Canine respiratory coronavirus: an emerging pathogen in the canine infectious respiratory disease complex.

Infectious respiratory disease in dogs is a constant challenge because of the involvement of several pathogens and environmental factors. Canine respiratory coronavirus (CRCoV) is a new coronavirus of dogs, which is widespread in North America, Japan, and several European countries. CRCoV has been associated with respiratory disease, particularly in kenneled dog populations. The virus is genetically and antigenically distinct from enteric canine coronavirus; therefore, specific tests are required for diagnosis.     

成都地区宠物犬感染犬瘟热病毒和犬呼吸道冠状病毒的分子流行病学调查

为了解成都地区宠物犬犬瘟热病毒（canine distemper virus,CDV）和犬呼吸道冠状病毒（canine respiratory coronavirus,CRCoV）的感染情况,本试验应用RT-PCR对采自成都地区8家动物医院共计420份出现呼吸道症状的宠物犬鼻腔棉拭子样本进行分子检测。结果发现,从420份样本中,检出213份CDV阳性,检出率为50.71%;检出247份CRCoV阳性,检出率为58.81%;CDV和CRCoV混合感染的检出率为41.19%。表明成都地区宠物犬感染CDV和CRCoV较为严重,且二者混合感染率较高。宠物犬CDV和CRCoV的检出率与年龄、性别、品种、季节和免疫状况等因素的关系存在不同程度的差异。其中,1~3月龄幼犬检出率最高,分别为74.40%和79.20%;纯种犬的检出率较其他犬种高,分别为59.37%和62.22%;春季CDV的检出率较高,为56.19%,而冬季CRCoV的检出率较高,为67.59%;未免疫犬的检出率较高,分别为64.42%和63.46%。该研究丰富了成都地区宠物犬CDV和CRCoV的流行病学资料,为该地区宠物犬CDV和CRCoV的诊断及防控提供了基本数据。     

Serological prevalence of canine respiratory coronavirus

Canine respiratory coronavirus (CRCoV) has recently been detected in dogs; it is a group 2 coronavirus showing similarity to bovine coronavirus (BCoV) but is distinct from canine enteric coronavirus (CECoV). CRCoV may play an important role in canine infectious respiratory disease (CIRD) either by predisposing to further and potentially more serious viral and bacterial infections or possibly as a primary pathogen. The prevalence of serum antibodies to CRCoV, in a population of dogs in the south east of England, has been shown previously to be 30.1% on the first day of entry to a rehoming kennel [Erles, K., Toomey, C., Brooks, H.W., Brownlie, J., 2003. Detection of a group 2 coronavirus in dogs with canine infectious respiratory disease. Virology 310, 216-223]. The purpose of this study was to establish the prevalence of CRCoV in the general canine population within as well as outside the UK. An ELISA, used to test for the presence of antibodies to CRCoV in canine serum samples, identified seropositive dogs in UK, USA, Canada, Republic of Ireland and Greece. The development of an ELISA based on CRCoV antigen and immunofluorescence assay are described here. 54.7% (547/1000) of North American and 36.0% (297/824) of United Kingdom dogs were seropositive for CRCoV. The age and geographical distribution of seropositive dogs was also assessed. The cross-reactivity demonstrated between CRCoV antibodies from different countries and a UK viral isolate suggests immunological similarity. The overall prevalence of this virus in both North America and the UK suggests that CRCoV has international significance and that further epidemiological studies are required.     

The seroprevalence of canine respiratory coronavirus and canine influenza virus in dogs in New Zealand

Abstract

AIM: To determine whether canine respiratory coronavirus (CRCoV) and canine influenza virus (CIV) are present in dogs in New Zealand.

METHODS: Serum samples from 251 dogs of varying age, breed and clinical histories were tested for the presence of antibodies to CRCoV and CIV, using indirect fluorescent antibody (IFA) analysis. The population sampled represented a wide geographic area but principally encompassed the central and lower North Island of New Zealand.

RESULTS: Seventy-three of the 251 samples (29%) were seropositive for CRCoV. Dogs <2 years old were less likely to be seropositive for CRCoV than older dogs. None was seropositive for CIV.

