Canine Parainfluenza Virus Research Articles

Establishment of reverse transcription loop-mediated isothermal amplification for rapid detection and differentiation of canine distemper virus infected and vaccinated animals

Although widespread vaccination against canine distemper virus (CDV) has been conducted for many decades, several canine distemper outbreaks in vaccinated animals have been reported frequently. In order to detect and differentiate the wild-type and vaccine strains of the CDV from the vaccinated animals, a novel reverse transcription loop-mediated isothermal amplification (RT-LAMP) method was developed. A set of four primers—two internal and two external—were designed to target the H gene for the specific detection of wild-type CDV variants. The CDV-H RT-LAMP assay rapidly amplified the target gene, within 60min, using a water bath held at a constant temperature of 65°C. The assay was 100-fold more sensitive than conventional RT-PCR, with a detection limit of 10−1TCID50ml−1. The system showed a preference for wild-type CDV, and exhibited less sensitivity to canine parvovirus, canine adenovirus type 1 and type 2, canine coronavirus, and canine parainfluenza virus. The assay was validated using 102 clinical samples obtained from vaccinated dog farms, and the results were comparable to a multiplex nested RT-PCR assay. The specific CDV-H RT-LAMP assay provides a simple, rapid, and sensitive tool for the detection of canines infected with wild-type CDV from canines vaccinated with attenuated vaccine.

Co-infections with respiratory viruses in dogs with bacterial pneumonia.

BackgroundBacterial pneumonia (BP) is an inflammation of the lower airways and lung parenchyma secondary to bacterial infection. The pathogenesis of BP in dogs is complex and the role of canine respiratory viruses has not been fully evaluated.ObjectivesThe aim of this study was to investigate the occurrence of viral co‐infections in dogs with BP and to assess demographic or clinical variables as well as disease severity associated with viral co‐infections.AnimalsTwenty household dogs with BP caused by opportunistic bacteria and 13 dogs with chronic (>30 days) tracheobronchitis caused by Bordetella bronchiseptica (BBTB).MethodsProspective cross‐sectional observational study. Diagnosis was confirmed by clinical and laboratory findings, diagnostic imaging, and cytologic and microbiologic analysis of bronchoalveolar lavage or transtracheal wash fluid. Canine parainfluenza virus (CPIV), canine adenovirus, canine herpes virus, canine influenzavirus, canine distemper virus, canine respiratory coronavirus (CRCoV) and canine pneumovirus, as well as B. bronchiseptica and Mycoplasma spp. were analyzed in respiratory samples using PCR assays.Results CPIV was detected in 7/20 and CRCoV in 1/20 dogs with BP. Respiratory viruses were not detected in dogs with BBTB. There were no significant differences in clinical variables between BP dogs with and without a viral co‐infection.Conclusion and Clinical ImportanceRespiratory viruses were found frequently in dogs with BP and may therefore play an important role in the etiology and pathogenesis of BP. Clinical variables and disease severity did not differ between BP dogs with and without viral co‐infection.

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

BackgroundCanine distemper virus (CDV) has been associated with outbreaks of canine infectious respiratory disease in shelters and boarding kennel environments. POCKITTM 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.ResultsAnalytical 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.ConclusionsThe 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.

Detection of respiratory viruses and Bordetella bronchiseptica in dogs with acute respiratory tract infections

Canine infectious respiratory disease (CIRD) is an acute, highly contagious disease complex caused by a variety of infectious agents. At present, the role of viral and bacterial components as primary or secondary pathogens in CIRD is not fully understood. The aim of this study was to investigate the prevalence of canine parainfluenza virus (CPIV), canine adenovirus type 2 (CAV-2), canine influenza virus (CIV), canine respiratory coronavirus (CRCoV), canine herpes virus-1 (CHV-1), canine distemper virus (CDV) and Bordetella bronchiseptica in dogs with CIRD and to compare the data with findings in healthy dogs. Sixty-one dogs with CIRD and 90 clinically healthy dogs from Southern Germany were prospectively enrolled in this study. Nasal and pharyngeal swabs were collected from all dogs and were analysed for CPIV, CAV-2, CIV, CRCoV, CHV-1, CDV, and B. bronchiseptica by real-time PCR.In dogs with acute respiratory signs, 37.7% tested positive for CPIV, 9.8% for CRCoV and 78.7% for B. bronchiseptica. Co-infections with more than one agent were detected in 47.9% of B. bronchiseptica-positive, 82.6% of CPIV-positive, and 100% of CRCoV-positive dogs. In clinically healthy dogs, 1.1% tested positive for CAV-2, 7.8% for CPIV and 45.6% for B. bronchiseptica. CPIV and B. bronchiseptica were detected significantly more often in dogs with CIRD than in clinically healthy dogs (P < 0.001 for each pathogen) and were the most common infectious agents in dogs with CIRD in Southern Germany. Mixed infections with several pathogens were common. In conclusion, clinically healthy dogs can carry respiratory pathogens and could act as sources of infection for susceptible dogs.

