[Show abstract][Hide abstract] ABSTRACT: Swine hepatitis E virus (HEV) is widespread throughout pigs in both developing and industrialized countries. This virus is an important zoonotic agent and a public concern worldwide. Infected pigs are asymptomatic, so diagnosing swine HEV relies on detection of the virus or antibodies against the virus. However, several obstacles need to be overcome for effective and practical serological diagnosis. In this study, we developed an enzyme-linked immunosorbent assay (ELISA) that used a purified recombinant capsid protein of swine HEV. The potential clinical use of this assay was evaluated by comparing it with a commercial kit (Genelabs Technologies, Diagnostics, Singapore). Results of the ELISA were highly correlated with those of the commercial kit with a sensitivity of 97% and specificity of 95%. ROC (receiving operator characteristic) analysis of the ELISA data produced a value of 0.987 (95% CI, 0.977~0.998, p < 0.01). The cut-off value for the ELISA was also determined using negative pig sera. In summary, the HEV-specific ELISA developed in the present study appears to be both practical and economical.
[Show abstract][Hide abstract] ABSTRACT: Brucella abortus is an intracellular zoonotic pathogen which causes undulant fever, endocarditis, arthritis and osteomyelitis in human and abortion and infertility in cattle. This bacterium is able to invade and replicate in host macrophage instead of getting removed by this defense mechanism. Therefore, understanding the interaction between virulence of the bacteria and the host cell is important to control brucellosis. Previously, we generated internalization defective mutants and analyzed the envelope proteins. The present study was undertaken to evaluate the changes in early transcriptional responses between wild type and internalization defective mutants infected mouse macrophage, RAW 264.7.
Both of the wild type and mutant infected macrophages showed increased expression levels in proinflammatory cytokines, chemokines, apoptosis and G-protein coupled receptors (Gpr84, Gpr109a and Adora2b) while the genes related with small GTPase which mediate intracellular trafficking was decreased. Moreover, cytohesin 1 interacting protein (Cytip) and genes related to ubiquitination (Arrdc3 and Fbxo21) were down-regulated, suggesting the survival strategy of this bacterium. However, we could not detect any significant changes in the mutant infected groups compared to the wild type infected group.
In summary, it was very difficult to clarify the alterations in host cellular transcription in response to infection with internalization defective mutants. However, we found several novel gene changes related to the GPCR system, ubiquitin-proteosome system, and growth arrest and DNA damages in response to B. abortus infection. These findings may contribute to a better understanding of the molecular mechanisms underlying host-pathogen interactions and need to be studied further.
[Show abstract][Hide abstract] ABSTRACT: Paratuberculosis (PTB) or Johne's disease (JD) is one of the most serious chronic debilitating diseases of ruminants worldwide that is caused by Mycobacterium avium subsp. paratuberculosis (MAP). MAP is a slow-growing bacterium that has very long latent periods resulting in difficulties in diagnosing and controlling the disease, especially regarding the diagnosis of fecal shedders of MAP without any clinical signs. Based on this situation, our attempts were made to identify biomarkers which were shown early responses to M. paratuberculosis infection in professional macrophage cell line, RAW264.7. In response to the infection with the bacterium, a lot of genes were turn on and/or turn off in the cells. Of the altered genes, three different categories were identified based on the time-dependent gene expression patterns. Those genes were considered as possible candidates for biomarkers of M. paratuberculosis infection after confirmation by quantitative RT-PCR analysis. To the best of our knowledge, this is the first attempt at discovering the host transcriptomic biomarkers of PBT, although it will be required further investigation to determine whether these biomarker candidates are associated within the natural host.