CONCLUSIONS: This study revealed the presence of antibodies to CRCoV in dogs in New Zealand. Young dogs are less likely to be seropositive than older dogs, probably due to increased opportunity for exposure to CRCoV over time. Serum antibodies to CIV were not detected in any of the dogs sampled, suggesting that this virus is unlikely to be present in dogs in New Zealand.

CLINICAL RELEVENCE: Canine respiratory coronavirus is present in New Zealand. Although the role of this virus in canine infectious tracheobronchitis has not been fully elucidated, evidence suggests that it may have a causal role in this disease. Veterinarians should consider CRCoV as a differential diagnosis in cases of respiratory disease in dogs in New Zealand. While CIV appears not to be currently present in New Zealand, veterinarians should consider infection with this virus as a differential diagnosis in dogs presenting with respiratory signs.     

北京地区犬呼吸道冠状病毒感染状况的监测与分析

本研究旨在分析犬呼吸道冠状病毒(canine respiratory coronavirus, CRCoV)的感染情况和在北京地区的流行病学状况。采用RT-PCR方法,对自2015年12月—2017年3月于中国农业大学动物医院采集的487份犬咽鼻拭子进行了CRCoV检测,同时,对部分样本进行了犬副流感病毒(canine parainfluenza virus, CPIV)、犬腺病毒II型(canine adenovirus type 2,CAV-2)、犬瘟热病毒(canine distemper virus, CDV)等病毒的混合感染情况调查。结果表明：CRCoV的阳性率为21.36%(104/487);CRCoV与CPIV、CAV-2、CDV的混合感染率分别为3.43%(11/321),0%(0/156)和3.85%(6/156)。在所有呼吸道症状记录完整的455例样本中,无呼吸道症状的犬CRCoV携带率为27.19%(31/114);呈轻度呼吸道症状(鼻液、咳嗽)的犬CRCoV感染率为19.73%(59/299);呈中至重度呼吸道症状(肺炎)的犬CRCoV感染率为14.28%(6/...     

Seroepidemiology of respiratory (group 2) canine coronavirus, canine parainfluenza virus, and Bordetella bronchiseptica infections in urban dogs in a humane shelter and in rural dogs in small communities

This prospective study evaluated seroepidemiologic features of canine respiratory coronavirus (CRCoV), canine parainfluenza virus (CPIV), and Bordetella bronchiseptica infections in dogs in an urban humane shelter and in rural/small community dog populations in western Canada. Seroprevalence of CRCoV and CPIV was low compared with other countries; seroprevalence of B. bronchiseptica was moderate to high in most populations examined. Rural dogs were 0.421 times (P ≤ 0.0001) less likely to be positive for CRCoV than dogs admitted to the shelter. There were no statistical differences in prevalence of antibodies to B. bronchiseptica and CPIV between urban and rural populations. Dogs from Fort Resolution, NWT were significantly (P < 0.05) less likely to have moderate or high antibody titers to the 3 agents than dogs in the shelter. Seroconversion to CRCoV was common in dogs in the shelter, but was not associated (P = 0.18) with respiratory disease. Antibodies to CRCoV, CPIV, or B. bronchiseptica on arrival were not significantly (P > 0.05) associated with disease-sparing after entry into the shelter.     

Serological prevalence of canine respiratory coronavirus in southern Italy and epidemiological relationship with canine enteric coronavirus.

Canine respiratory coronavirus (CRCoV) has been detected in dogs suffering from respiratory disease and is thought to be involved in canine infectious respiratory disease (CIRD) complex. Canine enteric coronavirus (CECoV) is a widespread pathogen of dogs, responsible for mild to severe diarrhea in pups. The purpose of this study was to establish the seroprevalence of CRCoV in Italy and its relationship to CECoV type II seroprevalence. The age and year of sample collection from seropositive dogs was also assessed. Of adult domestic dogs, 23.3% had antibodies to CRCoV, compared with 86.1% with antibodies to CECoV. Amongst a population of kenneled pups, 4.0% had antibodies to CRCoV, and 97.0% had antibodies to CECoV.     

A serological survey of canine respiratory coronavirus in New Zealand

ABSTRACT

Aims: To determine the seroprevalence of canine respiratory coronavirus (CRCoV) in New Zealand dogs, and to explore associations with age, sex, breed, month, and geographical region of sampling and reported presence of clinical signs suggestive of respiratory disease.

