The characteristic of the synonymous codon usage and phylogenetic analysis of hepatitis B virus

Decoding codon usage in human papillomavirus type 59

Human Papillomavirus Type 59 (HPV-59) is a high-risk subtype linked to cervical and other cancers. However, its codon usage patterns remain underexplored despite their importance in understanding viral behavior and vaccine optimization. This study reveals a mild codon usage bias in HPV-59, with a notable preference for A/T-ending codons and 29 favored codons, primarily ending in A or T. Additionally, CpG dinucleotides were significantly underrepresented, potentially aiding immune evasion. Analyses using the Parity Rule 2, Effective Number of Codons plot, and neutrality plot indicate that both mutational pressure and natural selection shape codon usage, with natural selection playing a dominant role. The virus's codon usage moderately aligns with human translational machinery, as shown by the Isoacceptor tRNA pool, Codon Adaptation Index, and Relative Codon Deoptimization Index, reflecting an evolutionary balance between protein synthesis efficiency and host compatibility. These findings provide valuable insights into HPV-59 biology, offering guidance for developing optimized vaccines.

Codon usage bias analysis of the gene encoding NAD+-dependent DNA ligase protein of Invertebrate iridescent virus 6

The genome of Invertebrate iridescent virus 6 (IIV6) contains a sequence that shows similarity to eubacterial NAD+-dependent DNA ligases. The 615-amino acid open reading frame (ORF 205R) consists of several domains, including an N-terminal domain Ia, followed by an adenylation domain, an OB-fold domain, a helix-hairpin-helix (HhH) domain, and a BRCT domain. Notably, the zinc finger domain, typically present in NAD+-dependent DNA ligases, is absent in ORF 205R. Since the protein encoded by ORF 205R (IIV6 DNA ligase gene) is involved in critical functions such as DNA replication, modification, and repair, it is crucial to comprehend the codon usage associated with this gene. In this paper, the codon usage bias (CUB) in DNA ligase gene of IIV6 and 11 reference iridoviruses was analyzed by comparing the nucleotide contents, relative synonymous codon usage (RSCU), effective number of codons (ENC), codon adaptation index (CAI), relative abundance of dinucleotides and other indices. Both the base content and the RCSU analysis indicated that the A- and T-ending codons were mostly favored in the DNA ligase gene of IIV6. The ENC value of 35.64 implied a high CUB in the IIV6 DNA ligase gene. The ENC plot, neutrality plot, parity rule 2 plot, correspondence analysis revealed that mutation pressure and natural selection had an impact on the CUB of the IIVs DNA ligase genes. Additionally, the analysis of codon adaptation index demonstrated that the IIV6 DNA ligase gene is strongly adapted to its host. These findings will improve our comprehension of the CUB of IIV6 DNA ligase and reference genes, which may provide the required information for a fundamental evolutionary analysis of these genes.

The first two mitochondrial genomes from Apiotrichum reveal mitochondrial evolution and different taxonomic assignment of Trichosporonales

Apiotrichum is a diverse anamorphic basidiomycetous yeast genus, and its mitogenome characterization has not been revealed. In this study, we assembled two Apiotrichum mitogenomes and compared them with mitogenomes from Agaricomycotina, Pucciniomycotina and Ustilaginomycotina. The mitogenomes of Apiotrichum gracile and A. gamsii comprised circular DNA molecules, with sizes of 34,648 bp and 38,096 bp, respectively. Intronic regions were found contributed the most to the size expansion of A. gamsii mitogenome. Comparative mitogenomic analysis revealed that 6.85-38.89% of nucleotides varied between tRNAs shared by the two Apiotrichum mitogenomes. The GC content of all core PCGs in A. gamsii was lower than that of A. gracile, with an average low value of 4.97%. The rps3 gene differentiated the most among Agaricomycotina, Pucciniomycotina and Ustilaginomycotina species, while nad4L gene was the most conserved in evolution. The Ka/Ks values for cob and rps3 genes were > 1, indicating the two genes may be subjected to positive selection in Agaricomycotina, Pucciniomycotina and Ustilaginomycotina. Frequent intron loss/gain events and potential intron transfer events have been detected in evolution of Agaricomycotina, Pucciniomycotina and Ustilaginomycotina. We further detected large-scale gene rearrangements between the 19 mitogenomes from Agaricomycotina, Pucciniomycotina and Ustilaginomycotina, and fifteen of the 17 mitochondrial genes shared by Apiotrichum varied in gene arrangements. Phylogenetic analyses based on maximum likelihood and Bayesian inference methods using a combined mitochondrial gene dataset revealed different taxonomic assignment of two Apiotrichum species, wherein A. gamsii had a more closely relationship with Trichosporon asahii. This study served as the first report on mitogenomes from the genus Apiotrichum, which promotes the understanding of evolution, genomics, and phylogeny of Apiotrichum.

