[Development of the Patient-Centered Nursing Culture Scale for Hospitals].

PURPOSE: This study aimed to develop a scale measuring the Patient-Centered Nursing Culture (PCNC) and provide a basic tool to improve PCNC in Korea. METHODS: A conceptual framework and construct factors were extracted through extensive literature review and in-depth interviews with nursing professionals. In total, 59 items were derived based on the pilot survey. Data were collected from 357 nurses working at general hospitals and analyzed for verifying the reliability and validity of the scale. RESULTS: Nine factors containing 54 items were extracted from the exploratory factor analysis to verify the construct validity. The nine factors were top management leadership, policy and procedure, education and training, middle management leadership, supportive teamwork, nursing workplace environment, professional competence, patient-centered nursing activity, and nurses' values. These items were verified by convergent, discriminant, and concurrent validity testing. The internal consistency reliability was acceptable (Cronbach's α=.96). CONCLUSION: The developed PCNC scale is expected to be used as the tool for the development of theory and improvement of PCNC, the empirical testing for cause and effect of PCNC, the development of interventions, education and training programs for improving PCNC, and indicators for evaluation or accreditation of hospital service quality.

Self-Directed Learning Among Nurse Learners in Sri Lanka.

BACKGROUND: Although self-directed learning (SDL) has become an essential instrument for educating nursing professionals, little is known about SDL among nurses in a developing country. METHOD: Data were collected using a structured self-reporting survey, which included Fisher's Self-Directed Learning Readiness (SDLR) scale, and a multiple linear regression analysis was conducted. RESULTS: The mean score per item on the SDLR was 4.31 of 5. The learning-related factors that influenced SDLR were motivation for learning and self-efficacy in English proficiency, and the working-related factor was job satisfaction. These variables accounted for 17.6% of the variance in SDLR scores. CONCLUSION: The SDLR of nurse learners in Sri Lanka was influenced not only by learning-related factors but also by working-related factors. Therefore, it is necessary to develop multidimensional strategies to strengthen nurses' SDLR. [J Contin Educ Nurs. 2019;50(1):41-48.].

Microbial community and functions associated with digestion of algal polysaccharides in the visceral tract of Haliotis discus hannai: Insights from metagenome and metatranscriptome analysis.

Haliotis discus hannai, a species of Pacific abalone, is a highly valuable food source throughout Northeast Asia. As H. discus hannai primarily feed on brown algae and largely extract their energy from algal polysaccharides, understanding the mechanisms by which they digest algal polysaccharides is essential for elucidating their energy metabolism. Gut microbes, as well as the host animal, are involved in the process of polysaccharide degradation. To identify algal polysaccharide-digestion mechanisms and their origin, we analyzed the metagenome and metatranscriptome of abalone visceral extracts. Microbial communities were characterized using the 16S rRNA gene sequences in the metagenome and our results differed significantly from those of previous studies using traditional microbiological methods such as bacterial cultivation and cloning. A greater diversity of bacterial taxa was identified here than was previously identified using cultivation methods. Furthermore, the most abundant bacterial taxa also differed from previous studies, which is not common when comparing the results of bacterial culturing with those of molecular methodologies. Based on the metatranscriptome, overall functions were identified and additional analyses were performed on the coding sequences of algal polysaccharide-digestive enzymes, including alginate lyase. Results of the transcriptomic analyses suggest that alginate lyase in the visceral extracts of H. discus hannai was produced by the host itself, not by visceral bacteria. This is the first next-generation sequencing study performed on abalone to characterize the visceral microbiota and the source of the ability to digest algal polysaccharides by analyzing the metagenome and metatranscriptome together.

Origin and spread of Thoroughbred racehorses inferred from complete mitochondrial genome sequences: Phylogenomic and Bayesian coalescent perspectives.