Methods: A total of 1,015 canine serum samples were randomly selected from submissions to a diagnostic laboratory between March and December 2014, and were analysed for CRCoV antibodies using a competitive ELISA. Logistic regression analysis was used to determine associations between seroprevalence of CRCoV and breed category, age, sex, sampling month, region, and reported health status of dogs.

Results: Overall, 538/1,015 (53.0%) samples were seropositive for CRCoV, with 492/921 (53.4%) positive dogs in the North Island and 46/94 (49%) in the South Island. Age of dog, sampling month, region, and presence of abnormal respiratory signs were included in the initial logistic regression model. Seroprevalence was higher in dogs aged ≥3 compared with ≤2 years (p?<?0.01). The lowest seroprevalence was observed in July (30/105; 28.5%) and August (32/100; 32%), and the highest in June (74/100; 74%). Seroprevalence in dogs from Auckland was higher than in dogs from the Hawkes Bay, Manawatu, Marlborough, and Waikato regions (p?<?0.05). Abnormal respiratory signs (coughing, nasal discharge, or sneezing) were reported for 28/1,015 (2.8%) dogs sampled. Seroprevalence for CRCoV tended to be higher among dogs with respiratory signs (67.9 (95% CI?=?47.6–83.4)%) than dogs with no reported respiratory signs (52.6 (95% CI?=?49.5–55.7)%).

Conclusions: Serological evidence of infection with CRCoV was present in more than half of the dogs tested from throughout New Zealand. Differences in CRCoV seroprevalence between regions and lack of seasonal pattern indicate that factors other than external temperatures may be important in the epidemiology of CRCoV in New Zealand.

Clinical relevance: Our data suggest that CRCoV should be included in investigations of cases of infectious canine tracheobronchitis, particularly if these occur among dogs vaccinated with current vaccines, which do not include CRCoV antigens.     

No Serologic Evidence for Zoonotic Canine Respiratory Coronavirus Infections among Immunocompetent Adults

Zoonotic diseases continue to emerge and threaten both human and animal health. Overcrowded shelters and breeding kennels create the perfect environment for amplified infectious disease transmission among dogs and present a critical opportunity for zoonotic pathogens to emerge and infect people who work in close contact with dogs. Coronaviruses’ widespread prevalence, extensive host range, various disease manifestations and increased frequency of recombination events all underline their potential for interspecies transmission (Methods Mol. Biol. 2008, 454, 43). The objectives of this study were to determine whether people with occupational contact with dogs were more likely to have antibodies against canine respiratory coronavirus (CRCoV) compared to persons with no dog exposure. A seroepidemiological cohort study was completed, for which 302 canine‐exposed and 99 non‐canine‐exposed study subjects enrolled in the study by providing a serum sample and completing a self‐administered questionnaire. A competitive enzyme‐linked immunosorbent assay (ELISA) was developed to detect human antibodies against CRCoV while controlling for cross‐reacting antibodies against the human coronavirus OC43. All study subjects were negative for antibodies against CRCoV by this competitive ELISA. This study supports the premise that humans are not at risk for CRCoV infections; however, infrequent cross‐species transmission of CRCoV cannot be ruled out.     

High-cell-passage canine coronavirus vaccine providing sterilising immunity

OBJECTIVES: To evaluate the ability of a high-cell-passage canine coronavirus vaccine to immunise dogs against challenge with a field isolate of the virus. METHODS: Three dogs that had previously tested seronegative and virus-negative for canine coronavirus were inoculated twice, at 21-day intervals, with the vaccine and kept under observation. Two seronegative and virus-negative dogs served as unvaccinated controls. For safety tests, two additional dogs were inoculated oronasally with 10 times the vaccinal dose and no reactions were observed. Faecal samples were collected daily from the vaccinated dogs after the first and second inoculations. Both vaccinated and control dogs were challenged two weeks after the second vaccination with a field canine coronavirus strain. Blood samples were collected for serological tests before vaccination and at weekly intervals after vaccinations and challenge. RESULTS: Virus was not detected in faecal samples after the first or second vaccinations by virus isolation assays and PCR. Significantly, the vaccinated dogs did not have clinical signs after challenge and no virus shedding was observed. The two unvaccinated control dogs had moderate enteritis, and virus was detected in cell cultures starting from three days postchallenge (dog 1) and two days postchallenge (dog 2), and by PCR for 23 median days. CLINICAL SIGNIFICANCE: This study showed the efficacy of a high-cell-passage canine coronavirus vaccine in preventing infection of dogs by virulent virus and, specifically, its ability to induce sterilising immunity.     

