Veterinary Integrative Sciences

Current strategies, advances, and challenges in multi-epitope subunit vaccine development for African swine fever virus

Ella Mae Joy S. Sira — 2024-04-25

African Swine Fever (ASF), a highly contagious and lethal viral disease affecting swine populations, presents a critical global threat with no approved vaccine. Traditional approaches such as whole virus-based vaccines have several limitations, prompting interest in peptide-based subunit vaccines. However, the inefficacy of existing peptides and the complexity of the ASFV genome further complicate antigen screening. Immunoinformatics has addressed this challenge by utilizing bioinformatics tools for the design and evaluation of multi-epitope subunit vaccines. Although multi-epitope subunit vaccines offer safety advantages, their potential to induce both humoral and cellular immune responses is crucial for protective immunity against ASFV infection. Despite the growing interest in computational vaccine design, a notable gap exists in in vivo confirmation studies. This review addresses the challenges and advances in ASFV multi-epitope subunit vaccine development, underlining the urgency of a safe and effective vaccine given ASF's global impact on swine populations and associated economic losses.

Multiplex PCR for simultaneous identification and differentiation of methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius isolated from dogs

Nguyen Pham Thao Nhi — 2024-03-14

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

Effects of polymorphisms in PIT1, H-FABP, PIK3C3 and CAST genes on chemical composition, amino acid content in meat of Vietnamese indigenous fatty pig breed “I”

Phan Thi Tuoi — 2024-03-26

This study aimed to evaluate the effects of polymorphisms of PIT1/RasI, H-FABP/HinfI, PIK3C3/Hpy8I, CAST/HinfI genes and gender on chemical composition, amino acid content in meat of Vietnamese indigenous fatty pig breed “I” raised under industrial condition at Dabaco Breeding Pig Company, Phu Tho Province, Vietnam. Samples of longissimus dorsi muscle from 23 “I” pigs (12 gilts and 11 barrows) at 8 months of age were used to measure chemical composition (dry matter, protein, lipids and ash) and content of 17 amino acids (aspartic, glutamic, serine, histidine, glycine, threonine, alanine, arginine, tyrosine, valine, methionine, phenylalanine, isoleucine, leucine, lysine, proline, cystine); while ear tissues were collected to identify polymorphisms of these genes. Chemical compositions were analyzed using ISO methods (1973, 1978, 1997, and 1998). The content of amino acids was quantified using high-performance liquid chromatography (HPLC) methods. The polymorphisms of four genes were identified by the PCR-RFLP technique. The results indicated that PIT1, H-FABP, PIK3C3, and CAST had no effects on chemical compositions and amino acid contents (P>0.05). Inversely, the contents of amino acids (aspartic, serine, threonine, arginine, phenylalanine, leucine, and lysine) were significantly different between gilts and barrows (P<0.05).

Effect of By-Product from C-Phycocyanin Extraction as a Prebiotic Properties and Probiotic Microbial Population

Kannikar Hamprakorn — 2024-03-26

This study was designed to investigate the efficacy of alternative prebiotic supplements derived from phycocyanin extraction by-product in enhancing the growth of probiotic. These alternative prebiotic supplements included Spirulina platensis, the by-product of phycocyanin extraction, and inulin. The efficacy of alternative prebiotics was assessed using beneficial bacteria (Lactobacillus johnsonii ck-3 and ck-8), pathogenic bacteria (Staphylococcus aureus and Escherichia coli), and yeast (Saccharomyces cerevisiae). The alternative prebiotics source was used to analyse the chemical composition, prebiotic activity, and bacteria growth. It was demonstrated that the phycocyanin extraction by-product included a high concentration of crude protein (67.74% DM), carbohydrates (31.29% DM). The phycocyanin extraction by-product has a high content of glucose, fructose, and sucrose (63.55, 68.00, and 0.24 µg/ml, respectively). The phycocyanin extraction by-product has presented hydrolysis ability (in vitro) at 2.51% while S. platensis showed at 1.81 %. The composition of the phycocyanin extraction by-product showed similar activation of probiotic bacteria to inulin. Especially, Lactobacillus strain showed the best growth was achieved with the phycocyanin extraction by-product with decrease the final pH and high microbial colony number at 48 hours in 7.5–9.5 log10 colony-forming unit per milliliter (CFU/ml) when compared with the glucose group. The study results revealed that the phycocyanin extraction by-product with the prebiotic potential are effective at increasing numbers of Lactobacillus strain. Consequently, the study reveals that phycocyanin extraction by-product are effective as alternative prebiotic supplement, significantly enhancing beneficial probiotic bacteria. These findings suggest the potential use of phycocyanin extraction by-products in creating new prebiotic formulations for gut microbiota modulation through dietary

