title: Avian paramyoxvirus-8 immunization reduces viral shedding after homologous APMV-8 challenge but fails to protect against Newcastle disease.
abstract: BACKGROUND
  Protection against infection by Newcastle disease virus (NDV), also designated as avian paramyxovirus subtype-1 (APMV-1), is mediated by immune responses to the two surface glycoproteins, hemagglutinin-neuraminidase (HN) and fusion (F) protein. Thus, a chimeric APMV-1 based vaccine that encodes APMV-8 HN- and F-proteins and expresses the hemagglutinin of avian influenza virus (AIV) H5N1, is able to protect against HPAIV H5N1 but fails to protect against NDV [PLoS One8:e72530, 2013]. However, it is unclear whether avirulent APMV-subtypes, like APMV-8 can induce subtype-specific immunity and protect from a homologous challenge.
  
  
  RESULTS
  APMV-8 infections of 3- and 6-weeks-old specific pathogen free (SPF)-chickens did not induce any clinical signs but was associated with virus shedding for up to 6 days. Viral replication was only detected in oropharyngeal- and never in cloacal swabs. Upon reinfection with homologous APMV-8, viral shedding was restricted to day 2 and in contrast to naive SPF-chickens, only RNA but no infectious virus was recovered. No protection was induced against virulent NDV challenge, although morbidity and mortality was delayed in APMV-8 primed chickens. This lack of protection is in line with a lack of reactivity of APMV-8 specific sera to APMV-1 HN-protein: Neither by hemagglutin-inhibition (HI) test nor immunoblot analyses, cross-reactivity was detected, despite reactivity to internal proteins.
  
  
  CONCLUSIONS
  Immune responses mounted during asymptomatic APMV-8 infection limit secondary infection against homologues reinfection and facilitates a delay in the onset of disease in a subtype independent manner but is unable to protect against Newcastle disease, a heterologous APMV-subtype.
authors.affiliation: Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, D-17493 Greifswald-Insel Riems, Germany. christian.grund@fli.bund.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Grund
authors.forename: Constanze
authors.initials: C
authors.lastname: Steglich
authors.forename: Eva
authors.initials: E
authors.lastname: Huthmann
authors.forename: Martin
authors.initials: M
authors.lastname: Beer
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Mettenleiter
authors.forename: Angela
authors.initials: A
authors.lastname: Römer-Oberdörfer
mesh_terms: D000818:Animals; D018109:Avulavirus / Q000235:genetics / Q000276:immunology*; D002645:Chickens; D056738:Cross Protection; D007114:Immunization; D009521:Newcastle Disease / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D009522:Newcastle disease virus / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D011201:Poultry Diseases / Q000276:immunology* / Q000821:virology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D017201:Virus Shedding
chemical_list: D014765:Viral Vaccines