http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/4 2026-05-12T12:20:04Z 2026-05-12T12:20:04Z Tran, Diem Hong Vo, Ngoc Truc Giang Phung, Thi Thu Huong Le, Minh Bui http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21699 2026-05-07T08:07:28Z 2025-01-01T00:00:00Z

Title: A colorimetric multiplex RPA approach for on-site dual monitoring of Vibrio parahaemolyticus and White Spot Syndrome Virus in Pacific Whiteleg shrimp Authors: Tran, Diem Hong; Vo, Ngoc Truc Giang; Phung, Thi Thu Huong; Le, Minh Bui Abstract: White spot syndrome virus (WSSV) and Vibrio parahaemolyticus represent the most prevalent and serious pathogens in Viet Nam's shrimp industry, annually inflicting major production losses. With no existing therapeutic measures, timely and accurate diagnosis is imperative for curbing outbreaks and limiting economic impacts through isolation and culling protocols. However, conventional techniques like polymerase chain reaction (PCR) and quantitative PCR require advanced laboratory infrastructure that is incompatible with rapid on-site pathogen surveillance. This work details the development of a multiplex recombinase polymerase amplification (RPA) assay for the simultaneous detection of WSSV and V. parahaemolyticus using a visual colorimetric readout amenable to field deployment. Primers targeting unique WSSV and V. parahaemolyticus sequences were designed for selective amplification. Specificity screening verified exclusive pathogen detection against common shrimp microbiota and human-handling contaminants with no cross-reactivity. Singleplex reactions identified 39 °C for 35 minutes as optimal conditions; hence, these parameters were subsequently applied in multiplex format. Incorporation of the Mg2+-sensitive eriochrome black T (EBT) dye enabled clear discrimination between positive blue and negative violet reactions by the naked eye. The multiplex assay demonstrated high analytical sensitivity, down to 1 copy of DNA template per reaction. Clinical validation of the multiplex RPA method using shrimp samples versus quantitative PCR showed 100% agreement. By coupling rapid isothermal amplification with visual indicator-based detection in a multiplexed format, this assay provides simple, robust, and user-friendly identification of major shrimp pathogens in resource-limited settings in less than one hour to facilitate prompt on-site disease control decisions. The field-suitable platform aims to mitigate outbreak magnitude and economic consequences through timely response.

2025-01-01T00:00:00Z Do, Thu Uyen Tran, Hoang Son Vu, Quang Dinh Nguyen, Quang Huy http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21698 2026-05-07T07:39:46Z 2025-01-01T00:00:00Z

Title: Distribution of antibiotic resistance genes in marine water and sediments in aquaculture areas in Khanh Hoa, Vietnam Authors: Do, Thu Uyen; Tran, Hoang Son; Vu, Quang Dinh; Nguyen, Quang Huy Abstract: The emergence of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) poses significant risks to ecological security and human health. Coastal areas affected by urban and aquaculture activities serve as critical reservoirs for pollutants, including ARGs. However, the data on the abundance and distribution of ARGs in marine sediments impacted by aquaculture activities in the East Sea, Vietnam, remain limited. This study investigated the distribution of ARGs across four aquaculture areas in the East Sea of Khanh Hoa province, Vietnam. The results revealed that sulfonamide-resistant genes, sul1and sul2, were present at all sampling sites (100%), with abundance ranging from 2.4 × 102to 2.0 × 105copies/ml in seawater and from 2.0 × 105to 2.57 × 107copies/g in sediments. Tetracycline-resistant genes, including tetQ, tetM, and tetX, were detected at most sampling sites, with abundances ranging from 1.29 × 101to 6.16 × 106copies/ml in seawater and from 1.64 × 104to 1.04 × 108copies/g in sediments. The vancomycin-resistant gene (vanA)exhibited significant abundance, ranging from 1.38 × 103to 3.22 × 104copies/ml in seawater and from 1.14 × 106to 1.9 × 107copies/g in sediments. Finally, integron class 1 (intI1) was detected at all sampling sites (100%) in both seawater and sediments, with abundances up to 6.86 × 105copies/ml in seawater and 2.06 × 108copies/g in sediments. Given aquaculture's significant role in Vietnam's economic growth, implementing effective technologies and national policies to manage and mitigate antimicrobial resistance in aquaculture environments is crucial

2025-01-01T00:00:00Z Tran, Dinh Long Nguyen, Xuan Bach Phan, Thanh Loc Nguyen, Quynh Thuong Nguyen, Thanh Duc Tran, Truc Thanh Tran, Van Ty http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21697 2026-05-07T03:44:31Z 2025-01-01T00:00:00Z

