Epidemiological and genetic characterization of porcine epidemic diarrhea virus in the Mekong Delta, Vietnam, from 2015 to 2017.

Porcine epidemic diarrhea (PED) virus (PEDV) is a highly contagious virus. PED was first identified in 2008 and has greatly affected the Vietnamese pig production economy. The aim of this study was to investigate the epidemiological and genetic characteristics of PEDV in piglet herds in the Mekong Delta, Vietnam. Diarrheal stool and intestinal samples from 2262 piglets from 191 herds in five provinces were collected to test for the presence of PEDV. Ten PEDV strains were randomly selected for sequencing, and four genes encoding PEDV structural proteins were analyzed. The rates of herds and samples positive for PEDV were 27.23% and 27.72%, respectively. In positive herds, the morbidity and mortality of PEDV-positive piglets were 97.97% and 79.06%, respectively, with most of the infected piglets under 7 days of age. Phylogenetic analysis showed that the 10 PEDV strains from this study clustered with genotype G2 strains from Vietnam and neighboring countries. Many amino acid substitutions were identified in important antigenic regions in the spike protein of the 10 strains when compared to four PEDV vaccine strains. This study provides novel insights into the epidemiology and genetic diversity of circulating PEDV strains, which could facilitate the development of an appropriate and proactive strategy for controlling PED.

Human papillomavirus prevalence and genotype distribution in Vietnamese male patients between 2016 and 2020.

Human papillomavirus (HPV) infection in men is a serious issue because it is associated with genital warts, anogenital cancers, and HPV transmission to their sex partners. This study aimed to investigate the prevalence and genotypes of HPVs in Vietnamese male patients hospitalized with sexually transmitted infection (STI) symptoms between 2016 and 2020 by using polymerase chain reaction and reverse dot blot hybridization analysis. HPV DNA was detected in 191/941 (20.3%) penile cell samples. The HPV patient's mean age was 30.3 in the range of 16- and 69-year-old. The highest HPV prevalence (84.7%) was found in patients between 20- and 39-year-old. A total of 313 HPV genotypes were identified. The multiple-infection rate was 42.9%. The most common high-risk (HR)-HPV genotypes were HPV-16 (8.0%), HPV-51 (7.7%), HPV-52 (4.8%), HPV-56 (4.2%), and HPV-18 (3.8%). Furthermore, HPV-11 and HPV-6 genotypes were the two most common low-risk (LR)-HPV genotypes with the rate of 36.7% and 21.4%, respectively. Notably, HPV-52 was found circulating in Vietnam for the first time. In conclusion, this study results showed that HPV prevalence in Vietnamese male patients was common and diverse. In addition, regarding public health and cancer prevention, the inclusion of the HPV vaccination into the national vaccination program for both men and women is recommended.

Phylogenetic analysis of porcine reproductive and respiratory syndrome virus in Vietnam, 2021.

The porcine reproductive and respiratory syndrome virus (PRRSV) causes more economic losses in the swine industry than any other virus. This study aimed to investigate the genetic diversity of PRRSV to assist in evaluating the effectiveness of PRRS vaccines. Twenty-eight samples from clinical cases were collected from 19 farms in seven provinces of Vietnam in 2021. Full-length PRRSV ORF5 genes from the 19 samples were amplified, sequenced, and compared to the corresponding sequences of referenced PRRSV strains from Genbank. The genetic analysis showed that 12 isolates were the highly pathogenic PRRSV subtype (HP-PRRSV) lineage 8, sublineage 8.7; six isolates were the classical North American PRRSV subtype (US-PRRSV), NADC-like group, lineage 1, sublineage 1.4, which were reported in Vietnam for the first time; and the final isolate was a vaccine-like strain. The field isolates of HP-PRRSV had relatively higher genetic diversity with US-PRRSV vaccine strains (84.0-94.5%) than HP-PRRSV vaccine strains (95.3-98.6%). Meanwhile, the six NADC-like isolates had low nucleotide similarity with US-PRRSV and HP-PRRSV vaccine strains (83.4-85.4% and 83.2-84.0%, respectively). Many amino acid substitutions were found in antigenic regions of GP5 involved in response to early antibody production, neutralizing antibodies, and viral immune evasion between these field strains and PRRSV vaccine strains. These findings provide insights into the molecular characteristics, genetic diversity, antigenicity, and evolution of PRRSV strains in Vietnam and postulate a compelling explanation for the limitations of current vaccination efforts.