Development of multiplex polymerase chain reaction for the simultaneous detection of bovine mastitis-associated pathogens

Pennapa Takam — 2024-03-27

A multiplex polymerase chain reaction (mPCR) assay was developed for the simultaneous detection of five bovine mastitis-associated pathogens including Staphylococcus simulans, Staphylococcus hominis, Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus genus-specific group. Results showed that the optimal annealing temperature for mPCR was 58 °C. The sensitivity of mPCR to detect the least DNA template concentration was 0.625 ng. The nucleotide sequences of PCR products were identified using the NCBI database. Results showed 99.15-100% homology to the gap gene of Staphylococcus simulans, 100% homology to the peptidase gene of Staphylococcus hominis, 98.76-99.69% homology to the clumping factor A gene of Staphylococcus aureus, 99.09-99.64% homology to the CAMP factor gene of Streptococcus agalactiae, and 99.13% to the elongation factor tu gene of the Streptococcus genus-specific group. This developed mPCR technique showed potential as a rapid, specific, highly sensitive, and low-cost diagnostic tool for the simultaneous detection of bovine mastitis-associated pathogens.

Prevalence of antibiotic resistance genes of Escherichia coli at the pig slaughterhouses in the Mekong Delta

Ngo Van Thong — 2024-03-28

The study was conducted to determine the antimicrobial susceptibility and antibiotic-resistance genes of Escherichia coli at the pig slaughterhouses in the Mekong Delta, Vietnam. A total of 60 samples were collected at the slaughterhouse in the Mekong Delta, including 24 feces, 24 carcasses, 8 floors, and 4 wastewater samples. The prevalence of E. coli in feces, wastewater, carcasses, and floor samples was 91.67%, 50.00%, 29.17%, and 25.00%, respectively. A total of 79 E. coli isolates were examined for antimicrobial susceptibility to 15 antibiotics using the disc diffusion method according to CLSI 2021 guidelines. E. coli strains were highly resistant to amoxicillin (83.54%), ampicillin (78.48%), streptomycin (63.29%), and florfenicol (63.29%). However, those E. coli strains were sensitive to amoxicillin + acid clavulanic and amikacin (97.47%), cefaclor (95.45%), cefuroxime (93.67%), and enrofloxacin (92.41%). The results showed that 96.2% of examined E. coli strains were resistant from one antibiotic to eight antibiotics, and the most frequent multidrug-resistance phenotype was amoxicillin + ampicillin + florfenicol + streptomycin (13.92%). The prevalence of antibiotic resistance genes (strA, sulII, qnrA, tetA, blaampC, blaTEM, and blaCTX-M) in E. coli was determined by PCR. The prevalence of strA, sulII, qnrA, tetA, blaampC, and blaTEM genes in E. coli strains was 75.67%, 72.97%, 75.67%, 83.78%, 91.89%, and 83.78% respectively; however, blaCTX-M gene was not detected. Therefore, the contamination of E. coli exhibiting antibiotic resistance in pig slaughterhouses should be controlled to prevent public health.

Effect of supplementations in drinking water on growth performance, health status, and carcass quality of local Tre chickens

Nguyen Thi Thuy — 2024-03-28

A study was carried out to determine the effect of probiotic, multivitamin, and organic acid (acid butyric) supplementations in drinking water on growth performances, health status, and carcass quality of local chicken (Tre). A total of 480 Tre chickens at 4 weeks of age were randomly distributed in a completely randomized design experiment, with 4 treatments and 4 replicates (2 male and 2 female pens); each replicate consisted of a pen with 30 chickens/pen, the experimental data was collected during 10 weeks. Treatments used: (1) Control (Cont): Basal diet (B) without any supplementation; (2) PRO: B + 1% probiotic; (3) VIT: B+ 1% multivitamin product; (4) OA: B+1% butyric acid, all supplements were supplied in drinking water. The results showed the use of PRO had a significant highest in final weight (1032 g/ chicken) compared with control group (981.6 g/chicken), lead to better daily gain (ADG) and feed conversion ratio (FCR) (13.31 g/head/day and 3.02 g feed/g gain) to compare with the control group (12.5 g/head/day and 3.28 g feed/g gain) (P<0.05). Daily feed intake (FI) was not affected by all supplementations (P>0.05). VIT and PRO adding in drinking water reduced feather pecking, and there was a reduction of Salmonella spp. and E. coli in the feces of Tre chickens in PRO and OA compared with control chickens. All treatments did not affect the carcass yield of the birds, but little improvement in the yellow meat color (b*=8.48) of chickens in VIT and PRO compared to the others. In general, adding probiotics at the level of 1% in drinking water could be better for improving ADG and FCR compared with multivitamins, acid butyric, and control treatments; adding probiotic and organic acid reduced Salmonella spp. and E. coli in the feces, while multivitamin supplementation reduced feather pecking and improved yellow meat color of Tre chickens.

