Avian Bornavirus Research—A Comprehensive Review

Aquatic bird bornavirus 1 (ABBV-1) is a neurotropic virus that infects waterfowls, resulting in persistent infection. Experimental infection showed that both Muscovy ducks and chickens support persistent ABBV-1 infection in the central nervous system (CNS), up to 12 weeks post-infection (wpi), without the development of clinical disease. The aim of the present study was to describe the transcriptomic profiles in the brains of experimentally infected Muscovy ducks and chickens infected with ABBV-1 at 4 and 12 wpi. Transcribed RNA was sequenced by next-generation sequencing and analyzed by principal component analysis (PCA) and differential gene expression. The functional annotation of differentially expressed genes was evaluated by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The PCA showed that the infected ducks sampled at both 4 and 12 wpi clustered separately from the controls, while only the samples from the chickens at 12 wpi, but not at 4 wpi, formed a separate cluster. In the ducks, more genes were differentially expressed at 4 wpi than 12 wpi, and the majority of the highly differentially expressed genes (DEG) were upregulated. On the other hand, the infected chickens had fewer DEGs at 4 wpi than at 12 wpi, and the majority of those with high numbers of DEGs were downregulated at 4 wpi and upregulated at 12 wpi. The functional annotation showed that the most enriched GO terms were immune-associated in both species; however, the terms associated with the innate immune response were predominantly enriched in the ducks, whereas the chickens had enrichment of both the innate and adaptive immune response. Immune-associated pathways were also enriched according to the KEGG pathway analysis in both species. Overall, the transcriptomic analysis of the duck and chicken brains showed that the main biological responses to ABBV-1 infection were immune-associated and corresponded with the levels of inflammation in the CNS.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transcriptome Analysis of Duck and Chicken Brains Infected with Aquatic Bird Bornavirus-1 (ABBV-1)

Pham

Tockovska

Leacy

et al. 2022

“…Since the description of Borna disease virus 1 (BoDV-1) in horses causing neurologic disorders (Borna disease), further family members have been discovered in the last years including five virus species affecting a variety of birds. Currently a novel naming of the members of the virus family Bornaviridae following a uniform binomial Linnean format was introduced by the International Committee on Taxonomy of Viruses (ICTV) [ 1 , 2 ] and mentioned in the latest official update on bornaviruses [ 3 , 4 ].…”

Section: Introductionmentioning

confidence: 99%

“…In 2008, parrot bornaviruses were detected as the cause of a fatal disease known as Proventricular Dilatation Disease (PDD) in Psittaciformes [ 5 , 6 ]. Parrot bornavirus 2 (PaBV-2) and PaBV-4 belonging to the genus Orthobornavirus and the species Orthobornavirus alphapsittaciforme are the primary affectants resulting in PDD, causing predominantly nervous and gastrointestinal symptoms [ 4 ]. Besides the classical PDD, subclinically PaBV-infected carriers and various combinations of viral distribution, inflammatory lesions, and disease status have also been described [ 4 , 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

Tissue Distribution of Parrot Bornavirus 4 (PaBV-4) in Experimentally Infected Young and Adult Cockatiels (Nymphicus hollandicus)

Petzold

Gartner

Malberg

et al. 2022

Proventricular dilatation disease (PDD) caused by parrot bornavirus (PaBV) infection is an often-fatal disease known to infect Psittaciformes. The impact of age at the time of PaBV infection on organ lesions and tissue distribution of virus antigen and RNA remains largely unclear. For this purpose, tissue sections of 11 cockatiels intravenously infected with PaBV-4 as adults or juveniles, respectively, were examined via histology, immunohistochemistry applying a phosphoprotein (P) antibody directed against the bornaviral phosphoprotein and in situ hybridisation to detect viral RNA in tissues. In both groups of adult- and juvenile-infected cockatiels, widespread tissue distribution of bornaviral antigen and RNA as well as histologic inflammatory lesions were demonstrated. The latter appeared more severe in the central nervous system in adults and in the proventriculus of juveniles, respectively. During the study, central nervous symptoms and signs of gastrointestinal affection were only demonstrated in adult birds. Our findings indicate a great role of the age at the time of infection in the development of histopathological lesions and clinical signs, and thus provide a better understanding of the pathogenesis, possible virus transmission routes, and the development of carrier birds posing a risk to psittacine collections.

“…In addition, after the discovery of the first avian bornavirus in 2008 [ 78 , 79 ], a variety of bornaviruses have been detected in birds [ 80 ]. In particular, PaBV-4, which is the most dominant genotype causing neurological disorders and proventricular dilatation disease (PDD), has been detected in a broad range of captive psittacines worldwide [ 81 , 82 ], resulting in great economic damage to the bird breeding industry.…”

Section: Perspectivesmentioning

confidence: 99%

Reverse Genetics and Artificial Replication Systems of Borna Disease Virus 1

Kanda

Tomonaga

2022

Borna disease virus 1 (BoDV-1) is a neurotropic RNA virus belonging to the family Bornaviridae within the order Mononegavirales. Whereas BoDV-1 causes neurological and behavioral disorders, called Borna disease (BD), in a wide range of mammals, its virulence in humans has been debated for several decades. However, a series of case reports in recent years have established the nature of BoDV-1 as a zoonotic pathogen that causes fatal encephalitis in humans. Although many virological properties of BoDV-1 have been revealed to date, the mechanism by which it causes fatal encephalitis in humans remains unclear. In addition, there are no effective vaccines or antiviral drugs that can be used in clinical practice. A reverse genetics approach to generating replication-competent recombinant viruses from full-length cDNA clones is a powerful tool that can be used to not only understand viral properties but also to develop vaccines and antiviral drugs. The rescue of recombinant BoDV-1 (rBoDV-1) was first reported in 2005. However, due to the slow nature of the replication of this virus, the rescue of high-titer rBoDV-1 required several months, limiting the use of this system. This review summarizes the history of the reverse genetics and artificial replication systems for orthobornaviruses and explores the recent progress in efforts to rescue rBoDV-1.