Characterization of an African Swine Fever Virus Field Isolate from Vietnam with Deletions in the Left Variable Multigene Family Region.

In this paper, we report the characterization of a genetically modified live-attenuated African swine fever virus (ASFV) field strain isolated from Vietnam. The isolate, ASFV-GUS-Vietnam, belongs to p72 genotype II, has six multi-gene family (MGF) genes deleted, and an Escherichia coli GusA gene (GUS) inserted. When six 6-8-week-old pigs were inoculated with ASFV-GUS-Vietnam oro-nasally (2 × 105 TCID50/pig), they developed viremia, mild fever, lethargy, and inappetence, and shed the virus in their oral and nasal secretions and feces. One of the pigs developed severe clinical signs and was euthanized 12 days post-infection, while the remaining five pigs recovered. When ASFV-GUS-Vietnam was inoculated intramuscularly (2 × 103 TCID50/pig) into four 6-8 weeks old pigs, they also developed viremia, mild fever, lethargy, inappetence, and shed the virus in their oral and nasal secretions and feces. Two contact pigs housed together with the four intramuscularly inoculated pigs, started to develop fever, viremia, loss of appetite, and lethargy 12 days post-contact, confirming horizontal transmission of ASFV-GUS-Vietnam. One of the contact pigs died of ASF on day 23 post-contact, while the other one recovered. The pigs that survived the exposure to ASFV-GUS-Vietnam via the mucosal or parenteral route were fully protected against the highly virulent ASFV Georgia 2007/1 challenge. This study showed that ASFV-GUS-Vietnam field isolate is able to induce complete protection in the majority of the pigs against highly virulent homologous ASFV challenge, but has the potential for horizontal transmission, and can be fatal in some animals. This study highlights the need for proper monitoring and surveillance when ASFV live-attenuated virus-based vaccines are used in the field for ASF control in endemic countries.

Detection of Recombinant African Swine Fever Virus Strains of p72 Genotypes I and II in Domestic Pigs, Vietnam, 2023.

African swine fever virus (ASFV) genotype II is endemic to Vietnam. We detected recombinant ASFV genotypes I and II (rASFV I/II) strains in domestic pigs from 6 northern provinces in Vietnam. The introduction of rASFV I/II strains could complicate ongoing ASFV control measures in the region.

Stixis scandens leaf extract-loading ZnO nanoparticles for porcine epidemic diarrhea virus (PEDV) treatment.

Porcine epidemic diarrhea (PED) is one of the diseases that causes great losses for livestock farmers. Because vaccines against the disease are not very effective, there is a great demand for biological products with effective resistance to PED virus (PEDV). One of the most important trends today is the use of active ingredients from nature in animal husbandry. This study aimed to create an effective agent against PEDV from the extract of Stixis scandens, which has been shown to inhibit PEDV. The aqueous (denoted as TCN) and ethanolic extracts (denoted as TCC) of Stixis scandens leaves were first prepared and then qualitatively analyzed for their chemical compositions. The TCN was used to synthesize ZnO nanoparticles (NPs) at various sizes from 20 to 120 nm. Subsequently, TCC was loaded on ZnO NPs to form ZnO-extract nanoformulations with an extract loading content of 5.8-7.6%. Total polyphenols (TP) and total alkaloids (TA) in TCC were 38.51 ± 0.25 µg GAE per mg and 22.37 ± 0.41 µg AtrE per mg, respectively. TP was less loaded but more released from the nanoformulations than TA. The A1T nanoformulation, containing only 7.6% extract, had a minimum PEDV inhibitory concentration of 3.9 µg mL-1, which was comparable to that of TCC. The experiments confirmed that the nanoformulations are promising for PEDV inhibition applications.

Detection and genetic characterization of canine distemper virus isolated in civets in Vietnam.

Canine distemper (CD), caused by the canine distemper virus (CDV), is a lethal systemic disease to a wide range of wild and domestic carnivorous hosts, including civets. In this study, a possible CD outbreak in a backyard farm with 32 diseased civets (Viverricula indica) in Hanoi, Vietnam, was investigated. The sick civets showed CD-like clinical signs such as anorexia, sedentary behavior, diarrhea, dermatitis, nasal, and footpad hyperkeratosis. Various tissue samples collected from the dead civets were utilized for molecular screening of CDV and histopathological examination. The genetic detection and characterization confirmed that samples collected from dead civets tested positive for CDV. The phylogenetic analysis based on the full-length H gene sequences indicated that all CDV strains isolated from civets belonged to the Asia-1 lineage and were closely related to the CDV strains previously reported from dogs in Thailand, China, and Vietnam. Histopathological examination showed severe interstitial pneumonia, hemorrhagic alveolar septa, necrotic alveolar epithelial cells, necrotic, degenerated, or lost Purkinje cells, eosinophilic intracytoplasmic inclusion bodies, edema, and perivascular cuff. This study confirmed the detection of CDV in civets for the first time in Vietnam.

Estimation of basic reproduction number (R0) of African swine fever (ASF) in mid-size commercial pig farms in Vietnam.