The Thoroughbred horse breed was developed primarily for racing, and has a significant contribution to the qualitative improvement of many other horse breeds. Despite the importance of Thoroughbred racehorses in historical, cultural, and economical viewpoints, there was no temporal and spatial dynamics of them using the mitogenome sequences. To explore this topic, the complete mitochondrial genome sequences of 14 Thoroughbreds and two Przewalski's horses were determined. These sequences were analyzed together along with 151 previously published horse mitochondrial genomes from a range of breeds across the globe using a Bayesian coalescent approach as well as Bayesian inference and maximum likelihood methods. The racing horses were revealed to have multiple maternal origins and to be closely related to horses from one Asian, two Middle Eastern, and five European breeds. Thoroughbred horse breed was not directly related to the Przewalski's horse which has been regarded as the closest taxon to the all domestic horses and the only true wild horse species left in the world. Our phylogenomic analyses also supported that there was no apparent correlation between geographic origin or breed and the evolution of global horses. The most recent common ancestor of the Thoroughbreds lived approximately 8,100-111,500 years ago, which was significantly younger than the most recent common ancestor of modern horses (0.7286 My). Bayesian skyline plot revealed that the population expansion of modern horses, including Thoroughbreds, occurred approximately 5,500-11,000 years ago, which coincide with the start of domestication. This is the first phylogenomic study on the Thoroughbred racehorse in association with its spatio-temporal dynamics. The database and genetic history information of Thoroughbred mitogenomes obtained from the present study provide useful information for future horse improvement projects, as well as for the study of horse genomics, conservation, and in association with its geographical distribution.

[Effects of Group Rational Emotive Behavior Therapy on the Nurses' Job Stress, Burnout, Job Satisfaction, Organizational Commitment and Turnover Intention].

PURPOSE: This study aimed to develop a Group REBT program with group counseling for nurses and test the effect of group counseling on their job stress, burnout, job satisfaction, organizational commitment, and turnover intention. METHODS: A quasi-experimental study with nonequivalent control group design was employed to identify the effect of the Group REBT program on nurses' job stress, burnout, job satisfaction, organizational commitment, and turnover intention. Data were collected from 47 participants from two hospitals. The data from the experimental (n=23) and control (n=24) groups were analyzed from January 5 to April 3, 2015. The Group REBT program was conducted eight tmes in all, once a week, with each session lasting 180 minutes. The effect of experimental intervention was measured for each group using a series of structured questionnaires at each of the phases: Pre-intervention, post-intervention (immediately after intervention), and post-intervention (four weeks after intervention). Following this, the significance of the changes in the scores was tested. RESULTS: The scores of the experimental group, which received the Group REBT program, were compared with those of the control group; the hypotheses were supported in terms of job stress (F=8.85, p<.001), burnout (F=5.62, p=.022), job satisfaction (F=2.70, p=.042), organizational commitment (F=2.97, p=.048), and turnover intention (F=4.60, p=.012). CONCLUSION: The Group REBT program was shown to be an effective intervention that could reduce nurses' job stress and burnout and increase job satisfaction and organizational commitment. Therefore, the Group REBT program can be adopted by nursing organizations to strategically decrease nurses' turnover intention.

Time-calibrated phylogenomics of the porcine epidemic diarrhea virus: genome-wide insights into the spatio-temporal dynamics.

Porcine epidemic diarrhea virus (PEDV), the causative agent of porcine epidemic diarrhea (PED), has led to tremendous economic losses in the global swine industry. Although the phylogeny of PEDV has been investigated extensively at the molecular level, there was no time-calibrated phylogenomic study on the virus. To improve insight into this topic, we analyzed 138 published genome sequences using the Bayesian coalescent analyses as well as Bayesian inferences and maximum likelihood methods. All of the global PEDV isolates were divided into six groups, except for one unclassified isolate. Of the six groups, Groups 1-5 comprised pandemic viruses while the remaining Group 6 contained classical isolates. Interestingly, the two clades, both pandemic and classical, consisted of clade-specific amino acid sequences in five genes: ORF1a, ORF1b, S, ORF3, and N. Within the pandemic clade, Group 1 and Group 2 originated from North America, whereas Group 3-Group 5 were derived from Asia. In Group 2, there was a common origin of S INDEL isolates. Within each group, there was no apparent association between temporal or geographic origin and heterogeneity of PEDVs. Our findings also showed that the PEDV virus evolved at a rate of 3.38 × 10-4 substitutions/site/year, and the most recent common ancestor of the virus emerged 75.9 years ago. Our Bayesian skyline plot analysis indicated that the PEDV had maintained constant effective population size excluding only a short period, around 2012, when a valley shaped decline in the effective number of infections occurred.

Horizontal gene transfer of Chlamydia: Novel insights from tree reconciliation.

