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African swine fever (ASF) is a highly infectious disease in pigs caused by the African swine fever virus (ASFV), which might result in 100% mortality. Pigs infected with ASFV might display different clinical and pathological features depending on virulence and host factors. This study aimed to determine features of clinical symptoms, macroscopic, and microscopic lesions of ASF in the Mekong Delta (MD), Vietnam during 2021–2022. The investigation was conducted following three fatal outbreaks of ASF in Hau Giang, Vinh Long, and Can Tho provinces, which are three central provinces out of thirteen in the MD. The spleen, lymph nodes, liver, kidney, and heart were collected from three infected pigs that displayed clinical symptoms of ASFV infection and confirmed the presence of ASFV by conventional PCR. The results indicated that infected pigs showed common clinical symptoms including high fever, anorexia, and moderate petechiae on the skin. Severe hemorrhage was observed in lymph nodes, spleen, kidneys, intestines, and gallbladders which were the main lesions during post-mortem examination. Microscopic lesions were characterized by lymphocytopenia, atrophy of lymphoid follicles in the immune system. However, distinct variations in clinical symptoms, macroscopic, and microscopic features among ASFV infection cases were not documented. This study provides a further understanding of the clinical presentation and pathological lesions caused by the ASFV strain circulating in the MD.

Mangiferin is a xanthonoid found in Mango leaves in abundance with many effects as a hypoglycemic, antioxidant, and anti-inflammatory agent, plant metabolite, and so on. However, nowadays, mango leaves are merely a waste product in Vietnam. To take advantage of this valuable medicinal resource, extraction conditions of mangiferin using classical and ultrasound methods were researched, and mangiferin was purified from Cat Chu mango leaves (Mangifera indica L., Anacardiaceae) collected in Dong Thap. Ultrasound-assisted extraction method was conducted with the following conditions and mangiferin was extracted at a percentage of 6.728% with a purity of 91.11%. Purified mangiferin was evaluated using molecular absorption spectroscopy UV-Vis, scanning electron microscopy (SEM), X-ray diffraction (XRD) spectroscopy, simultaneous thermal analysis (STA: TGA/DSC), and dissolution measurement method. To optimize the solubility and permeability of mangiferin, the solid dispersion system (HPTR) was made by the combination of HPMC 6M:mangiferin at the ratio of 1:5. To investigate the acute, sub-chronic toxicity and hypolipidemia effect of HPTR as compared to purified mangiferin, we followed guidelines for preclinical and clinical trials of Traditional Medicine and Herbal Medicines by the Vietnam Ministry of Health and OECD, and used tyloxapol (Triton WR1339, 400 mg/kg, i.p.) to induce hyperlipidemia. Our results indicated that purified mangiferin and HPTR extract showed no acute toxicity and sub-chronic toxicity and has potential as an antihyperlipidemic agent. The HPTR brought about a significant decrease in total cholesterol, triglycerides and LDL-c when compared to mangiferin, however there was no significance between them.

Staphylococci are one of the most commonly found opportunistic bacteria in animals and human. The objective of this study was to determine the prevalence of Staphylococcus spp. isolated from healthy and sick dogs visiting veterinary clinics in Ho Chi Minh city, Vietnam from January 2022 to December 2022. A total of 123 nasal swab samples were collected, including 40 samples from healthy dogs and 83 samples from dogs with respiratory symptoms. Staphylococcus spp. were isolated from 47.5% of healthy animals and 60.24% of dogs showing respiratory symptoms. The study showed that isolation rates from confined, semi-confined and free-ranging dogs were 75.86%, 54.84% and 40.63%, respectively. Furthermore, the prevalence was higher in dogs over one year old compared to younger dogs (64.10% and 42.22%, respectively). Several subspecies of Staphylococci, including S. aureus, S. pseudintermedius and S. epidermidis were identified, in which S. pseudintermedius accounted for the highest proportion (48.28%). The prevalence of S. pseudintermedius also varied across different age groups. Coagulase activity of the isolated Staphylococcus strains was also determined and indicated that coagulase-positive Staphylococci constituted 80.46% of the isolates. This study represents the first report on the prevalence of Staphylococci in dogs in Vietnam and reemphasizes the zoonotic significance of Staphylococcus at the interface between dogs and humans.

