Emergence and Pathogenesis of Swine Influenza Viruses in Humans

2014 ◽  
pp. 495-521
Author(s):  
Jennifer L. Smith ◽  
Frederick T. Koster ◽  
Robert J. Hogan
Keyword(s):  
Swine Influenza ◽  
Influenza Viruses

scholarly journals Origin of the European avian-like swine influenza viruses

2014 ◽  
Vol 95 (11) ◽  
pp. 2372-2376 ◽  
Author(s):  
Andi Krumbholz ◽  
Jeannette Lange ◽  
Andreas Sauerbrei ◽  
Marco Groth ◽  
Matthias Platzer ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Phylogenetic Trees ◽  
Sequence Data ◽  
Swine Influenza ◽  
H1n1 Influenza ◽  
Molecular Data ◽  
Influenza Viruses ◽  
Time Resolved ◽  
Genotype Constellation ◽  
Tree Inference

The avian-like swine influenza viruses emerged in 1979 in Belgium and Germany. Thereafter, they spread through many European swine-producing countries, replaced the circulating classical swine H1N1 influenza viruses, and became endemic. Serological and subsequent molecular data indicated an avian source, but details remained obscure due to a lack of relevant avian influenza virus sequence data. Here, the origin of the European avian-like swine influenza viruses was analysed using a collection of 16 European swine H1N1 influenza viruses sampled in 1979–1981 in Germany, the Netherlands, Belgium, Italy and France, as well as several contemporaneous avian influenza viruses of various serotypes. The phylogenetic trees suggested a triple reassortant with a unique genotype constellation. Time-resolved maximum clade credibility trees indicated times to the most recent common ancestors of 34–46 years (before 2008) depending on the RNA segment and the method of tree inference.

scholarly journals Positive Selection in CD8+T-Cell Epitopes of Influenza Virus Nucleoprotein Revealed by a Comparative Analysis of Human and Swine Viral Lineages

2015 ◽  
Vol 89 (22) ◽  
pp. 11275-11283 ◽  
Author(s):  
Heather M. Machkovech ◽  
Trevor Bedford ◽  
Marc A. Suchard ◽  
Jesse D. Bloom
Keyword(s):  
T Cells ◽  
Influenza Virus ◽  
T Cell ◽  
Positive Selection ◽  
Swine Influenza ◽  
Selective Advantage ◽  
Influenza Viruses ◽  
T Cell Epitopes ◽  
Human Influenza ◽  
Human Influenza Virus

ABSTRACTNumerous experimental studies have demonstrated that CD8+T cells contribute to immunity against influenza by limiting viral replication. It is therefore surprising that rigorous statistical tests have failed to find evidence of positive selection in the epitopes targeted by CD8+T cells. Here we use a novel computational approach to test for selection in CD8+T-cell epitopes. We define all epitopes in the nucleoprotein (NP) and matrix protein (M1) with experimentally identified human CD8+T-cell responses and then compare the evolution of these epitopes in parallel lineages of human and swine influenza viruses that have been diverging since roughly 1918. We find a significant enrichment of substitutions that alter human CD8+T-cell epitopes in NP of human versus swine influenza virus, consistent with the idea that these epitopes are under positive selection. Furthermore, we show that epitope-altering substitutions in human influenza virus NP are enriched on the trunk versus the branches of the phylogenetic tree, indicating that viruses that acquire these mutations have a selective advantage. However, even in human influenza virus NP, sites in T-cell epitopes evolve more slowly than do nonepitope sites, presumably because these epitopes are under stronger inherent functional constraint. Overall, our work demonstrates that there is clear selection from CD8+T cells in human influenza virus NP and illustrates how comparative analyses of viral lineages from different hosts can identify positive selection that is otherwise obscured by strong functional constraint.IMPORTANCEThere is a strong interest in correlates of anti-influenza immunity that are protective against diverse virus strains. CD8+T cells provide such broad immunity, since they target conserved viral proteins. An important question is whether T-cell immunity is sufficiently strong to drive influenza virus evolution. Although many studies have shown that T cells limit viral replication in animal models and are associated with decreased symptoms in humans, no studies have proven with statistical significance that influenza virus evolves under positive selection to escape T cells. Here we use comparisons of human and swine influenza viruses to rigorously demonstrate that human influenza virus evolves under pressure to fix mutations in the nucleoprotein that promote escape from T cells. We further show that viruses with these mutations have a selective advantage since they are preferentially located on the “trunk” of the phylogenetic tree. Overall, our results show that CD8+T cells targeting nucleoprotein play an important role in shaping influenza virus evolution.

