This study aimed to simultaneously detect three important viruses reported to be involved in the reproductive problems of sows. A multiplex PCR (mPCR) test was developed to provide rapid diagnosis of porcine circovirus type 2 and 3 (PCV2, PCV3) and to illustrate parvovirus (PPV) prevalence in sow herds. Three pairs of specific primers were designed to target PCV2 Cap gene, PCV3 Cap gene and PPV NS1 gene, with predicted mPCR products of 702 bp, 267 bp and 380 bp, respectively. The detection limit of mPCR was 100 copies/reaction per target gene. The mPCR was run against a panel of 94 swine serum samples whose infection status had been pre-determined by commercial real-time PCR kits. Sequencing of mPCR products performed with clinical serum samples accurately confirmed the results. Overall, the results indicated that the mPCR functioned accurately and specifically and matched 100% with the single-target real-time PCRs. The mPCR was developed successfully and can be used in routine diagnosis of PCV2, PCV3 and PPV.

Porcine circovirus type 3 (PCV3) is an emerging circovirus species that has recently been reported in different countries around the world, suggesting a widespread circulation. This study was carried out in order to investigate the presence and further genetic characteristics of PCV3 from swine herds in Southern and Central provinces of Vietnam. A duplex PCR assay for rapid detection of PCV3 in pigs was established with a pair of specific primers designed between rep and cap gene segment to amplify full-length ORF2 and another set of primers binding to COX1gene serving as an internal amplification control (IAC). The resulting duplex PCR was used to examine PCV3 presence in 94tissue and serum samples. Subsequently, PCV3 was detected in 10 out of 94 cases (10.6%). The infection rate in sows (14.3%) was higher than that in grower pigs (7.7%). Regarding nucleotide sequence comparison, 10 ORF2 genes were selected for nucleotide sequencing and their alignment showed 97.2% - 99.5% homology. According to the phylogenetic analysis and sequence alignment of cap gene, all the sequences were clustered into group PCV3a,including 9 strains of sub-group PCV3a1 and only one strain of subgroup PCV3a2. These findings indicated that the PCV3a group is circulating in swine farms in Vietnam. This study provides better insights into epidemiology of this pathogen in the national swine industry.

The purpose of this study was to investigate the presence of Avian paramyxovirus 1 (APMV-1), also known as Newcastle disease virus (NDV), and Avian influenza type A, especially H5 subtype (AIV-H5) in swiftlet houses and swiftlet nest by multiplex RT-PCR (mRT-PCR). The assay used two specific primer pairs designed to detect the conserved sequence of the F gene of NDV and the HA gene of the AIV-H5, with product sizes of 282 bp and 420 bp, respectively. The mRT-PCR was established with detection limit of 25 copies/reaction for each target virus. The thermal cycle was optimized as follows: cDNA synthesis at 45ºC for 20 min, an initial denaturation at 95ºC for 5 min, followed by 35 cycles of amplification encompassing denaturation at 95ºC for 30 sec, annealing at 58ºC for 30 sec, and extension at 72ºC for 45 sec, ending by a final extension step at 72ºC for 7 min. Eighty-eight field samples including feces and swabs of the nest surface were examined and all samples were confirmed to be negative for these two viruses. The results of this study indicated that the swiftlet nests and the environment of swiftlet houses were not contaminated with NDV or AIV-H5 viruses. Moreover, the established mRT-PCR protocol had good specificity, detection limit, and can apply for routine veterinary diagnosis.

