This report describes the naturally occurring atypical neuropathological manifestation of systemic canine distemper virus (CDV) infection in two 16-day-old Pit Bull pups. CDV-induced changes affected the gray and white matter of the forebrain while sparing the hindbrain. Histologically, there was necrosis with destruction of the nervous parenchyma due to an influx of inflammatory and reactive cells associated with eosinophilic intranuclear inclusion bodies within glial cells. Positive immunoreactivity against CDV antigens was predominantly observed within astrocytes and neurons. RT-PCR was used to amplify CDV-specific amplicons from brain fragments. These findings suggest the participation of CDV in the etiopathogenesis of these lesions.
Animals ; Antigens, Viral ; Central Nervous System/pathology/virology ; Distemper/*virology ; *Distemper Virus, Canine ; Dogs ; Encephalitis/pathology/*veterinary/virology ; Necrosis/pathology/*veterinary/virology

Oral rabies vaccination (ORV) program for the wild animals in rabies risk regions of Korea has been conducted since 2000. Evaluation of ORV program under field condition and information concerning the incidence of exposure to canine distemper and canine parvovirus (CPV) are needed in wild raccoon dogs (Nyctereutes procyonoides koreensis). Ninety four sera of wild raccoon dogs were screened for antibodies against rabies, canine distemper virus (CDV) and CPV in Korea. The overall prevalence of antibodies against rabies virus (RABV), CDV and CPV in wild raccoon dogs was 35.1%, 89.4% and 24.5%, respectively. Comparisons of sero-prevalences of RABV, CDV and CPV were assayed in two regions (Gyeonggi-do and Gangwon-do). The Gyeonggi-do (36.4%) showed higher sero-positive rate against CPV than Gangwon-do (20.8%). In contrast, Gangwon-do (41.7% and 97.2%) showed higher sero-positive rates against RABV and CDV than Gyeonggi-do (13.6% and 63.6%). These results indicate that there was severe circulation of CDV and CPV among wild raccoon dogs in the two regions of Korea. Furthermore, raccoon dogs showing a protective antibody titer (0.5 IU/ml) were 15.9%, suggesting that new rabies control program such as trap-vaccination-release (TVR) should be launched urgently in rabies risk regions.
Animals ; Animals, Wild ; Antibodies ; Distemper ; Distemper Virus, Canine ; Incidence ; Korea ; Parvovirus ; Parvovirus, Canine ; Prevalence ; Rabies ; Rabies virus ; Raccoon Dogs ; Raccoons ; Vaccination

In order to establish an infectious clone for CDV-3, a commercial vaccine strain of canine distemper virus for mink, to provide reference for the studies of pathogenesis and novel vaccine development of CDV. Thirteen pairs of primers were used to amplify the full-length genome of CDV-3 strain. Five long fragments were obtained based on single restriction site analysis of the whole genome of CDV-3 by RT-PCR. Five fragments were successively inserted into the multiple clone sites in the modified eukaryotic vector of pcDNA3.2 by restriction enzymes and splicing. Meanwhile, the hammerhead ribozyme and hepatitis delta virus ribozyme sequences were added to the beginning of F1 fragment and the ending of F5 fragment, respectively. Then, the full-length cDNA recombinant plasmid of CDV-3 was obtained and named as pcDNA3.2-CDV-3. In addition, three helper plasmids, expressing the N protein, P protein and L protein of the CDV-3 strain respectively, were constructed. The 293T cells were transfected with the full-length cDNA recombinant plasmid and three helper plasmids by Lipofectamine™ 2000. At 3 days post transfection, the supernatant was added to the monolayer of Vero cells to observe the typical syncytium of CDV. Indirect immunofluorescence and artificial label identification of recombinant virus rCDV-3 were conducted after the occurrence of lesions. Finally, the growth characteristics of wtCDV-3 and rCDV-3 were compared after passaging of rCDV-3. The identification of the full-length cDNA recombinant plasmid and three helper plasmids by restriction enzyme digestion and sequencing were consistent with expected. The Vero cells infected with the recombinant rCDV-3 showed typical syncytic. The identification of indirect immunofluorescence and labeled marker, and observation under electron microscope proved that the rCDV-3 was indeed rescued from the recombinant plasmid of pcDNA3.2-CDV-3. In comparison of the virus titers of wtCDV-3, rCDV-3 replicated massively and rapidly and reached the maximize virus titer of 10⁷·⁶⁶⁷ TCID₅₀/mL within 36 h post infection (p.i.) in Vero cells, while wtCDV-3 grew gradually to 10⁶·⁶⁶⁷ TCID₅₀/mL at 72 h p.i. in Vero cells. This reverse genetic system of CDV-3 strain has been established successfully, to provide reference for the studies of pathogenesis and novel vaccine development of CDV.
Animals ; Chlorocebus aethiops ; Clone Cells ; DNA, Complementary ; Distemper Virus, Canine/genetics* ; Plasmids/genetics* ; Vero Cells

