Immunogenicity of baculovirus expressed recombinant proteins of Japanese encephalitis virus in mice.

Genes encoding for the premembrane and envelope (prME), envelope (E) and nonstructural protein (NS1) of Japanese encephalitis virus (JEV) were cloned. Each protein was expressed in baculovirus expression system. Of the three proteins expressed in baculovirus system, only prME had hemagglutination activity. The prME (72 and 54 kDa), E (54 kDa) and NS1 (46 kDa) proteins could be detected by Western blotting in the recombinant virus infected cells. Immunogenicity of the recombinant proteins obtained from infected Spodoptera frugiperda (Sf-9) cells was examined in mice. The 3 week-old ICR mice immunized intraperitoneally with three recombinant proteins three times were challenged with a lethal JEV. A survival rate was increased from about 7.7% in unimmunized mice to 92.3% in E+prME and only E groups. The complete protection was shown in prME and live vaccine inoculated groups, respectively. We also measured neutralizing antibody and three immunoglobulin subtypes of IgG1, IgG2a and IgG2b in the sera of mice before and after challenge. Titers of IgG1 antibodies were approximately two to three times higher than that of IgG2b antibodies in all the immunized groups as compared to the control group. However, IgG2a antibody level somewhat increased after challenge, indicating T-helper type 1 (Th1) cell response. The results of this study can provide useful information for developing efficacious subunit vaccine against JEV.

Molecular cloning of the cDNA of canine homeodomain-interacting protein kinase 2.

The research of p53 is being conducted to find the mechanisms of tumorigenesis and to treat various cancers. Homeodomain-interacting protein kinase2 (HIPK2) is an important factor to regulate p53 and to increase the stability of p53. Activation of HIPK2 leads to the selective phosphorylation of p53, resulting in growth arrest and the enhancement of apoptosis. In this study, the canine HIPK2 cDNA fragments were obtained, and their overlapping regions were aligned to give a total sequence of 3489 bp. The canine HIPK2 cDNA (GenBank accession number; AY800385) shares 93% and 90% sequence identity with those of human and mouse HIPK2, respectively. The canine HIPK2 cDNA contains an open reading frame encoding 1163 amino acid residues and the predicted amino acid sequence has 98% and 96% identity with those of human and mouse, respectively. The deduced amino acid sequence of canine HIPK2 has also all domains' sites compared with human and mouse HIPK2. Therefore, these structural similarities suggested that the canine HIPK2 shares the basic biological functions that HIPK2 exhibit in other species.

TaqMan reverse transcription polymerase chain reaction for the detection of Japanese encephalitis virus.

One step TaqMan reverse transcription polymerase chain reaction (RT-PCR) using TaqMan probe was developed for detection of Japanese encephalitis virus (JEV). Real-time RT-PCR was optimized to quantify JEV using the detection system (Rotor Gene 2000 detector) and dual-labeled fluorogenic probes. The gene specific labeled fluorogenic probe for the 3' non-translated region (3' NTR) was used to detect JEV. When the specificity of the assay using specific JEV primers was evaluated by testing three different JEV strains, other swine viruses and bovine viral diarrhea virus, no cross-reactions were detected with non-JE reference viruses. A single tube TaqMan assay was shown to be 10-fold more sensitive than the conventional two-step RT-PCR method. Detection limits of two step and real-time RT-PCR for JEV were 112 TCID(50) /ml and 11.2 TCID(50) /ml, respectively. Quantification of JEV was accomplished by a standard curve plotting cycle threshold values (C(t)) versus infectivity titer. Real-time RT-PCR assay using single tube method could be used as a sensitive diagnostic test, and supplied the results in real time for detection and quantification of JEV. We could detect JEV RNA genome in plasma samples of pigs inoculated with KV1899 strain at 2 days post inoculation, but couldn't in 41 fetus samples. This assay was sensitive, specific, rapid and quantitative for the detection of JEV from laboratory and field samples.

Molecular characterization of full-length genome of Japanese encephalitis virus (KV1899) isolated from pigs in Korea.

