Substantial Antigenic Drift in the Hemagglutinin Protein of Swine Influenza A Viruses
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Substantial Antigenic Drift in the Hemagglutinin Protein of Swine Influenza A Viruses. / Ryt-Hansen, Pia; Pedersen, Anders Gorm; Larsen, Inge; Kristensen, Charlotte Sonne; Krog, Jesper Schak; Wacheck, Silke; Larsen, Lars Erik.
I: Viruses, Bind 12, Nr. 2, 248, 2020.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Substantial Antigenic Drift in the Hemagglutinin Protein of Swine Influenza A Viruses
AU - Ryt-Hansen, Pia
AU - Pedersen, Anders Gorm
AU - Larsen, Inge
AU - Kristensen, Charlotte Sonne
AU - Krog, Jesper Schak
AU - Wacheck, Silke
AU - Larsen, Lars Erik
PY - 2020
Y1 - 2020
N2 - The degree of antigenic drift in swine influenza A viruses (swIAV) has historically been regarded as minimal compared to that of human influenza A virus strains. However, as surveillance activities on swIAV have increased, more isolates have been characterized, revealing a high level of genetic and antigenic differences even within the same swIAV lineage. The objective of this study was to investigate the level of genetic drift in one enzootically infected swine herd over one year. Nasal swabs were collected monthly from sows (n = 4) and piglets (n = 40) in the farrowing unit, and from weaners (n = 20) in the nursery. Virus from 1-4 animals were sequenced per month. Analyses of the sequences revealed that the hemagglutinin (HA) gene was the main target for genetic drift with a substitution rate of 7.6 × 10-3 substitutions/site/year and evidence of positive selection. The majority of the mutations occurred in the globular head of the HA protein and in antigenic sites. The phylogenetic tree of the HA sequences displayed a pectinate typology, where only a single lineage persists and forms the ancestor for subsequent lineages. This was most likely caused by repeated selection of a single immune-escape variant, which subsequently became the founder of the next wave of infections.
AB - The degree of antigenic drift in swine influenza A viruses (swIAV) has historically been regarded as minimal compared to that of human influenza A virus strains. However, as surveillance activities on swIAV have increased, more isolates have been characterized, revealing a high level of genetic and antigenic differences even within the same swIAV lineage. The objective of this study was to investigate the level of genetic drift in one enzootically infected swine herd over one year. Nasal swabs were collected monthly from sows (n = 4) and piglets (n = 40) in the farrowing unit, and from weaners (n = 20) in the nursery. Virus from 1-4 animals were sequenced per month. Analyses of the sequences revealed that the hemagglutinin (HA) gene was the main target for genetic drift with a substitution rate of 7.6 × 10-3 substitutions/site/year and evidence of positive selection. The majority of the mutations occurred in the globular head of the HA protein and in antigenic sites. The phylogenetic tree of the HA sequences displayed a pectinate typology, where only a single lineage persists and forms the ancestor for subsequent lineages. This was most likely caused by repeated selection of a single immune-escape variant, which subsequently became the founder of the next wave of infections.
KW - antigenic drift
KW - enzootic infections
KW - genetic drift
KW - hemagglutinin
KW - immune escape variants
KW - molecular clock
KW - selection
KW - sows
KW - substitution rate
KW - swine influenza A virus
U2 - 10.3390/v12020248
DO - 10.3390/v12020248
M3 - Journal article
C2 - 32102230
AN - SCOPUS:85080124532
VL - 12
JO - Viruses
JF - Viruses
SN - 1999-4915
IS - 2
M1 - 248
ER -
ID: 237648845