title: A novel psittacine adenovirus identified during an outbreak of avian chlamydiosis and human psittacosis: zoonosis associated with virus-bacterium coinfection in birds.
abstract: Chlamydophila psittaci is found worldwide, but is particularly common among psittacine birds in tropical and subtropical regions. While investigating a human psittacosis outbreak that was associated with avian chlamydiosis in Hong Kong, we identified a novel adenovirus in epidemiologically linked Mealy Parrots, which was not present in healthy birds unrelated to the outbreak or in other animals. The novel adenovirus (tentatively named Psittacine adenovirus HKU1) was most closely related to Duck adenovirus A in the Atadenovirus genus. Sequencing showed that the Psittacine adenovirus HKU1 genome consists of 31,735 nucleotides. Comparative genome analysis showed that the Psittacine adenovirus HKU1 genome contains 23 open reading frames (ORFs) with sequence similarity to known adenoviral genes, and six additional ORFs at the 3' end of the genome. Similar to Duck adenovirus A, the novel adenovirus lacks LH1, LH2 and LH3, which distinguishes it from other viruses in the Atadenovirus genus. Notably, fiber-2 protein, which is present in Aviadenovirus but not Atadenovirus, is also present in Psittacine adenovirus HKU1. Psittacine adenovirus HKU1 had pairwise amino acid sequence identities of 50.3-54.0% for the DNA polymerase, 64.6-70.7% for the penton protein, and 66.1-74.0% for the hexon protein with other Atadenovirus. The C. psittaci bacterial load was positively correlated with adenovirus viral load in the lung. Immunostaining for fiber protein expression was positive in lung and liver tissue cells of affected parrots, confirming active viral replication. No other viruses were found. This is the first documentation of an adenovirus-C. psittaci co-infection in an avian species that was associated with a human outbreak of psittacosis. Viral-bacterial co-infection often increases disease severity in both humans and animals. The role of viral-bacterial co-infection in animal-to-human transmission of infectious agents has not received sufficient attention and should be emphasized in the investigation of disease outbreaks in human and animals.
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, University of Hong Kong, Hong Kong, China; Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Kelvin K W
authors.initials: KK
authors.lastname: To
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, University of Hong Kong, Hong Kong, China; Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Herman
authors.initials: H
authors.lastname: Tse
authors.affiliation: Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Wan-Mui
authors.initials: WM
authors.lastname: Chan
authors.affiliation: Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Garnet K Y
authors.initials: GK
authors.lastname: Choi
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, University of Hong Kong, Hong Kong, China; Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Anna J X
authors.initials: AJ
authors.lastname: Zhang
authors.affiliation: Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Siddharth
authors.initials: S
authors.lastname: Sridhar
authors.affiliation: Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Sally C Y
authors.initials: SC
authors.lastname: Wong
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, University of Hong Kong, Hong Kong, China; Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Jasper F W
authors.initials: JF
authors.lastname: Chan
authors.affiliation: Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Andy S F
authors.initials: AS
authors.lastname: Chan
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, University of Hong Kong, Hong Kong, China; Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, University of Hong Kong, Hong Kong, China; Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Susanna K P
authors.initials: SK
authors.lastname: Lau
authors.affiliation: Centre for Health Protection, Department of Health, Hong Kong, China.
authors.forename: Janice Y C
authors.initials: JY
authors.lastname: Lo
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, University of Hong Kong, Hong Kong, China; Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Kwok-Hung
authors.initials: KH
authors.lastname: Chan
authors.affiliation: Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Vincent C C
authors.initials: VC
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases, University of Hong Kong, Hong Kong, China; Research Centre of Infection and Immunology, University of Hong Kong, Hong Kong, China; Department of Microbiology, University of Hong Kong, Hong Kong, China.
authors.forename: Kwok-Yung
authors.initials: KY
authors.lastname: Yuen
mesh_terms: D000256:Adenoviridae / Q000145:classification* / Q000235:genetics; D000257:Adenoviridae Infections / Q000453:epidemiology / Q000382:microbiology* / Q000662:veterinary / Q000821:virology; D000818:Animals; D001715:Bird Diseases / Q000453:epidemiology / Q000382:microbiology* / Q000821:virology; D002642:Chick Embryo; D002691:Chlamydophila psittaci / Q000302:isolation & purification; D002522:Chlorocebus aethiops; D060085:Coinfection / Q000453:epidemiology / Q000382:microbiology* / Q000662:veterinary / Q000821:virology; D004196:Disease Outbreaks; D006801:Humans; D008297:Male; D008875:Middle Aged; D011563:Psittaciformes / Q000382:microbiology / Q000821:virology; D009956:Psittacosis / Q000453:epidemiology / Q000382:microbiology* / Q000662:veterinary / Q000821:virology; D014709:Vero Cells; D015047:Zoonoses / Q000453:epidemiology / Q000382:microbiology* / Q000821:virology