We have determined the complete nucleotide and deduced amino acid sequences of the Japanese encephalitis virus (JEV) strain KV1899, isolated from a fattening pig in Korea. In comparison with 22 fully sequenced JEV genomes currently available, we found that the 10,963-nucleotide RNA genome of KV1899 has a 13-nucleotide deletion in the 3' non-translated variable region and 53 unique nucleotide sequences including 3' non-translated region (NTR). Its single open reading frame has a total of 28 amino acid substitutions. Comparison of the KV1899 genomic sequence with those of the 21 fully sequenced JEV strains in published databases showed nucleotide homology ranging from 97.4% (Ishikawa strain) to 87.0% (CH2195 strain). Amino acid homology with KV1899 strain ranged from 96.4% (K94P05) to 91.0% (GP78). The KV1899 showed the highest nucleotide homology with Ishikawa strain and the highest amino acid homology with K94P05. We performed an extensive E gene based phylogenetic analysis on a selection of 41 JEV isolates available from the GenBank. Compared with Anyang strain, isolated from a pig in 1969, that is current live vaccine strain for swine in Korea, the homology of nucleotide sequence in envelope gene was only 87.1%. The prM gene of the isolate was closely related with those of Ishikawa and K94P05 strains, which were grouped into genotype I of JEV.

Biophysical characterization of Japanese encephalitis virus (KV1899) isolated from pigs in Korea.

A virus strain, showing cytopathic effect in Vero cell, was isolated from plasma of a fattening pig in Gyeonggi province, Korea in October 1999. The evaluation of physicochemical/biological properties of the isolate showed that the virus, KV1899, inoculated suckling mouse showed paralysis and died within 7 days post-inoculation, the mouse brain suspension had hemagglutinating activity with goose RBC. Pathogenicity of isolate was carried out by intracranial and intraperitoneal inoculation of 3-4 weeks mice. The mice inoculated with isolate showed 10(4.5) LD50/ 0.03 ml and 10(3.0) LD50/0.5 ml according to the inoculation route. The isolate was identified as RNA and enveloped virus using IUDR and chloroform sensitivity test. The virus particles within the infected Vero cell were measured to be 40-50 nm in size by electron microscopy. The isolate was further characterized by immuno-fluorescence assay using Japanese encephalitis virus (JEV) specific monoclonal antibodies. Reverse transcription polymerase chain reaction (RT-PCR) revealed the presence of JE specific conserved sequences in this isolate. The artificially inoculated pigs had HI titer of 320 to 2,560 against JEV at 14 to 42 days post inoculation. We confirmed this isolate as Japanese encephalitis virus. It was the second isolation of JEV in pigs in Korea.

Immunological responses of dogs experimentally infected with Dirofilaria immitis.

Three dogs were experimentally infected with Dirofilaria immitis. All dogs were euthanised at 30, 36 and 37 weeks after inoculation of D. immitis for the recovery of adult worms. Three cases accounted to 42.91 % recovery of inoculated worms. Serum samples from dogs experimentally inoculated with D. immitis were analyzed by ELISA and immunoblotting methods. Antibody titers of dogs detected by ELISA peaked between 7 and 14 weeks then decreased between weeks 15 to 24 followed by another increase during weeks 25 to 30 and persisted throughout the remainder of the experiment period. Analysis of adult D. immitis protein stained with Coomassie brilliant blue R-250 indicated separately more than 10 bands, and the major bands were 22, 40, 46, 56, 70, 72 and 89 kDa. Antigenic identification of extracts antigens of adults D. immitis by immunoblotting analysis revealed several bands from pooled sera of patent infection (30 weeks after inoculation). The detected bands were 24, 70, 80 and 110 kDa, 22, 72 and 84 kDa, and 58 and 72 kDa in dogs 1, 2 and 3, respectively. Results of antibody titers reached high levels on the 4th molting stage after inoculation of infective larva (L3), and reinforced previous findings that high molecular weight regions are detected in young animals.

Prevalence and clinical characterization of gastric Helicobacter species infection of dogs and cats in Korea.