Genetic Characterization of African Swine Fever Virus in Various Outbreaks in Central and Southern Vietnam During 2019-2021.

This study aimed to identify potential genetic diversity among African swine fever virus (ASFV) strains circulating in central and southern Vietnam. Thirty ASFV strains were collected from domestic pigs and convalescent pigs with ASFV-infected clinical signs from 19 different provinces of central and southern Vietnam during 2019-2021. A portion of the B646L (p72) gene and the entire E183L (p54), CP204L (p30), and B602L (CVR) genes were amplified, purified, and sequenced. Web-based BLAST and MEGA X software were used for sequence analysis. Analysis of the partial B646L (p72) gene, the full-length E183L (p54) and CP204L (p30) genes, and the central hypervariable region (CVR) of the B602L gene sequence showed that all 30 ASFV isolates belonged to genotype II and were 100% identical to the previously identified strains in Vietnam and China. Analysis of the p72, p54, and p30 regions did not indicate any change in the nucleotide and amino acid sequences among these strains in 3 years of research. No novel variant was found in the CVR within the B602L gene. Analysis of the CVR showed that these ASFV strains belong to subgroup XXXII. The results of this study revealed that these ASFVs shared high similarity with ASFV isolates detected previously in northern Vietnam and China. Taken together, the results of this study and a previous study in Vietnam showed high stability and no genetic diversity in the ASFV genome.

A novel signature predicts recurrence risk and therapeutic response in breast cancer patients.

Acetylserotonin O-methyltransferase (ASMT) is a key enzyme in the synthesis of melatonin. Although melatonin has been shown to exhibit anticancer activity and prevents endocrine resistance in breast cancer, the role of ASMT in breast cancer progression remains unclear. In this retrospective study, we analyzed gene expression profiles in 27 data sets on 7244 patients from 11 countries. We found that ASMT expression was significantly reduced in breast cancer tumors relative to healthy tissue. Among breast cancer patients, those with higher levels of ASMT expression had better relapse-free survival outcomes and longer metastasis-free survival times. Following treatment with tamoxifen, patients with greater ASMT expression experienced longer periods before relapse or distance recurrence. Motivated by these results, we devised an ASMT gene signature that can correctly identify low-risk cases with a sensitivity and specificity of 0.997 and 0.916, respectively. This signature was robustly validated using 23 independent breast cancer mRNA array data sets from different platforms (consisting of 5800 patients) and an RNAseq data set from TCGA (comprising 1096 patients). Intriguingly, patients who are classified as high-risk by the signature benefit from adjuvant chemotherapy, and those with grade II tumors who are classified as low-risk exhibit improved overall survival and distance relapse-free outcomes following endocrine therapy. Together, our findings more clearly elucidate the roles of ASMT, provide strategies for improving the efficacy of tamoxifen treatment and help to identify those patients who may maximally benefit from adjuvant or endocrine therapies.

Porcine circovirus genotypes and their copathogens in pigs with respiratory disease in southern provinces of Vietnam.

This study was conducted to investigate the genetic diversity of porcine circovirus type 2 (PCV2) and its coinfecting pathogens in pigs with respiratory disease in Vietnam. Samples from 127 clinical cases were obtained from different southern provinces of Vietnam from January 2018 to January 2020 for PCR and sequence analysis. The infection rate of PCV2 was 78.8%, and the major pathogens found in coinfections with PCV2 were porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, and Haemophilus parasuis. Forty-three PCV2-positive clinical samples were selected for amplification and sequencing of the ORF2 region. Phylogenetic analysis of PCV2 ORF2 showed that five of the sequences belonged to PCV2b (11.6%) and 38 belonged to PCV2d (88.4%), indicating that PCV2d strains were predominant in southern provinces of Vietnam. Alignment of the predicted amino acid sequences of the PCV2 capsid protein revealed polymorphic sites in the antibody recognition regions. This study demonstrates the prevalence of the PCV2d genotype in southern Vietnam and presents a comprehensive overview of the coinfecting pathogens associated with PCV2 in young pigs with respiratory disease.

Identification and whole-genome characterization of a novel Porcine Circovirus 3 subtype b strain from swine populations in Vietnam.