Wild raccoon dogs (Nyctereutes procyonoides koreensis) may play a role transmitting several pathogens to humans and pet animals. Information concerning the incidence of rabies, canine distemper virus (CDV), canine parvovirus (CPV), canine adenovirus type 2 (CAdV-2), canine parainfluenza virus type 5 (CPIV-5), and canine herpesvirus (CHV) is needed in wild raccoon dogs. In total, 62 brain samples of raccoon dogs were examined for rabies virus (RABV) and CDV, and 49 lung samples were screened for CDV, CAdV-2, CPIV-5, and CHV. No RABV, CAdV-2, CPIV-5, or CHV was identified, but nine CDV antigens (8.1%, 9/111) were detected. Moreover, 174 serum samples from wild raccoon dogs were screened for antibodies against the five major viral pathogens. The overall serosurveillance against CDV, CPV, CAdV-2, CPIV-5, and CHV in wild raccoon dogs was 60.3%, 52.9%, 59.8%, 23.6%, and 10.3%, respectively. Comparisons of the sero-surveillance of the five pathogens showed that raccoon dogs of Gyeonggi province have slightly higher sero-positive rates against CDV, CPV, and CHV than those of Gangwon province. These results indicate high incidences of CDV, CPV, and CAdV-2 in wild raccoon dogs of two Korean provinces and a latent risk of pathogen transmission to companion and domestic animals.
Adenoviruses, Canine ; Animals ; Animals, Domestic ; Antibodies ; Brain ; Disease Transmission, Infectious ; Distemper ; Distemper Virus, Canine ; Friends ; Gangwon-do ; Gyeonggi-do ; Humans ; Incidence ; Lung ; Paramyxoviridae Infections ; Parvovirus, Canine ; Rabies ; Rabies virus ; Raccoon Dogs* ; Raccoons*

Simple methods for measuring the levels of serum antibody against canine distemper virus (CDV) would assist in the effective vaccination of dogs. To develop an enzyme-linked immunosorbent assay (ELISA) specific for CDV, we expressed hydrophilic extra-viral domain (HEVD) protein of the A75/17-CDV H gene in a pET 28a plasmid-based Escherichia (E.) coli vector system. Expression was confirmed by dot and Western blotting. We proposed that detection of E. coli-expressed H protein might be conformation-dependent because intensities of the reactions observed with these two methods varied. The H gene HEVD protein was further purified and used as an antigen for an ELISA. Samples from dogs with undetectable to high anti-CDV antibody titers were analyzed using this HEVD-specific ELISA and a commercial CDV antibody detection kit (ImmunoComb). Levels of HEVD antigenicity measured with the assays and immunochromatography correlated. These data indicated that the HEDV protein may be used as antigen to develop techniques for detecting antibodies against CDV.
Animals ; Antigens, Viral/*diagnostic use ; Distemper/diagnosis/*virology ; Distemper Virus, Canine/*immunology ; Dog Diseases/*diagnosis/virology ; Dogs ; Enzyme-Linked Immunosorbent Assay/*veterinary ; Escherichia coli/genetics ; Genetic Vectors/genetics ; Hemagglutinins, Viral/*diagnostic use

Canine respiratory coronavirus (CRCoV) is commonly associated with canine kennel cough worldwide. Clinically infected dogs present coughing, sneezing, and nasal discharge. Severe infections may progress to pneumonia. Through serological surveys, CRCoV has been identified as a worldwide pathogen found in the respiratory tracts of dogs suffering from mild or severe respiratory disease. In this study, three dogs were obtained from a dog kennel. Over the previous 5 days, the dogs showed coughing, sneezing, and nasal discharge. To detect the etiologic pathogen, we performed multiplex RT-PCR (mRT-PCR) to amplify the genes encoding canine influenza virus matrix protein, canine distemper virus nucleocapsid protein, and CRCoV spike protein. Dot blotting was achieved with a CRCoV-specific probe. Nasal-secreting CRCoV was detected by the 442 bp CRCoV-positive PCR reaction in the nasal swabbing samples from dogs. Further, CRCoV-positive reactions by dot blot hybridization were detected in the nasal swabbing samples from dogs. In conclusion, we detected CRCoV in kenneled dogs with respiratory disease in Korea. Multiplex RT-PCR was able to detect successfully CRCoV infection in dogs. We suggest that mRT-PCR would be useful and effective for monitoring CRCoV infection in various kinds of dogs.
Animals ; Coronavirus* ; Cough ; Distemper Virus, Canine ; Dogs* ; Korea ; Nucleocapsid Proteins ; Orthomyxoviridae ; Pneumonia ; Polymerase Chain Reaction ; Respiratory System ; Sneezing

