Vol. 24 No. đặc biệt 1 (2026): Tạp chí Khoa học Nông nghiệp Việt Nam

African swine fever (ASF) is a highly contagious disease with mortality rates of up to 100%. ASF virus (ASFV) can persist in livestock wastewater; however, its concentration is often low and affected by PCR inhibitors, posing challenges for detection. This study aimed to refine a polyethylene glycol (PEG)-based method for ASFV concentration before DNA extraction to improve detection efficiency using real-time PCR. The results identified optimal processing conditions, including a sample volume of 15ml, pre-centrifugation at 2,000g for 10 minutes, and the use of the supernatant for virus concentration. The optimal PEG 6000 concentration was 15% (w/v), with virus pelleting performed at 10,000g for 30 minutes. Two DNA extraction methods yielded comparable performance. Application of the PEG-based concentration protocol significantly improved ASFV detection compared to untreated samples. In field samples, the number of positive detections increased from 1/56 (untreated) to 8/56 (PEG-treated). These findings suggest that PEG-based virus concentration has strong potential for environmental surveillance and early detection of ASFV in pig production systems.

Trypanosoma evansi, Theileria spp., and Anaplasma spp. are important blood-borne parasites in cattle that adversely affect animal health and production efficiency. This study aimed to establish a multiplex PCR assay for the simultaneous detection of these three pathogens and to preliminarily evaluate its applicability to field blood samples collected in Hanoi. Three specific primer pairs targeting the 16S rDNA gene of Anaplasma spp., the 18S rRNA gene of Theileria spp., and the RoTat 1.2 VSG gene of T. evansi were used in the assay. The results showed that the optimal multiplex PCR conditions were an annealing temperature of 54°C and a primer concentration of 10.0 pmol for each primer, producing clear amplicons of the expected sizes without non-specific amplification with Babesia spp., Haemoplasma spp., or Rickettsia spp. The assay detected target DNA at concentrations as low as 0.2 ng/µl. When applied to 54 cattle blood samples collected from Phu Dong farm, Hanoi, 19 samples (35.2%) were positive, with Theileria spp. showing the highest detection rate. The multiplex PCR results were fully consistent with those of simplex PCR performed on the same samples. These findings suggest that multiplex PCR is a promising tool for rapid simultaneous screening of major blood parasites in cattle under field conditions in Vietnam.

Taenia taeniaeformis is a prevalent tapeworm species that parasitizes felines, distinguished by variability in the number of rostellar hooks, a notable morphological characteristic of the genus. This investigation aimed to identify and assess the intraspecific genetic diversity of T. taeniaeformis in domestic cats utilizing two mitochondrial markers, cox1 and nad1. Nine adult tapeworm specimens, possessing 32-48 rostellar hooks, were subjected to PCR amplification and DNA sequencing. The sequences obtained demonstrated a high degree of nucleotide similarity to reference sequences in GenBank, achieving 99.53% for cox1 and 99.78% for nad1, thereby confirming the specimens' classification as T. taeniaeformis. Genetic analyses indicated that the nad1 gene exhibited greater genetic variability than cox1, as evidenced by a higher nucleotide diversity value ( = 0.066 versus 0.017), suggesting its enhanced potential for resolving population structure and phylogenetic analyses. The findings also suggested that the genetic diversity of T. taeniaeformis was not solely reliant on variations in the number of rostellar hooks. This study contributes significant molecular data on T. taeniaeformis in cats in Vietnam.

This study was conducted to investigate ornamental bird keeping practices and determine the antimicrobial resistance of Escherichia coli isolated from bird’s feces in Long Bien, Hanoi. A total of 48 bird-keeping households were interviewed, and fecal swab samples were collected. E. coli was isolated on MacConkey agar and identification was performed using biochemical tests. Disk diffusion method was used for antimicrobial susceptibility testing. The results showed that the red-whiskered bulbul is the commonly kept species among households (50,0%). All households kept birds exclusively in cages, and the majority did not own other animal species (60.4%). Most households (95.8%) reported cleaning bird feces either daily or every 2-3 days. However, only 10.9% of households used gloves during feces handling, and 78.3% reported washing their hands with soap after handling bird feces. E. coli was detected in 13/48 samples (27.1%). All 13 E. coli isolates were resistant to at least one antimicrobial, 6 multidrug resistant E. coli isolates were observed (46.2%). The E. coli isolates showed the high resistance rates to sulfamethoxazole/trimethoprim (84.6%), tetracycline (53.8%), ampicillin (46.2%) and streptomycin (38.5%).