Synonymous Codon Usage Analysis of Three Narcissus Potyviruses

Narcissus degeneration virus (NDV), narcissus late season yellows virus (NLSYV) and narcissus yellow stripe virus (NYSV), which belong to the genus Potyvirus of the family Potyviridae, cause significant losses in the ornamental value and quality of narcissus. Several previous studies have explored the genetic diversity and evolution rate of narcissus viruses, but the analysis of the synonymous codons of the narcissus viruses is still unclear. Herein, the coat protein (CP) of three viruses is used to analyze the viruses’ phylogeny and codon usage pattern. Phylogenetic analysis showed that NYSV, NDV and NLSYV isolates were divided into five, three and five clusters, respectively, and these clusters seemed to reflect the geographic distribution. The effective number of codon (ENC) values indicated a weak codon usage bias in the CP coding region of the three narcissus viruses. ENC-plot and neutrality analysis showed that the codon usage bias of the three narcissus viruses is all mainly influenced by natural selection compared with the mutation pressure. The three narcissus viruses shared the same best optimal codon (CCA) and the synonymous codon prefers to use codons ending with A/U, compared to C/G. Our study shows the codon analysis of different viruses on the same host for the first time, which indicates the importance of the evolutionary-based design to control these viruses.

Relative synonymous codon usage of ORF1ab in SARS-CoV-2 and SARS-CoV

Background

COVID-19, as a novel coronavirus disease caused by new coronavirus SARS-CoV-2, spreads all over the world, and brings harm to human in many countries. Humans suffered a lot from both SARS-CoV-2 now and by SARS-CoV in the year 2003. It is important to understand the differences and the relationships between these two types of viruses.

Objective

To compare relative synonymous codon usage of ORF1ab gene in SARS-CoV-2 and SARS-CoV, relative synonymous codon usage of their genomes are studied in this paper from the bioinformatics perspective.

Methods

The ORF1ab gene, which is an important non-structural polyprotein coding gene and now used for nucleic acid detection markers in many measurement method, in both SARS-CoV-2 (30 strains) and SARS-CoV (20 strains) are considered to be the research object in the present paper. The relative synonymous codon usage values of the ORF1ab gene are calculated to characterize the differences and the evolutionary characteristics among 50 strains.

Results

There is a significant difference between SARS-CoV and SARS-CoV-2 when the relative synonymous codon usage value of ORF1ab genes is concerned. The results suggest that codon usage pattern of SARS-CoV is more similar to human than that of the SARS-CoV-2, and that the inner difference in SARS-CoV-2 strains is larger than that of SARS-CoV, which denote the larger diversity exits in the SARS-CoV-2 virus.

Conclusion

These results show that the relative synonymous codon usage values in the coronavirus could be used for further research on their evolutionary phenomenon.

Edging on Mutational Bias, Induced Natural Selection From Host and Natural Reservoirs Predominates Codon Usage Evolution in Hantaan Virus

The molecular evolutionary dynamics that shape hantaviruses’ evolution are poorly understood even now, besides the contribution of virus-host interaction to their evolution remains an open question. Our study aimed to investigate these two aspects in Hantaan virus (HTNV)—the prototype of hantaviruses and an emerging zoonotic pathogen that infects humans, causing hemorrhagic fever with renal syndrome (HFRS): endemic in Far East Russia, China, and South Korea—via a comprehensive, phylogenetic-dependent codon usage analysis. We found that host- and natural reservoir-induced natural selection is the primary determinant of its biased codon choices, exceeding the mutational bias effect. The phylogenetic analysis of HTNV strains resulted in three distinct clades: South Korean, Russian, and Chinese. An effective number of codon (ENC) analysis showed a slightly biased codon usage in HTNV genomes. Nucleotide composition and RSCU analyses revealed a significant bias toward A/U nucleotides and A/U-ended codons, indicating the potential influence of mutational bias on the codon usage patterns of HTNV. Via ENC-plot, Parity Rule 2 (PR2), and neutrality plot analyses, we would conclude the presence of both mutation pressure and natural selection effect in shaping the codon usage patterns of HTNV; however, natural selection is the dominant factor influencing its codon usage bias. Codon adaptation index (CAI), Relative codon deoptimization index (RCDI), and Similarity Index (SiD) analyses uncovered the intense selection pressure from the host (Human) and natural reservoirs (Striped field mouse and Chinese white-bellied rat) in shaping HTNV biased codon choices. Our study clearly revealed the evolutionary processes in HTNV and the role of virus-host interaction in its evolution. Moreover, it opens the door for a more comprehensive codon usage analysis for all hantaviruses species to determine their molecular evolutionary dynamics and adaptability to several hosts and environments. We believe that our research will help in a better and deep understanding of HTNV evolution that will serve its future basic research and aid live attenuated vaccines design.