African swine fever (ASF) is a devastating disease affecting the global swine industry. Recently, it has spread to many countries in Africa, Europe, Asia, and the Caribbean, leaving severe damage to local, regional, national, and global economies. Due to its highly complex molecular characteristics and pathogenesis, the development of a successful vaccine has been an unmet challenge. Therefore, ASF control relies solely on biosecurity, rapid detection, and elimination. Epidemiological information obtained from natural ASF outbreaks is critical for designing and implementing ASF control measures. Basic reproduction number (R0), an epidemiological metric used to describe the contagiousness or transmissibility of infectious agents, is an important epidemiological tool. In this study, we have calculated R0 for the in-farm spread of ASF among fattening pigs and sows in two midsize commercial pig farms, HY1 and HY2, that practice the spot removal approach in controlling ASF outbreaks in Vietnam. The R0 values for the sows and fattening pigs were 1.78 (1.35-2.35) and 4.76 (4.18-5.38) for HY1 and 1.55 (1.08-2.18) and 3.8 (3.33-4.28) for HY2. This is the first study to evaluate the transmission potential of ASF in midsize commercial pig farms in Vietnam. Based on the R0 values, we predict that the spot removal approach could be used to successfully control ASF outbreaks in midsize commercial sow barns but not in fattening pens.

Molecular and histopathological characterization of lumpy skin disease in cattle in northern Vietnam during the 2020-2021 outbreaks.

Lumpy skin disease (LSD) is a serious emerging infectious disease in cattle caused by a virus of the family Poxviridae. According to the Department of Animal Health, LSD first occurred in Vietnam at the end of October 2020 in Cao Bang and Lang Son provinces. So far, the disease has infected over 63,000 animals, resulting in 9170 deaths occurring in 32 different provinces in northern and central Vietnam. In this study, skin samples from lumpy skin disease virus (LSDV)-infected cattle from the northern provinces of Vietnam displaying clinical symptoms including fever (> 40 °C), runny nose, drooling, and skin lesions were used for genetic characterization and histopathology. Genetic analysis of the partial P32 (LSDV074), partial F (LSDV117), complete RPO30 (LSDV035), and complete G-protein-coupled-chemokine-like receptor (GPCR) (LSDV011) genes showed that all Vietnamese LSDV strains belonged to the genus Capripoxvirus and were closely related to LSDV strains isolated in China. Microscopic examination of the skin lesions showed thickening of the epidermal layer of the skin and hair follicles, hyperplasia of sebaceous glands, intracytoplasmic inclusion bodies, and hemorrhages in the mesoderm.

Nutritional composition and antioxidant properties of the sim fruit (Rhodomyrtus tomentosa).

In this study, detailed chemical properties of sim (Rhodomyrtus tomentosa (Ait.) Hassk.) fruit including nutritional composition, phenolic content and antioxidant capacity were determined for the first time. A 150g serving of sim fruit contained high levels of dietary fibre (69.94-87.43% of Recommended Daily Intake (RDI)), α-tocopherol (38.90-51.87% RDI), manganese (>100% RDI), and copper (44.44% RDI) but low levels of protein (2.63% RDI), lipid (1.59-3.5% RDI), and sugars (5.65% RDI). The predominant fatty acid in the sim fruit sample was linoleic acid (75.36% of total fatty acids). Interestingly, total phenolics (49.21±0.35mg gallic acid equivalent (GAE)/g dry weight (DW)) were particularly high and resulted in a high antioxidant capacity (431.17±14.56µmol Trolox equivalent (TE)/g DW). These results, together with our recent discovery of high amount of piceatannol, a stilbene with potent biological activities, highlight the potential of sim, an under-utilised plant species from South-East Asia, as a new source of health-promoting compounds including dietary fibres, essential fatty acids, and phenolic compounds.

Piceatannol, a potent bioactive stilbene, as major phenolic component in Rhodomyrtus tomentosa.

The sim fruit (Rhodomyrtus tomentosa) has long been used in folk medicine to treat diarrhoea, dysentery, and to boost the immune system. The purpose of this work was to determine its phenolic profile and to evaluate the changes of content during maturation, as well as the variations induced by environmental conditions. Using HPLC-ESI-HR-MS, 19 phenolic compounds (PCs) were tentatively characterised and included stilbenes and ellagitannins as major components, followed by anthocyanins, flavonols, and gallic acid. PCs were then further quantified by HPLC-DAD. Piceatannol, a promising health-promoting stilbene component, was the major PC in the fruit with a concentration of 2.3mg/g dry weight at full maturity stage. This concentration is 1000-2000 times higher than that of red grapes, a major source of stilbene in the human diet. During maturation, the contents in piceatannol and other stilbenes, ellagitannins, and flavonols decreased while the anthocyanin content increased. Shade-grown sim fruits showed significantly higher piceatannol levels than sun-exposed fruits. Taken together, these findings highlight the potential of sim, an under-utilised plant species from South-East Asia, as a source of health-promoting fruits.