Recent comparative genomics studies have suggested that horizontal gene transfer (HGT) is one of the major processes in bacterial evolution. In this study, HGT events of 64 Chlamydia strains were investigated based on the pipeline employed in HGTree database constructed in our recent study. Tree reconciliation method was applied in order to calculate feasible HGT events. Following initial detection and an evaluation procedure, evidence of the HGT was identified in 548 gene families including 42 gene families transferred from outside of Chlamydiae phylum with high reliability. The donor species of inter-phylum HGT consists of 12 different bacterial and archaeal phyla, suggesting that Chlamydia might have even more various host range than in previous reports. In addition, each species of Chlamydia showed varying preference towards HGT, and genes engaged in HGT within Chlamydia and between other species showed different functional distribution. Also, examination of individual gene flows of niche-specific genes suggested that many of such genes are transferred mainly within Chlamydia genus. Our results uncovered novel features of HGT acting on Chlamydia genome evolution, and it would be also strong evidence that HGT is an ongoing process for intracellular pathogens. We expect that the results provide more insight into lineage- and niche-specific adaptations regarding their infectivity and pathogenicity.

Comparative genomic analysis of Lactobacillus plantarum GB-LP4 and identification of evolutionarily divergent genes in high-osmolarity environment.

Lactobacillus plantarum is one of the widely-used probiotics and there have been a large number of advanced researches on the effectiveness of this species. However, the difference between previously reported plantarum strains, and the source of genomic variation among the strains were not clearly specified. In order to understand further on the molecular basis of L. plantarum on Korean traditional fermentation, we isolated the L. plantarum GB-LP4 from Korean fermented vegetable and conducted whole genome assembly. With comparative genomics approach, we identified the candidate genes that are expected to have undergone evolutionary acceleration. These genes have been reported to associate with the maintaining homeostasis, which are generally known to overcome instability in external environment including low pH or high osmotic pressure. Here, our results provide an evolutionary relationship between L. plantarum species and elucidate the candidate genes that play a pivotal role in evolutionary acceleration of GB-LP4 in high osmolarity environment. This study may provide guidance for further studies on L. plantarum.

Tracing the spatio-temporal dynamics of endangered fin whales (Balaenoptera physalus) within baleen whale (Mysticeti) lineages: a mitogenomic perspective.

To explore the spatio-temporal dynamics of endangered fin whales (Balaenoptera physalus) within the baleen whale (Mysticeti) lineages, we analyzed 148 published mitochondrial genome sequences of baleen whales. We used a Bayesian coalescent approach as well as Bayesian inferences and maximum likelihood methods. The results showed that the fin whales had a single maternal origin, and that there is a significant correlation between geographic location and evolution of global fin whales. The most recent common female ancestor of this species lived approximately 9.88 million years ago (Mya). Here, North Pacific fin whales first appeared about 7.48 Mya, followed by a subsequent divergence in Southern Hemisphere approximately 6.63 Mya and North Atlantic about 4.42 Mya. Relatively recently, approximately 1.76 and 1.42 Mya, there were two additional occurrences of North Pacific populations; one originated from the Southern Hemisphere and the other from an uncertain location. The evolutionary rate of this species was 1.002 × 10-3 substitutions/site/My. Our Bayesian skyline plot illustrates that the fin whale population has the rapid expansion event since ~ 2.5 Mya, during the Quaternary glaciation stage. Additionally, this study indicates that the fin whale has a sister group relationship with humpback whale (Meganoptera novaeangliae) within the baleen whale lineages. Of the 16 genomic regions, NADH5 showed the most powerful signal for baleen whale phylogenetics. Interestingly, fin whales have 16 species-specific amino acid residues in eight mitochondrial genes: NADH2, COX2, COX3, ATPase6, ATPase8, NADH4, NADH5, and Cytb.

Comparative Genomic Analysis of Lactobacillus plantarum GB-LP1 Isolated from Traditional Korean Fermented Food.

As probiotics play an important role in maintaining a healthy gut flora environment through antitoxin activity and inhibition of pathogen colonization, they have been of interest to the medical research community for quite some time now. Probiotic bacteria such as Lactobacillus plantarum, which can be found in fermented food, are of particular interest given their easy accessibility. We performed whole-genome sequencing and genomic analysis on a GB-LP1 strain of L. plantarum isolated from Korean traditional fermented food; this strain is well known for its functions in immune response, suppression of pathogen growth, and antitoxin effects. The complete genome sequence of GB-LP1 is a single chromosome of 3,040,388 bp with 2,899 predicted open reading frames. Genomic analysis of GB-LP1 revealed two CRISPR regions and genes showing accelerated evolution, which may have antibiotic and antitoxin functions. The aim of the present study was to predict strain specific-genomic characteristics and assess the potential of this new strain as lactic acid bacteria at the genomic level using in silico analysis. These results provide insight into the L. plantarum species as well as confirm the possibility of its utility as a candidate probiotic.

