Simultaneous detection of canine respiratory disease associated viruses by a multiplex reverse transcription-polymerase chain reaction assay

Development of a three-panel multiplex real-time PCR assay for simultaneous detection of nine canine respiratory pathogens

Infectious respiratory disease is one of the most common diseases in dogs worldwide. Several bacterial and viral pathogens can serve as causative agents of canine infectious respiratory disease (CIRD), including Mycoplasma cynos, Mycoplasma canis, Bordetella bronchiseptica, canine adenovirus type 2 (CAdV-2), canine herpesvirus 1 (CHV-1), canine parainfluenza virus (CPIV), canine distemper virus (CDV), canine influenza virus (CIA) and canine respiratory coronavirus (CRCoV). Since these organisms cause similar clinical symptoms, disease diagnosis based on symptoms alone can be difficult. Therefore, a quick and accurate test is necessary to rapidly identify the presence and relative concentrations of causative CIRD agents. In this study, a multiplex real-time PCR panel assay was developed and composed of three subpanels for detection of the aforementioned pathogens. Correlation coefficients (R²) were >0.993 for all singleplex and multiplex real-time PCR assays with the exception of one that was 0.988; PCR amplification efficiencies (E) were between 92.1% and 107.8% for plasmid DNA, and 90.6-103.9% for RNA templates. In comparing singular and multiplex PCR assays, the three multiplex reactions generated similar R² and E values to those by corresponding singular reactions, suggesting that multiplexing did not interfere with the detection sensitivities. The limit of detection (LOD) of the multiplex real-time PCR for DNA templates was 5, 2, 3, 1, 1, 1, 4, 24 and 10 copies per microliter for M. cynos, M. canis, B. brochiseptica, CAdV-2, CHV-1, CPIV, CDV, CIA and CRCoV, respectively; and 3, 2, 6, 17, 4 and 8 copies per microliter for CAdV-2, CHV-1, CPIV, CDV, CIA and CRCoV, respectively, when RNA templates were used for the four RNA viruses. No cross-detection was observed among the nine pathogens. For the 740 clinical samples tested, the newly designed PCR assay showed higher diagnostic sensitivity compared to an older panel assay; pathogen identities from selected samples positive by the new assay but undetected by the older assay were confirmed by Sanger sequencing. Our data showed that the new assay has higher diagnostic sensitivity while maintaining the assay's specificity, as compared to the older version of the panel assay.

A multiplex nanoparticle-assisted polymerase chain reaction assay for detecting three canine epidemic viruses using a dual priming oligonucleotide system

A rapid and accurate diagnosis of mixed viral infections is important for providing timely therapeutic interventions. The aim of this study was to develop a highly sensitive and specific method for the simultaneous detection of canine distemper virus (CDV), canine parvovirus (CPV) and canine coronavirus (CCV) in mixed infections by combining the high specificity of a dual priming oligonucleotide (DPO) primer system with the high sensitivity of a nanoparticle-assisted PCR (nanoPCR) assay. Under the optimised assay conditions, the multiplex DPO-nanoPCR assay developed using DPO primers was 100-fold more sensitive than the multiplex PCR assay using conventional primers. The detection limits of the multiplex DPO-nanoPCR assay for the recombinant plasmids containing the cloned CDV, CPV and CCV target sequences were 5.4 × 10², 6.5 × 10² and 1.6 × 10² copies in a 25 μL assay, respectively. No cross-reaction with other canine viruses was observed. This is the first reported use of a multiplex nanoPCR assay with the DPO primer system for the simultaneous detection of CDV, CPV and CCV in mixed infections. The high sensitivity and specificity of the assay indicated its potential for use in clinical diagnosis and field surveillance of animal epidemics.

Cross-sectional investigation and risk factor analysis of community-acquired and hospital-associated canine viral infectious respiratory disease complex

Canine infectious respiratory disease complex (CIRDC) is associated with multiple factors. The possible transmission source can be via community-acquired infection (CAI) or hospital-associated infection (HAI), but the variable factors within these two routes are not well described. This study aimed to (i) investigate a cross-sectional incidence of canine respiratory viruses, including influenza (CIV), parainfluenza, distemper (CDV), respiratory coronavirus (CRCoV), adenovirus-2, and herpesvirus, in respiratory-diseased dogs, and (ii) analyze the possibly related risk factors. In total 209 dogs with respiratory illness, consisting of 133 CAI and 76 HAI dogs, were studied. Both nasal and oropharyngeal swabs were sampled from each dog and subjected for CIRDC virus detection using multiplex PCRs. Common six viruses associated with CIRDC were detected in both groups with CIV and CRCoV being predominantly found. Only CDV was significantly more prevalent in CAI than HAI dogs. Multiple virus detections were found in 81.2% and 78.9% of CAI and HAI dogs, respectively. Co-detection of CIV and CRCoV was represented the highest proportion and most often found with other CIRD viruses. Moreover, the clinical severity level was notably related to the age of infected dogs, but not to the vaccination status, sex and transmission route. Since healthy or control dogs were not included in this study, the prevalence of the CIRD virus infections could not be assessed.

