Phylodynamics of influenza A(H3N2) in South America, 1999-2012.
The limited influenza A(H3N2) genetic data available from the Southern Hemisphere (particularly from Africa and Latin America), constrains the accurate reconstruction of viral dissemination dynamics within those regions. Our objective was to describe the spatial dissemination dynamics of influenza A(H3N2) within South America. A total of 469 sequences of the HA1 portion of the hemagglutinin gene (HA) from influenza A(H3N2) viruses sampled in temperate and tropical South American countries between 1999 and 2012 were combined with available contemporary sequences from Australia, Hong Kong, United Kingdom and the United States. Phylogenetic analyses revealed that influenza A(H3N2) sequences from South America were highly intermixed with sequences from other geographical regions, although a clear geographic virus population structure was detected globally. We identified 14 clades mostly (≥80%) composed of influenza sequences from South American countries. Bayesian phylogeographic analyses of those clades support a significant role of both temperate and tropical regions in the introduction and dissemination of new influenza A(H3N2) strains within South America and identify an intensive bidirectional viral exchange between different geographical areas. These findings indicate that seasonal influenza A(H3N2) epidemics in South America are seeded by both the continuous importation of viral variants from other geographic regions and the short-term persistence of local lineages. This study also supports a complex metapopulation model of influenza A(H3N2) dissemination in South America, with no preferential direction in viral movement between temperate and tropical regions.
Respiratory Viruses and Measles Laboratory, Oswaldo Cruz Institute/Fiocruz, Av. Brasil 4365, 21040-360 Rio de Janeiro, RJ, Brazil. Electronic address: psborn@ioc.fiocruz.br.
Priscila Silva
PS
Born
Respiratory Viruses and Measles Laboratory, Oswaldo Cruz Institute/Fiocruz, Av. Brasil 4365, 21040-360 Rio de Janeiro, RJ, Brazil.
Marilda Mendonça
MM
Siqueira
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.
Nuno Rodrigues
NR
Faria
Respiratory Viruses and Measles Laboratory, Oswaldo Cruz Institute/Fiocruz, Av. Brasil 4365, 21040-360 Rio de Janeiro, RJ, Brazil.
Paola Cristina
PC
Resende
Respiratory Viruses and Measles Laboratory, Oswaldo Cruz Institute/Fiocruz, Av. Brasil 4365, 21040-360 Rio de Janeiro, RJ, Brazil.
Fernando Couto
FC
Motta
AIDS and Molecular Immunology Laboratory, Oswaldo Cruz Institute/Fiocruz, Av. Brasil 4365, 21040-360 Rio de Janeiro, RJ, Brazil.
Gonzalo
G
Bello
D001315:Australia / Q000453:epidemiology; D001499:Bayes Theorem; D066264:Datasets as Topic; D015870:Gene Expression; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype / Q000145:classification / Q000235:genetics*; D007251:Influenza, Human / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology; D010802:Phylogeny; D058974:Phylogeography; D017422:Sequence Analysis, DNA; D013020:South America / Q000453:epidemiology; D014481:United States / Q000453:epidemiology
D019267:Hemagglutinin Glycoproteins, Influenza Virus
H3N2; Influenza A; Phylogeography; South America; Viral evolution