Comparative genome analysis of Lactobacillus plantarum GB-LP3 provides candidates of survival-related genetic factors.

Lactobacillus plantarum is found in various environmental niches such as in the gastrointestinal tract of an animal host or a fermented food. This species isolated from a certain environment is known to possess a variety of properties according to inhabited environment's adaptation. However, a causal relationship of a genetic factor and phenotype affected by a specific environment has not been systematically comprehended. L. plantarum GB-LP3 strain was isolated from Korean traditional fermented vegetable and the whole genome of GB-LP3 was sequenced. Comparative genome analysis of GB-LP3, with other 14 L. plantarum strains, was conducted. In addition, genomic island regions were investigated. The assembled whole GB-LP3 genome contained a single circular chromosome of 3,206,111bp with the GC content of 44.7%. In the phylogenetic tree analysis, GB-LP3 was in the closest distance from ZJ316. The genomes of GB-LP3 and ZJ316 have the high level of synteny. Functional genes that are related to prophage, bacteriocin, and quorum sensing were found through comparative genomic analysis with ZJ316 and investigation of genomic islands. dN/dS analysis identified that the gene coding for phosphonate ABC transporter ATP-binding protein is evolutionarily accelerated in GB-LP3. Our study found that potential candidate genes that are affected by environmental adaptation in Korea traditional fermented vegetable.

Complete mitochondrial genome sequences of Korean native horse from Jeju Island: uncovering the spatio-temporal dynamics.

The Korean native horse (Jeju horse) is one of the most important animals in Korean historical, cultural, and economical viewpoints. In the early 1980s, the Jeju horse was close to extinction. The aim of this study is to explore the phylogenomics of Korean native horse focusing on spatio-temporal dynamics. We determined complete mitochondrial genome sequences for the first Korean native (n = 6) and additional Mongolian (n = 2) horses. Those sequences were analyzed together with 143 published ones using Bayesian coalescent approach as well as three different phylogenetic analysis methods, Bayesian inference, maximum likelihood, and neighbor-joining methods. The phylogenomic trees revealed that the Korean native horses had multiple origins and clustered together with some horses from four European and one Middle Eastern breeds. Our phylogenomic analyses also supported that there was no apparent association between breed or geographic location and the evolution of global horses. Time of the most recent common ancestor of the Korean native horse was approximately 13,200-63,200 years, which was much younger than 0.696 My of modern horses. Additionally, our results showed that all global horse lineages including Korean native horse existed prior to their domestication events occurred in about 6000-10,000 years ago. This is the first study on phylogenomics of the Korean native horse focusing on spatio-temporal dynamics. Our findings increase our understanding of the domestication history of the Korean native horses, and could provide useful information for horse conservation projects as well as for horse genomics, emergence, and the geographical distribution.

Whole genome scan reveals the genetic signature of African Ankole cattle breed and potential for higher quality beef.

