Analysis of codon usage pattern in the viral proteins of chicken anaemia virus and its possible biological relevance

Codon usage bias of goose circovirus and its adaptation to host

Goose circovirus (GoCV), a potential immunosuppressive virus possessing a circular single-stranded DNA genome, is widely distributed in both domesticated and wild geese. This virus infection causes significant economic losses in the waterfowl industry. The codon usage patterns of viruses reflect the evolutionary history and genetic architecture, allowing them to adapt quickly to changes in the external environment, particularly to their hosts. In this study, we retrieved the coding sequences (Rep and Cap) and the genome of GoCV from GenBank, conducting comprehensive research to explore the codon usage patterns in 144 GoCV strains. The overall codon usage of the GoCV strains was relatively similar and exhibited a slight bias. The effective number of codons (ENC) indicated a low overall extent of codon usage bias (CUB) in GoCV. Combined with the base composition and relative synonymous codon usage (RSCU) analysis, the results revealed a bias toward A- and G-ending codons in the overall codon usage. Analysis of the ENC-GC3s plot and neutrality plot suggested that natural selection plays an important role in shaping the codon usage pattern of GoCV, with mutation pressure having a minor influence. Furthermore, the correlations between ENC and relative indices, as well as correspondence analysis (COA), showed that hydrophobicity and geographical distribution also contribute to codon usage variation in GoCV, suggesting the possible involvement of natural selection. In conclusion, GoCV exhibits comparatively slight CUB, with natural selection being the major factor shaping the codon usage pattern of GoCV. Our research contributes to a deeper understanding of GoCV evolution and its host adaptation, providing valuable insights for future basic studies and vaccine design related to GoCV.

Analysis of codon usage bias of exonuclease genes in invertebrate iridescent viruses

Invertebrate iridescent viruses (IIVs) are double-stranded DNA viruses that belong to the Iridoviridae family. IIVs result diseases that vary in severity from subclinical to lethal in invertebrate hosts. Codon usage bias (CUB) analysis is a versatile method for comprehending the genetic and evolutionary aspects of species. In this study, we analyzed the CUB in 10 invertebrate iridescent viruses exonuclease genes by calculating and comparing the nucleotide contents, effective number of codons (ENC), codon adaptation index (CAI), relative synonymous codon usage (RSCU), and others. The results revealed that IIVs exonuclease genes are rich in A/T. The ENC analysis displayed a low codon usage bias in IIVs exonuclease genes. ENC-plot, neutrality plot, and parity rule 2 plot demonstrated that besides mutational pressure, other factors like natural selection, dinucleotide content, and aromaticity also contributed to CUB. The findings could enhance our understanding of the evolution of IIVs exonuclease genes.

Genetic changes and evolutionary analysis of canine circovirus

Canine circovirus (canineCV) has been found to be associated with vasculitis, hemorrhage, hemorrhagic enteritis, and diarrhea of canines. CanineCV, like other circoviruses, may also be associated with lymphoid depletion and immunosuppression. This circovirus has been detected worldwide in different countries and species. Recombination and mutation events in the canineCV genome have been described, indicating that the virus is continuing to evolve. However, the origin, codon usage patterns, and host adaptation of canineCV remain to be studied. Here, the coding sequences of 93 canineCV sequences available in the GenBank database were used for analysis. The results showed that canineCV sequences could be classified into five genotypes, as confirmed by phylogenetic and principal component analysis (PCA). Maximum clade credibility (MCC) and maximum-likelihood (ML) trees suggested that canineCV originated from bat circovirus. G/T and A/C nucleotide biases were observed in ORF1 and ORF2, respectively, and a low codon usage bias (CUB) was found in canineCV using an effective number of codon (ENC) analysis. Correlation analysis, ENC plot analysis and neutrality plot analysis indicated that the codon usage pattern was mainly shaped by natural selection. Codon adaptation index (CAI) analysis, relative codon deoptimization index (RCDI) analysis, and similarity index (SiD) analysis revealed a better adaption to Vulpes vulpes than to Canis familiaris. Furthermore, a cross-species transmission hypothesis that canineCV may have evolved from bats (origin analysis) and subsequently adapted to wolves, arctic foxes, dogs, and red foxes, was proposed. This study contributes to our understanding of the factors related to canineCV evolution and host adaption.

Insight into Codon Utilization Pattern of Tumor Suppressor Gene EPB41L3 from Different Mammalian Species Indicates Dominant Role of Selection Force

Simple Summary

The present study envisaged the codon usage pattern analysis of tumor suppressor gene EPB41L3 for the human, brown rat, domesticated cattle, and Sumatran orangutan. Most amino acids are coded by more than one synonymous codon, but they are used in a biased manner. The codon usage bias results from multiple factors like compositional properties, dinucleotide abundance, neutrality, parity, tRNA pool, etc. Understanding codon bias is central to fields as diverse as molecular evolution, gene expressivity, protein translation, and protein folding. This kind of studies is important to see the effects of various evolutionary forces on codon usage. The present study indicated that the selection force is dominant over other forces shaping codon usage in the envisaged organisms.

