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Abstract

Introduction

A high-performance liquid chromatographic–diode array detector (HPLC-DAD) method for the determination of amoxicillin in medicated feedingstuffs was developed and validated. The method was used to investigate the quality requirements of animal feedingstuffs (declared content of active substance and feed homogeneity).

Material and Methods

Two-gram samples were extracted by potassium phosphate buffer solution. Extracts were filtered and directly analysed by HPLC-DAD without further clean-up. Amoxicillin was separated by acetonitrile and 0.01M phosphate buffer (pH 5.0) on a Phenomenex Luna C18 column.

Results

This method provided average recoveries of 76.1 to 81.6% with coefficients of variation (CV, %) for repeatability and reproducibility in the ranges of 3.7–7.2% and 5.3–7.6%, respectively. The limit of detection was 51.2 mg/kg and limit of quantification was 103.0 mg/kg.

Conclusion

The method was successfully validated and proved to be efficient, precise, and useful for quantification of amoxicillin in medicated feedingstuffs.

Abstract

Introduction

Although peripheral blood analysis has become increasingly automated, microscopy is the only available method for the diagnosis of anisocytosis and poikilocytosis. The aims of the study were to compare RBC volume data obtained with two different analysers and by manual assessment of smears and to compare this data between dogs in various stages of heart failure secondary to degenerative mitral valvular (DMV) disease. The impact of diuretic administration on RBC morphology was also assessed.

Material and Methods

Sixty-eight dogs, 56 in different stages of DMV disease and 12 as healthy controls, were studied. Impedance and flow cytometry haematological analyses were performed for each animal. Additionally, two smears were prepared for manual analysis. RBC structure, staining, and size differences were recorded.

Results

There were no significant differences between the blood morphological parameters assessed using haematological analysers nor between dogs receiving diuretic treatment and those not treated. Based on the manual smear, significantly higher erythrocyte anisocytosis was observed in the dogs with symptomatic DMV disease than in the control group.

Conclusion

Haematological analysers based on impedance and flow cytometry provide reliable and comparable morphological results in dogs with heart failure. However, microscopic assessment of blood smears is a more reliable tool to detect erythrocyte anisocytosis.

Abstract

Introduction

The objective of this research was to evaluate the antibody response to multiple doses of an inactivated mixed vaccine against Histophilus somni, Pasteurella multocida, and Mannheimia haemolytica, and to investigate the influence of age at time of vaccination in the field.

Material and Methods

Healthy female Holstein calves received the vaccine at the age of 5–12 days and 2, 3, or 4 weeks later in the first experiment or at 1, 2, or 3 weeks of age and 4 weeks later in the second. Blood samples were collected at each vaccination and 3 weeks after the booster dose. Based on the antibody titres after the vaccinations, calves were divided into positive and negative groups for each of the bacteria. Calves in the control group were vaccinated only once at the age of 19–26 days.

Results

Antibody titres against H. somni and P. multocida were significantly increased by the booster. After the second vaccinations, the titres against each bacterium were higher than those of the control group, and the M. haemolytica-positive percentage in calves with high maternal antibody levels (MAL) exceeded that in calves with low MAL. In the first experiment, a majority of the M. haemolytica-positive calves tended to have received the primary dose at seven days of age or older.

Conclusion

A booster dose of the inactivated bacterial vaccine in young Holstein calves increased antibody production and overcame the maternal antibodies. Calves should be vaccinated first at seven days of age or older.

Abstract

Introduction

African swine fever (ASF) was officially reported in Vietnam in February 2019 and spread across the whole country, affecting all 63 provinces and cities.

Material and Methods

In this study, ASF virus (ASFV) VN/Pig/HaNam/2019 (VN/Pig/HN/19) strain was isolated in primary porcine alveolar macrophage (PAM) cells from a sample originating from an outbreak farm in Vietnam’s Red River Delta region. The isolate was characterised using the haemadsorption (HAD) test, real-time PCR, and sequencing. The activity of antimicrobial feed products was evaluated via a contaminated ASFV feed assay.