Porcine circovirus 3 (PCV3) is a novel circovirus detected in pigs suffering from porcine dermatitis and nephropathy syndrome (PDNS), reproductive failure, and multisystemic infection. In this study, we identified PCV3 infection in aborted fetuses and reported the full-length genome sequence of a PCV3 strain identified from southern Vietnam. The complete genome of this PCV3 strain is 2000 nucleotides in length. We found that it shares 98.5-99.25% sequence identity with other reference sequences and that it clusters with the PCV3b subtype. Several specific mutated sites were found to be unique to this Vietnamese PCV3b strain, including I14M in the Rep protein and K139R, I150F, and P169T in the Cap protein. The sequence data that have been made publically available as part of this study will help investigators to better understand the molecular characteristics, genetic diversity, and evolutionary history of PCV3. Careful and in-depth investigations into the epidemiology, pathogenicity, and the evolution of this novel virus is a matter of urgent economic and agricultural interest in Vietnam.

Genetic Diversity of Porcine Circovirus Subtypes from Aborted Sow Fetuses in Vietnam.

Porcine circovirus type 3 (PCV3) is an emerging circovirus that is highly distributed among swine worldwide and associated with porcine dermatitis and nephropathy syndrome, reproductive failure, and multisystemic inflammation. Here, we investigated and characterized PCV3 from aborted fetuses in Vietnam. We found that the whole genomes of PCV3 collected in these Vietnamese pig farms share 98.4-99.45% sequence identity with reference PCV3 sequences. Several distinct mutation were identified in both the Rep protein and Cap protein of these strains. These strains were clustered into two distinct subtypes (3a1 and 3b). This study contributes to a better understanding of the molecular characteristics and genetic diversity of PCV3 in Vietnam.

Cyclophilin B induces chemoresistance by degrading wild-type p53 via interaction with MDM2 in colorectal cancer.

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Chemoresistance is a major problem for effective therapy in CRC. Here, we investigated the mechanism by which peptidylprolyl isomerase B (PPIB; cyclophilin B, CypB) regulates chemoresistance in CRC. We found that CypB is a novel wild-type p53 (p53WT)-inducible gene but a negative regulator of p53WT in response to oxaliplatin treatment. Overexpression of CypB shortens the half-life of p53WT and inhibits oxaliplatin-induced apoptosis in CRC cells, whereas knockdown of CypB lengthens the half-life of p53WT and stimulates p53WT-dependent apoptosis. CypB interacts directly with MDM2, and enhances MDM2-dependent p53WT ubiquitination and degradation. Furthermore, we firmly validated, using bioinformatics analyses, that overexpression of CypB is associated with poor prognosis in CRC progression and chemoresistance. Hence, we suggest a novel mechanism of chemoresistance caused by overexpressed CypB, which may help to develop new anti-cancer drugs. We also propose that CypB may be utilized as a predictive biomarker in CRC patients. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

RNA therapeutics in cancer treatment.

RNA therapeutics are a class of drugs that use RNA molecules to treat diseases, including cancer. RNA therapeutics work by targeting specific genes or proteins involved in the disease process, with the aim of blocking or altering their activity to ultimately halt or reverse the disease progression. The use of RNA therapeutics in cancer treatment has shown great potential, as they offer the ability to specifically target cancer cells while leaving healthy cells intact. This is in contrast to traditional chemotherapy and radiation treatments, which can damage healthy cells and cause unpleasant side effects. The field of RNA therapeutics is rapidly advancing, with several types of RNA molecules being developed for cancer treatment, including small interfering RNA, microRNA, mRNA, and RNA aptamers. Each type of RNA molecule has unique properties and mechanisms of action, allowing for targeted and personalized cancer treatments. In this chapter, we will explore the different types of RNA therapeutics used in cancer treatment, their mechanisms of action, and their potential applications in treating different types of cancer. We will also discuss the challenges and opportunities in the development and research of RNA therapeutics for cancer, as well as the future outlook for this promising field.

Mitochondria-targeted antioxidant MitoQ ameliorates experimental mouse colitis by suppressing NLRP3 inflammasome-mediated inflammatory cytokines.