Title: In vitro antifungal activity of Chitosan derived from shrimp co-products against pathogenic fungi isolated in Vietnam Authors: Tran, Dinh Long; Nguyen, Xuan Bach; Phan, Thanh Loc; Nguyen, Quynh Thuong; Nguyen, Thanh Duc; Tran, Truc Thanh; Tran, Van Ty Abstract: The global overuse of antibiotics and agrochemicals in Vietnam leads to antibiotic resistance, health risks, and environmental damage. This study evaluates in vitro antifungal properties of different types of shrimp waste-derived chitosan against Vietnamese agricultural fungi as a sustainable alternative to chemical fungicides. Several pathogenic microbe strains were isolated and identified by morphological and molecular gene sequencing: Neoscytalidium dimidiatum causing brown spot on dragon fruit; Fusarium fujikuroi & Fusarium subglutinans causing banana crown rot; Fusarium oxysporum & Fusarium odoratissimum causing banana stem rot; Lasiodiplodia theobromae causing fruit rot & Colletotrichum queenslandicum causing anthracnose on passion fruit; Fusarium equiseti & Fusarium napiforme causing swollen swim bladder on striped catfish. The antifungal properties of several chitosan types were investigated following the inhibition of the fungal mycelial growth method. CTIC15 & OLIC25 demonstrated significant fungal growth inhibition from 90% to 100% at 0.328 g/L to 0.625 g/L for all isolated fungal strains. Chitooligosaccharide COSL02 exhibited an antifungal effect against L. theobromae, F. oxysporum, N. dimidiatum, and F. odoratissimum with inhibition rates from 53.11 ± 2.74% to 100 ± 0.00% at 0.438 g/L to 0.876 g/L. Low molecular weight LV01 displayed broad-spectrum antifungal efficacy, excluding F. subglutinans, with inhibition rates from 74.11 ± 10.36% to 100 ± 0.00% at 0.2 g/L, and above 42.08 ± 5.87% at 0.1 g/L. Medium molecular weight MV01 shared comparable antifungal potency to LV01, except for F. equiseti and N. dimidiatum, with inhibition rates from above 74.09 ± 7.09% to 100 ± 0.00% at 0.2 g/L, and above 58.77 ± 0.87% at 0.1 g/L. This study suggested chitosan (shrimp waste) could serve as an effective and sustainable alternative to chemical fungicides in controlling pathogenic microbes.

2025-01-01T00:00:00Z Nguyen, Thi Hai Thanh Khang, Quy Dao, Thi Mai Lan http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21696 2026-05-07T03:43:34Z 2025-01-01T00:00:00Z

Title: Construction of a CRISPR vector for inducing TYR gene mutations in anemonefish Amphiprion ocellaris Authors: Nguyen, Thi Hai Thanh; Khang, Quy; Dao, Thi Mai Lan Abstract: The anemonefish Amphiprion ocellarisis highly popular in the ornamental fish trade due to its distinctive coloration, which features a combination of orange, black, and white. The formation of black pigmentation in teleost fish is controlled by the tyrosinase-producing gene (tyr), which is responsible for melanin production. Studies have indicated that deletion mutations in the tyrgene family in fish and many other vertebrates lead to skin color abnormalities, such as albinism. The clustered regularly interspaced short palindromic repeat (CRISPR) system has emerged as a powerful and precise tool for gene editing with diverse applications. In this study, we construct a CRISPR/Cas9 system targeting the exon 2 region of the tyrgene in A. ocellaris. A guide RNA (gRNA) was designed and incorporated into the gRNA cloning vector and was subsequently introduced into Escherichia colistrain DH5-α. Afterward, the successfully incorporated gRNA sequence was validated via Sanger sequencing. The E. coliDH5-α strains carrying this recombinant plasmid were subsequently checked and screened for stability via generations. This gRNA vector together with the Cas9 plasmid will be used to generate knock-out mutations, enabling further investigation ofthe function of the tyrgene in melanin formation in anemonefish A. ocellaris.

2025-01-01T00:00:00Z Nguyen, Thi Phuong Thao Ta, Thi Thu Thuy Bui, Van Ngoc http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21695 2026-05-07T03:43:54Z 2025-01-01T00:00:00Z

Title: Evaluation of the antioxidant activity of coral mucus isolated from poriteslobatain vitro Authors: Nguyen, Thi Phuong Thao; Ta, Thi Thu Thuy; Bui, Van Ngoc Abstract: Marine-derived natural products have attracted much interest from scientists (chemists and pharmacologists), since many of their potential bioactivities are still unexplored. Among marine natural products discovered to date, 56% are anticancer, 13% are antibacterial, 5% are antifungal, and 3% are antiviral compounds. These compounds come from green algae (1%), red algae (4%), brown algae (5%), sponges (31%), corals (24%), and marine microorganisms (15%). Coral reefs, especially Porites lobata, secrete surface mucus layers (SMLs) that serve as essential barriers in host defense and microbial regulation. However, environmental stressors such as bleaching may alter the biochemical composition of this mucus, compromising its biological functions. This study aimed to compare the antioxidant properties of mucus obtained from healthy and bleached P. lobatacorals to assess the impact of bleaching on their natural protective capabilities. The DPPH assay and flow cytometry with dihydroethidium (DHE) staining were used to evaluate the free radical scavenging activity and antioxidant capacity of coral surface mucus layer samples. The antioxidant activity of healthy coral mucus was significantly higher than that of bleached mucus, with a 2-fold increase at 1/5 and 1/10 dilutions, and nearly a 2.8-fold increase at 1/20 dilution. Theresults indicate that mucus from healthy corals exhibited significantly higher antioxidant activity than that from bleached corals. DPPH analysis showed stronger radical scavenging ability in healthy mucus extracts, while flow cytometry demonstrated a marked reduction in reactive oxygen species (ROS) accumulation in treated HCT116 cells compared to both bleached mucus and control groups. These findings suggest a decline in the coral’s natural defense mechanisms post-bleaching. The mucus from healthy corals has the ability to reduce the accumulation of intracellular ROS in HCT116 cells, indicating its potential to against oxidative stress-related diseases. The robust antioxidant activity of healthy coral mucus highlights its potential as a source of novel marine-derived antioxidants. This study supports further investigation into the bioactive compounds from the surface mucus layer of healthy Porites spp. corals for potential therapeutic applications against oxidative stress-related diseases.

2025-01-01T00:00:00Z