Serum antibody responses to vaccinal antigens in lean and obese geriatric dogs

The immune responses in control dogs [1 to 4 years of age, body condition score (BCS): 4 to 5 out of 9] were compared to those of aging dogs (based on breed and body size) either categorized as lean (BCS: 4 to 5 out of 9) or obese (BCS: 8 to 9 out of 9). Of interest were the serum titers to the following common agents found in vaccines, canine parainfluenza virus (CPIV), canine parvovirus (CPV), canine distemper virus (CDV), canine respiratory coronavirus (CRCoV), and Bordetella bronchiseptica. There were no statistical differences in the antibodies to CPIV, B. bronchispetica, and CRCoV, among the age/weight categories, nor among the age/weight categories and the time, in days, between the date of sample collection and the date of the last recorded vaccination for CPIV, B. bronchiseptica, CPV, and CDV. For CPV, the control dogs had significantly (P < 0.002) higher serum neutralization (SN) titers than the lean geriatric dogs and the obese geriatric dogs. For CDV SN titers, the only statistically significant (P = 0.01) difference was that the control dogs had higher SN titers than the lean geriatric dogs.     

The infectivity and pathogenicity of a group 2 bovine coronavirus in pups

Canine respiratory coronavirus (CRCoV), which is more closely related to the bovine coronavirus (BCoV), has recently been detected in dogs. In this study, we examined whether BCoV was capable of infecting and exhibiting pathogenicity in dogs. Three 1-month-old pups were oronasally given field isolates of BCoV, and were kept together with 2 control animals. As a result, increases in BCoV-neutralizing antibody titers were confirmed in all pups in the challenged and control groups. Moreover, the virus gene was also detected in oral and rectal swabs by RT-PCR. These results indicate that BCoV infects dogs, and easily infects other dogs that are kept together. However, no clinical symptoms such as respiratory symptoms and diarrhea were observed.     

Detection of canine coronaviruses genotype I and II in raised Canidae animals in China

An RT-nPCR assay was used for testing fecal samples of dogs, foxes, raccoon dogs and minks for the presence of canine coronavirus (CCV). The animals were raised in homes, dog schools or farms. Seventy out of 81 healthy dog feces from three cities and 21 out of 48 diarrhea feces from pet dogs were positive for type II CCV. From a total of 61 healthy fox feces, 43 were positive for type II and 29 for type I CCV, out of which 25 were simultaneously positive for the two different genotypes. Among 24 raccoon dogs samples, 22 were CCV type II-positive, and from those 16 were additionally type I positive. No CCVs was detected from healthy mink feces. Sequence analysis found that ten type II CCVs fragments of M gene shared a high similarity with reference strain CCV 1-71 (96.5-99.5%), and four type I CCVs shared a high similarity (96.7%-98.1%) with a reported FCV-like CCV strain. The sequence of one particular M gene fragment was found to cluster between the type I and type II CCV branches in phylogenetic analysis, suggesting the existence of a novel strain. Our study confirmed that type II CCVs infection is very common in domestic dog, fox, and raccoon dog populations in China. This is also the first report on the co-existence of two CCV genotypes in healthy foxes and raccoon dogs.     