Effect of Aquilaria malaccensis leaves aqueous extract supplementation on testicular seminiferous tubules and testosterone level in adult male Sprague Dawley rats

Norahidah Zaidi — 2024-04-02

Phytochemical screening was performed on A. malaccensis leaves to assess their impact on testicular seminiferous tubule diameter (STD) and seminiferous epithelial height (SEH), as well as testosterone level in adult male Sprague Dawley rats. The study involved 24 male rats, divided into four groups: Control (C: 0 g A. malaccensis/kg body weight, n=6), Treatment 1 (T1: 1 g A. malaccensis/kg body weight, n=6), Treatment 2 (T2: 2 g A. malaccensis/kg body weight, n=6), and Treatment 3 (T3: 3 g A. malaccensis/kg body weight, n=6), respectively. The extract of A. malaccensis leaves was administered orally once daily for 28 days and the rats were euthanized on Day 29 to assess their reproductive function. Phytochemical screening revealed the presence of various compounds in A. malaccensis leaves, including tannins, saponins, glycosides, flavonoids, terpenoids, steroids, and alkaloids. No significant differences were found in STD and SEH between the Control and Treated groups. A significant increase in testosterone level was observed in the T1 group (1.18 ng/mL) when compared to the C group. Incremental dosage of A. malaccensis appeared to significantly decrease testosterone level (0.92 ng/mL). No correlation was observed between the testicular seminiferous tubules and testosterone level. In conclusion, doses of 1, 2, and 3 g/kg of A. malaccensis did not appear to affect the seminiferous tubules of the testis. Specifically, 1 g/kg of A. malaccensis demonstrated potential benefits for male reproduction by elevating testosterone levels, whereas 2 and 3 g/kg exhibited potential harm by decreasing testosterone levels in male rats.

The effect of tropical alfalfa (Medicago sativa L. cv Kacang Ratu BW) supplementation on performance, intestinal histomorphology, and nutrient digestibility in hybrid ducks

Makmun Murod — 2024-04-05

Tropical alfalfa is a legume nutritionally complete and palatable to poultry. Hybrid ducks are aquatic birds with a higher tolerance to fiber-sourced feed than other breeds. This study aimed to determine the effects of tropical alfalfa (Medicago sativa L. cv Kacang Ratu BW) or KRBW supplementation on growth performance, histomorphology, and nutrient digestibility. Seventy-five hybrid ducks were used in this study. The treatments included T1 (basal feed or control), T2 (4% KRBW supplementation in basal feed), T3 (8% KRBW supplementation in basal feed), and water was provided ad libitum. The KRBW supplement was prepared in powder. Data were collected based on performance including feed intake, final body weight gain, feed conversion ratio (FCR); digestible dry matter (DDM), digestible organic matter (DOM), digestible crude fiber (DCF), and digestible ether extract (DEE); and the histomorphology of the intestine (duodenum, jejunum, and ileum). All data obtained in this study were analyzed using a completely randomized design. Data were analyzed using SPSS version 27 software. The results of this study showed that KRBW supplementation significantly decreased body weight gain. In contrast, control and 4% KRBW supplementation rates had no effects compared with 8% KRBW supplementation on feed consumption. However, KRBW supplementation had no significant effect on the FCR. Supplementation with 4% and 8% significantly decreased the DDM, DOM, DCF, and DEE. Furthermore, KRBW supplementation affected the histomorphology of the villi surface area in the duodenum, jejunum, and ileum. It could be concluded that the KRBW supplement reduced performance, intestinal histomorphology, and nutrient digestibility in hybrid ducks.

