweden
| | - Péter Gyarmati
- Joint Research and Development Unit for Virology, Immunobiology, and Parasitology, of the National Veterinary Institute (SVA) and Swedish University of Agricultural Sciences (SLU), and Department of Biomedical Sciences and Public Health, Section of Parasitology and Virology, SLU, Ulls väg 2B, SE-751 89 Uppsala, Sweden
| | - Anneli Ejdersund
- Unit for Virology, Immunobiology, and Parasitology, SVA, Ulls väg 2B, SE-751 89 Uppsala, Sweden
| | - Ulla Berglöf
- Unit for Virology, Immunobiology, and Parasitology, SVA, Ulls väg 2B, SE-751 89 Uppsala, Sweden
| | - Peter Thorén
- Unit for Virology, Immunobiology, and Parasitology, SVA, Ulls väg 2B, SE-751 89 Uppsala, Sweden
| | - Maria Ehrenberg
- Unit for chemistry, environment and feed safety of National Veterinary Institute (SVA) Ulls väg 2B, SE 751 89 Uppsala, Sweden
| | - György Czifra
- Unit for Virology, Immunobiology, and Parasitology, SVA, Ulls väg 2B, SE-751 89 Uppsala, Sweden
| | - Sándor Belák
- Joint Research and Development Unit for Virology, Immunobiology, and Parasitology, of the National Veterinary Institute (SVA) and Swedish University of Agricultural Sciences (SLU), and Department of Biomedical Sciences and Public Health, Section of Parasitology and Virology, SLU, Ulls väg 2B, SE-751 89 Uppsala, Sweden
| | - Jonas Waldenström
- Department of Medical Sciences, Section of Infectious Diseases, Uppsala University Hospital, SE 751 85 Uppsala, Sweden
- Section for Zoonotic Ecology and Epidemiology, Kalmar University, SE-321 85 Kalmar, Sweden
| | - Björn Olsen
- Department of Medical Sciences, Section of Infectious Diseases, Uppsala University Hospital, SE 751 85 Uppsala, Sweden
- Section for Zoonotic Ecology and Epidemiology, Kalmar University, SE-321 85 Kalmar, Sweden
| | - Mikael Berg
- Joint Research and Development Unit for Virology, Immunobiology, and Parasitology, of the National Veterinary Institute (SVA) and Swedish University of Agricultural Sciences (SLU), and Department of Biomedical Sciences and Public Health, Section of Parasitology and Virology, SLU, Ulls väg 2B, SE-751 89 Uppsala, Sweden
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