Multiplex PCR methods for detection of several viruses associated with canine respiratory and enteric diseases

Viral respiratory and intestinal infections are the most common causes of canine viral illness. Infection with multiple pathogens occurs in many cases. Rapid diagnosis of these multiple infections is important for providing timely and effective treatment. To improve diagnosis, in this study, two new multiplex polymerase chain reactions (mPCRs) were developed for simultaneous detection of canine respiratory viruses (CRV) and canine enteric viruses (CEV) using two separate primer mixes. The viruses included canine adenovirus type 2 (CAV-2), canine distemper virus (CDV), canine influenza virus (CIV), canine parainfluenza virus (CPIV), canine circovirus (CanineCV), canine coronavirus (CCoV) and canine parvovirus (CPV). The sensitivity of the mPCR results showed that the detection limit of both mPCR methods was 1×10⁴ viral copies. Twenty nasal swabs (NS) and 20 anal swabs (AS) collected from dogs with symptoms of respiratory disease or enteric disease were evaluated using the novel mPCR methods as a clinical test. The mPCR protocols, when applied to these respiratory specimens and intestinal samples, could detect 7 viruses simultaneously, allowing rapid investigation of CRV (CAV-2, CDV, CIV and CPIV) and CEV (CAV-2, CanineCV, CCoV and CPV) status and prompt evaluation of coinfection. Our study provides an effective and accurate tool for rapid differential diagnosis and epidemiological surveillance in dogs.

One-step triplex PCR/RT-PCR to detect canine distemper virus, canine parvovirus and canine kobuvirus

To rapidly distinguish Canine distemper virus (CDV), canine parvovirus (CPV), and canine kobuvirus (CaKoV) in practice, a one-step multiplex PCR/RT-PCR assay was developed, with detection limits of 10^2.1 TCID₅₀ for CDV, 10^1.9 TCID₅₀ for CPV and 10³ copies for CaKoV. This method did not amplify nonspecific DNA or RNA from other canine viruses. Therefore, the assay provides a sensitive tool for the rapid clinical detection and epidemiological surveillance of CDV, CPV and CaKoV in dogs.

The detection and differentiation of canine respiratory pathogens using oligonucleotide microarrays

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Multiple canine respiratory pathogens were differentiated simultaneously.

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Wild type and vaccine strains of canine distemper virus were distinguished.

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Results were read with naked eye and no reader equipment was needed.

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High sensitivity, specificity and efficiency.

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Low money and time costs.

Canine respiratory diseases are commonly seen in dogs along with co-infections with multiple respiratory pathogens, including viruses and bacteria. Virus infections in even vaccinated dogs were also reported. The clinical signs caused by different respiratory etiological agents are similar, which makes differential diagnosis imperative. An oligonucleotide microarray system was developed in this study. The wild type and vaccine strains of canine distemper virus (CDV), influenza virus, canine herpesvirus (CHV), Bordetella bronchiseptica and Mycoplasma cynos were detected and differentiated simultaneously on a microarray chip. The detection limit is 10, 10, 100, 50 and 50 copy numbers for CDV, influenza virus, CHV, B. bronchiseptica and M. cynos, respectively. The clinical test results of nasal swab samples showed that the microarray had remarkably better efficacy than the multiplex PCR-agarose gel method. The positive detection rate of microarray and agarose gel was 59.0% (n = 33) and 41.1% (n = 23) among the 56 samples, respectively. CDV vaccine strain and pathogen co-infections were further demonstrated by the microarray but not by the multiplex PCR-agarose gel. The oligonucleotide microarray provides a highly efficient diagnosis alternative that could be applied to clinical usage, greatly assisting in disease therapy and control.