This study reports the green synthesis of silver nanoparticles (AgNPs) stabilized in mixtures of oligochitosan and oligo-β-glucan (AgNPs@OCTS+OβGC) via gamma irradiation. UV-Vis spectra showed surface plasmon resonance bands at 406–423 nm. TEM showed spherical nanoparticles of 10.2–14.7 nm, depending on the OCTS/OβGC ratio. DLS showed monomodal distributions (Z-average 36.4–46.1 nm; PDI 0.227–0.260), and the zeta potential of AgNPs@OCTS+OβGC rose from +7.6 to +42.5 mV with OCTS content. FTIR spectra were consistent with the participation of amino- and oxygen-containing groups of the OCTS/OβGC matrix in AgNP stabilization. EDX confirmed silver, and XRD revealed face-centered cubic metallic silver. OCTS-rich formulations showed stronger antibacterial activity against Staphylococcus aureus, Escherichia coli, and Salmonella enterica (inhibition zones up to 21.33 mm; MIC 3.91–7.81 µg.Ag.mL⁻¹), while OβGC-rich formulations showed stronger antioxidant activity (IC₅₀ 3.09 µg.Ag.mL⁻¹ for ABTS and 3.49 µg.Ag.mL⁻¹ for DPPH). AgNPs@OCTS5+OβGC5 had the highest desirability index (D = 0.76): it retained the MIC values of the OCTS-only sample with improved antioxidant activity and remained stable for six months at 25 °C. These in vitro results support further evaluation of radiation-synthesized AgNPs@OCTS+OβGC against poultry-associated bacteria, including safety and in vivo efficacy studies.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically important diseases to swine industry worldwide. Due to the heterogeneity of field isolates, accurate detection of the PRRS virus is a diagnostic challenge. Recently, co-infection with NA-PRRSV, EU-PRRSV and HP-PRRSV isolates continuously increases in many countries, resulting in a significant impact on PRRSV diagnostics and disease control on farms. To facilitate rapid diagnosis and reliable discrimination of NA-PRRSV, EU-PRRSV and HP-PRRSV, a multiplex RT-PCR assay was established with three pairs of primers targeting highly conservative regions of nsp2 gene with predicted multiplex RT-PCR products of 364 bp, 161 bp and 259 bp, respectively. The primer pairs were optimized to be highly specific for PRRSV genotypes and were able to detect the target gene at the limit of 102 copies/μL for each gene. Clinical samples were used to evaluate this multiplex RT-PCR in parallel with a commercial real-time RT-PCR kit. Results showed over 95.2% (20/21 samples) agreement between the mRT-PCR and the real-time RT-PCR kit. Hence, it indicated that this multiplex RT-PCR could be useful for rapid and deferential diagnosis of NA-PRRSV, EU-PRRSV and HP-PRRSV in swine farms.

Haemophilus parasuis(HPS) causes polyserositis in swine andis characterized by pneumonia, pleurisy, peritonitis, cardiomy-opathy, arthritis and meningitis. To assess the current status ofantibiotic resistance of HPS in industrial pig farms, 245 specimenswere collected to isolate HPS on chocolate (PVX) supplementedwith NAD. A total of 51/245 specimens had suspected HPScolonies (20.8%) and those colonies were subsequently identifiedby traditional methods (gram staining and biochemical tests) incombination with PCR using primers specific to a fragment of275 bp of peptidase M1 gene. Twenty-one colonies (8.6%) wereidentified as HPS and then were tested for resistance to the nineantibiotics which are popularly used in swine farms. The resultsof the antibiogram showed that all of these HPS were multiresis-tant bacteria. The percentage of isolates resistant to 7 types, 6types and 5 types of antibiotics was 33.33%, 28.6% and 23.8% re-spectively. Resistance rate was highest forty losin (91%), followedby tilmicosin (81%), tulathromycin (62%), enrofloxacin (62%),lincomycin/spectinomycin (57%), amoxicillin (52%), florfenicol(48%); ceftiofur (10%) and doxycycline (5%). These findingspose a big concernabout the antibiotic resistance of HPS in pigsand that measures should be taken soon to improve this situation. Haemophilus parasuis (HPS) gây bệnh viêm đa thanh dịch với những biểu hiện viêm phổi, màng phổi, phúc mạc, xoang bao tim, khớp, và viêm màng não trên heo. Để đánh giá hiện trạng đề kháng kháng sinh của vi khuẩn HPS trên các trại heo công nghiệp, 245 mẫu bệnh phẩm được thu thập nhằm phân lập HPS, định danh và xét nghiệm kháng sinh đồ. Tổng số 51/245 mẫu có khuẩn lạc nghi ngờ HPS (20,8%) và được định danh bằng phương pháp nhuộm gram, xét nghiệm sinh hóa kết hợp với phương pháp PCR với cặp mồi phát hiện gen mã hóa peptidase M1 có kích thước sản phẩm khuếch đại 275 bp. Kết quả khuẩn lạc trong 21 mẫu (8,6%) được xác định là HPS và được kiểm tra tính kháng đối với 09 loại kháng sinh thông dụng. Kết quả kháng sinh đồ cho thấy các HPS này đều có tính đa kháng. Số vi khuẩn kháng với 7 loại, 6 loại và 5 loại kháng sinh lần lượt là 33,33%, 28,6% và 23,8%. Trong đó, tỷ lệ đề kháng là cao nhất với tylosin (91%), tiếp đó là tilmicosin (81%), tulathromycin (62%), enrofloxacin (62%), lincomycin/spectinomycin (57%), amoxicillin (52%), florfenicol (48%); thấp nhất là ceftiofur (10%) và doxycycline (5%). Số liệu này cho thấy tình hình đề kháng kháng sinh ở vi khuẩn HPS trên heo là rất đáng quan tâm và cần sớm có biện pháp góp phần cải thiện tình trạng này.