Evolutionary Analysis of a Parrot Bornavirus 2 Detected in a Sulphur-Crested Cockatoo (Cacatua galerita) Suggests a South American Ancestor

Abstract

Parrot bornavirus (PaBV) is an RNA virus that causes Proventricular Dilatation Disease (PDD), neurological disorders, and death in Psittaciformes. Its diversity in South America is poorly known. We examined a Cacatua galerita presenting neuropathies, PDD, and oculopathies as the main signs. We detected PaBV through reverse transcription polymerase chain reaction (RT-PCR) and partial sequencing of the nucleoprotein (N) and matrix (M) genes. Maximum likelihood and Bayesian phylogenetic inferences classified it as PaBV-2. The nucleotide identity of the sequenced strain ranged from 88.3% to 90.3% against genotype PaBV-2 and from 80.2% to 84.4% against other genotypes. Selective pressure analysis detected signs of episodic diversifying selection in both the N and M genes. No recombination events were detected. Phylodynamic analysis estimated the time to the most recent common ancestor (TMRCA) as the year 1758 for genotype PaBV-2 and the year 1049 for the Orthobornavirus alphapsittaciforme species. Substitution rates were estimated at 2.73 × 10−4 and 4.08 × 10−4 substitutions per year per site for N and M, respectively. The analysis of population dynamics showed a progressive decline in the effective population size during the last century. Timescale phylogeographic analysis revealed a potential South American ancestor as the origin of genotypes 1, 2, and 8. These results contribute to our knowledge of the evolutionary origin, diversity, and dynamics of PaBVs in South America and the world. Additionally, it highlights the importance of further studies in captive Psittaciformes and the potential impact on endangered wild birds.

Surveillance of Parrot Bornavirus in Taiwan Captive Psittaciformes

“…Taiwan strain NTUCL7 PaBV-4 has 95.89% sequence similarity with NPUSTIAVT-PaBV/Brain-2208023 and 99.7% sequence similarity with NPUSTIAVT-PaBV/Brian-2302010, while Taiwan strain NTUCL51 PaBV-2 has 97.80% sequence similarity with NPUSTIAVT-PaBV/Brain-2301024. Recently, phylogeographic analysis revealed that the South American ancestor could be the origin of PaBV-1, -2, and -8 genotypes [42]. This highlights the importance of further surveillance of Orthobornavirus for captive Psittaciformes, similar to Taiwan.…”

“…Since the first report of avian bornaviruses in 2008, there has been an increase in the number of countries reporting the presence of PaBV, a novel infectious viral agent causing proventricular dilatation disease affecting psittacine birds [1,11,14,[16][17][18][19]21,[35][36][37][38][39][40][41]. In Taiwan, the presence of PaBV has been known through the submitted sequences of the matrix protein (M) gene (MK736729.1-MK736782.1), nucleoprotein (N) gene (MK770085.1-MK770118.1), and PaBV-2 (OM933586.1), PaBV-4 (OM939725.1), and PaBV-5 (OM777141.1) complete genome in GenBank [42]. To further elucidate the PaBV presence in Taiwan, we screened feces samples from 124 psittacine birds collected for a year (June 2022 to May 2023), and demonstrated that 57 were PaBV-positive, with a prevalence of 45.97% and a low survival rate of 8.77%.…”

“…The presence of PaBV in the environment and horizontal transmission to companion psittacine birds is still a challenge to understand [8]. Potential viral reservoirs such as wild free-ranging psittacine birds or other potential host carriers have not been fully illustrated, similar to PaBV host species which are most prevalent, and surveillance reports were carried out in captive, breeding, or companion psittacine birds [1,2,39,42,44,50,51]. In Taiwan, all psittacine birds were introduced, mostly kept as captive, companion, or breeding birds.…”