BACKGROUND: MitoQ is a mitochondria-targeted derivative of the antioxidant ubiquinone, with antioxidant and anti-apoptotic functions. Reactive oxygen species are involved in many inflammatory diseases including inflammatory bowel disease. In this study, we assessed the therapeutic effects of MitoQ in a mouse model of experimental colitis and investigated the possible mechanisms underlying its effects on intestinal inflammation. METHODS: Reactive oxygen species levels and mitochondrial function were measured in blood mononuclear cells of patients with inflammatory bowel disease. The effects of MitoQ were evaluated in a dextran sulfate sodium-induced colitis mouse model. Clinical and pathological markers of disease severity and oxidative injury, and levels of inflammatory cytokines in mouse colonic tissue were measured. The effect of MitoQ on inflammatory cytokines released in the human macrophage-like cell line THP-1 was also analyzed. RESULTS: Cellular and mitochondrial reactive oxygen species levels in mononuclear cells were significantly higher in patients with inflammatory bowel disease (P <0.003, cellular reactive oxygen species; P <0.001, mitochondrial reactive oxygen species). MitoQ significantly ameliorated colitis in the dextran sulfate sodium-induced mouse model in vivo, reduced the increased oxidative stress response (malondialdehyde and 3-nitrotyrosine formation), and suppressed mitochondrial and histopathological injury by decreasing levels of inflammatory cytokines IL-1 beta and IL-18 (P <0.001 and P <0.01 respectively). By decreasing mitochondrial reactive oxygen species, MitoQ also suppressed activation of the NLRP3 inflammasome that was responsible for maturation of IL-1 beta and IL-18. In vitro studies demonstrated that MitoQ decreases IL-1 beta and IL-18 production in human THP-1 cells. CONCLUSION: Taken together, our results suggest that MitoQ may have potential as a novel therapeutic agent for the treatment of acute phases of inflammatory bowel disease.

Phylogenetic and genotypic characteristics of the foot-and-mouth disease virus from outbreaks in southern Vietnam, 2019.

In 2019, multiple FMD outbreaks occurred in swine farms vaccinated against FMDV in southern Vietnam. This study investigated the genotypic characteristics of FMDV strains from these outbreaks. Seven samples were collected from pigs exhibiting FMD clinical signs. All FMDV-positive samples were amplified and sequenced for the gene encoding the VP1. Results were analyzed and compared with sequences of reference strains and vaccine strains on GenBank. Phylogenetic analysis showed that all seven field isolates belonged to serotype O, topotype SEA/Mya-98. These strains shared high homology with strains from Vietnam (2018), Korea, and China, but low homology with vaccine strains. Moreover, 21 amino acid substitutions were found in the VP1 protein of the FMDV field strains, many of which were crucial antigenic determinants involved in the neutralization of FMDV. These findings suggest that the current vaccine may not be effective against the emerging FMDV strains in southern Vietnam.

TOR1B: a predictor of bone metastasis in breast cancer patients.

Recent therapeutic advances in breast cancer (BC) have improved survival outcomes; however, the prognosis for patients with bone metastasis (BM) remains poor. Hence, novel clinical biomarkers are needed to accurately predict BC BM as well as to promote personalized medicine. Here, we discovered a novel biomarker, TOR1B, for BM in BC patients via analysis of BC gene expression data and clinical information downloaded from open public databases. In cancer cells, we found high expression levels of TOR1B in the nucleus and endoplasmic reticulum. Regarding gene expression, the level of TOR1B was significantly upregulated in BC patients with BM (p < 0.05), and the result was externally validated. In addition, gene expression clearly demonstrated two distinct types of prognoses in ER- and PR-positive patients. In multivariate regression, the gene could be an independent predictor of BM in BC patients, i.e., a low expression level of TOR1B was associated with delayed metastasis to bone in BC patients (HR, 0.28; 95% CI 0.094-0.84). Conclusively, TOR1B might be a useful biomarker for predicting BM; specifically, patients with ER- and PR-positive subtypes would benefit from the clinical use of this promising prognostic biomarker.

Predicting the severity of COVID-19 patients using the CD24-CSF1R index in whole blood samples.

Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, has become one of the most serious public health crises worldwide. Most infected people are asymptomatic but are still able to spread the virus. People with mild or moderate illnesses are likely to recover without hospitalization, while critically ill patients face a higher risk of organ injury or even death. In this study, we aimed to identify a novel biomarker that can predict the severity of COVID-19 patients. Clinical information and RNA-seq data of leukocytes from whole blood samples with and without a COVID-19 diagnosis (n = 100 and 26, respectively) were retrieved from the National Center for Biotechnology Information Gene Expression Omnibus database. Raw data were processed using the Transcripts Per Million (TPM) method and then transformed using log2 (TPM+1) for normalization. The CD24-CSF1R index was established. Violin plots, Kaplan-Meier curves, ROC curves, and multivariate Cox proportional hazards regression analyses were performed to evaluate the prognostic value of the established index. The CD24-CSF1R index was significantly associated with ICU admission (n = 50 ICU, 50 non-ICU) and ventilatory status (n = 42 ventilation, 58 non-ventilation) with p = 4.186e-11 and p = 1.278e-07, respectively. The ROC curve produced a relatively accurate prediction of ICU admission with an AUC of 0.8524. Additionally, patients with a high index had significantly fewer mechanical ventilation-free days than patients with a low index (p = 6.07e-07). Furthermore, the established index showed a strong prognostic ability for the risk of using a ventilator in the multivariate Cox regression model (p < 0.001). The CD24-CSF1R index was significantly associated with COVID-19 severity. The established index could have potential implications for prognosis, disease severity stratification, and clinical management.

Clinical Characteristics and Outcomes of Long COVID-19 Hospitalized Children in Vietnam.

A cross-sectional study was conducted on 205 pediatric patients, including 150 post-COVID-19 patients and 55 noninfected patients. The study identified 10 common respiratory symptoms in post-COVID-19 patients, with significant differences in clinical symptoms between the 2 groups. Post-COVID-19 pediatric patients had a lower lymphocyte count and a higher rate of pneumonia diagnosis, which can persist for up to 16 weeks after discharge. The study's findings can help monitor and manage the clinical burden of post-COVID-19 symptoms in the pediatric population.

Insights into the epidemiology and clinical aspects of post-COVID-19 conditions in adult.

OBJECTIVES: While most individuals infected with COVID-19 recover completely within a few weeks, some continue to experience lingering symptoms. This study was conducted to identify and describe the clinical and subclinical manifestations of adult patients from the long-term effects of COVID-19. METHODS: The study analyzed 205 medical records of inpatients (age ≥ 16 years, ≥ 4 weeks post-COVID-19 recovery, and a negative SARS-CoV-2 status at enrollment) at Thong Nhat Hospital, Vietnam, from 6 September 2021 to 26 August 2022, using R language software. RESULTS: The majority of patients hospitalized with long COVID-19 symptoms (92.68%) had normal consciousness. The most common symptoms on admission were fatigue (59.02%), dyspnea (52.68%), and cough (42.93%). In total, 80% of patients observed respiratory symptoms, primarily dyspnea, while 42.44% reported neurological symptoms, with sleep disturbance being the most common. Noticeably, 42.93% of patients experienced respiratory failure in the post-COVID-19 period, resembling acute respiratory distress syndrome. DISCUSSION: These findings provide crucial insights into the epidemiology, clinical, and subclinical aspects of post-COVID-19 conditions, shedding light on the prevalence of common symptoms and the demographic distribution of affected patients. Understanding these manifestations is vital for patient well-being, improved clinical practice, and targeted healthcare planning, potentially leading to better patient care, management, and future interventions.

Genotypic diversity of CSFV field strains: A silent risk reduces vaccination efficacy of CSFV vaccines in Vietnam.

Classical swine fever (CSF) is a highly contagious, devastating, and transboundary viral disease that afflicts swine industries worldwide. Immunization with vaccines is one of the most effective strategies for controlling this disease. However, shifts in the antigenicity and pathogenicity of novel evolving viral strains have the potential to evade vaccination. In this study, 352 samples from swines exhibiting fever, hemorrhages, lethargy, and diarrhea in different pig farms located in 9 provinces of Vietnam were collected. CSFV was identified even within farms that had been vaccinated against CSFV. Several farms had swine which had been co-infection with CSFV and other pathogens. Copies of the E2 gene of 21 samples were isolated, cloned, sequenced, analyzed, and compared with copies of E2 in four vaccine strains. We identified a total of 42 amino acid substitutions in this glycoprotein, including 11 positions that affect the antigenic properties of E2 and 7 positions that are associated with neutralizing epitopes. The E2 glycoprotein of CSFV strains circulating in Vietnam and vaccine strains differ in their antigenicity. These findings provide deep insights into the molecular characteristics, genetic diversity, pathogenicity, antigenicity, and evolution of CSFV strains in Vietnam. Understanding the pathogenicity, antigenicity, and evolution of circulating CSFV strains will provide avenues for developing new vaccines and efficient approaches to control this disease.