BACKGROUND: Africa is home to numerous cattle breeds whose diversity has been shaped by subtle combinations of human and natural selection. African Sanga cattle are an intermediate type of cattle resulting from interbreeding between Bos taurus and Bos indicus subspecies. Recently, research has asserted the potential of Sanga breeds for commercial beef production with better meat quality as compared to Bos indicus breeds. Here, we identified meat quality related gene regions that are positively selected in Ankole (Sanga) cattle breeds as compared to indicus (Boran, Ogaden, and Kenana) breeds using cross-population (XP-EHH and XP-CLR) statistical methods. RESULTS: We identified 238 (XP-EHH) and 213 (XP-CLR) positively selected genes, of which 97 were detected from both statistics. Among the genes obtained, we primarily reported those involved in different biological process and pathways associated with meat quality traits. Genes (CAPZB, COL9A2, PDGFRA, MAP3K5, ZNF410, and PKM2) involved in muscle structure and metabolism affect meat tenderness. Genes (PLA2G2A, PARK2, ZNF410, MAP2K3, PLCD3, PLCD1, and ROCK1) related to intramuscular fat (IMF) are involved in adipose metabolism and adipogenesis. MB and SLC48A1 affect meat color. In addition, we identified genes (TIMP2, PKM2, PRKG1, MAP3K5, and ATP8A1) related to feeding efficiency. Among the enriched Gene Ontology Biological Process (GO BP) terms, actin cytoskeleton organization, actin filament-based process, and protein ubiquitination are associated with meat tenderness whereas cellular component organization, negative regulation of actin filament depolymerization and negative regulation of protein complex disassembly are involved in adipocyte regulation. The MAPK pathway is responsible for cell proliferation and plays an important role in hyperplastic growth, which has a positive effect on meat tenderness. CONCLUSION: Results revealed several candidate genes positively selected in Ankole cattle in relation to meat quality characteristics. The genes identified are involved in muscle structure and metabolism, and adipose metabolism and adipogenesis. These genes help in the understanding of the biological mechanisms controlling beef quality characteristics in African Ankole cattle. These results provide a basis for further research on the genomic characteristics of Ankole and other Sanga cattle breeds for quality beef.

Comparative Analysis of the Complete Genome of Lactobacillus plantarum GB-LP2 and Potential Candidate Genes for Host Immune System Enhancement.

Acute respiratory virus infectious diseases are a growing health problem, particularly among children and the elderly. Much effort has been made to develop probiotics that prevent influenza virus infections by enhancing innate immunity in the respiratory tract until vaccines are available. Lactobacillus plantarum GB-LP2, isolated from a traditional Korean fermented vegetable, has exhibited preventive effects on influenza virus infection in mice. To identify the molecular basis of this strain, we conducted a whole-genome assembly study. The single circular DNA chromosome of 3,284,304 bp was completely assembled and 3,250 proteinencoding genes were predicted. Evolutionarily accelerated genes related to the phenotypic trait of anti-infective activities for influenza virus were identified. These genes encode three integral membrane proteins, a teichoic acid export ATP-binding protein and a glucosamine - fructose-6-phosphate aminotransferase involved in host innate immunity, the nonspecific DNA-binding protein Dps, which protects bacteria from oxidative damage, and the response regulator of the three-component quorum-sensing regulatory system, which is related to the capacity of adhesion to the surface of the respiratory tract and competition with pathogens. This is the first study to identify the genetic backgrounds of the antiviral activity in L. plantarum strains. These findings provide insight into the anti-infective activities of L. plantarum and the development of preventive probiotics.

Combined effect of body mass index and body size perception on metabolic syndrome in South Korea: results of the fifth Korea National Health and Nutrition Examination Surveys (2010-2012).

BACKGROUND: Body mass index (BMI) has been used as an indirect predictor for the risk of metabolic syndrome. However, there are challenges in evaluating the risk of metabolic syndrome using BMI in certain parts of the world. Therefore, it is worth exploring additional factors that could supplement BMI to predict the risk of metabolic syndrome. In this study, we assessed the combined effect of BMI and perception for predicting metabolic syndrome. METHODS: We used the fifth Korea National Health and Nutrition Examination Surveys (KNHANES V, 2010-12, N = 16,537) in this study. Multivariable logistic regression analysis was performed to examine the association while controlling for potential confounding variables. We also performed an analysis for the combined effect of BMI and perception of body size, and subgroup analysis by age group or moderate physical activity. RESULTS: Data from 16,537 participants were analyzed in this study (males: 6,978, females: 9,559). Among them, metabolic syndrome was diagnosed in 1,252 (17.9%) males and 2,445 (25.6%) females, respectively. The combination of BMI and body size perception had a positive relation with the presence of metabolic syndrome. People who perceived themselves to be overweight for their body size had a higher risk for metabolic syndrome even if they have the same BMI. CONCLUSION: Our findings suggest that the combination of body size perception and BMI is useful in predicting the risk of metabolic syndrome. The use of complementary predictors could reduce the risk for inaccurate prediction of metabolic syndrome.

Time-calibrated phylogenomics of the classical swine fever viruses: genome-wide bayesian coalescent approach.

