Evolutionary History and Genetic Variation of Zika Virus: Connection Between Thailand Zika Viruses and Global Outbreaks Strains.

Background: Zika virus (ZIKV) has significant potential to cause future outbreaks due to insufficient countermeasures. The evolution of ZIKV in Southeast Asian countries remains poorly understood. Materials and Methods: The phylogenetic, phylogeographic network, and recombination analyses of 366 ZIKV complete genome sequences identified between 1947 and 2021 were performed and the amino acid variation landscape was determined to reveal the evolutionary characteristics. Results: ZIKV falls into two major genogroups: GI and GII, segregated into further subgenogroups (GI-1 to GI-3) and (GII-1 to GII-3), respectively. Importantly, Thailand strains cluster with Southeast Asian outbreak strains (Singapore 2016, the Philippines 2012, Cambodia 2010) into GII-2 and form a lineage independent of French Polynesia and the Americas large outbreak strains. Thailand ZIKV strains shared their ancestral route to the strains from French Polynesia, which further connects to Brazil ZIKV through a short mutational branch. Both recombination and specific mutations may contribute to the emergence of new virus lineage in Thailand. Conclusion: This report provides insights into the evolutionary characteristics of ZIKV in Southeast Asia, which may be helpful for epidemiological investigation, vaccine development, and surveillance of the virus.

Genetic Characteristics and Phylogeographic Dynamics of Echovirus.

Echoviruses belong to the genus Enterovirus in the Picornaviridae family, forming a large group of Enterovirus B (EV-B) within the Enteroviruses. Previously, Echoviruses were classified based on the coding sequence of VP1. In this study, we performed a reliable phylogenetic classification of 277 sequences isolated from 1992 to 2019 based on the full-length genomes of Echovirus. In this report, phylogenetic, phylogeographic, recombination, and amino acid variability landscape analyses were performed to reveal the evolutional characteristics of Echovirus worldwide. Echoviruses were clustered into nine major clades, e.g., G1-G9. Phylogeographic analysis showed that branches G2-G9 were linked to common strains, while the branch G1 was only linked to G5. In contrast, strains E12, E14, and E16 clustered separately from their G3 and G7 clades respectively, and became a separate branch. In addition, we identified a total of 93 recombination events, where most of the events occurred within the VP1-VP4 coding regions. Analysis of amino acid variation showed high variability in the a positions of VP2, VP1, and VP3. This study updates the phylogenetic and phylogeographic information of Echovirus and indicates that extensive recombination and significant amino acid variation in the capsid proteins drove the emergence of new strains.

Duck hepatitis a virus: Full-length genome-based phylogenetic and phylogeographic view during 1986-2020.

Duck hepatitis A virus (DHAV) is one of key pathogens for duck viral hepatitis, especially in Asian duck industry. Currently, two main genotypes (DHAV-1 and -3) exist. To explore insightfully the evolutionary character, we assessed the available 141 full-length genome sequences of DHAV isolated in 1986-2020 globally and divided DHAV-1 and DHAV-3 into further seven (DHAV-1 a-g) and five (DHAV-3 a-e) sub-clades, respectively. Phylogenetic and phylogeographic network analyses indicated great genetic diversity of DHAV identified in China, where the DHAV-1 cluster and DHAV-3 cluster were linked by virus strain HDHV1-BJ (GenBank ID: FJ157172.1) and Du_CH_LSD_090612 (GenBank ID: JF828995.1) via a long mutational branch and intermediate strains. Several strains previously identified as DHAV-1 according to the partial gene sequences were actually clustered within DHAV-3 in full-length genome-based analysis. Furthermore, we identified 32 recombination events across virus genome with the recombination hotspot at the 5' end and upstream of the capsid coding region. The highest variability of DHAV polyprotein was shown at the upstream region of the N terminus P-loop region, e.g., amino acids 672-716, followed by the aa 334-359 in the Capsid encoding region. The results presented here provides a robust insight into the genetic exchange patterns of DHAV genomes during the past decades, which may be used to map the evolutionary history and facilitate preventive measures of DHAVs.

Multiple potential recombination events among Newcastle disease virus genomes in China between 1946 and 2020.