Results

Phylogenetic analysis of the viral p72 and EP402R genes placed VN/Pig/HN/19 in genotype II and serogroup 8 and related it closely to Eastern European and Chinese strains. Infectious titres of the virus propagated in primary PAMs were 106 HAD50/ml. Our study reports the activity against ASFV VN/Pig/HN/19 strain of antimicrobial Sal CURB RM E Liquid, F2 Dry and K2 Liquid. Our feed assay findings suggest that the antimicrobial RM E Liquid has a strong effect against ASFV replication. These results suggest that among the Sal CURB products, the antimicrobial RM E Liquid may have the most potential as a mitigant feed additive for ASFV infection. Therefore, further studies on the use of antimicrobial Sal CURB RM E Liquid in vivo are required.

Conclusions

Our study demonstrates the threat of ASFV and emphasises the need to control and eradicate it in Vietnam by multiple measures.

Abstract

Introduction

Despite vaccination against avian metapneumoviruses (aMPV), cases of turkey rhinotracheitis (TRT) caused by aMPV field strains are frequently reported. Differences have been shown in the level of immune system stimulation after aMPV vaccination between turkeys that do and do not possess specific anti-aMPV maternally derived antibodies (MDA). The article describes the influence of MDA on the production of IFNγ in the spleen of aMPV-vaccinated turkeys.

Material and Methods

MDA+ or MDA− turkeys were vaccinated against TRT after hatching or on the 14th day of life. Spleen samples were collected 3, 7, and 14 days post vaccination for mononuclear cell isolation. Real-time PCR, flow cytometry, and the enzyme-linked immunospot assay were used to evaluate the levels of IFNγ gene expression, production, and secretion by cells within the spleen samples.

Results

Increased IFNγ gene expression was noticed after vaccination only in birds that did not possess MDA or possessed MDA at relatively low level (MDA+ birds vaccinated at 14 DOL). In all birds, an increased percentage of T lymphocytes producing IFNγ was recorded. The proportion of anti-aMPV IFNγ-secreting cells was increased only in MDA− birds.

Conclusion

Besides having a protective role, MDA are known to interfere with vaccination efficacy. The analysis of our results confirms that MDA can decrease the level of immune system stimulation after aMPV vaccination of turkeys.

Abstract

Introduction

African swine fever (ASF) is a pressing economic problem in a number of Eastern European countries. It has also depleted the Chinese sow population by 50%. Managing the disease relies on culling infected pigs or hunting wild boars as sanitary zone creation. The constraints on the development of an efficient vaccine are mainly the virus’ mechanisms of host immune response evasion. The study aimed to adapt a field ASFV strain to established cell lines and to construct recombinant African swine fever virus (ASFV) strain.

Material and Methods

The host immune response modulation genes A238L, EP402R, and 9GL were deleted using the clustered regularly interspaced short palindromic repeats/caspase 9 (CRISPR/Cas9) mutagenesis system. A representative virus isolate (Pol18/28298/Out111) from Poland was isolated in porcine primary pulmonary alveolar macrophage (PPAM) cells. Adaptation of the virus to a few established cell lines was attempted. The plasmids encoding CRISPR/Cas9 genes along with gRNA complementary to the target sequences were designed, synthesised, and transfected into ASFV-infected PPAM cells.

Results

The reconstituted virus showed similar kinetics of replication in comparison to the parent virus isolate.

Conclusion

Taking into account the usefulness of the developed CRISPR/Cas9 system it has been shown that modification of the A238L, EP402R, and 9GL genes might occur with low frequency, resulting in difficulties in separation of various virus populations.

Abstract

A pilot study was performed to evaluate the safety and serological responses after co-administration of two multivalent inactivated vaccines to pregnant cattle. One vaccine was directed against bovine respiratory disease (BRD) and contained antigens of bovine respiratory syncytial virus (BRSV), parainfluenza 3 virus (PI3) and Mannheimia haemolytica (Mh). The second vaccine targeted neonatal calf diarrhoea (NCD) and was composed of inactivated antigens of bovine rotavirus (BRV), bovine coronavirus (BCV) and E. coli. The use of these combinations have been used more and more by veterinary practitioners as there exist some clear evidence that both vaccines improves the passive protection via the colostrum for the relevant pathogens. However, up until now, no safety or efficacy data has been available concerning such co-administrations. The safety of both vaccines and the serological responses to the BRD vaccine has been evaluated when used at the same time, but without mixing and compared to the responses to the administration of each vaccine independently. There was no evidence of any negative effect on calving or calf health in any of the vaccinated animals. The antibody levels against BRSV and Mh in the sera of the calves from cows vaccinated with both vaccines were not significantly different from the levels in the sera of calves vaccinated with the BRD vaccine alone. The results from this pilot study demonstrated that the co-administration of the two multivalent inactivated vaccines had no detrimental effect on the safety or serological responses to the BRD vaccine compared to the independent use of the vaccines.