The phylogeny of classical swine fever virus (CSFV), the causative agent of classical swine fever (CSF), has been investigated extensively. However, no evolutionary research has been performed using the whole CSFV genome. In this study, we used 37 published genome sequences to investigate the time-calibrated phylogenomics of CSFV. In phylogenomic trees based on Bayesian inference (BI) and Maximum likelihood (ML), the 37 isolates were categorized into five genetic types (1.1, 1.2, 2.1, 2.3, and 3.4). Subgenotype 1.1 is divided into 3 groups and 1 unclassified isolate, 2.1 into 4 groups, 2.3 into 2 groups and 1 unclassified isolate, and subgenotype 1.2 and 3.4 consisted of one isolate each. We did not observe an apparent temporal or geographical relationship between isolates. Of the 14 genomic regions, NS4B showed the most powerful phylogenetic signal. Results of this evolutionary study using Bayesian coalescent approach indicate that CSFV has evolved at a rate of 13×.010-4 substitutions per site per year. The most recent common ancestor of CSFV appeared 2770.2 years ago, which was about 8000 years after pig domestication. The effective population size of CSFV underwent a slow increase until the 1950s, after which it has remained constant.

Cetaceans evolution: insights from the genome sequences of common minke whales.

BACKGROUND: Whales have captivated the human imagination for millennia. These incredible cetaceans are the only mammals that have adapted to life in the open oceans and have been a source of human food, fuel and tools around the globe. The transition from land to water has led to various aquatic specializations related to hairless skin and ability to regulate their body temperature in cold water. RESULTS: We present four common minke whale (Balaenoptera acutorostrata) genomes with depth of ×13 ~ ×17 coverage and perform resequencing technology without a reference sequence. Our results indicated the time to the most recent common ancestors of common minke whales to be about 2.3574 (95% HPD, 1.1521 - 3.9212) million years ago. Further, we found that genes associated with epilation and tooth-development showed signatures of positive selection, supporting the morphological uniqueness of whales. CONCLUSIONS: This whole-genome sequencing offers a chance to better understand the evolutionary journey of one of the largest mammals on earth.

Uncovering genomic features and maternal origin of korean native chicken by whole genome sequencing.

The Korean Native Chicken (KNC) is an important endemic biological resource in Korea. While numerous studies have been conducted exploring this breed, none have used next-generation sequencing to identify its specific genomic features. We sequenced five strains of KNC and identified 10.9 million SNVs and 1.3 million InDels. Through the analysis, we found that the highly variable region common to all 5 strains had genes like PCHD15, CISD1, PIK3C2A, and NUCB2 that might be related to the phenotypic traits of the chicken such as auditory sense, growth rate and egg traits. In addition, we assembled unaligned reads that could not be mapped to the reference genome. By assembling the unaligned reads, we were able to present genomic sequences characteristic to the KNC. Based on this, we also identified genes related to the olfactory receptors and antigen that are common to all 5 strains. Finally, through the reconstructed mitochondrial genome sequences, we performed phylogenomic analysis and elucidated the maternal origin of the artificially restored KNC. Our results revealed that the KNC has multiple maternal origins which are in agreement with Korea's history of chicken breed imports. The results presented here provide a valuable basis for future research on genomic features of KNC and further understanding of KNC's origin.

Complete genome sequences of porcine reproductive and respiratory syndrome viruses: perspectives on their temporal and spatial dynamics.

Porcine reproductive and respiratory syndrome virus (PRRSV) has been investigated extensively at the molecular level. Nevertheless, genome wide study on the temporal and spatial dynamics of the virus is non-existed. To explore this topic, we determined complete coding genome sequences for four PRRSV isolates and analyzed them together with 122 global published ones using the Bayesian coalescent approach as well as Bayesian inferences and maximum likelihood methods. All EU-type viruses belonged to one of two groups or were unclassified (5 isolates), and all NA-type isolates were divided into one of three major groups or were unclassified (1 isolate). Here, there was no apparent association between temporal or geographic origin and heterogeneity of global PRRSVs. Of the eight ORFs, ORF1a showed the most powerful evolutionary signal. Our findings also indicated that the PRRS virus evolved at a rate of 1.98 × 10-3 substitutions/site/year, and the most recent common ancestor of the virus existed 786.4 years ago. Here, EU-type viruses segregated 115.7 years ago, while NA-type isolates diverged 179.8 years before the present. In addition, our reconstruction of the effective population size depicted five phases of epidemic growth: an initial constant, followed sequentially by slow decrease, slight increase, sharp decline, and then a rapid expansion approaching the present.