Evaluating a Parainfluenza Virus 5-Based Vaccine in a Host with Pre-Existing Immunity against Parainfluenza Virus 5

Parainfluenza virus 5 (PIV5), formerly known as simian virus 5 (SV5), is a paramyxovirus often referred to as canine parainfluenza virus (CPI) in the veterinary field. PIV5 is thought to be a contributing factor to kennel cough. Kennel cough vaccines containing live PIV5 have been used in dogs for many decades. PIV5 is not known to cause any diseases in humans or other animals. PIV5 has been used as a vector for vaccine development for humans and animals. One critical question concerning the use of PIV5 as a vector is whether prior exposure to PIV5 would prevent the use of PIV5-based vaccines. In this work, we have examined immunogenicity of a recombinant PIV5 expressing hemagglutinin (HA) of influenza A virus subtype 3 (rPIV5-H3) in dogs that were immunized against PIV5. We found that vaccination of the dogs containing neutralizing antibodies against PIV5 with rPIV5-H3 generated immunity against influenza A virus, indicting that PIV5-based vaccine is immunogenic in dogs with prior exposure. Furthermore, we have examined exposure of PIV5 in human populations. We have detected neutralizing antibody (nAb) against PIV5 in 13 out of 45 human serum samples (about 29 percent). The nAb titers in humans were lower than that in vaccinated dogs, suggesting that nAb in humans is unlikely to prevent PIV5 from being an efficacious vector in humans.

Duration of serological response to canine parvovirus‐type 2, canine distemper virus, canine adenovirus type 1 and canine parainfluenza virus in client‐owned dogs inAustralia

To determine whether client-owned dogs in Australia, last vaccinated with Canvac(®) vaccines containing canine parvovirus-type 2 (CPV-2), canine distemper virus (CDV), canine adenovirus type 2 (CAV-2) ± canine parainfluenza virus (CPiV) at least 18 months ago, were seropositive or responded serologically to revaccination. A total of 235 dogs were recruited from 23 veterinary clinics, representing a variety of breeds, ages and time since last vaccination (TSLV: range 1.5-9 years, mean 2.8 years). Dogs had a blood sample taken and were revaccinated on day 0. A second blood sample was taken 7-14 days later. Blood samples were assessed for antibody titres to CPV-2 (by haemagglutination inhibition) and CDV, CAV type 1 (CAV-1) and CPiV (by virus neutralisation). Dogs with a day 0 titre >10 or a four-fold increase in titre following revaccination were considered to be serological responders. The overall percentage of dogs classified as serological responders was 98.7% for CPV-2, 96.6% for CDV, 99.6% for CAV-1 and 90.3% for CPiV. These results suggest that the duration of serological response induced by modified-live vaccines against CPV-2, CDV, CAV-1 and CPiV, including Canvac(®) vaccines, is beyond 18 months and may extend up to 9 years. Accordingly, these vaccines may be considered for use in extended revaccination interval protocols as recommended by current canine vaccine guidelines.