Quantification of mRNA encoding cytokines and chemokines and assessment of ciliary function in canine tracheal epithelium during infection with canine respiratory coronavirus (CRCoV)

One of the first lines of defence against viral infection is the innate immune response and the induction of antiviral type I interferons (IFNs). However some viruses, including the group 2 coronaviruses, have evolved mechanisms to overcome or circumvent the host antiviral response. Canine respiratory coronavirus (CRCoV) has previously been shown to have a widespread international presence and has been implicated in outbreaks of canine infectious respiratory disease (CIRD). This study aimed to quantify pro-inflammatory cytokine mRNAs following infection of canine air-interface tracheal cultures with CRCoV. Within this system, immunohistochemistry identified ciliated epithelial and goblet cells as positive for CRCoV, identical to naturally infected cases, thus the data obtained would be fully transferable to the situation in vivo. An assay of ciliary function was used to assess potential effects of CRCoV on the mucociliary system. CRCoV was shown to reduce the mRNA levels of the pro-inflammatory cytokines TNF-alpha and IL-6 and the chemokine IL-8 during the 72 h post-inoculation. The mechanism for this is unknown, however the suppression of a key antiviral strategy during a period of physiologic and immunological stress, such as on entry to a kennel, could potentially predispose a dog to further pathogenic challenge and the development of respiratory disease.     

Prevalence of canine enteric coronavirus in a cross-sectional survey of dogs presenting at veterinary practices

In order to determine the prevalence of canine enteric coronavirus (CECoV) in the general dog population, faecal samples were obtained in a cross-sectional study of 249 dogs presenting for any reason at veterinary practices randomly selected from across the UK. Demographic and clinical data was obtained for each of the samples, including signalment, number of dogs in the household, reason for visiting the practice, and any recent history of diarrhoea. The samples were tested by RT-PCR for the presence of both type I and type II CECoV. Seven samples were positive (three from dogs in the same household), a prevalence of 2.8% (95% confidence intervals 1.1–5.7). Phylogenetic analysis of partial M gene sequences revealed that all seven positive samples grouped with type I CECoV, the first report of this virus in the UK. None of the positive dogs presented for gastrointestinal disease. Interestingly five of the positive dogs from three separate households were aged over 6 years, suggesting that older dogs may play an important role in the persistence of CECoV in such populations.     

Factors associated with development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics

This study investigated the association between presence of respiratory pathogens and development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics. In total, 86 dogs were tested using a commercial PCR respiratory panel; 64 dogs were considered as cases and 22 were control dogs matched by veterinary clinic. No control animals (0/22) were positive for canine parainfluenza virus (CPIV), whereas 27/64 (42%) CIRDC cases were positive. Furthermore, 81% of case dogs tested positive for Mycoplasma cynos, compared with 73% of control dogs. Canine respiratory corona virus (CRCoV) was detected in no control dogs compared with 9.4% of clinical dogs. No animals were positive for any influenza virus type A present in the diagnostic panel. Presence of CPIV was associated (P < 0.01) with the occurrence of CIRDC after adjustment for demographic factors and presence of CRCoV (P = 0.09).     

重庆市2009-2010年动物狂犬病检测及流行病学调查

用RT-PCR方法检测重庆地区2009—2010年发生的36份临床疑似狂犬病脑组织样品和969份临床健康犬唾液拭子样品,并利用流行病学调查方法对阳性样品进行疫情溯源。结果从20份临床疑似狂犬病样品中检测出狂犬病毒,流行病学调查显示未免疫的流浪犬是主要的传染源,而农民(55.95%)和儿童(30.95%)是最容易受到狂犬攻击的人群。从969份临床健康犬唾液拭子和犬脑组织样品中未检出阳性样品。因此重庆地区狂犬病防控应加强对犬的免疫及流浪犬的管理,实行强制性疫苗免疫,加强对儿童和农民的狂犬病知识宣传和安全防护工作。     

The prevalence of a group 2 coronavirus in dogs in Japan

Canine coronavirus (CCoV) has been reported to cause acute diarrhea mainly in young pups. CCoV and feline coronavirus are classified as group 1 coronaviruses. However, it has recently been reported in the United Kingdom that the group 2 coronavirus gene, which is more closely related to the bovine coronavirus (BCoV) and human coronavirus strain OC43, has been detected in respiratory tract tissue samples from dogs with respiratory disease. In this study, we examined the prevalence of antibodies to group 2 coronaviruses in domestic dogs and cats in Japan by a neutralization test using BCoV. All 104 feline serum samples were negative (<1:5) for anti-BCoV antibodies. In contrast, of the 898 canine serum samples, 160 (17.8%) were positive for anti-BCoV antibodies, and the antibody titers ranged from 1:5 to more than 1:640, with 1:160 being the most frequent. No correlation was found between the titers of the anti-BCoV and anti-CCoV antibodies in the 198 serum samples of dogs with a known history of CCoV vaccination. We amplified, by RT-PCR, group 2 coronavirus-specific hemagglutination/esterase genes in the oral swabs of a total of 10 young pups presenting with or having recovered from respiratory signs, or having anti-BCoV antibodies, with the result that 2 pups were positive for the hemagglutination/esterase genes. These results strongly suggest that an unknown group 2 coronavirus as well as the known enteritis-causing CCoV (group 1 coronavirus) is prevalent among domestic dogs in Japan.     

