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- Nordling, D, et al.
(author)
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Reproductive effort reduces specific immune response and parasite resistance
- 1998
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In: PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES. - : ROYAL SOC LONDON. - 0962-8452. ; 265:1403, s. 1291-1298
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Journal article (other academic/artistic)abstract
- If a trade-off exists between reproductive effort and immune function, life-history decisions may have important implications for parasite resistance. Here, we report effects of experimental manipulation of reproductive effort on subsequent specific immun
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| 4. |
- Osbjer, Kristina, et al.
(author)
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Influenza A Virus in Backyard Pigs and Poultry in Rural Cambodia
- 2017
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In: Transboundary and Emerging Diseases. - : WILEY. - 1865-1674 .- 1865-1682. ; 64:5, s. 1557-1568
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Journal article (peer-reviewed)abstract
- Surveillance of influenza virus in humans and livestock is critical, given the worldwide public health threats and livestock production losses. Livestock farming involving close proximity between humans, pigs and poultry is often practised by smallholders in low-income countries and is considered an important driver of influenza virus evolution. This study determined the prevalence and genetic characteristics of influenza A virus (IAV) in backyard pigs and poultry in Cambodia. A total of 751 animals were tested by matrix gene-based rRT-PCR, and influenza virus was detected in 1.5% of sampled pigs, 1.4% of chickens and 1.0% of ducks, but not in pigeons. Full-length genome sequencing confirmed triple reassortant H3N2 in all IAV-positive pigs and various low pathogenic avian influenza subtypes in poultry. Phylogenetic analysis of the swine influenza viruses revealed that these had haemagglutinin and neuraminidase genes originating from human H3N2 viruses previously isolated in South-East Asia. Phylogenetic analysis also revealed that several of the avian influenza subtypes detected were closely related to internal viral genes from highly pathogenic H5N1 and H9N2 formerly sequenced in the region. High sequence homology was likewise found with influenza A viruses circulating in pigs, poultry and wild birds in China and Vietnam, suggesting transboundary introduction and cocirculation of the various influenza subtypes. In conclusion, highly pathogenic subtypes of influenza virus seem rare in backyard poultry, but virus reassortment, involving potentially zoonotic and pandemic subtypes, appears to occur frequently in smallholder pigs and poultry. Increased targeted surveillance and monitoring of influenza circulation on smallholdings would further improve understanding of the transmission dynamics and evolution of influenza viruses in humans, pigs and poultry in the Mekong subregion and could contribute to limit the influenza burden.
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- Zohari, Siamak, et al.
(author)
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Phylogenetic analysis of the non-structural (NS) gene of influenza A viruses isolated from mallards in Northern Europe in 2005
- 2008
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In: Virology Journal. - 1743-422X. ; 5:Article ID: 147
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Journal article (peer-reviewed)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 NSI 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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- Zohari, Siamak, et al.
(author)
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Serologic and virologic screening of paramyxovirus type 1 and avian influenza virus (H5∓mp;H7) in wild migratory birds in Sweden (preliminary study)
- 2001
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In: Proceedings of the joint seventh annual meetings of the national Newcastle disease and avian influenza laboratories of countries of the European Union.
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Conference paper (peer-reviewed)abstract
- Following outbreaks of Newcastle disease in 1995 and 1997 in Sweden, and anoutbreak of highly pathogenic avian influenza (HPAI) in Northern Italy during thewinter of 1999/2000 a study was initiated to evaluate the presence of paramyxovirustype 1 (PMV-1) and avian influenza viruses (H5&H7) (AIV) in the wild avifauna inSweden.Materials and MethodsThe study was performed during the spring of 2000. In total, 150 serum samples and120 cloacal swabs were obtained from 53 migrating bird species (orders Anseriformes,Charadriiformes, Columbiformes, Strigiformes, Piciformes and Passerinformes) (Table1) at Ottenby Bird Station on southern Öland (an island in the Baltic off the south-eastcoast of Sweden). The swabs were obtained from the same, but not all, individual birdsas the serum samples. The bird species were selected based on their winter habitat, inorder to sample migratory birds which were likely to have either spent the previouswinter in Italy or visited Italy while migrating northwards. Additionally, cloacal swabsfrom Anseriformes in southern Sweden will be analysed during the spring of 2001.The serum samples were tested by hemagglutination-inhibition test for the presence ofantibodies to AIV, and by a blocking ELISA (SVANOVIR Svanova Biotech,Uppsala, Sweden) for antibodies to PMV-1. All cloacal swabs were cultured accordingto Council directive 92/66/EEC and 92/40/EEC. Following each of the three passagesthe allantoic fluid was tested for hemagglutinating (HA) virus.ResultsOne serum sample from a Ringed Plover (Charadrius hiaticula) showed a low titer(1:16) against AIV (H5). None of the serum samples were positive for PMV-1, howeverthree Ringed Plovers showed PI-values of 40%. No cloacal swabs were available fromthese four birds. No viruses were isolated from any of the cloacal swabs.
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