Journal of Microbiology and Biotechnology 06/2013; · 1.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Field efficacy of enterotoxigenic Escherichia coli-specific phage () as a feed additive was evaluated in weaning piglets. Fifty-four piglets at 3-4 weeks old were allocated in three different groups and two of them were fed with bacteriophage at different concentrations ( feed and feed, respectively) for 30 days. Body weight and feed intake were measured at 10 days interval and body condition and fecal score were inspected every day. Based on the measurement, feed conversion rate (FCR) and average daily gain (ADG) of each group during 30 days were analyzed. The analysis suggests that the bacteriophage may help the improvement of FCR and ADG at of bacteriophage feeding group in 30 days. A result from analysis of fecal score indicates that the bacteriophage also may help to relieve the intermittent diarrhea in post-weaning stage. Those results suggest that bacteriophage might help the growth of piglets in post-weaning stage.
Korean Journal of Veterinary Research. 01/2013; 53(2).
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to applicate and evaluate a SYBR Green real-time PCR for the specific detection of Salmonella spp. Specificity of the PCR method was confirmed with 48 Salmonella spp. and 5 non-Salmonella strains using invA gene primer. The average threshold cycle () of Salmonella spp. was while non-Salmonella spp. was . Correlation coefficients of standard curves constructed using versus copy number of Salmonella Enteritidis ATCC 13076 showed good linearity (; slope = 3.563). Minimum level of detection with the method was > colony forming units (CFU)/mL. These results suggested that the SYBR Green real-time PCR might be applicable for the specific detection of Salmonella spp. isolates.
Korean Journal of Veterinary Research. 01/2013; 53(1).
[Show abstract][Hide abstract] ABSTRACT: Key words: Bovine herpesvirus-1 Calves Germanium biotite Immune stimulator Mannheimia haemolytica Serotype A1 Germanium biotite, a natural mineral, is comprised of mainly silicate. This mineral showed activities of increase in feed efficiency and non-specific immunostimulation in previous studies. The aims of the present study were to evaluate the prophylactic effects of germanium biotite against respiratory diseases in calves as a feed supplement and investigate the possibilities of the substitution of antibiotics with germanium biotite as feed additive. To achieve these purposes, bovine herpesvirus-1 (BHV-1) and Mannheimia haemolytica serotype A1 were experimentally inoculated into the calves. After challenge, germanium biotite showed a lower cumulative clinical score (CCS) than the control group. In accordance with these clinical results, enhanced clearance of BHV-1, a low infection rate of Mannheimia haemolytica serotype A1, tempered superficial lesions, and moderated histopathological signs were observed in the germanium biotite group, compared with the control group. The results of the present study indicated that germanium biotite had prophylactic effects against bovine respiratory disease and could be a candidate for a new alternative feed supplement in calves, through its effects as a non-specific immune stimulator., 2012. The effects of germanium biotite supplement as a prophylactic agent against respiratory infection in calves. Pak Vet J, 32(3): 319-324.
[Show abstract][Hide abstract] ABSTRACT: We evaluated effect of enterotoxigenic Escherichia coli (ETEC) specific lytic phage CJ12 in ETEC infected pigs. Phage was mixed with feed at a ratio of 1:1,000 (0.1%). One week after initially providing phage mixed feed, pigs were challenged orally with 10(11) CFU of ETEC and body weight, diarrhea score, bacterial CFU and phage PFU in the feces were measured. Pigs of phage treated groups C (10(6) PFU/g) and D (10(8) PFU/g) showed more resistance to diarrhea due to ETEC infection compared to positive control group B on the third day after the initial challenge. Moreover, during the quantitation of ETEC in feces, both groups C and D showed approximately 63.92 and 60.73% reduced ETEC compared to positive control group B. Phages were successfully isolated from feces in both groups C and D during the experiment without any adverse effects, suggesting the possibility of using CJ12 as a feed additive.
Journal of Veterinary Medical Science 03/2012; 74(8):1037-9. · 0.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Germanium biotite, a natural mineral, has been used as a feed supplement to reinforce innate immune ability. The aim of the present study was to evaluate the effects of germanium biotite on the adsorptive and inhibition of growth abilities against Escherichia (E.) coli and Salmonella spp. in vitro. Two strains of enterotoxigenic E. coli and four strains of two Salmonella serotypes (Salmonella Derby and Salmonella Typhimurium), major bacterial diarrheal pathogens, were used for this experiment. The absorptive ability of germanium biotite against most Salmonella used in present experiment was observed weakly. The germanium biotite, however, showed significant effect of bacterial growth inhibition in most experiment bacteria. These results suggest that the use of the germanium biotite as feed supplement could alleviate diarrhea following inhibition of bacteria growth. It is also presumed that antibiotics usage for farm animals, considered as causes of antibiotic residue in meat and emerging antibiotic resistance, could be reduced through the use of germanium biotite as a feed supplement, in place of antibiotics used for the prevention of diarrhea.