Research Progress of Canine Coronavirus and Feline Coronavirus

Canine coronavirus (CCoV) and feline coronavirus (FCoV) belong to α-genus coronavirus of coronavirus family,porcine transmissible gastroenteritis virus (TGEV),porcine epidemic diarrhea virus (PEDV) also belong to the same genus.Genetic evolution analysis showed that different genotype of the virus could produce new variant strains through gene recombination,which caused great obstacles to the diagnosis and control of the disease.β-genus coronaviruses include bovine coronavirus (BCoV),canine respiratory coronavirus (CRCoV) and severe acute respiratory syndrome coronavirus (SARS-CoV).Among them,CRCoV has the highest homology with BCoV,but there are great differences in genomic structure,pathogenic mechanism and infection symptoms between this kind of coronavirus and α-coronavirus.CCoV and FCoV are widely spreading around the world,characterized by high morbidity and low mortality.Due to the characteristics of RNA virus and the influence of environmental selection pressure,the viruses continue to mutate and evolve,and new virulent strains appear one after another.The virulence of feline infectious peritonitis virus (FIPV) is greatly enhanced,some specific point mutations in the virus genome change the cellular tropism against the host.The pathogenesis of the virus mainly depends on the antibody-dependent enhancement (ADE) induced by virus infection.The epidemiological investigation and prevention and control of CCoV and FCoV should not only rely on the single factor of vaccine immunity,but also comprehensively consider the virulence of the virus,environmental conditions,pet self-immune resistance, and so on.The identification of CCoV and FCoV should be based on clinical symptoms,combined with routine hematological examination,serum biochemical examination and laboratory diagnosis techniques to prevent false positive and false negative results.     

犬猫冠状病毒研究进展

犬冠状病毒（canine coronavirus,CCoV）与猫冠状病毒（feline coronavirus,FCoV）同属于冠状病毒科冠状病毒属α属,与其同属的病毒还有猪传染性胃肠炎病毒（porcine transmissible gastroenteritis virus,TGEV）、猪流行性腹泻病毒（porcine epidemic diarrhea virus,PEDV）等。遗传进化分析表明,该种属不同基因型病毒通过基因重组能产生新型变异毒株,为疾病的诊断与防控造成了很大的阻碍。β属冠状病毒包括牛冠状病毒（bovine coronavirus,BCoV）、犬呼吸道冠状病毒（canine respiratory coronavirus,CRCoV）、严重急性呼吸综合征冠状病毒（severe acute respiratory syndrome coronavirus,SARS-CoV）等,其中CRCoV与BCoV同源性较高,该类病毒与α属冠状病毒在基因组结构、致病机制、感染症状等方面差异较大。CCoV与FCoV在全球范围内广泛传播,具有发病率高、死亡率低的特点。由于RNA病毒本身的特点和环境选择压力的影响,这两种病毒不断变异进化,新的强致病力毒株相继出现。经FCoV基因突变演化而来的猫传染性腹膜炎病毒（feline infectious peritonitis virus,FIPV）毒力大大增强,病毒基因组中某些特异性的点突变使得针对宿主的细胞嗜性发生改变,该病毒的致病机制主要依赖于病毒感染后诱导机体产生的抗体依赖性增强作用（ADE）。针对犬猫冠状病毒的流行病学调查及防控不能仅依赖于疫苗免疫单一因素,还应综合考虑病毒毒力、环境条件、宠物自身免疫抵抗力状态等。针对犬猫冠状病毒的诊断应根据临床症状,结合常规血液学检查、血清生化检查和实验室诊断技术来进行全面的鉴定,防止出现假阳性及假阴性结果。