This study was conducted to evaluate microbial contamination in Vietnamese pork sausages (gio, cha) collected from retail markets in Hanoi and to identify select virulence genes in the isolated bacterial strains. From February to November 2025, thirty “gio” and eighty “cha” samples were collected from 21 traditional markets in the northern suburbs of Hanoi to evaluate several microbiological indicators. The results showed that 68.2% of samples failed to meet the total aerobic bacteria criterion and 46.4% failed to meet the E. coli criterion; 100% of samples met the Salmonella criterion. However, only 18.2% of samples met all required microbiological standards. PCR detection of virulence genes showed that the isolated E. coli strains did not carry the stx1, stx2, eaeA, and hlyA genes. However, five out of 51 isolated E. coli strains (9.8%) carried at least one gene producing either Heat-STable toxin (ST) or Heat-Labile toxin (LT). Specifically, two strains (3.92%) carried only the STa gene, and three strains (5.88%) carried both the LT and STa genes. The study results highlighted the hygiene status of processed foods and warned of the potential risk posed by E. coli strains carrying toxin genes in processed meat products. Therefore, the processing and distribution stages need to be managed and monitored to ensure food safety.

Taenia hydatigena is a tapeworm species parasitizing dogs and is of important veterinary significance because its larval stage, Cysticercus tenuicollis, causes considerable economic losses in intermediate hosts. This study aimed to identify and evaluate the genetic characteristics of T. hydatigena parasitizing dogs in Hanoi based on two mitochondrial markers, cox1 and 12S rRNA. Adult tapeworms were collected, followed by DNA extraction, PCR amplification, and sequencing. The obtained cox1 and 12S rRNA sequences showed 100% nucleotide identity with reference sequences deposited in GenBank, confirming the species as T. hydatigena. Based on 100 cox1 gene sequences and 104 sequences of 12S rRNA gene, a total of 13 and 49 haplotypes were identified, respectively. Genetic diversity indices indicated that the 12S rRNA gene exhibited a higher level of variation than the cox1 gene (Hd = 0.863 vs. 0.442; = 0.068 vs. 0.020). The haplotype network displayed a star-like structure with one dominant central haplotype, suggesting a recent population expansion from a common ancestor. In addition, several haplotypes formed distinct genetic clusters, indicating genetic differentiation of this species. The findings provide important molecular data for future epidemiological studies of T. hydatigena.

This study was conducted to evaluate and screen guide RNAs (gRNAs) targeting the myostatin (MSTN) gene for bovine embryo genome editing using the CRISPR/Cas9 system. In vitro-fertilized zygotes were electroporated with ribonucleoprotein (RNP) complexes consisting of Cas9 protein and either single gRNAs (gRNA#2, gRNA#4, gRNA#8) or dual-gRNA combinations (gRNA#8&2, gRNA#8&4). Editing efficiency was assessed based on cleavage rate, blastocyst formation rate, and sequencing analysis of the MSTN target locus in blastocysts to determine mutation frequency and biallelic mutation rate. The cleavage rates ranged from 66.5% to 77.1%, with the gRNA#8&4 group showing a significantly lower cleavage rate compared with the gRNA#2 and gRNA#4 groups (P

This study was conducted to investigate the presence of Gyrovirus in chickens raised in several communes in Bac Ninh province. A total of 60 pooled samples were obtained from chickens exhibiting symptoms of lethargy, poor growth, and diarrhea at farms located in Tien Luc, Nha Nam, Yen The, and Yen Dinh communes of Bac Ninh province from May to November 2025. Polymerase chain reaction (PCR) analysis revealed that the detection rates of chicken Gyrovirus homsa2 virus was 11.11%, 6.67%, 9.09%, and 18.75% in districts Tien Luc, Nha Nam, Yen The, and Yen Dinh, respectively. The partial sequencing of the VP1 gene regions indicated that the circulating strains in chickens belonged to the Gyrovirus homsa2 and were genetically close to the Chinese Gyrovirus homsa2 reported in 2024. These findings provide additional evidence of the presence of Gyrovirus homsa2 at several districts of Bac Ninh province in chickens and contribute a foundation for further studies on Gyrovirus.