This study was carried out to evaluate the prevalence and clinical characterizations of gastric Helicobacter spp. infection of dogs and cats in Korea. The prevalence of Helicobacter spp. infection of dogs and cats determined by urease test was 78.4% and 64%, respectively, although Helicobacter genus-specific PCR assay showed that it was 82.3% and 84%. Urease mapping results based on urease test showed that total positive rate of tested tissues from clinically abnormal dogs was significantly higher than that from clinically normal dogs (p=0.0018; Odds ratio = 6.118; 95% Confidence Interval = 1.96-19.103). These findings were consistent with the results of Helicobacter genus-specific PCR assay which showed that positive rate of the fundus (100%) and the antrum (100%) of clinically abnormal dogs was significantly higher than that of same gastric regions of clinically normal dogs (77.5 and 67.5% respectively). In comparison of gastric regions between clinically normal dogs and abnormal dogs, positive rate of urease test for the fundus (100%) and body (90.9%) in clinically abnormal dogs was significantly higher than that of abnormal dogs (72.5% and 57.5% respectively; p<0.05). The results of urease mapping in dogs and cats also indicated that Helicobacter colonization in the fundus was more dense compared with the density in the body and antrum. In Helicobacter species-specific PCR assay for dogs, 32 of 42 fundic tissues (76.2%) were positive for H. heilmannii and two (4.8%) were positive for H. felis. In cats, 18 of 21 fundic tissues (85.7%) were positive for H. heilmannii and 2 (9.5%) were positive for H. felis. Gastritis scores of fundic tissues from clinically abnormal infected dogs were similar to that from noninfected dogs and evidence of upregulation of IL-1beta, IL-8, and TNF-alpha mRNA was not detected in gastric fundic tissues from clinically abnormal infected dogs. This study suggested that Helicobacter spp. infection in domestic dogs including private owned pet dogs and cats is highly prevalent usually with no clinical sign but high density of colonization can be related to gastrointestinal signs

Production and characterization of biodegradable Povidone-iodine microsphere as a intramammary disinfectant.

Microspheres composed of biocompatible, biodegradable poly DL-lactide-co-glycolide (DL-PLGA) and Povidone-iodine were evaluated as an intramammary disinfectant delivery system in vitro prior to infusion into mammary glands. Microsphere was prepared by solvent evaporation method and particle size, morphology and in vitro release kinetics were examined. The microspheres were ranged in size from 25 microm to 155 microm (mean diameter = 65.7 microm). Povidone-iodine was dispersed on the surface of microsphere and microsphere was spherical in shape with a smooth surface. The yield of microsphere was 57.3% and the encapsulation efficiency was 69.6%. In in vitro release study, a burst effect (50.9%) was observed during the first two days and a sustained release then continued for the next 28 days. Results of the present study demonstrated that microsphere have the potential for new intramammary disinfectant formulations that can provide increased efficacy of therapy against mastitis pathogens.

Allergens causing atopic diseases in canine.

Canine atopic skin disease is seasonal or sometimes non-seasonal immune-mediated skin disease which occurs commonly in Korea. The definite clinical sign is systemic pruritus, especially on periocular parts, external ear, interdigit spaces and lateral flank. For diagnosis of this dermatitis, complete history taking followed by intradermal skin test and serum in vitro IgE test needs to be performed. Allergen selection for the diagnosis and treatment of atopic dermatitis should be varied geographically. In this study, with intradermal skin test(IDST) the prevalence of atopic disease and what allergens are involved in are researched. Allergens used for IDST included 26 allergen extracts from six allergen groups: grasses, trees, weeds, molds, epidermal allergens and environmental allergens. The number of allergens was 42 in which the positive and negative controls are included. The most common positive allergen reaction was the house dust mites on IDST(22/35, 63%). The other positive allergen reactions were to flea(3/35, 9%), molds(1/35, 3%), house dusts(2/35, 6%), feathers (1/35, 3%), cedar/juniper(1/35, 3%), timothy grass(1/35, 3%) and dandelion(1/35, 3%). In this study, the most prevalent allergen causing atopic dermatitis in dogs in Korea was the house dust mites followed by the flea.