Canine infectious respiratory disease (CIRD) viruses, particularly canine distemper virus (CDV), canine adenovirus type 2 (CAV-2), and canine parainfluenza virus (CPIV), are the primary agents responsible for respiratory diseases in dogs. A dog can be infected with a single or multiple viruses with similar clinical signs. Although CIRD is globally prevalent in dogs, investigation into the causative viruses in Vietnam remains limited. This study aims to identify the presence of CIRD virus(es) in dogs via molecular detection. Three primer sets were newly designed and applied into (RT)-PCR reaction to detect viral genes of CDV, CAV-2, and CPIV in a commercial vaccine (Vanguard® Plus 5/L, Zoetis, USA). Both simplex and multiplex (RT)-PCR reactions using the three primer sets could detect the presence of CAV-2, CDV, and CPIV in the vaccine sample. Subsequently, the applicability of the one-step multiplex (RT)-PCR was demonstrated to test for 27 clinical nasal swab samples collected from dogs suspected of having CIRD. The results showed that our (RT)-PCR could detect CIRD virus(es) in all tested clinical samples. PCR amplicons for each representative CAV-2, CDV, and CPIV were selected for sequencing and showed high genetic similarity to respective field viruses. In conclusion, this study successfully developed a one-step multiplex (RT)-PCR reaction to detect and differentiate causative viruses of CIRD in dogs.

Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) are opportunistic pathogens that cause significant diseases in both human and veterinary medicine, particularly in pet animals. In recent decades, the emergence of MRSA and MRSP in pet animals has raised substantial public health concerns due to the high multidrug resistance exhibited by these zoonotic bacteria. Therefore, a rapid and accurate diagnosis is crucial as one of the key strategies for controlling infections caused by MRSA and MRSP. In this study, we applied a simple and cost-effective DNA extraction method, establishing a multiplex PCR assay for the identification and differentiation of MRSA and MRSP isolated from dogs in Vietnam. The results of this study indicate that DNA extraction of MRSA and MRSP using the Tris-EDTA-NaCl-Triton X100 (TENT) method yielded comparable efficacy to using a commercial DNA extraction kit, and the TENT method proved to be more cost-effective. Additionally, a multiplex PCR assay with four primer pairs (27F/1492R, mecA_F/mecA_R, au-F3/au-nucR, and pse-F2/pse-R5) successfully identified and discriminated between MRSA and MRSP. The multiplex PCR demonstrated high specificity with the desired amplification of targeted amplicons and no cross-reactions. Furthermore, the applicability of the diagnostic procedure was demonstrated by identifying field MRSA and MRSP isolated from clinical samples of dogs in Vietnam. Our study, therefore, provides an effective identification procedure for MRSA and MRSP, serving as a prompt countermeasure against the rapid emergence of MRSA and MRSP in Vietnam

Background: Chicken infectious anemia (CIA) caused by chicken infectious anemia virus (CIAV) is considered one of the most important immunosuppressive diseases affecting chicken and recently poses a great economic burden to the poultry industry worldwide. Aim: This study aims to identify the presence of CIAV in the Mekong delta (MD), Vietnam and to determine genotypes of CIAVs that are currently circulating in this area. Methods: Organ samples (spleen, liver, and thymus) of 144 chickens suspected with CIA from 47 poultry farms were collected. A total of 47 pooled samples, each containing two to four chickens of each farm, were tested for the presence of CIAV. Results: Twenty out of 47 pooled organ samples (pool of two to four chickens per farm) were positive for CIAV using PCR targeting the viral VP1 gene. The VP1 amplicons of eight representative CIAVs were subjected for sequencing and genetic characterization. Phylogenetic analysis based on partial VP1 gene sequence revealed that the CIAVs detected in the MD grouped into different genotypes of II, IIIa, and IIIc together with CIAVs previously detected in the northern Vietnam and other Asian countries. The phylogenetic analysis also confirmed that detected CIAVs genetically differed from vaccine strains. In addition, deduced amino acids of the VP1 identified several critical amino acid substitutions in the VP1 protein that are likely associated with the virulence of CIAV. Conclusion: This is the first report to detect and determine genetic characterization of the circulating CIAVs in the MD. Therefore, this study provides important understanding on the evolution of CIAVs and highlights the importance of implementing prompt control measures against CIAVs in the MD and Vietnam. [Open Vet J 2023; 13(6.000): 690-696]

