Molecular Characterization of a Novel Budgerigar Fledgling Disease Virus Strain From Budgerigars in China

Abstract

Budgerigar fledgling disease virus (BFDV) is the causative polyomavirus of budgerigar fledgling disease, an important avian immunosuppressive disease in budgerigars (Melopsittacus undulatus). In the current study, we explored the etiological role and molecular characteristics of BFDV. We identified a novel BFDV strain, designated as SC-YB19, belonging to a unique cluster with three other domestic strains (WF-GM01, SD18, and APV-P) and closely related to Polish isolates based on complete sequences. Sequence analysis showed that SC-YB19 had an 18-nucleotide (nt) deletion in the enhancer region, corresponding to the sequence position 164–181 nt, which differed significantly from all other BFDV strains. Based on sequence alignment, three unique nucleotide substitutions were found in VP4 (position 821), VP1 (position 2,383), and T-antigen (position 3,517) of SC-YB19, compared with SD18, WF-GM01, QDJM01, HBYM02, APV7, and BFDV1. Phylogenetic analyses based on complete sequences suggested that SC-YB19, along with the domestic WF-GM01, SD18, and APV-P strains, formed a single branch and were closely related to Polish, Japanese, and American isolates. These results demonstrate that BFDV genotype variations are co-circulating in China, thus providing important insight into BFDV evolution.

Prevalence, genotypes, and infection risk factors of psittacine beak and feather disease virus and budgerigar fledgling disease virus in captive birds in Hong Kong

“…PBFDV was detected in 24.07% of the samples from pet shops in Hong Kong, which is similar to the reported prevalence in breeding facilities in Eastern Turkey (23.00%) [ 28 ] but lower than that in Bangladesh (54.05%) [ 33 ], Fuzhou, China (80.00%) [ 34 ], and Taiwan (29.7% and 41.18%) [ 57 , 59 ]. No BFDV-positive samples were found in pet shops, which is in contrast to reports from Sichuan China [ 29 ], Japan [ 59 ], and Eastern Turkey [ 28 ], where infection rates ranged from 2.7% to 100%. The prevalence of PBFDV and BFDV in households in Hong Kong was also lower than in Taiwan, which was 21.7%-41.2% and 8.3%-15.2%, respectively, according to different studies [ 35 , 57 , 58 ].…”

Molecular characteristics of Budgerigar fledgling disease polyomavirus detected from parrots in South Korea

“…The early region encodes two non-structural proteins, large T antigen and small t antigen. On the other hand, the late region encodes structural proteins, VP1, VP2, VP3, and VP4 [ 3 4 ]. The genome also contains a non-coding control region which was located between the early and late regions.…”

“…The genome also contains a non-coding control region which was located between the early and late regions. A non-coding control region contains promoter, polyadenylation signal, DNA replication origin, and enhancer regions [ 4 5 ]. Unlike mammalian polyomaviruses, which have well-defined tissue tropism and high host-specificity, avian polyomaviruses, such as BFDV, have low host specificity and can replicate in various organs; where they can be detected in all organs if infected [ 1 6 ].…”

“…BFDV is the etiologic agent of budgerigar fledgling disease, an important immunosuppressive disease in different psittacine species [ 4 9 10 ]. However, this virus has also been reported in non-psittacine species, such as buzzards, falcons, and pigeons [ 11 12 ].…”

“…However, BFDV infection in adults is only associated with mild symptoms such as feather dystrophies (French molt) [ 9 13 ]. BFDV infection has been reported in several species of psittacine birds on almost every continent, including countries such as China [ 4 ], Japan [ 14 ], Taiwan [ 2 15 ], Turkey [ 16 ], Pakistan [ 17 ], Thailand [ 18 ], Australia [ 19 ], New Zealand [ 20 ], Egypt [ 21 ], Germany [ 22 ], Czech Republic [ 23 ], Italy [ 24 ], Poland [ 25 ], Chile [ 26 ], Costa Rica [ 27 ], and USA [ 28 ]. In Korea, the virus was first detected in an Alexandrine parakeet ( Psittacula eupatria ) in 2014 [ 29 ], and in an African gray parrot ( Psittacus erithacus ) that was co-infected with Psittacine beak and feather disease, as well as and Aspergillus fumigatus and BFDV in 2017 [ 30 ].…”