Kidney cells of canine embryos were separated into single cells using collagenase and dispase. Primary culture was conducted using these cells. To remove fibroblasts, these cells were treated with edetate disodium dihydrate (Na2EDDA), and pure epithelial cells were separated. Recombinant retrovirus particles that manifest teromerase were produced and inoculated into primary culture cells to produce immortalized canine cell strains (JNUCK-1 and JNUCK-2). To examine the characteristics of the produced cell strains, the growth curve, maximum cultured households, and expressed proteins (keratin) were identified. The JNUCK-1 and JNUCK-2 cell lines showed division ability until the 30th generation without growth retardation. JNUCK-1 and JNUCK-2 cell lines clearly expressed telomerase until the 25th generation. The canine distemper virus (CDV) was inoculated into the JNUCK-1 and JNUCK-2 cell lines, as well as in the Madin-Darby canine kidney (MDCK) cell line. The maximum titer of CDV from the JNUCK-1 cell strain was about 200 times higher than that from the MDCK cell strain. However, the JNUCK-2 cell strain produced a lower titer than the MDCK cell strain. We established a new canine kidney epithelial cell line (JNUCK-1) that could produce CDV with high titer.
Cell Line* ; Collagenases ; Distemper Virus, Canine* ; Embryonic Structures ; Epithelial Cells ; Family Characteristics ; Fibroblasts ; Kidney* ; Madin Darby Canine Kidney Cells ; Retroviridae ; Telomerase

A one step reverse transcription PCR (RT-PCR) combined nested PCR was set up to increase efficiency in the diagnosis of canine distemper virus (CDV) infection after developement of nested PCR. Two PCR primer sets were designed based on the sequence of nucleocapsid gene of CDV Onderstepoort strain. One-step RT-PCR with the outer primer pair was revealed to detect 10(2) PFU/ml. The sensitivity was increased hundredfold using the one-step RT-PCR combined with the nested PCR. Specificity of the PCR was also confirmed using other related canine virus and peripheral blood mononuclear cells (PBMC) and body secretes of healthy dogs. Of the 51 blood samples from dogs clinically suspected of CD, 45 samples were revealed as positive by one-step RT-PCR combined with nested PCR. However, only 15 samples were identified as positive with a single one step RT-PCR. Therefore approximately 60% increase in the efficiency of the diagnosis was observed by the combined method. These results suggested that one step RT-PCR combined with nested PCR could be a sensitive, specific, and practical method for diagnosis of CDV infection.
Animals ; Distemper Virus, Canine/genetics/*isolation & purification ; Dogs ; Polymerase Chain Reaction/*methods/*veterinary ; RNA, Viral/genetics/isolation & purification ; Reverse Transcriptase Polymerase Chain Reaction ; Vaccines, Attenuated ; Viral Vaccines

Both IFN-omega and IFN-alpha belong to type I interferon and have antiviral, antiproliferative, immunomodulatory activities, but their bioactivities are usually different. FeIFN-omega gene was amplified by PCR. FeIFN-alpha gene was synthesized based on the published sequences of GenBank. Then the two types of feline interferon genes were subcloned into the pET-His vector, and expressed in Escherichia coli Rosetta (DE3). Recombinant interferons were purified by affinity chromatography with immobilized nickel chelating NTA (Ni-NTA) and their antiviral activity was estimated according to the ability of IFNs to inhibit the cytopathic effects (CPE) of virus on cells. Results showed that the antiviral activities against various viruses of FeIFN-omega were higher than those of FeIFN-alpha. Against H9N2 subtype avian influenza virus (AIV) and canine distemper virus (CDV), the antiviral activities of FeIFN-omega were 160 folds and 4 folds higher than those of FeIFN-alpha.
Animals ; Antiviral Agents ; pharmacology ; Cats ; Distemper Virus, Canine ; drug effects ; Influenza A Virus, H9N2 Subtype ; drug effects ; Interferon Type I ; biosynthesis ; genetics ; pharmacology ; Interferon-alpha ; biosynthesis ; genetics ; pharmacology

Canine coronavirus is a single-stranded RNA virus that causes enteritis in dogs of any age. Coronaviral enteritis is seldom definitively diagnosed, since it is usually much less severe than many other types of enteritis and is self-limiting. Conventional diagnostics for the canine coronaviral enteritis such as polymerase chain reaction (PCR), virus isolation, and electron microscopic examination are inappropriate for small animal clinics due to the complicated experimental processes involved. Therefore, a commercially available lateral flow test kit based on chromatographic immunoassay techniques was tested to evaluate its performance as a first-line diagnostic test kit that could be used in clinics. The coronavirus antigen test kit detected canine coronavirus-infected dogs with 93.1% sensitivity and 97.5% specificity. The detection limit of the test kit was between 1.97 × 10⁴/mL and 9.85 × 10³/mL for samples with a 2-fold serial dilution from 1.25 × 10⁶ TCID₅₀ (TCID₅₀, 50% tissue culture infectious dose). Additionally, the test kit had no cross-reactivity with canine parvovirus, distemper virus, or Escherichia coli. Overall, the commercially available test kit showed good diagnostic performance in a clinical setting, with results similar to those from PCR, confirming their potential for convenient and accurate use in small animal clinics.
Animals ; Coronavirus ; Coronavirus, Canine ; Diagnostic Tests, Routine ; Distemper ; Dogs ; Enteritis ; Escherichia coli ; Immunoassay ; Limit of Detection ; Parvovirus, Canine ; Polymerase Chain Reaction ; Reagent Kits, Diagnostic ; RNA Viruses ; Sensitivity and Specificity