A fast and simple one-step duplex PCR assay for canine distemper virus (CDV) and canine coronavirus (CCoV) detection

Trace detection of canine distemper virus based on Michelson-interferometer sensing probe

A single-mode-fiber (SMF)-multimode-fiber (MMF)-tri-core-fiber (TCF) Michelson probe structure is proposed for trace detection of canine distemper virus (CDV). One end of the TCF is cut flat and fused with the multimode fiber, and the other end is coated with a silver film to enhance the reflection, and an optic-fiber sensing probe with SMF-MMF-TCF structure is obtained. The (PDDA/PSS)3 multilayer film is modified on the surface of the fiber by layer-by-layer self-assembly method as a polyelectrolyte binder to immobilize CDV antibodies to form a (PDDA/PSS)3 /CDV antibody composite membrane for specific detection of CDV antigens. The response-recovery test of the sensor is performed to verify its repeatability. The detection limit, the sensitivity, and the linear fitting degree for CDV antigen are 0.1236 pg/mL, 1.1776 dB/(pg/mL), and 0.9899, respectively. At the same time, the stability, selectivity, and clinical samples of the sensors were also verified.

Molecular epidemiology and genetic diversity of canine coronavirus from domestic dogs in Chengdu, China from 2020 to 2021 using a multiplex RT-PCR

Recent reports on identification of canine coronavirus (CCoV) in humans have emphasized the urgency to strengthen surveillance of animal CoVs. The fact that recombinations between CCoV with feline, porcine CoVs brought about new types of CoVs indicated that more attention should be paid to domestic animals like dogs, cats and pigs, and the CoVs they carried. However, there are about ten kinds of CoVs that infect above animals, and thus representative CoVs with zoonotic potentials were considered in this study. Multiplex RT-PCR against CCoV, Feline coronavirus (FCoV), porcine deltacoronavirus and porcine acute diarrhea syndrome coronavirus was developed to investigate the prevalence of CoVs from domestic dogs in Chengdu, Southwest China. Samples from a total of 117 dogs were collected from a veterinary hospital, and only CCoV (34.2%, 40/117) was detected. Therefore, this study focused on CCoV and its characteristics of S, E, M, N and ORF3abc genes. Compared with CoVs that are capable of infecting humans, CCoV strains showed highest nucleotide identity with the novel canine-feline recombinants detected from humans (CCoV-Hupn-2018). Based on S gene, CCoV strains were not only clustered with CCoV-II strains, but also closely related to FCoV-II strains ZJU1617 and SMU-CD59/2018. As for assembled ORF3abc, E, M, N sequences, CCoV strains had the closest relationship with CCoV-II (B203_GZ_2019, B135_JS_2018 and JS2103). What's more, specific amino acid variations were found, especially in S and N proteins, and some mutations were consistent with FCoV, TGEV strains. Altogether, this study provided a novel insight into the identification, diversification and evolution of CoVs from domestic dogs. It is of top priority to recognize zoonotic potential of CoVs, and continued comprehensive surveillance will help better understand the emergence, spreading, and ecology of animal CoVs.

Canine morbillivirus (CDV): a review on current status, emergence and the diagnostics

The increasing host range of canine morbillivirus (CDV) affecting important wildlife species such as Lions, Leopard, and Red Pandas has raised the concern. Canine distemper is a pathogen of dogs affecting the respiratory, gastrointestinal, and nervous systems. Seventeen lineages of CDV are reported, and the eighteenth lineage was proposed in 2019 from India. Marked genomic differences in the genome of wild-type virus and vaccine strain are also reported.The variations at the epitope level can be differentiated using specific monoclonal antibodies in neutralization tests. Keeping in mind the current status of the emergence of CDV, genetic and molecular study of circulating strains of the specific geographical region are the essential components of the disease control strategy. New target-based diagnostics and vaccines are in need to counter the effects of the emerging virus population. Control of CDV is necessary to save the endangered, vulnerable, and many other wildlife species to maintain balance in the ecological system. This review provides an overview on emergence reported in CDV, diagnostics developed till today, and a perspective on the disease control strategy, keeping wildlife in consideration.