Abstract

The administration of antibiotics to day old chicks as a means of prevention or treatment of suspected hatchery or farm-borne infections is common, especially in developing countries. This practice could contribute to a poor immune response following Newcastle disease (ND)-LaSota vaccinations, in addition to the sluggish growth in broiler chickens. This study was aimed at determining: the antibody titre to ND-LaSota vaccine, live weight, weight gain and feed conversion efficiency (FCE) of broiler chicken exposed early to gentamicin and doxycycline. One hundred, day-old broiler chicks were randomly assigned to four groups (n = 25). Group 1 served as a control, while groups 2 and 4 received gentamycin and doxycycline, respectively. The chicks in group 3 were treated with a combination of gentamicin and doxycycline (1 : 1). All drugs were administered via the drinking water from the 2nd to the 6th day of the chicks’ life. On day 18, the birds received ND-LaSota vaccine intraocularly. At weekly intervals, the post-vaccination antibody titre, live weight and weight gain were determined. The feed conversion efficiency (FCE) of the different groups was calculated at the end of the experiments. The results showed that the NDV antibody titre of the antibiotic-treated groups did not differ significantly (P < 0.05) from that of the control. However, there was a significant (P < 0.05) increase in the live weight, weight gain and FCE of the control birds when compared to the antibiotic-treated groups.

Abstract

Foodborne pathogens are the leading cause of illness and death in developing countries and are often associated with poor hygiene and unsafe food storage conditions. Using central cold rooms with alternate power supply in preserving meats due to erratic power supply is common among meat traders in Nigeria. However, the public health safety of the operations of this practice remains un-investigated. We conducted a microbial assessment of aseptically collected meat swabs from three selected major cold rooms in Ibadan for Staphylococcus aureus, Listeria monocytogenes, Salmonella spp. and Escherichia coli using standard procedures. Antibiotic susceptibility was determined using 14 different antibiotics at standard concentrations following Kirby-Bauer Assays. The data were analysed with Stata 12.0 using bivariate and logistic regression analyses. Of 180 meat swabs collected, 42.2 % were positive for S. aureus, 22.2 % for L. monocytogenes, 20.0 % for Salmonella spp. and 6.7 % for E. coli. All of the isolates exhibited total resistance to seven of the antibiotics. Escherichia coli showed the highest resistance to 12 antibiotics, followed by Salmonella spp. (11 antibiotics), L. monocytogenes (10 antibiotics) and S. aureus (7 antibiotics). Sampling locations were significantly associated with the prevalence of L. monocytogenes (P = 0.008) and S. aureus (P = 0.000), but not with Salmonella spp. (P = 0.435) or E. coli (P = 0.117). The study revealed a heavy microbial contamination with major foodborne pathogens characterized by a high level of antibiotic resistance. These findings portend that the current operations associated with the practice of using central cold rooms in meat preservation in Nigeria undermine public health safety and need to be urgently addressed.

Abstract

The nucleotides are the building blocks of nucleic acids and determining their sequential arrangement had always been an integral part of biological research. Since the past seven decades, researchers from multi-disciplinary fields has been working together to innovate the best sequencing methods. Various methods had been proposed, from some oligonucleotides to the whole genome sequencing, and the growth had gone through adolescence to the mature phase where it is now capable of sequencing the whole genome at a low cost and within a short time frame. DNA sequencing has become a key technology in every discipline of biology and medicine. This review aims to highlight the evolution of DNA sequencing techniques and the machines used, including their principles and key achievements.