Abstract

Uneven codon usage within genes as well as among genomes is a usual phenomenon across organisms. It plays a significant role in the translational efficiency and evolution of a particular gene. EPB41L3 is a tumor suppressor protein-coding gene, and in the present study, the pattern of codon usage was envisaged. The full-length sequences of the EPB41L3 gene for the human, brown rat, domesticated cattle, and Sumatran orangutan available at the NCBI were retrieved and utilized to analyze CUB patterns across the selected mammalian species. Compositional properties, dinucleotide abundance, and parity analysis showed the dominance of A and G whilst RSCU analysis indicated the dominance of G/C-ending codons. The neutrality plot plotted between GC12 and GC3 to determine the variation between the mutation pressure and natural selection indicated the dominance of selection pressure (R = 0.926; p < 0.00001) over the three codon positions across the gene. The result is in concordance with the codon adaptation index analysis and the ENc-GC3 plot analysis, as well as the translational selection index (P2). Overall selection pressure is the dominant pressure acting during the evolution of the EPB41L3 gene.

Analysis of the Codon Usage Pattern of HA and NA Genes of H7N9 Influenza A Virus

Novel H7N9 influenza virus transmitted from birds to human and, since March 2013, it has caused five epidemic waves in China. Although the evolution of H7N9 viruses has been investigated, the evolutionary changes associated with codon usage are still unclear. Herein, the codon usage pattern of two surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), was studied to understand the evolutionary changes in relation to host, epidemic wave, and pathogenicity. Both genes displayed a low codon usage bias, with HA higher than NA. The codon usage was driven by mutation pressure and natural selection, although the main contributing factor was natural selection. Additionally, the codon adaptation index (CAI) and deoptimization (RCDI) illustrated the strong adaptability of H7N9 to Gallus gallus. Similarity index (SiD) analysis showed that Homo sapiens posed a stronger selection pressure than Gallus gallus. Thus, we assume that this may be related to the gradual adaptability of the virus to human. In addition, the host strong selection pressure was validated based on CpG dinucleotide content. In conclusion, this study analyzed the usage of codons of two genes of H7N9 and expanded our understanding of H7N9 host specificity. This aids into the development of control measures against H7N9 influenza virus.

Novel Gyrovirus genomes recovered from free-living pigeons in Southern Brazil

Wild birds carry a number of infectious agents, some of which may have pathogenic potential for the host and others species, including humans. Domestic pigeons (Columba livia) are important targets of study since these increasingly cohabit urban spaces, being possible spillover sources of pathogens to humans. In the present study, two genomes (PiGyV_Tq/RS/Br and PiGyV_RG/RS/Br), representative of Gyrovirus genus, family Anelloviridae, were detected in sera of free-living pigeons collected in Southern Brazil. The genomes exhibit less than 50% identity to previously described members of Gyrovirus genus, suggesting that they constitute a new viral species circulating in pigeons, to which the name "pigeon gyrovirus (PiGyV)" is proposed. The current study characterizes these two PiGyV genomes which, to date, are the first gyrovirus species identified in domestic pigeons.

Genetic Analysis and Evolutionary Changes of the Torque teno sus Virus

The torque teno sus virus (TTSuV) is an emerging virus threating the Suidae species of unclear pathogenicity, although it was previously reported as a worsening factor of other porcine diseases, in particular, porcine circovirus associated disease (PCVAD). Here, a comprehensive codon usage analysis of the open reading frame 1 (ORF1), which encodes the viral capsid protein, was undertaken for the first time to reveal its evolutionary history. We revealed independent phylogenetic processes for the two genera during TTSuV evolution, which was confirmed by principal component analysis (PCA). A low codon usage bias was observed in different genera and different species, with Kappatorquevirus a (TTSuVk2a) displaying the highest, which was mainly driven by mutation pressure and natural selection, especially natural selection. Overall, ATs were more abundant than GCs, along with more A-ended synonymous codons in relative synonymous codon usage (RSCU) analysis. To further confirm the role of natural selection and TTSuV adaptation to the Suidae species, codon adaptation index (CAI), relative codon deoptimization index (RCDI), and similarity index (SiD) analyses were performed, which showed different adaptations for different TTSuVs. Importantly, we identified a more dominant role of Sus scrofa in the evolution of Iotatorquevirus (TTSuV1), with the highest CAI values and lowest RCDI values compared to Sus scrofa domestica. However, in TTSuVk2, the roles of Sus scrofa and Sus scrofa domestica were the same, regarding codon usage, with similar CAI and RCDI values. Our study provides a new perspective of the evolution of TTSuV and valuable information to develop control measures against TTSuV.