Detection and characterization of a distinct bornavirus lineage from healthy Canada geese (Branta canadensis)

Abstract

Avian bornaviruses (ABV), identified in 2008, infect captive parrots and macaws worldwide. The natural reservoirs of these viruses are unknown. Reverse transcription-PCR (RT-PCR) was used to screen oropharyngeal/cloacal swab and brain samples from wild Canada geese (Branta canadensis) for ABV. Approximately 2.9% of swab samples were positive for bornavirus sequences. Fifty-two percent of brain samples from 2 urban flocks also tested positive, and brain isolates were cultured in duck embryo fibroblasts. Phylogenetic analyses placed goose isolates in an independent cluster, and more notably, important regulatory sequences present in Borna disease virus but lacking in psittacine ABVs were present in goose isolates.

Fig. 1.

Phylogeny based on partial M sequences of bornaviruses from birds and mammals. A consensus tree was generated using a neighbor-joining algorithm, with no outgroup assigned. To generate the consensus tree, 1,000 bootstrap replicates were generated. The bootstrap values are shown at the major nodes. Previously identified psittacine ABV groups 1 to 5 are in green. The CG cluster is red; mammalian bornaviruses are in blue. Isolates are identified by accession number: FJ620690 (ABV2, 6609), EU781967 (ABV2, bil), HM998710 (ABV2NM-CT15), GU24959 (ABV1, NM-M25), FJ002329 (ABV1, VTH1561/06), FJ002328 (ABV3, KD), FJ002331 (ABV4, VTH1688/07), HQ123584 (strain CG_2002), NM-20 (JN014949), NM-06 (JN014948), FJ002334 (ABV5, ABRC-98-512), NC_001607 (BDV), and AJ311524 (BDV, strain No/98). Canada goose viruses are as follows: JN251048 (CG-NY86-2008), JN251049 (CG-NH1502008), JN251050 (CG-OR409-2009), JN251051 (CG-NY89-2008), JN251052 (CG-OR377-2009), JN251053 (CG-OR380-2009), JN251054 (CG-OR332-2009), JN251055 (CG-OR-378-2009), JN251056 (CG-EWR64-2011), JN251057 (CG-EWR62-2011), JN251058 (CG-EWR72-2011), JN251059 (CG-NJ81-2011), JN251060 (CG-NJ82-2011), JN251061 (CG-MN-2008), JN251062 (CGWA400-2009), JN251063 (CG-WA363-2008), JN251064 (CG-OR381-2009), JN251065(CG-EWR71-2011), JN251066 (CG-EWR66-2011), JN251067 (CG-EWR65-2011), JN251068 (CG-EWR76-2011), JN251069 (CG-EWR68-2011), JN251070 (CGNJ83-2011), JN251071 (CGNJ84-2011), JN251072 (CG-EWR64-2011), JN251073 (CG-EWR-64-2011), JN251074 (CG-NJ82-2011), and JN251075 (CG-NJ82-2011).

Fig. 2.

Phylogenies generated from partial N, X, P, M, and G sequences of avian and mammalian bornaviruses. Accession numbers of sequences used to develop these phylogenies are as follows: FJ620690 (ABV2, 6609), EU781967 (ABV2, bil), HM998710 (ABV2 NM-CT15), GU24959 (ABV1 NM-M25), FJ002329 (ABV1 VTH1561/06), FJ002328 (ABV3, KD), FJ002331 (ABV4, VTH1688/07), JN035149 (ABV4, NM-01), FJ002334 (ABV5, ABRC-98-512), NC_001607 (BDV), HQ123584 (ABV CG_2002), and GQ161095 (canary). Sequences used to generate the M tree are provided in Fig. 1.

Fig. 3.

Comparison of bornavirus N-X intergenic regions. The end of the N gene (red) and the start of the X gene (green) are shown. The BDV uORF and proposed CG bornavirus uORFs are indicated in blue. The S2 transcription initiation site and the T1 termination site for BDV are also shown (2, 3, 17).