Shubhagata Das

Evolution of circoviruses in lorikeets lags behind its hosts.

The presence of endogenous viral elements in host genomes hints towards much older host-virus relationships than predicted by exogenous phylogenies, with highly mutable single-stranded DNA (ssDNA) viruses and RNA viruses often occupying entangled multispecies ecological niches. The difficulty lies in unravelling the long-term evolutionary history of vertebrate virus-host relationships and determining the age of a potentially ancient tree based only fresh shoots at the tips. Resolving such lineages, and the sometimes great discrepancy amongst evolutionary timescales, is problematic, especially when purifying selection or recombination can significantly alter the accuracy of phylogenetic reconstruction methods. Pathogens which occupy entangled multispecies ecological niches add a further layer of complexity but we show that multi-host scenarios may also provide opportunities to identify allopatric or sympatric paleobiological signals that can unlock longer term phylogenies. We identified host-based, cryptic, sympatric differentiation in beak and feather disease virus in the Psittaciformes tribe Loriini along with endogenous circovirus motifs in Kea (Nestor notabilis) and Gondwanan vicariance estimates to infer the evolutionary timescale of the circoviruses. This demonstrated a chronology of psittacine circovirus speciation aligned to conservative Zealandic divergences for relic circovirus motifs in Kea and a 10million year divergence coinciding with the Papuan central range orogeny that triggered the radiation of Loriini and segregation of an antecedent viral clade in Australian lorikeets. Estimates of circovirus speciation in birds highlighted a Gondwanan dominant group in Neoaves with passerine, columbid and larid circoviruses deeply separated from those in waterfowl, consistent with a Triassic divergence of Galloanserae. The circovirus tree had a deep ancestry in invertebrates with a Palaeozoic expansion in fish and mammals. We show that longer term evolutionary relationships in viruses which have a high rate of mutation and admixture can be disentangled, highlighting that contemporary virus host-switching can be explained by deep intra-lineage host phylogeny.

Characterization of the Whole-Genome Sequence of a Beak and Feather Disease Virus Isolate from a Mallee Ringneck Parrot (Barnardius zonarius barnardi).

ABSTRACT The complete genome sequence of beak and feather disease virus (BFDV) from a wild Australian Mallee ringneck parrot (Barnardius zonarius barnardi) was characterized. The genome consists of 1,995 nucleotides and encodes two major proteins in opposing directions. This is the first evidence of BFDV infectivity and the first complete genome sequence for this novel host.

A novel pathogenic aviadenovirus from red-bellied parrots (Poicephalus rufiventris) unveils deep recombination events among avian host lineages

Competing roles of coevolution, selective pressure and recombination are an emerging interest in virus evolution. We report a novel aviadenovirus from captive red-bellied parrots (Poicephalus rufiventris) that uncovers evidence of deep recombination among aviadenoviruses. The sequence identity of the virus was most closely related to Turkey adenovirus D (42% similarity) and other adenoviruses in chickens, turkeys and pigeons. Sequencing and comparative analysis showed that the genome comprised 40,930 nucleotides containing 42 predicted open reading frames (ORFs) 19 of which had strong similarity with genes from other adenovirus species. The new genome unveiled a lineage that likely participated in deep recombination events across the genus Aviadenovirus accounting for an ancient evolutionary relationship. We hypothesize frequent host switch events and recombination among adenovirus progenitors in Galloanserae hosts caused the radiation of extant aviadenoviruses and the newly assembled Poicephalus adenovirus genome points to a potentially broader host range of these viruses among birds.

Molecular Characterization of Genome Sequences of Beak and Feather Disease Virus from the Australian Twenty-Eight Parrot (Barnardius zonarius semitorquatus).

ABSTRACT Three complete genomes of beak and feather disease virus (BFDV) were recovered from wild twenty-eight parrots (Polytelis anthopeplus monarchoides). The genomes consisted of 1,996 bp with 1,934 identical sites and a typically content stem-loop structure between ORF1 and ORF2. This is the first report of BFDV infection as well as the complete genome sequences for this host species globally.

Genome sequence of an Australian strain of canid alphaherpesvirus 1

OBJECTIVE Characterisation of a complete genome sequence of an Australian strain of canid alphaherpesvirus 1 (CHV-1) and its phylogenetic relationship with other varicellovirus species. METHODS Standard pathology and PCR methods were used to initially detect herpesvirus in hepatic tissue from an infected 4-week-old Labrador Retriever puppy. The complete CHV-1 genome was sequenced using next-generation sequencing technology followed by de novo and reference assembly, and genome annotation. RESULTS The CHV-1 genome was 125 kbp in length and contained 74 predicted open reading frames encoding functional proteins, all of which have counterparts in other alphaherpesviruses. Phylogenetic analysis using the DNA polymerase gene revealed that the newly sequenced CHV-1 clustered with canid alphaherpesvirus isolated from the UK and shared a 99% overall nucleotide sequence similarity. CONCLUSION This is the first complete genome of an Australian strain of CHV-1, which will contribute to our understanding of the genetics and evolution of herpesvirus.