Swine influenza vaccines: current status and future perspectives

2010 ◽  
Vol 11 (1) ◽  
pp. 81-96 ◽  
Author(s):  
Wenjun Ma ◽  
Jürgen A. Richt
Keyword(s):  
Influenza A ◽  
Swine Influenza ◽  
Influenza Viruses ◽  
Current Status ◽  
Economic Losses ◽  
Influenza A Viruses ◽  
Swine Industry ◽  
Effective Strategies ◽  
Swine Disease ◽  
And Control

AbstractSwine influenza is an important contagious disease in pigs caused by influenza A viruses. Although only three subtypes of influenza A viruses, H1N1, H1N2 and H3N2, predominantly infect pigs worldwide, it is still a big challenge for vaccine manufacturers to produce efficacious vaccines for the prevention and control of swine influenza. Swine influenza viruses not only cause significant economic losses for the swine industry, but are also important zoonotic pathogens. Vaccination is still one of the most important and effective strategies to prevent and control influenza for both the animal and human population. In this review, we will discuss the current status of swine influenza worldwide as well as current and future options to control this economically important swine disease.

scholarly journals Cross-protection between antigenically distinct H1N1 swine influenza viruses from Europe and North America

2010 ◽  
Vol 5 (2) ◽  
pp. 115-122 ◽  
Author(s):  
Annebel R. De Vleeschauwer ◽  
Sjouke G. Van Poucke ◽  
Alexander I. Karasin ◽  
Christopher W. Olsen ◽  
Kristien Van Reeth
Keyword(s):  
North America ◽  
Swine Influenza ◽  
Influenza Viruses ◽  
Cross Protection

scholarly journals Hemagglutinin mutations related to antigenic variation in H1 swine influenza viruses.

1992 ◽  
Vol 66 (2) ◽  
pp. 1066-1073 ◽  
Author(s):  
S M Luoh ◽  
M W McGregor ◽  
V S Hinshaw
Keyword(s):  
Antigenic Variation ◽  
Swine Influenza ◽  
Influenza Viruses

scholarly journals Cluster analysis of the origins of the new influenza A(H1N1) virus

2009 ◽  
Vol 14 (21) ◽  
Author(s):  
A Solovyov ◽  
G Palacios ◽  
T Briese ◽  
W I Lipkin ◽  
R Rabadan
Keyword(s):  
Cluster Analysis ◽  
Influenza A ◽  
H1n1 Virus ◽  
Swine Influenza ◽  
The United States ◽  
Influenza Viruses ◽  
World Health ◽  
Influenza A H1n1 ◽  
The World ◽  
Health Organization

In March and April 2009, a new strain of influenza A(H1N1) virus has been isolated in Mexico and the United States. Since the initial reports more than 10,000 cases have been reported to the World Health Organization, all around the world. Several hundred isolates have already been sequenced and deposited in public databases. We have studied the genetics of the new strain and identified its closest relatives through a cluster analysis approach. We show that the new virus combines genetic information related to different swine influenza viruses. Segments PB2, PB1, PA, HA, NP and NS are related to swine H1N2 and H3N2 influenza viruses isolated in North America. Segments NA and M are related to swine influenza viruses isolated in Eurasia.

Lack of cross-protection between European H1N1 and H1N2 swine influenza viruses

2001 ◽  
Vol 1219 ◽  
pp. 341-345 ◽  
Author(s):  
Kristien Van Reeth ◽  
Sophie De Clercq ◽  
Maurice Pensaert
Keyword(s):  
Swine Influenza ◽  
Influenza Viruses ◽  
Cross Protection

scholarly journals Genotype patterns of contemporary reassorted H3N2 virus in US swine

2013 ◽  
Vol 94 (6) ◽  
pp. 1236-1241 ◽  
Author(s):  
Pravina Kitikoon ◽  
Martha I. Nelson ◽  
Mary Lea Killian ◽  
Tavis K. Anderson ◽  
Leo Koster ◽  
...  
Keyword(s):  
North American ◽  
Swine Influenza ◽  
Cross Reactivity ◽  
Influenza Viruses ◽  
Antigenic Drift ◽  
H3n2 Virus ◽  
Specific Subset ◽  
The Usa ◽  
Genome Scale ◽  
Viral Isolates

To understand the evolution of swine-origin H3N2v influenza viruses that have infected 320 humans in the USA since August 2011, we performed a phylogenetic analysis at a whole genome scale of North American swine influenza viruses (n  =  200). All viral isolates evolved from the prototypical North American H3 cluster 4 (c4), with evidence for further diversification into subclusters. At least ten distinct reassorted H3N2/pandemic H1N1 (rH3N2p) genotypes were identified in swine. Genotype 1 (G1) was most frequently detected in swine and all human H3N2v viruses clustered within a single G1 clade. These data suggest that the genetic requirements for transmission to humans may be restricted to a specific subset of swine viruses. Mutations at putative antigenic sites as well as reduced serological cross-reactivity among the H3 subclusters suggest antigenic drift of these contemporary viruses.

Molecular epidemiology and glycomics of swine influenza viruses circulating in commercial swine farms in the southeastern and midwest United States

2020 ◽  
Vol 251 ◽  
pp. 108914
Author(s):  
Abhijeet A. Bakre ◽  
Les P. Jones ◽  
Constantinos S. Kyriakis ◽  
Jarod M. Hanson ◽  
Davis E. Bobbitt ◽  
...  
Keyword(s):  
United States ◽  
Molecular Epidemiology ◽  
Swine Influenza ◽  
Influenza Viruses ◽  
Midwest United States ◽  
Swine Farms
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