Effect of diet and MC4R genotype on nutrient digestibility and nitrogen balance in Kacang goats

Kustantinah Adiwimarta — 2024-04-22

This study aims to determine the effect of the relationship between feed treatment and Melanocortin 4 receptor (MC4R) genotypes on nutrient digestibility and nitrogen balance in Kacang goats. Blood samples were collected from 20 Kacang goats, and genomic DNA was extracted by using a Geneaid isolation kit. Polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) was used to genotype blood samples at the SNP position g.1079C/T cut by the KpnI enzyme. A 2 × 3 factorial design with two diet factors (diets 1 and 2) and three genotypes (homozygotes CC and TT and heterozygote CT) was used. The diet 1 and 2 groups comprised 4 goats with the TT genotype, 4 goats with the CT genotype and 2 goats with the CC genotype. Diet 1 contained an additional 400 g of concentrate with 11.25% crude protein (CP) and 55.88% total digestible nutrient (TDN) and diet 2 contained a total mixed ration containing 12.46% CP and 67.92% TDN. Results demonstrated that diet and MC4R genotype had a nonsignificant interactive effect (P>0.05) on nutrient digestibility, N balance and blood composition. However, feed factor shown a significant result (P<0.05) on EEI, NDFI, DM, CP, EE, NDF, DM, CP, EE and NDF on TT genotype (P0) with the highest level than CC and CT genotype (P1). The P0 goat group absorbs a lot of nitrogen in the body, however the P1 goat group is able to utilize the nutrient efficiently in the body. Kacang goats with the TT genotype can be selected as livestock that excel in utilizing nutrients in feed

Isolation, molecular identification, and pathogenicity of Aeromonas hydrophila disease in clown knife fish (Chitala chitala) in the Mekong Delta, Vietnam

Tu Thanh Dung — 2024-04-24

Hemorrhagic septicemia disease caused by Aeromonas hydrophila bacteria appears to be more common and causes severe damage to many fish species worldwide. This research aimed to isolate, identify, and determine the pathogenicity and antibiotic susceptibility of A. hydrophila in septicemic clown knife (Chitala chitala) fish in the Mekong Delta, Vietnam. As a result, 116 bacterial strains were isolated from 176 septicemic fish samples. Two strains of bacteria, D2F71 and H1F39, were identified as A. hydrophila based on colony morphology, identification results by the API 20E kit, PCR technique, and aerolysin gene sequencing. In addition, these two strains of bacteria were experimentally infected on healthy clown knife fish (weight 15±4 g/fish) by injection method. The experimental results fulfilled Koch's postulates: infected fish showed signs of disease symptoms similar to those of naturally diseased fish. In particular, the two strains of bacteria D2F71 and H1F39 in the experiment had relatively high virulence, with LD50 values of 1.26×104 CFU/mL and 4.06×103 CFU/mL, respectively. The obtained findings demonstrated that the bacteria were susceptible to doxycycline, florfenicol, cefotaxime, flumequine, enrofloxacin, and sulfamethoxazole-trimethoprim at a rate of over 70%. On the contrary, the study found that bacterial isolates were resistant to ampicillin (100%), cefazolin (85%), streptomycin (80%), and colistin (80%). To our knowledge, this is the first report on hemorrhagic septicemic clown knife fish caused by A. hydrophila in Vietnam.

Early-life development of spleen in white rabbit (Oryctolagus cuniculus): A morphometric and histochemical analysis

Omar Younis Altaey — 2024-04-25

The spleen's significant immunological and protective role has long inspired researchers to explore its developmental characteristics. This study intended to understand the splenic morphological developmental changes during postnatal life. Samples obtained form 25 (Oryctolagus cuniculus) white rabbits, divided into five age groups in :1, 10, 15, 30, and 90 postnatal days. The samples were measured to determine the length, breadth, thickness, and weight. afterward, the samples sectioned and stained using hematoxylin and eosin (H&E) and Masson's trichrome stains (MTs). And for histochemical analysis, additional slides were stained with Periodic acid schiff (PAS) and Alcian blue (AB) 2.5 pH stains. The histological measurements included the thickness of the capsule and trabeculae, diameter of white pulp follicle, and central artery, and the ratio of white and red pulps. The macroscopic findings showed a significant increase in dimensional measurements. Histologically, the capsule and trabeculae exhibited thickening, and the diameter of the white pulp follicles and central arteries expanded. And the splenic sinuses enlarged with age progression. The histochemical evaluation revealed intense staining with PAS in the capsule, trabeculae, and walls of splenic arteries in first postnatal day group, with moderate staining affinity in the other groups. Furthermore, there was positive staining with AB in the white pulp follicles of the first postnatal day group compared to weaker staining affinity in the older age groups. This study demonstrated that the critical development period begins after birth and continues until 30 postnatal days. During this period, the development of the immune response triggers significant alterations in the spleen's structural, morphometric, and histochemical parameters.