This study aimed to investigate the prevalence of Ehrlichia canis infection in dogs at three veterinary clinics in Hanoi during January - December 2025. A total of 1,381 dogs were presented, of which 302 were tested for blood parasites; 44 dogs (14.57%) showed clinical signs suggestive of blood-borne parasitic infection. Suspected cases were diagnosed using the rapid serological Ehrlichia canis Ab Test and DiffQuick blood smear staining. Results showed that 22.73% (10/44) were positive for Ehrlichia canis by the Ab Test and 13.64% (6/44) by blood smear, and Ehrlichia canis was not the predominant pathogen. Dogs with Rhipicephalus sanguineus ticks had a higher positive rate than those without ticks (25.80% vs. 15.40%), but the difference was not statistically significant (P = 0.68). The most common clinical signs in positive dogs were lethargy, fatigue and anorexia (80%), abdominal hemorrhage (60%), epistaxis and pale mucous membranes (50%). The findings confirm that Ehrlichia canis is circulating in dogs in Hanoi and emphasize the need to combine multiple diagnostic methods to improve accuracy in clinical diagnosis and epidemiological surveillance.

Selecting appropriate reference genes is crucial for ensuring the reliability of RT-qPCR-based gene expression analysis. This study aimed to compare β-actin and GAPDH as reference genes for evaluating the expression of BDNF and BACE1 in the mouse hypothalamus under a fasting-refeeding model. Healthy male mice were divided into three groups: control, 48-hour complete fasting (with free access to water), and 4-hour refeeding after 48 hours of fasting. Hypothalamic samples were collected, total RNA was extracted, cDNA was synthesized, and gene expression was analyzed by RT-qPCR. When normalized to -actin, BDNF expression was significantly decreased in the 48-hour fasting group and was no longer significantly different from the control group after 4 hours of refeeding. In contrast, when normalized to GAPDH, BDNF expression showed no significant changes in either treatment group. For BACE1, expression levels did not differ significantly among groups and yielded consistent results regardless of normalization with either reference gene. These findings indicate that -actin and GAPDH are not fully equivalent as reference genes in the fasting–refeeding model, and β-actin may be more suitable for evaluating genes sensitive to metabolic status in the mouse hypothalamus.

This cross-sectional study aimed to isolate and identify Streptococcus equi subsp. zooepidemicus (SEZ), determine the SEZ positivity rate, and explore differences among age and breed groups in cats presenting with respiratory signs at selected veterinary facilities in Hanoi. From January to December 2025, combined nasal-oropharyngeal swab samples were collected from 116 individual cats using purposive sampling for bacterial culture and phenotypic identification. Suspected isolates were further identified using PCR assays targeting the sodA and seM genes; isolates were considered consistent with SEZ when positive for sodA and negative for seM. SEZ was detected in 69 of 116 cats, corresponding to a positivity rate of 59.48% (95% CI: 50.38-67.97%). No statistically significant differences in SEZ positivity were detected among age groups (P = 0.878) or breed groups (P = 0.923). Three selected isolates exhibited 100% sequence identity to one another across a 517-bp fragment spanning the V1-V3 region of the 16S rRNA gene and provisionally clustered with reference sequences assigned to genogroup 1. These findings confirm the presence of SEZ in the sampled cats but do not establish its etiological role or permit extrapolation of the observed positivity rate to the general cat population in Hanoi.

Duck adenovirus type 3 (DAdV-3-1), a member of the Aviadenovirus, is an important pathogene causing significant economic losses to the duck industry in China. However, studies and information regarding the circulation of DAdV-3 in duck populations in Vietnam remain limited. This study was aimed to isolate and molecularly characterize a DAdV-3 strain, designated VNUA-DAdV3-1, from clinical samples collected from a diseased duck flock in December 2025 in My An, Bac Ninh province, Vietnam. The VNUA-DAdV3-1 strain was successfully isolated and propagated in duck embryo fibroblast (DEF) cells. Cytopathic effects (CPE) were first observed at 24h post-inoculation, became evident at 48 and 72h, and reached maximum severity at 96 h, characterized by cell rounding, shrinkage, detachment, and extensive destruction of the cell monolayer with the viral titer peaked at 1.36 × 10⁷ TCID50/ml. PCR and real-time PCR assays confirmed that the isolate belonged to DAdV-3. Sequence analysis of the Hexon gene revealed more than 99% nucleotide identity with DAdV-3 strains reported in China during 2015-2022. To our knowledge, this study represents the first documentation of DAdV-3 isolation and confirmation of its circulation in Vietnam. These findings provide essential baseline data for epidemiological surveillance and the development of effective control strategies against Duck adenovirus type 3 infection in duck populations.