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VanInsberghe D, McBride DS, DaSilva J, Stark TJ, Lau MSY, Shepard SS, Barnes JR, Bowman AS, Lowen AC, Koelle K. Genetic drift and purifying selection shape within-host influenza A virus populations during natural swine infections. PLoS Pathog 2024; 20:e1012131. [PMID: 38626244 PMCID: PMC11051653 DOI: 10.1371/journal.ppat.1012131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 04/26/2024] [Accepted: 03/16/2024] [Indexed: 04/18/2024] Open
Abstract
Patterns of within-host influenza A virus (IAV) diversity and evolution have been described in natural human infections, but these patterns remain poorly characterized in non-human hosts. Elucidating these dynamics is important to better understand IAV biology and the evolutionary processes that govern spillover into humans. Here, we sampled an IAV outbreak in pigs during a week-long county fair to characterize viral diversity and evolution in this important reservoir host. Nasal wipes were collected on a daily basis from all pigs present at the fair, yielding up to 421 samples per day. Subtyping of PCR-positive samples revealed the co-circulation of H1N1 and H3N2 subtype swine IAVs. PCR-positive samples with robust Ct values were deep-sequenced, yielding 506 sequenced samples from a total of 253 pigs. Based on higher-depth re-sequenced data from a subset of these initially sequenced samples (260 samples from 168 pigs), we characterized patterns of within-host IAV genetic diversity and evolution. We find that IAV genetic diversity in single-subtype infected pigs is low, with the majority of intrahost Single Nucleotide Variants (iSNVs) present at frequencies of <10%. The ratio of the number of nonsynonymous to the number of synonymous iSNVs is significantly lower than under the neutral expectation, indicating that purifying selection shapes patterns of within-host viral diversity in swine. The dynamic turnover of iSNVs and their pronounced frequency changes further indicate that genetic drift also plays an important role in shaping IAV populations within pigs. Taken together, our results highlight similarities in patterns of IAV genetic diversity and evolution between humans and swine, including the role of stochastic processes in shaping within-host IAV dynamics.
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Affiliation(s)
- David VanInsberghe
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, United States of America
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
| | - Dillon S. McBride
- Department of Veterinary Preventive Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Juliana DaSilva
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Thomas J. Stark
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Max S. Y. Lau
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America
| | - Samuel S. Shepard
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - John R. Barnes
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Andrew S. Bowman
- Department of Veterinary Preventive Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Anice C. Lowen
- Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, United States of America
- Emory Center of Excellence for Influenza Research and Response (Emory-CEIRR), Atlanta, Georgia, United States of America
| | - Katia Koelle
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
- Emory Center of Excellence for Influenza Research and Response (Emory-CEIRR), Atlanta, Georgia, United States of America
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VanInsberghe D, McBride DS, DaSilva J, Stark TJ, Lau MS, Shepard SS, Barnes JR, Bowman AS, Lowen AC, Koelle K. Genetic drift and purifying selection shape within-host influenza A virus populations during natural swine infections. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.23.563581. [PMID: 37961583 PMCID: PMC10634741 DOI: 10.1101/2023.10.23.563581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Patterns of within-host influenza A virus (IAV) diversity and evolution have been described in natural human infections, but these patterns remain poorly characterized in non-human hosts. Elucidating these dynamics is important to better understand IAV biology and the evolutionary processes that govern spillover into humans. Here, we sampled an IAV outbreak in pigs during a week-long county fair to characterize viral diversity and evolution in this important reservoir host. Nasal wipes were collected on a daily basis from all pigs present at the fair, yielding up to 421 samples per day. Subtyping of PCR-positive samples revealed the co-circulation of H1N1 and H3N2 subtype IAVs. PCR-positive samples with robust Ct values were deep-sequenced, yielding 506 sequenced samples from a total of 253 pigs. Based on higher-depth re-sequenced data from a subset of these initially sequenced samples (260 samples from 168 pigs), we characterized patterns of within-host IAV genetic diversity and evolution. We find that IAV genetic diversity in single-subtype infected pigs is low, with the majority of intra-host single nucleotide variants (iSNVs) present at frequencies of <10%. The ratio of the number of nonsynonymous to the number of synonymous iSNVs is significantly lower than under the neutral expectation, indicating that purifying selection shapes patterns of within-host viral diversity in swine. The dynamic turnover of iSNVs and their pronounced frequency changes further indicate that genetic drift also plays an important role in shaping IAV populations within pigs. Taken together, our results highlight similarities in patterns of IAV genetic diversity and evolution between humans and swine, including the role of stochastic processes in shaping within-host IAV dynamics.