Introduction: Newcastle Disease Virus (NDV) is a highly adaptable virus with large genetic diversity that has been widely studied for its oncolytic activities and potential as a vector vaccine. This study investigated the molecular characteristics of 517 complete NDV strains collected from 26 provinces across China between 1946-2020. Methods: Herein, phylogenetic, phylogeographic network, recombination, and amino acid variability analyses were performed to reveal the evolutionary characteristics of NDV in China. Results and discussions: Phylogenetic analysis revealed the existence of two major groups: GI, which comprises a single genotype Ib, and GII group encompassing eight genotypes (I, II, III, VI. VII. VIII, IX and XII). The Ib genotype is found to dominate China (34%), particularly South and East China, followed by VII (24%) and VI (22%). NDV strains from the two identified groups exhibited great dissimilarities at the nucleotide level of phosphoprotein (P), matrix protein (M), fusion protein (F), and haemagglutinin-neuraminidase (HN) genes. Consistently, the phylogeographic network analysis revealed two main Network Clusters linked to a possible ancestral node from Hunan (strain MH289846.1). Importantly, we identified 34 potential recombination events that involved mostly strains from VII and Ib genotypes. A recombinant of genotype XII isolated in 2019 seems to emerge newly in Southern China. Further, the vaccine strains are found to be highly involved in potential recombination. Therefore, since the influence of recombination on NDV virulence cannot be predicted, this report's findings need to be considered for the security of NDV oncolytic application and the safety of NDV live attenuated vaccines.

Genetic Characteristics and Phylogeographic Dynamics of Lagoviruses, 1988-2021.

Rabbit haemorrhagic disease virus (RHDV), European brown hare syndrome virus (EBHSV), rabbit calicivirus (RCV), and hare calicivirus (HaCV) belong to the genus Lagovirus of the Caliciviridae family that causes severe diseases in rabbits and several hare (Lepus) species. Previously, Lagoviruses were classified into two genogroups, e.g., GI (RHDVs and RCVs) and GII (EBHSV and HaCV) based on partial genomes, e.g., VP60 coding sequences. Herein, we provide a robust phylogenetic classification of all the Lagovirus strains based on full-length genomes, grouping all the available 240 strains identified between 1988 and 2021 into four distinct clades, e.g., GI.1 (classical RHDV), GI.2 (RHDV2), HaCV/EBHSV, and RCV, where the GI.1 clade is further classified into four (GI.1a-d) and GI.2 into six sub-clades (GI.2a-f). Moreover, the phylogeographic analysis revealed that the EBHSV and HaCV strains share their ancestor with the GI.1, while the RCV shares with the GI.2. In addition, all 2020-2021 RHDV2 outbreak strains in the USA are connected to the strains from Canada and Germany, while RHDV strains isolated in Australia are connected with the USA-Germany haplotype RHDV strain. Furthermore, we identified six recombination events in the VP60, VP10, and RNA-dependent RNA polymerase (RdRp) coding regions using the full-length genomes. The amino acid variability analysis showed that the variability index exceeded the threshold of 1.00 in the ORF1-encoded polyprotein and ORF2-encoded VP10 protein, respectively, indicating significant amino acid drift with the emergence of new strains. The current study is an update of the phylogenetic and phylogeographic information of Lagoviruses that may be used to map the evolutionary history and provide hints for the genetic basis of their emergence and re-emergence.

Genetic diversity, distribution, and evolution of chicken anemia virus: A comparative genomic and phylogenetic analysis.

Chicken infectious anemia (CIA) is an immunosuppressive poultry disease that causes aplastic anemia, immunosuppression, growth retardation and lymphoid tissue atrophy in young chickens and is responsible for huge economic losses to the poultry industry worldwide. The disease is caused by the chicken anemia virus (CAV), which belongs to the genus Gyrovirus, family Anelloviridae. Herein, we analyzed the full-length genomes of 243 available CAV strains isolated during 1991-2020 and classified them into two major clades, GI and GII, divided into three and four sub-clades, GI a-c, and GII a-d, respectively. Moreover, the phylogeographic analysis revealed that the CAVs spread from Japan to China, China to Egypt and subsequently to other countries, following multiple mutational steps. In addition, we identified eleven recombination events within the coding and non-coding regions of CAV genomes, where the strains isolated in China were the most active and involved in ten of these events. Furthermore, the amino acids variability analysis indicated that the variability coefficient exceeded the estimation limit of 1.00 in VP1, VP2, and VP3 proteins coding regions, demonstrating substantial amino acid drift with the rise of new strains. The current study offers robust insights into the phylogenetic, phylogeographic and genetic diversity characteristics of CAV genomes that may provide valuable data to map the evolutionary history and facilitate preventive measures of CAVs.