Korean Journal of Veterinary Research. 01/2012; 52(1).
[Show abstract][Hide abstract] ABSTRACT: Brucella abortus is a facultative intracellular bacteria that replicates within a macrophage without producing any classical virulence factors. It can become internalized to cells by zipper-like and/or swimming internalization mechanisms. However, the bacterial proteins involved in internalization remain unclear. To define these bacterial proteins, random insertion mutants of B. abortus were generated by the Tn5 transposome complexes. In all, 132 mutants were screened, cellular internalization-defective mutants were selected, and these genomic and envelope proteomic features were identified. The transposon insertion sites were ccmC,ppk and BruAb2_0168 for the mutant C10, C29 and D7, respectively. Mutant C10 showed a deficiency in internalization without any changes in expression of the cell envelope proteins; however, mutant C29 showed a reduced expression of OMP25, and a mutant D7 also showed reduced expression of OMP25, OMP28 and Porin2b. These results suggest OMP25 is not an essential factor, but might be involved in host cellular internalization. We identified the ppk gene and BruAb2_0168 locus which are associated to expression of OMP25, OMP28 and Porin2b as well as pleiotropic effects of ccmC gene.
[Show abstract][Hide abstract] ABSTRACT: Actinobacillus pleuropneumoniae is the etiologic agent of porcine pleuropneumonia, a highly contagious pulmonary disease in pigs with major economic losses for pig producers worldwide. Whereas A. pleuropneumoniae isolates are divided into 15 serotypes, the isolates secrete 4 types of exotoxins (ApxI, ApxII, ApxIII, and ApxIV), which are known as major virulence factors. In the current study, the ApxIA, ApxIIA, and ApxIIIA genes were amplified and their recombinant proteins expressed in Escherichia coli M15 cells. The antigenicity of each recombinant protein was demonstrated by Western blot and enzyme-linked immunosorbent assay (ELISA) using sera from pigs vaccinated with a subunit vaccine. When ELISAs using the recombinant antigens were optimized and then applied to sera from 320 randomized pigs in Korea, an observed increase in seroprevalence was found among sows in comparison with weaned piglets and growing pigs, indicating an age-dependent seroprevalence. The results obtained in the study suggest that the developed ELISAs may be useful for A. pleuropneumoniae vaccination strategy as a screening tool for pig herds as well as for detection of specific antibodies to Apx exotoxins.
Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 07/2011; 23(4):736-42. · 1.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study, we focused on determining the distribution and prevalence of major plasmid replicons in β-lactam-resistant Escherichia fergusonii and Enterobacteriaceae of animal and human origin. A high degree of plasmid variability and multiple plasmid replicons were observed among the isolates. The IncF and IncI1 replicons were the most prevalent in E. fergusonii and Salmonella enterica serovar Indiana isolated from swine and poultry in South Korea, respectively. The presence of broad-host-range plasmid replicons such as IncN, IncA/C, IncHI1, and IncHI2 that are associated with important virulence genes and toxins as well as antimicrobial resistance determinants indicates that E. fergusonii has the potential to become an important pig pathogen and possible emerging opportunistic zoonotic pathogen.
Applied and Environmental Microbiology 03/2011; 77(9):3163-6. · 3.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to analyze the significance of leucine to proline substitution at position 138(Leu138Pro) on the hydrolysis of penicillin and ampicillin that we identified in the blaSHV gene of clinical Escherichia coli swine isolate.