Dietary carbohydrates: Pathogenesis and potential therapeutic targets to obesity-associated metabolic syndrome.

Metabolic syndrome (MetS) is a common feature in obesity, comprising a cluster of abnormalities including abdominal fat accumulation, hyperglycemia, hyperinsulinemia, dyslipidemia, and hypertension, leading to diabetes and cardiovascular diseases (CVD). Intake of carbohydrates (CHO), particularly a sugary diet that rapidly increases blood glucose, triglycerides, and blood pressure levels is the predominant determining factor of MetS. Complex CHO, on the other hand, are a stable source of energy taking a longer time to digest. In particular, resistant starch (RS) or soluble fiber is an excellent source of prebiotics, which alter the gut microbial composition, which in turn improves metabolic control. Altering maternal CHO intake during pregnancy may result in the child developing MetS. Furthermore, lifestyle factors such as physical inactivity in combination with dietary habits may synergistically influence gene expression by modulating genetic and epigenetic regulators transforming childhood obesity into adolescent metabolic disorders. This review summarizes the common pathophysiology of MetS in connection with the nature of CHO, intrauterine nutrition, genetic predisposition, lifestyle factors, and advanced treatment approaches; it also emphasizes how dietary CHO may act as a key element in the pathogenesis and future therapeutic targets of obesity and MetS.

Down-regulation of solute carrier family 10 member 1 is associated with early recurrence and poorer prognosis of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the most frequent malignancies and the fourth-leading cancer-related death worldwide. Most patients with HCC are diagnosed at a late stage in which curable therapies are limited. Thus, identifying biomarkers for early diagnosis and prognosis of HCC is essential for improving the treatment effectiveness in patients with HCC. In this paper, the SLC10A1 expression levels in the cells and the tissues and their correlation with HCC were analyzed using bioinformatics tools. Clinical information data and gene expression profiles were retrieved from the Gene Expression Omnibus and The Cancer Genome Atlas. Chi-square tests, log-rank tests, and Kaplan-Meier curves were performed using R packages. In all statistical analyses, a p-value of less than 0.05 was considered significant. We found that SLC10A1 primarily expresses in the liver, especially on the plasma membrane. The expression levels of SLC10A1 in tumors were consistently lower than that in normal tissue. Down-regulation of SLC10A1 was correlated with a poor survival outcome [p = 4.50e-05] and recurrence-free survival [p = 8.0e-04] in patients with HCC. In addition, multivariate analysis indicated that the expression of SLC10A1 was an independent predictor for survival outcome [p = 2.17e-05] and recurrence-free survival [p = 1.63e-04]. We concluded that SLC10A1 is a potential biomarker for the early diagnosis and prognosis of HCC in the era of personalized medicine.

Genetic diversity and molecular characterization of classical swine fever virus envelope protein genes E2 and Erns circulating in Vietnam from 2017 to 2019.

Classical swine fever virus (CSFV) is an RNA virus that incurs severe economic costs to swine industries worldwide. This study was conducted to investigate the genetic diversity among CSFV strains circulating in Vietnam, with a focus on their genetic variants relative to four vaccine strains. Samples from clinical cases were collected from different provinces of Central and Southern Vietnam from 2017 to 2019. 21 CSFV-positive samples were selected for amplification and sequencing of the full-length Erns and E2 genes. Phylogenetic analyses of these two genes showed that most CSFV strains circulating in Central and Southern Vietnam from 2017 to 2019 belong to subgroup 2.1c, whereas the remaining strains cluster into subgroup 2.2. All CSFV field strains in this study were genetically distant from group 1 strains. Analysis of the E2 and Erns genes indicated that all CSFV field strains have low sequence identity with the vaccine strains (80-83.5% and 82.3-86% sequence identity for E2 and Erns, respectively). Likewise, amino acid-level sequence analysis showed 87.3-91.1% and 87.6-91.6% sequence identity for E2 and Erns, respectively. Together, our findings indicate that CSFV strains circulating in Vietnam belong to subtypes 2.2 and 2.1c, and we also provide novel insights into the epidemiology, molecular characteristics, genetic diversity, and evolution of these circulating CSFV strains.