Evolutionary plasticity of zoonotic porcine Deltacoronavirus (PDCoV): genetic characteristics and geographic distribution.

The emergence and rapid spread of the acute respiratory syndrome coronavirus-2 have confirmed that animal coronaviruses represent a potential zoonotic source. Porcine deltacoronavirus is a worldwide evolving enteropathogen of swine, detected first in Hong Kong, China, before its global identification. Following the recent detection of PDCoV in humans, we attempted in this report to re-examine the status of PDCoV phylogenetic classification and evolutionary characteristics. A dataset of 166 complete PDCoV genomes was analyzed using the Maximum Likelihood method in IQ-TREE with the best-fitting model GTR + F + I + G4, revealing two major genogroups (GI and GII), with further seven and two sub-genogroups, (GI a-g) and (GII a-b), respectively. PDCoV strains collected in China exhibited the broadest genetic diversity, distributed in all subgenotypes. Thirty-one potential natural recombination events were identified, 19 of which occurred between China strains, and seven involved at least one China strain as a parental sequence. Importantly, we identified a human Haiti PDCoV strain as recombinant, alarming a possible future spillover that could become a critical threat to human health. The similarity and recombination analysis showed that PDCoV spike ORF is highly variable compared to ORFs encoding other structural proteins. Prediction of linear B cell epitopes of the spike glycoprotein and the 3D structural mapping of amino acid variations of two representative strains of GI and GII showed that the receptor-binding domain (RBD) of spike glycoprotein underwent a significant antigenic drift, suggesting its contribution in the genetic diversity and the wider spread of PDCoV.

Identification of novel recombinants and proposed standard reference genomes for phylogenetic classification of canine parvovirus-2 (CPV-2): Comprehensive analysis revealing global evolutionary trait.

Sustained spread and continuous evolution of CPV-2 generate new genetic information; nevertheless, there is no adopted phylogenetic tool, and parvo virologists still refer to the three antigenic variants. Herein, this report attempted to review the evolutionary trait of CPV-2 and proposed standard reference genomes using the Maximum Likelihood-based phylogenetic analysis and Parsimony-Informative Sites. The analysis revealed three main evolutionary pathways where CPV-2 strains cluster into distinct clades depicted as GI, GII, or GIII, respectively. Furthermore, novel CPV-2 natural recombinants were detected, occurring only between the newly identified strains (2017-2020). Those findings provide unique insights into the evolutionary relatedness of CPV-2, clarify discrepancies between different geographic areas and will contribute to achieving a more reliable CPV-2 genetic and evolutionary genotyping classification.

Complete genome sequences of classical swine fever virus: Phylogenetic and evolutionary analyses.

The classical swine fever virus (CSFV) outbreaks cause colossal losses of pigs and drastic economic impacts. The current phylogenetic CSFV groups were determined mainly based on the partial genome. Herein, 203 complete genomic sequences of CSFVs collected worldwide between 1998 and 2018 available on the GenBank database were retrieved for re-genotyping and recombination analysis. The maximum likelihood phylogenetic tree determined two main groups, GI and GII, with multiple sub-genotypes. The "strain 39" (GenBank ID: AF407339), previously identified as belonging to sub-genotypes 1.1 or 2.2 based on the partial sequences, is found to be genetically distinct and independent, forming a new lineage depicted as GI-2.2b. Ten potential natural recombination events were identified, seven of which were collected in China and found involved in the genetic diversity of CSFVs. Importantly, the vaccine strains and highly virulent strains were all involved in the recombination events, which would induce extra challenges to vaccine development. These findings alarm that attenuated vaccines should be applied with discretion and recommend using subunit vaccines in parallel with other preventive strategies for better management of CSFVs.

Global Distribution and Natural Recombination of Hepatitis D Virus: Implication of Kyrgyzstan Emerging HDVs in the Clinical Outcomes.

