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Influenza A H5N1 Immigration Is Filtered Out at Some International Borders

BACKGROUND: Geographic spread of highly pathogenic influenza A H5N1, the bird flu strain, appears a necessary condition for accelerating the evolution of a related human-to-human infection. As H5N1 spreads the virus diversifies in response to the variety of socioecological environments encountered,...

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Autores principales: Wallace, Robert G., Fitch, Walter M.
Formato: Texto
Lenguaje:English
Publicado: Public Library of Science 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2244808/
https://www.ncbi.nlm.nih.gov/pubmed/18301773
http://dx.doi.org/10.1371/journal.pone.0001697
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author Wallace, Robert G.
Fitch, Walter M.
author_facet Wallace, Robert G.
Fitch, Walter M.
author_sort Wallace, Robert G.
collection PubMed
description BACKGROUND: Geographic spread of highly pathogenic influenza A H5N1, the bird flu strain, appears a necessary condition for accelerating the evolution of a related human-to-human infection. As H5N1 spreads the virus diversifies in response to the variety of socioecological environments encountered, increasing the chance a human infection emerges. Genetic phylogenies have for the most part provided only qualitative evidence that localities differ in H5N1 diversity. For the first time H5N1 variation is quantified across geographic space. METHODOLOGY AND PRINCIPAL FINDINGS: We constructed a statistical phylogeography of 481 H5N1 hemagglutinin genetic sequences from samples collected across 28 Eurasian and African localities through 2006. The MigraPhyla protocol showed southern China was a source of multiple H5N1 strains. Nested clade analysis indicated H5N1 was widely dispersed across southern China by both limited dispersal and long distance colonization. The UniFrac metric, a measure of shared phylogenetic history, grouped H5N1 from Indonesia, Japan, Thailand and Vietnam with those from southeastern Chinese provinces engaged in intensive international trade. Finally, H5N1's accumulative phylogenetic diversity was greatest in southern China and declined beyond. The gradient was interrupted by areas of greater and lesser phylogenetic dispersion, indicating H5N1 migration was restricted at some geopolitical borders. Thailand and Vietnam, just south of China, showed significant phylogenetic clustering, suggesting newly invasive H5N1 strains have been repeatedly filtered out at their northern borders even as both countries suffered recurring outbreaks of endemic strains. In contrast, Japan, while successful in controlling outbreaks, has been subjected to multiple introductions of the virus. CONCLUSIONS: The analysis demonstrates phylogenies can provide local health officials with more than hypotheses about relatedness. Pathogen dispersal, the functional relationships among disease ecologies across localities, and the efficacy of control efforts can also be inferred, all from viral genetic sequences alone.
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spelling pubmed-22448082008-02-27 Influenza A H5N1 Immigration Is Filtered Out at Some International Borders Wallace, Robert G. Fitch, Walter M. PLoS One Research Article BACKGROUND: Geographic spread of highly pathogenic influenza A H5N1, the bird flu strain, appears a necessary condition for accelerating the evolution of a related human-to-human infection. As H5N1 spreads the virus diversifies in response to the variety of socioecological environments encountered, increasing the chance a human infection emerges. Genetic phylogenies have for the most part provided only qualitative evidence that localities differ in H5N1 diversity. For the first time H5N1 variation is quantified across geographic space. METHODOLOGY AND PRINCIPAL FINDINGS: We constructed a statistical phylogeography of 481 H5N1 hemagglutinin genetic sequences from samples collected across 28 Eurasian and African localities through 2006. The MigraPhyla protocol showed southern China was a source of multiple H5N1 strains. Nested clade analysis indicated H5N1 was widely dispersed across southern China by both limited dispersal and long distance colonization. The UniFrac metric, a measure of shared phylogenetic history, grouped H5N1 from Indonesia, Japan, Thailand and Vietnam with those from southeastern Chinese provinces engaged in intensive international trade. Finally, H5N1's accumulative phylogenetic diversity was greatest in southern China and declined beyond. The gradient was interrupted by areas of greater and lesser phylogenetic dispersion, indicating H5N1 migration was restricted at some geopolitical borders. Thailand and Vietnam, just south of China, showed significant phylogenetic clustering, suggesting newly invasive H5N1 strains have been repeatedly filtered out at their northern borders even as both countries suffered recurring outbreaks of endemic strains. In contrast, Japan, while successful in controlling outbreaks, has been subjected to multiple introductions of the virus. CONCLUSIONS: The analysis demonstrates phylogenies can provide local health officials with more than hypotheses about relatedness. Pathogen dispersal, the functional relationships among disease ecologies across localities, and the efficacy of control efforts can also be inferred, all from viral genetic sequences alone. Public Library of Science 2008-02-27 /pmc/articles/PMC2244808/ /pubmed/18301773 http://dx.doi.org/10.1371/journal.pone.0001697 Text en Wallace, Fitch. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Wallace, Robert G.
Fitch, Walter M.
Influenza A H5N1 Immigration Is Filtered Out at Some International Borders
title Influenza A H5N1 Immigration Is Filtered Out at Some International Borders
title_full Influenza A H5N1 Immigration Is Filtered Out at Some International Borders
title_fullStr Influenza A H5N1 Immigration Is Filtered Out at Some International Borders
title_full_unstemmed Influenza A H5N1 Immigration Is Filtered Out at Some International Borders
title_short Influenza A H5N1 Immigration Is Filtered Out at Some International Borders
title_sort influenza a h5n1 immigration is filtered out at some international borders
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2244808/
https://www.ncbi.nlm.nih.gov/pubmed/18301773
http://dx.doi.org/10.1371/journal.pone.0001697
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