title: Lethal nephrotropism of an H10N1 avian influenza virus stands out as an atypical pathotype.
abstract: A nephrotropic H10N1 avian influenza virus (AIV) with an intravenous pathogenicity index (IVPI) of 1.9 and a haemagglutinin monobasic amino acid cleavage site motif, was genetically and phenotypically characterized. Specific pathogen free chickens of 3 or 6 weeks of age were challenged with a 10(6)EID50/0.1mL dose by either oro-nasal or intravenous route, to study the distribution, tissue tropism and virulence of the virus. Direct transmission was tested by introducing sentinel birds on day 4 post infection. Virus shedding and viremia were investigated by means of type A influenza real-time RT-PCR. Dead birds were necropsied and selected organs were collected for histology, immunohistochemistry, and to detect and re-isolate the virus. Serological analyses were carried out to evaluate seroconversion, three weeks from challenge. The oro-nasal challenge of the 6-week-old birds elicited 47% mortality as a result of viremia and massive replication of the virus in the kidneys. Unexpectedly, among birds of 3 weeks of age the same challenge caused 5% mortality and few clinical signs. Surprisingly the intravenous administration of the virus in the 3-week-old birds recorded an IVPI of 2.4. A full genome characterization of the virus could not identify any molecular determinant underlying the observed phenotype. Our findings describe the complex pathobiology of an AIV of the H10 subtype that stands out for its peculiar pathogenicity and tissue tropism in chickens.
authors.affiliation: Department of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Universita' 10, 35020 Legnaro (PD), Italy. Electronic address: fbonfante@izsvenezie.it.
authors.forename: Francesco
authors.initials: F
authors.lastname: Bonfante
authors.affiliation: Department of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Universita' 10, 35020 Legnaro (PD), Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Fusaro
authors.affiliation: Histopathology Department, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Universita' 10, 35020 Legnaro (PD), Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Zanardello
authors.affiliation: Department of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Universita' 10, 35020 Legnaro (PD), Italy; Department of Animal Medicine, Production and Health, University of Padua, Agripolis, Viale dell'Universita', 35020 Legnaro (PD), Italy.
authors.forename: Livia Victoria
authors.initials: LV
authors.lastname: Patrono
authors.affiliation: Department of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Universita' 10, 35020 Legnaro (PD), Italy; Department of Animal Medicine, Production and Health, University of Padua, Agripolis, Viale dell'Universita', 35020 Legnaro (PD), Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: De Nardi
authors.affiliation: Department of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Universita' 10, 35020 Legnaro (PD), Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Maniero
authors.affiliation: Department of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Universita' 10, 35020 Legnaro (PD), Italy.
authors.forename: Calogero
authors.initials: C
authors.lastname: Terregino
mesh_terms: D000367:Age Factors; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D009980:Influenza A virus / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D005585:Influenza in Birds / Q000401:mortality / Q000473:pathology* / Q000821:virology*; D007668:Kidney / Q000821:virology*; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D017422:Sequence Analysis, DNA; D013047:Specific Pathogen-Free Organisms; D014774:Virulence; D017201:Virus Shedding
keywords: Age; Atypical pathotype; Low pathogenicity avian influenza virus H10N1; Nephrotropism