Discrepancies in human hepatitis delta virus (HDV) genotypes impact the virus' biological behavior, clinical manifestation, and treatment response. Herein, this report aims to explore the role of recombination in the worldwide genotypic distribution and genetic diversity of HDV. Three-hundred-forty-eight human HDV full-length genomic sequences of ~1678 nt in length, isolated in twenty-eight countries worldwide between 1986 and 2018, were analysed. Similarity analysis and recombination mapping were performed, and forty-eight recombination events were identified, twenty-nine of which were isolated from Kyrgyzstan and determined to be involved in the diversity and extension of HDV sub-genotypes. HDV recombination occurred only between the genetically close genotypes (genotype 5 and genotype 2) or mainly within genotype 1, suggesting the complex replicative molecular mechanisms of HDV-RNA. The global distribution and classification of HDV genotypes have been updated, indicating that HDV recombination is one of the driving forces behind the biodiversity and the evolution of human HDV genomes. The outcome analysis suggests that the expansion of HDV sub-genotypes and the complex recombination networks might be related to the genomic character of Kyrgyzstan circulating strains and extensive mobility within countries and across borders. These findings will be of great importance in formulating more effective public health HDV surveillance strategies and guiding future molecular and epidemiological research to achieve better clinical outcomes.

Genomic characteristics and recombination patterns of swine hepatitis E virus in China.

Zoonotic hepatitis E, mainly caused by swine hepatitis E virus (sHEV), is endemic in China, causing great economic disruption and public health threats. Although recombination is critical for the evolution of viruses, there is a limited assessment of its occurrence among sHEVs. Herein, we analysed all available sHEV full-length genomes isolated in China during the past two decades (40 isolates) compared to 72 other sHEV strains isolated in different countries and determined that sHEV genotype 4 (sHEV4) dominates China. Eight potential natural recombination events were identified, four of which occurred in China and were mainly between sHEV4 strains, indicating the distinct character of China sHEV. One intergenotype recombination event was found in China, alarming the emergence of a new sHEV lineage that could become a critical threat to human health.

Genetic Characteristics of Porcine Hemagglutinating Encephalomyelitis Coronavirus: Identification of Naturally Occurring Mutations Between 1970 and 2015.

Porcine hemagglutinating encephalomyelitis virus (PHEV) is a Betacoronavirus characterized by neurological symptoms and a worldwide prevalence. Although PHEV is one of the earliest discovered porcine coronaviruses, it remains poorly studied. The full-length genome of the earliest PHEV strain collected in 1970 in the United States (PHEV/67 N/US/1970) was determined in October 2020. Using this virus as a prototype, we comparatively analyzed all available PHEV full-length sequences during 1970-2015. In phylogenetic trees based on PHEV full-length or spike glycoprotein open reading frame genomic sequences, PHEV/67 N/US/1970 was sorted into a clade different from that of viruses isolated in the United States in 2015. Intriguingly, United States and Belgium viruses isolated in 2015 and 2005, respectively, revealed multiple deletion mutation patterns compared to the strain PHEV/67 N/US/1970, leading to a truncated or a non-functional NS2A coding region. In addition, the genomic similarity analysis showed a hypervariability of the spike glycoprotein coding region, which can affect at least eight potential linear B cell epitopes located in the spike glycoprotein. This report indicates that PHEVs in the United States underwent a significant genetic drift, which might influence PHEV surveillance in other countries.

Genetic drift of MERS-CoV in Saudi Arabia during 2012-2019.

Middle East respiratory syndrome (MERS) is caused by MERS-CoV that infects both human and camel. Camel is supposed to be the natural reservoir for human infection while the sources for most of the primary human infection cases are still not known. We identified two conserved pyrimidine nucleotides that flank UAAU element in MERS-CoV 5'-UTR. These conserved pyrimidine nucleotides distinguish MERS-CoVs into 3 types, that is, UUAAUU, CUAAUU and CUAAUC (referred to as U----U, C----U, and C----C types, respectively). Human MERS-CoV displays a genetic drift from U----U, C----U, to C----C from 2012 to 2019. Camel virus displays a genetic drift from U----U to C----U with a time lag when compared with human virus. The discrepancy in genetic drift seems not to support the notion that camel serves as the only natural reservoir for human infection.