The complete mitochondrial genome sequence of an Endangered powerful owl (Ninox strenua)

Abstract In this paper, the complete mitochondrial genome of an Endangered Ninox strenua is sequenced and reported for the first time. The mitogenome of N. strenua is a circular molecule of 16,206 bp in length, consisting of 13 protein-coding genes (PCGs), 22 tRNA, 2 rRNA, and a control region (D-loop). All the genes in N. strenua are distributed on the H-strand, except for the ND6 subunit gene and eight tRNA genes, which are encoded on the L-strand. Phylogenetic analysis using an available mitogenome of Strigidae family revealed a close evolutionary relationship of N. strenua with N. novaeseelandiae, a Tasmanian spotted owl found throughout the Australasia.

A comparison of PCR assays for beak and feather disease virus and high resolution melt (HRM) curve analysis of replicase associated protein and capsid genes.

Beak and feather disease virus (BFDV) threatens a wide range of endangered psittacine birds worldwide. In this study, we assessed a novel PCR assay and genetic screening method using high-resolution melt (HRM) curve analysis for BFDV targeting the capsid (Cap) gene (HRM-Cap) alongside conventional PCR detection as well as a PCR method that targets a much smaller fragment of the virus genome in the replicase initiator protein (Rep) gene (HRM-Rep). Limits of detection, sensitivity, specificity and discriminatory power for differentiating BFDV sequences were compared. HRM-Cap had a high positive predictive value and could readily differentiate between a reference genotype and 17 other diverse BFDV genomes with more discriminatory power (genotype confidence percentage) than HRM-Rep. Melt curve profiles generated by HRM-Cap correlated with unique DNA sequence profiles for each individual test genome. The limit of detection of HRM-Cap was lower (2×10-5ng/reaction or 48 viral copies) than that for both HRM-Rep and conventional BFDV PCR which had similar sensitivity (2×10-6ng or 13 viral copies/reaction). However, when used in a diagnostic setting with 348 clinical samples there was strong agreement between HRM-Cap and conventional PCR (kappa=0.87, P<0.01, 98% specificity) and HRM-Cap demonstrated higher specificity (99.9%) than HRM-Rep (80.3%).

The first complete mitogenome of red-bellied parrot (Poicephalus rufiventris) resolves phylogenetic status within Psittacidae

Abstract This paper describes the genomic architecture of a complete mitogenome from a red-bellied parrot (Poicephalus rufiventris). The mitogenome sequence was circular and 15,524 bp in length. Compared to other Psittacidae species, the genome encoded a conserved structure consisting of 13 protein-coding genes (PCGs), two rRNA genes, 21 tRNA genes, and two control regions, however, the mitogenome was missing a part of control region and a tRNA-Leu. The lengths of 12S and 16S ribosomal RNA were 975 bp and 1569 bp, respectively. The overall base composition of the mitogenome of P. rufiventris was dominated by higher AT (51.6%) than GC (48.4%) content. The complete mitogenome sequence determined in this study would be useful to track the deeper evolutionary history and the conservation of P. rufiventris.

The first complete mitogenome of Indian star tortoise (Geochelone elegans)

Abstract The complete mitochondrial genome of Indian star tortoise (Geochelone elegans) was characterized having 16,446 bp nucleotides encoding 37 genes in circular orientation comprising 13 protein-coding genes, 22 tRNA genes and two rRNA genes. The lengths of 12S and 16S ribosomal RNA were 973 bp and 1600 bp. A non-coding control region (D-Loop) of 966 bp was identified between tRNAPro and tRNAPhe having seven interrupted tandem repeats. A single A + 1 frameshift insertion in the ND3 gene (ND3-174) was also discovered. The complete mitogenome of G. elegans would contribute in deeper understanding of the evolutionary dynamics and conservation effort of vulnerable testudine families.

Complete mitochondrial genome sequence of an Australian little penguin (Eudyptula minor novaehollandia), J.R. Forster, 1781).

Abstract In this paper, we report the complete mitochondrial genome of an Australian little penguin (Eudyptula minor novaehollandia). The mitogenome sequence has been found to be circular, and 17,608 bp in length. Similar to other Spheniscidae species, the genome encoded a typically conserved structure consisting of 13 protein-coding genes (PCGs), two rRNA genes, and 22 tRNA genes, as well as all protein coding sequences started with methionine. The lengths of 12S ribosomal RNA and 16S ribosomal RNA were 977 bp and 1612 bp, respectively, and were located between tRNA-Phe and tRNA-Leu. The overall base composition of the mitogenome of E. minor novaehollandia had slightly higher AT (55.5%) content than GC (45.5%). The complete mitogenome sequence determined in this study would be useful to track the deeper evolutionary history and conservation of E. minor novaehollandia.