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Affiliation(s)
- David VanInsberghe
- Department of Microbiology and Immunology, Emory University, Atlanta, GA, 30322
- Department of Biology, Emory University, Atlanta, GA, 30322
| | - Dillon S. McBride
- Department of Veterinary Preventive Medicine, The Ohio State University, Columbus, OH 43210
| | - Juliana DaSilva
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA
| | - Thomas J. Stark
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA
| | - Max S.Y. Lau
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, GA, 30322
| | - Samuel S. Shepard
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA
| | - John R. Barnes
- Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA
| | - Andrew S. Bowman
- Department of Veterinary Preventive Medicine, The Ohio State University, Columbus, OH 43210
| | - Anice C. Lowen
- Department of Microbiology and Immunology, Emory University, Atlanta, GA, 30322
- Emory Center of Excellence for Influenza Research and Response (Emory-CEIRR)
| | - Katia Koelle
- Department of Biology, Emory University, Atlanta, GA, 30322
- Emory Center of Excellence for Influenza Research and Response (Emory-CEIRR)
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Chauhan RP, Gordon ML. Review of genome sequencing technologies in molecular characterization of influenza A viruses in swine. J Vet Diagn Invest 2022; 34:177-189. [PMID: 35037523 PMCID: PMC8921814 DOI: 10.1177/10406387211068023] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The rapidly evolving antigenic diversity of influenza A virus (IAV) genomes in swine makes it imperative to detect emerging novel strains and track their circulation. We analyzed in our review the sequencing technologies used for subtyping and characterizing swine IAV genomes. Google Scholar, PubMed, and International Nucleotide Sequence Database Collaboration (INSDC) database searches identified 216 studies that have utilized Sanger, second-, and third-generation sequencing techniques to subtype and characterize swine IAV genomes up to 31 March 2021. Sanger dideoxy sequencing was by far the most widely used sequencing technique for generating either full-length (43.0%) or partial (31.0%) IAV genomes in swine globally; however, in the last decade, other sequencing platforms such as Illumina have emerged as serious competitors for the generation of whole-genome sequences of swine IAVs. Although partial HA and NA gene sequences were sufficient to determine swine IAV subtypes, whole-genome sequences were critical for determining reassortments and identifying unusual or less frequently occurring IAV subtypes. The combination of Sanger and second-generation sequencing technologies also greatly improved swine IAV characterization. In addition, the rapidly evolving third-generation sequencing platform, MinION, appears promising for on-site, real-time sequencing of complete swine IAV genomes. With a higher raw read accuracy, the use of the MinION could enhance the scalability of swine IAV testing in the field and strengthen the swine IAV disease outbreak response.
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Affiliation(s)
| | - Michelle L. Gordon
- Michelle L. Gordon, School of Laboratory Medicine and Medical Sciences, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, 719 Umbilo Rd, Durban 4001, South Africa.
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Piva MM, Schwertz CI, Bianchi RM, Kemper RT, Henker LC, Nagae RY, Cê TRM, Barcellos DES, Driemeier D, Pavarini SP. Causes of death in growing-finishing pigs in two technified farms in southern Brazil. PESQUISA VETERINÁRIA BRASILEIRA 2020. [DOI: 10.1590/1678-5150-pvb-6708] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
ABSTRACT: The aim of this study was to investigate the main causes of death in growing-finishing pigs in southern Brazil. During a one-year period (from 2018 to 2019), two industrial pig herds (18 and 20 thousand pigs each farm) in southern Brazil were monitored along the four seasons of the year (12 days per season on each farm), in order to perform necropsies of all pigs that died in that period. The two farms had an average monthly mortality rate ranging from 0.94 to 3.93% in the evaluated months. At necropsy, tissues were collected, fixed in 10% formalin solution and processed routinely for histopathological examination. When necessary, samples were sent for bacterial culture and PCR to identify etiologic agents. A total of 601 necropsies were performed, with 94.9% of conclusive diagnoses. Infectious diseases corresponded to 64.4% of conclusive diagnosis and non-infectious diseases to 35.6%. The most prevalent causes of death were: pneumonia (33%), gastric ulcers (15.4%), circovirosis (9.9%), systemic bacterial embolism (5.4%), polyserositis (4.4%), dilated cardiomyopathy and torsion of abdominal organs (4.3% each), and bacterial pericarditis (3.4%). Regarding pneumonias (199/601), the main agents identified in these cases were Pasteurella multocida, Influenza A virus and Mycoplasma hyopneumoniae, mainly in associations.
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Affiliation(s)
| | | | | | | | | | - Ricardo Y. Nagae
- Empresa Seara Alimentos, Brazil; Universidade Federal do Rio Grande do Sul, Brazil
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