Development and application of multiplex PCR assays for detection of virus-induced respiratory disease complex in dogs

Canine infectious respiratory disease complex (CIRDC) viruses have been detected in dogs with respiratory illness. Canine influenza virus (CIV), canine parainfluenza virus (CPIV), canine distemper virus (CDV), canine respiratory coronavirus (CRCoV), canine adenovirus type 2 (CAdV-2) and canine herpesvirus 1 (CaHV-1), are all associated with the CIRDC. To allow diagnosis, two conventional multiplex polymerase chain reactions (PCR) were developed to simultaneously identify four RNA and two DNA viruses associated with CIRDC. The two multiplex PCR assays were then validated on 102 respiratory samples collected from 51 dogs with respiratory illness by sensitivity and specificity determination in comparison to conventional simplex PCR and a rapid three-antigen test kit. All six viruses were detected in either individual or multiple infections. The developed multiplex PCR assays had a >87% sensitivity and 100% specificity compared to their simplex counterpart. Compared to the three-antigen test kit, the multiplex PCR assays yielded 100% sensitivity and more than 83% specificity for detection of CAdV-2 and CDV, but not for CIV. Therefore, the developed multiplex PCR modalities were able to simultaneously diagnose a panel of CIRDC viruses and facilitated specimen collection through being suitable for use of nasal or oral samples.

Rapid and sensitive detection of canine distemper virus by one-tube reverse transcription-insulated isothermal polymerase chain reaction

Background

Canine distemper virus (CDV) has been associated with outbreaks of canine infectious respiratory disease in shelters and boarding kennel environments. POCKIT^TM Nucleic Acid Analyzer is a field-deployable device capable of generating automatically interpreted insulated isothermal polymerase chain reaction (iiPCR) results from extracted nucleic acid within one hour. In this study, reverse transcription iiPCR (RT-iiPCR) was developed to facilitate point-of-need diagnosis of CDV infection.

Results

Analytical sensitivity (limit of detection 95%) of the established CDV RT-iiPCR was about 11 copies of in vitro transcribed RNA per reaction. CDV RT-iiPCR generated positive signals from CDV, but not Bordetella bronchiseptica, canine parvovirus, canine herpesvirus, canine adenovirus 2, canine influenza virus (subtype H3N8), canine parainfluenza virus, and canine respiratory coronavirus. To evaluate accuracy of the established reaction in canine distemper clinical diagnosis, 110 specimens from dogs, raccoons, and foxes suspected with CDV infection were tested simultaneously by CDV RT-iiPCR and real-time RT-PCR. CDV RT-iiPCR demonstrated excellent sensitivity (100%) and specificity (100%), compared to real-time RT-PCR.

Conclusions

The results indicated an excellent correlation between RT-iiPCR and a reference real time RT-PCR method. Working in a lyophilized format, the established method has great potential to be used for point-of-care diagnosis of canine distemper in animals, especially in resource-limited facilities.

Evaluation of virus isolation, one-step real-time reverse transcription polymerase chain reaction assay, and two rapid influenza diagnostic tests for detecting canine Influenza A virus H3N8 shedding in dogs

Sustained transmission of canine Influenza A virus (CIV) H3N8 among U.S. dogs underscores the threat influenza continues to pose to canine health. Because rapid and accurate detection of infection is critical to the diagnosis and control of CIV, the 2 main objectives of the current study were to estimate and compare the sensitivities of CIV testing methods on canine swab samples and to evaluate the performance of Flu Detect™ (Synbiotics Corp., Kansas City, MO) for detecting CIV nasal shedding in high-risk shelter dogs. To address the first objective, nasal and pharyngeal swab samples were collected from 124 shelter and household dogs seen by Colorado State University Veterinary Teaching Hospital clinicians for canine infectious respiratory disease between April 2006 and March 2007 and tested for CIV shedding using virus isolation, the rapid influenza diagnostic test Directigen Flu A+B™ (BD Diagnostic Systems, Sparks, MD), and real-time reverse transcription polymerase chain reaction (RT-PCR). For the second objective, 1,372 dogs with unknown respiratory health status were sampled from 6 U.S. shelters from December 2009 to November 2010. Samples were tested for presence of CIV using real-time RT-PCR and Flu Detect. Using a stochastic latent class modeling approach, the median sensitivities of virus isolation, rapid influenza diagnostic test, and real-time RT-PCR were 72%, 65%, and 95%, respectively. The Flu Detect test performed poorly for detecting CIV nasal shedding compared to real-time RT-PCR. In conclusion, the real-time RT-PCR has the highest sensitivity for detecting virus nasal shedding and can be used as a rapid diagnostic test for CIV.