Establishment of hydrolysis probe system real-time PCR assay for rapid detection of canine circovirus

In the study, we established a hydrolysis probe-based real-time polymerase chain reaction (PCR) assay to rapidly detect Canine circovirus (CanineCV) DNA in faecal samples. We designed a pair of specific primers and one probe targeting Rep in CanineCV, and sensitivity, specificity, and repeatability tests were performed to evaluate the efficacy of the assay. The assay showed high sensitivity and a minimum detection limit of 8.42 × 10¹ copies/μL, which is 1000-fold more sensitive compared to traditional PCR. The method was also highly specific, without cross-reaction with other common canine viruses. Moreover, the assay showed high repeatability, and the mean intra-assay and inter-assay coefficients of variation were 0.26 and 0.36%, respectively. The results of the detection of clinical samples showed that the positive detection rate of CanineCV was 14.04% (8/57). Notably, 8% of clinical samples were co-infected with other canine pathogens. In conclusion, the establishment of a hydrolysis probe-based real-time PCR method provides a fast, sensitive, specific, reliable, and repeatable method for CanineCV detection.

A meta-analysis of cross-sectional studies on the frequency and risk factors associated with canine morbillivirus infection in China

BACKGROUND

The canine morbillivirus, previously known as canine distemper virus (CDV), is a pathogen which infects dogs worldwide and causes fatal disease. CDV has a broad range of hosts and can infect at least six orders and more than 20 mammalian families. Domestic dogs are the main hosts of CDV and play a central role in the transmission of the virus. However, the prevalence of CDV infection in China remains unknown since there are only a few studies which systematically analysed the prevalence of CDV in domestic dogs in the country. Therefore, we conducted a systematic review and meta-analysis of the frequency of CDV positivity and associated risk factors of CDV in Chinese domestic dogs.

METHODS

We systematically searched for studies on the frequency of CDV in Chinese domestic dogs published in English and Chinese to conduct a meta-analysis using the random-effects model with a forest plot with a 95% confidence interval.

RESULTS

The overall estimated frequency of CDV positivity in Chinese domestic dogs was 22%. In addition, our data show that sampling season, age, breed, and immunisation status are associated with CDV infection frequency.

CONCLUSION

In a word, CDV is circulating in domestic dogs in China. Continued intervention strategies based on risk factors are necessary to reduce the frequency of CDV infection, especially in endemic regions.

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.

Development of a double monoclonal antibody-based sandwich enzyme-linked immunosorbent assay for detecting canine distemper virus

Abstract

Canine distemper virus (CDV) infection causes mass mortality in diverse carnivore species. For effective virus surveillance, rapid and sensitive assays are needed to detect CDV in field samples. In this study, after BABL/c mice were immunized with recombinant CDV-fusion (F) protein, monoclonal antibodies (mAbs) against recombinant CDV-F protein (designated 1A5, 1A6, and 7D5) were produced using traditional hybridoma cell technology. Next, capture antibody (1A6, 800 ng/well) and horseradish peroxidase (HRP)–conjugated detection antibody (HRP-7D5, 1:100, 500 ng/well) were used in a double monoclonal antibody–based sandwich enzyme-linked immunosorbent assay (ELISA) for CDV detection after optimization of both mAb amounts per well using a checkerboard titration test. Based on sandwich ELISA test results for 120 known CDV-negative samples, the cutoff value for a positive result was set to an OD_450 nm value ≥ 0.196. As compared with test results obtained from commercial immune colloidal gold test strips, the low limits of detection for the two assays were revealed to be 100 TCID₅₀ per 100 μL. In addition, the sandwich ELISA agreed 100% and 96.4% with commercial immune colloidal gold test strips when testing serum and stool samples. The sandwich ELISA assay provided statistically similar CDV detection. Thus, the sandwich ELISA developed here to detect CDV in fecal and serum samples provided good sensitivity, high specificity, and good reproducibility and should serve as an ideal method for large-scale surveillance of CDV infections in carnivores.

Key points

• Three CDV mAbs that recognized different epitopes and bound to virion were generated.

• The sandwich ELISA based mAbs to detect CDV in fecal and serum samples was developed.

• The sandwich ELISA is an ideal method for detecting CDV infections in the field.