Kinetic analysis of the mutant proteins showed that K(m) value of the purified L138P mutant was comparatively higher than SHV-1, SHV-33 and SHV-33(L138P) enzyme for penicillin and ampicillin. Docking simulation of the SHV-1 and SHV-(L138P) enzymes also confirmed that β-lactamases preferred penicillin to ampicillin and the SHV-1 had a higher binding affinity for antibiotics compared to the SHV-(L138P) and other mutants.
Our result demonstrated that L138P has a reduced role in penicillin and ampicillin hydrolyzing properties of SHV β-lactamases. These naturally occurring mutations rendering reduced function of the existing protein could trigger the emergence or acquisition of more effective alternative mechanisms for β-lactam hydrolysis.
[Show abstract][Hide abstract] ABSTRACT: Fifteen nonrepetitive ampicillin-resistant Salmonella spp. were identified among 91 Salmonella sp. isolates during nationwide surveillance of Salmonella in waste from 131 chicken farms during 2006 and 2007. Additional phenotyping and genetic characterization of these 15 isolates by using indicator cephalosporins demonstrated that resistance to ampicillin and reduced susceptibility to cefoxitin in three isolates was caused by TEM-1 and DHA-1 beta-lactamases. Plasmid profiling and Southern blot analysis of these three DHA-1-positive Salmonella serovar Indiana isolates and previously reported unrelated clinical isolates of DHA-1-positive Salmonella serovar Montevideo, Klebsiella pneumoniae, and Escherichia coli from humans and swine indicated the involvement of the large-size plasmid. Restriction enzyme digestion of the plasmids from the transconjugants showed variable restriction patterns except for the two Salmonella serovar Indiana isolates identified in this study. To the best of our knowledge, this is the first report of the presence of the DHA-1 gene among Salmonella spp. of animal origin.
Applied and Environmental Microbiology 07/2010; 76(14):4760-4. · 3.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The discovery of antibiotics has helped to save the lives of an uncountable number of people. Antibiotics have been grouped in different classes based on their origin, structure, and mechanism of action. An intrinsic and acquired mechanism of antimicrobial resistance has been identified in many bacterial strains that are of high clinical importance. This has seriously jeopardized the use of antibiotics and has also caused the spread of microbes that are resistant to effective first-choice, or "first-line" drugs. Thus, sensible use of antibiotics and the search for effective alternative measures are of high importance in order to minimize the effect due to existing and emerging antimicrobial resistant microbes.
Journal of Biomedical Research. 06/2010; 11:65-80.
[Show abstract][Hide abstract] ABSTRACT: Adherence factors and enterotoxins are major virulence factors of enterotoxigenic Escherichia coli (ETEC). Antibiotics have been used frequently for the treatment and prevention of ETEC infection in piggeries worldwide, including Korea. Therefore, data on both virulence profiles and antibiotic resistance patterns are useful in the epidemiological study of ETEC. A total number of 198 E. coli field isolates were examined. The most prevalent pathotype was F1, followed by a combination of F1 and EAST1. All of the 71 isolates were resistant to more than 2 antibiotics used in a disk diffusion test, and 87.94% of the isolates were found to be resistant to more than 4 antibiotics. Investigations were also conducted to correlate the virulence gene profiles with antibiogram and pulsed-field gel electrophoresis (PFGE). Although a high degree of polymorphism was noted among strains having the same virulence patterns, the highest similarity pattern was observed carrying the same virulence profiles and similar antibiogram. Thus, investigation of both virulence profiles and antibiogram is essential to the epidemiological study of ETEC. Moreover, the PFGE method might be applicable as a tool to reveal genetic relatedness among E. coli strains from piggeries in Korea.
Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 08/2009; 21(4):510-6. · 1.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Florfenicol resistance was analyzed in 230 enteric pig isolates collected between 1998 and 2006. PCR, plasmid profiling, Southern blot hybridization, and a mixed-broth conjugation assay suggested the intra- and interspecies plasmid-mediated transfer of florfenicol resistance among the isolates that exhibited MICs for florfenicol between 4 to 128 mg/liter.
Applied and Environmental Microbiology 08/2009; 75(17):5700-3. · 3.95 Impact Factor