title: No evidence for homosubtypic immunity of influenza H3 in Mallards following vaccination in a natural experimental system.
abstract: The Mallard (Anas platyrhynchos) is an important reservoir species for influenza A viruses (IAV), and in this host, prevalence and virus diversity are high. Studies have demonstrated the presence of homosubtypic immunity, where individuals are unlikely to be reinfected with the same subtype within an autumn season. Further, evidence for heterosubtypic immunity exists, whereby immune responses specific for one subtype offer partial or complete protection against related HA subtypes. We utilized a natural experimental system to determine whether homo- or heterospecific immunity could be induced following experimental vaccination. Thirty Mallards were vaccinated with an inactivated H3, H6 or a sham vaccine and after seroconversion were exposed to naturally infected wild conspecifics. All ducks were infected within 2 days and had both primary and secondary infections. Overall, there was no observable difference between groups; all individuals were infected with H3 and H10 IAV. At the cessation of the experiment, most individuals had anti-NP antibodies and neutralizing antibodies against H10. Not all individuals had H3 neutralizing antibodies. The isolated H3 IAVs revealed genetic dissimilarity to the H3 vaccine strain, specifically substitutions in the vicinity of the receptor-binding site. There was no evidence of vaccine-induced homosubtypic immunity to H3, a likely result of both a poor H3 immune response in the ducks and H3 immune escape. Likewise, there was no observed heterosubtypic protection related to H6 vaccination. This study highlights the need for experimental approaches to assess how exposure to pathogens and resulting immune processes translates to individual and population disease dynamics.
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, SE-391 82, Kalmar, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Wille
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, SE-391 82, Kalmar, Sweden.|Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, Department of Population Health, The University of Georgia, Athens, GA, 30602, USA.
authors.forename: N
authors.initials: N
authors.lastname: Latorre-Margalef
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, SE-391 82, Kalmar, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Tolf
authors.affiliation: Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, Department of Population Health, The University of Georgia, Athens, GA, 30602, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Stallknecht
authors.affiliation: Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, SE-391 82, Kalmar, Sweden.
authors.forename: J
authors.identifier: http://orcid.org/0000-0002-1152-4235
authors.initials: J
authors.lastname: Waldenström
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D004372:Ducks / Q000276:immunology* / Q000821:virology; D009980:Influenza A virus; D005585:Influenza in Birds / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral
keywords: 
  Anas platyrhynchos
  ; H3; Mallard; homosubtypic immunity; humoral immunity; immunity; influenza A virus