African swine fever (ASF) is a highly contagious and deadly viral disease in domestic and feral pigs. Since 2018, the disease has spread and caused large socioeconomic consequences to the pig industry in several Asian countries including China, Vietnam, and South Korea. This study aims to determine the genotype, serotype, and genetic variation of representative ASF viruses (ASFV) responsible for the outbreaks in 2019–2022 in Can Tho city, a central administrative province in the Mekong delta, Vietnam. For outbreak investigation, the presence of causative ASFVs was tested using conventional PCR targeting the B646L gene. Subsequently, the amplification and sequencing of the DNA fragments of the putative B646L gene encoding the major capsid protein p72, EP402R gene encoding the viral hemagglutinin CD2-like protein (CD2v), and intergenic region (IGR) between the l73R and I329L genes were performed for molecular characterization. Phylogenetic analyses based on B646L and EP402R genes confirmed that all ASFVs detected in Can Tho city belonged to genotype 2 and serotype 8. In addition, this study revealed that at least two variants of ASFVs, namely, IGR II and IGR III, based on the nucleotide variation of the IGR sequence, cocirculated, and caused outbreaks in Can Tho city. The molecular characterization study provides great significance for understanding the evolution of ASFVs and tracing possible sources of infection in Can Tho and Mekong delta.

The H9 and H6 subtypes of low pathogenicity avian influenza viruses (LPAIVs) cause substantial economic losses in poultry worldwide, including Vietnam. Herein, we characterized Vietnamese H9 and H6 LPAIVs to facilitate the control of avian influenza. The space–time representative viruses of each subtype were selected based on active surveillance from 2014 to 2018 in Vietnam. Phylogenetic analysis using hemagglutinin genes revealed that 54 H9 and 48 H6 Vietnamese LPAIVs were classified into the sublineages Y280/BJ94 and Group II, respectively. Gene constellation analysis indicated that 6 and 19 genotypes of the H9 and H6 subtypes, respectively, belonged to the representative viruses. The Vietnamese viruses are genetically related to the previous isolates and those in neighboring countries, indicating their circulation in poultry after being introduced into Vietnam. The antigenicity of these subtypes was different from that of viruses isolated from wild birds. Antigenicity was more conserved in the H9 viruses than in the H6 viruses. Furthermore, a representative H9 LPAIV exhibited systemic replication in chickens, which was enhanced by coinfection with avian pathogenic Escherichia coli O2. Although H9 and H6 were classified as LPAIVs, their characterization indicated that their silent spread might significantly affect the poultry industry.

The objective of this study is to report the complete-genome sequence of a field African swine fever (ASF) virus (ASFV), namely ASF/VN/CanTho-OM/2021, which caused a fatal outbreak in domestic pigs in the Mekong Delta. Complete-genome sequencing detected an 18 bp nucleotide deletion in the EP402R gene (encoding for serotype-specific proteins CD2v) of ASF/VN/CanTho-OM/2021, which was determined to belong to genotype 2 and serotype 8. This mutation pattern was confirmed as unique in GenBank; thus, ASF/VN/CanTho-OM/2021 can be considered a novel variant, with a potential change of sero-characteristics within genotype 2. An additional unique mutation of 78 bp nucleotide insertion was also observed in the B475L gene. Additionally, four copies of tandem repeat sequences were found in the intergenic region (IGR) located between I73R and I329L, previously assigned as the IGR III variant. This study is the first to report the complete genome of ASFV in the Mekong Delta, and it highlights the necessity of strengthening molecular surveillance to provide further knowledge on the evolution and incursion of ASFV in the Mekong Delta and Vietnam.