Novel Genotype Definition and the First Epidemiological Investigation of Canine Adenovirus Type 2 in Dogs in Central China

Infections caused by canine adenovirus (CAdV) type 1 have been reported worldwide in the past two decades. However, only few studies have specifically reported the prevalence of CAdV type 2 (CAdV-2). The present study investigated the persistent circulation of CAdV-2 in dogs with diarrhea in the Henan, Hubei, and Jiangsu provinces in central China from 2017 to 2019. We conducted polymerase chain reaction for detecting CAdV-2 and other related pathogens in 224 rectal swabs of pet dogs and the co-infection of canine diseases was also analyzed. In addition, the structural protein genes-Fiber, Hexon, and Penton-of the isolated CAdV-2 strains were sequenced and analyzed. The similarity between Hexon and Penton among the 19 strains was 97.4%, as revealed by sequence alignment. Multiple sequence alignment results showed that the Fiber gene sequences of these CAdV-2 strains shared 97.4-99.8% nucleotide and 94.1-99.3% amino acid identity with reference sequences and shared only 79.0-80.5% nucleotide and 77.3-80.5% amino acid identity with the vaccine strain CLL, indicating that Fiber harbored most of the variant sites. Furthermore, pairwise sequence comparisons of Hexon of CH-JS-1901 and CH-HN-1801 with that of India2006 revealed a novel genotype. Furthermore, protein model prediction showed that the amino acid mutation of fiber protein in 19 strains was located in the head region, that may cause structural changes on the surface of the fiber protein. These findings are of significance for monitoring the epidemiology of CAdV-2 infection and developing a novel vaccine which contribute to understanding genetic evolution of CAdV-2 in China.

Identification of Linear B-Cell Epitopes on Hemagglutinin Protein of Canine Distemper Virus Using Two Monoclonal Antibodies

Canine distemper virus (CDV) belongs to the Morbillivirus genus of the Paramyxoviridae family, which causes a threat to the domestic dog and fur-animal industry. Hemagglutinin protein is a major membrane protein of the vital molecular factor in CDV tropism, also known to induce hosts to produce neutralizing antibodies. In the current study, we prepared two monoclonal antibodies, 1A5 and 2B8, against the H protein of the CDV-PS strain. A series of partially overlapping synthetic peptides covering the hemagglutinin protein (amino acids 50–204) were screened to define the linear epitope identified by 1A5 and 2B8 mAbs. ¹²⁰QKTNFFNPNREFDFR¹³⁴ (F8) and ¹⁷⁸ARGDIFPPY¹⁸⁶ (F14-1) are minimal linear epitopes recognized by 1A5 and 2B8 mAbs, respectively. Further investigations revealed that F8 is conserved in different CDV strains; however, F14-1 contains mutant residues 178, 179, and 180. The epitopes F8 and F14-1 localized at the surface of hemagglutinin protein in a three-dimensional (3D) structure. CDV-infected dog serum can also recognize the identified B-cell epitopes.

Molecular and serological surveys of canine distemper virus: A meta-analysis of cross-sectional studies

BACKGROUND

Canine morbillivirus (canine distemper virus, CDV) persists as a serious threat to the health of domestic dogs and wildlife. Although studies have been conducted on the frequency and risk factors associated with CDV infection, there are no comprehensive data on the current epidemiological magnitude in the domestic dog population at regional and national levels. Therefore, we conducted a cross-sectional study and included our results in a meta-analysis to summarize and combine available data on the frequency and potential risk factors associated with CDV infection.

METHODS

For the cross-sectional study, biological samples from dogs suspected to have canine distemper (CD) were collected and screened for viral RNA. Briefly, the PRISMA protocol was used for the meta-analysis, and data analyses were performed using STATA IC 13.1 software.

RESULTS

CDV RNA was detected in 34% (48/141) of dogs suspected to have CD. Following our meta-analysis, 53 studies were selected for a total of 11,527 dogs. Overall, the pooled frequency of CDV positivity based on molecular and serological results were 33% (95% CI: 23-43) and 46% (95% CI: 36-57), respectively. The pooled subgroup analyses of clinical signs, types of biological samples, diagnostic methods and dog lifestyle had a wide range of CDV positivity (range 8-75%). Free-ranging dogs (OR: 1.44, 95% CI: 1.05-1.97), dogs >24 months old (OR: 1.83, 95% CI: 1.1-3) and unvaccinated dogs (OR: 2.92, 95% CI: 1.26-6.77) were found to be positively associated with CDV infection. In contrast, dogs <12 months old (OR: 0.36, 95% CI: 0.20-0.64) and dogs with a complete anti-CDV vaccination (OR: 0.18, 95% CI: 0.05-0.59) had a negative association.

CONCLUSION

Considering the high frequency of CDV positivity associated with almost all the variables analyzed in dogs, it is necessary to immediately and continuously plan mitigation strategies to reduce the CDV prevalence, especially in determined endemic localities.