Pathogens of Wild Maned Wolves (Chrysocyon brachyurus) in Brazil

The maned wolf, Chrysocyon brachyurus, is an endangered Neotropical canid that survives at low population densities. Diseases are a potential threat for its conservation but to date have been poorly studied. We performed clinical evaluations and investigated the presence of infectious diseases through serology and coprologic tests on maned wolves from Galheiro Natural Private Reserve, Perdizes City, Minas Gerais State, southeastern Brazil. Fifteen wolves were captured between 2003 and 2008. We found high prevalences of antibody to canine distemper virus (CDV; 13/14), canine parvovirus (CPV; 4/14), canine adenovirus type 2 (13/14), canine coronavirus (5/11), canine parainfluenza virus (5/5), and Toxoplasma gondii (6/8), along with Ancylostomidae eggs in all feces samples. Antibodies against Leishmania sp. were found in one of 10 maned wolves, and all samples were negative for Neospora caninum. Evidence of high exposure to these viral agents was also observed in unvaccinated domestic dogs from neighboring farms. High prevalence of viral agents and parasites such as CDV, CPV, and Ancylostomidae indicates that this population faces considerable risk of outbreaks and chronic debilitating parasites. This is the first report of exposure to canine parainfluenza virus in Neotropical free-ranging wild canids. Our findings highlight that canine pathogens pose a serious hazard to the viability of maned wolves and other wild carnivore populations in the area and emphasize the need for monitoring and protecting wildlife health in remaining fragments of the Cerrado biome.

A review of canine parainfluenza virus infection in dogs

A review of canine parainfluenza virus infection in dogs

Pharmacovigilance in veterinary medicine in Chile: a pilot study

Iragüen, D., Urcelay, S., San Martín, B. Pharmacovigilance in veterinary medicine in Chile: a pilot study. J. vet. Pharmacol. Therap.34, 108-115. In Chile, there is no present government policy to survey and analyse adverse drug reactions (ADRs) in the field of veterinary medicine. The intent of this study is to assess, for the first time, ADR frequency in treated animals. To this purpose, a 6-month period pilot study based on WHO recommendations was conducted to monitor ADRs in cats and dogs for frequently used drugs and common labelled signs. Of a total of 149 detected ADRs, 29 (6 in cats and 23 in dogs) were notified by means of ADR report forms, while the rest was identified after reviewing patient clinical records, thus evidencing strong under-reporting problems. More than 70% of ADRs were related to antimicrobials, vaccines and tranquilizers. In dogs, there was a significant effect on ADRs' presentation when acepromazine, amoxicillin, carprofen, ivermectin, sextuple vaccine (polyvalent vaccine that confers immunity against canine distemper virus, canine parvovirus, Leptospira canicola, L.icterohemmoragiae, canine adenovirus type 2 and canine parainfluenza virus) and phytomenadione (subcutaneous injection) were administered. In the case of cats, a significant influence on ADRs was detected when acepromazine, amoxicillin or vitamin K was administered. Present results suggest the need for a pharmacovigilance programme in veterinary medicine for timely ADR-presenting drug detection and drug safety improvement.

Prevalence of respiratory viruses isolated from dogs in Thailand during 2008-2009

Abstract Background: A highly contagious respiratory disease in canines is infectious tracheobronchitis or kennel cough characterized by inflammation of the upper respiratory tract. The cause of kennel cough has been associated with multiple or complex agents such as canine adeno virus (CAV), canine influenza virus (CIV), canine distemper virus (CDV), and canine para influenzavirus (CPIV). Objective: Study the prevalence of canine respiratory viruses detected from in Thailand during 2008-2009. Methods: Nasal swab samples collected from 102 healthy dogs and 109 dogs with respiratory diseases. Then CAV, CIV, CDV, and CPIV were detected by in-house nested PCR and further confirmed by nucleotide sequencing. Results: Nested PCR showed that primers designed and used in this study yielded high specificity without any non-specific amplification. The prevalence of CAV, CIV, CDV and CPIV in healthy dogs was 0%, 2.94%, 2.94%, and 0.98%, whereas that found in dogs with respiratory diseases was 9.17%, 1.83%, 2.75%, and 11.93%, respectively. In healthy dogs, co-infection with CPIV + CDV was detected in only 0.98%. On the other hand, dogs with respiratory symptoms showed multiple infections with CAV + CIV in 1.83%, CIV + CPIV in 0.92%, CAV + CPIV in 1.83%, and CAV + CDV + CPIV in 0.92%. Conclusion: The prevalence data obtained from this study may be useful for outbreak preventions and to raise awareness of potential transmission of the newly emerged canine influenza virus to humans.

Simultaneous analysis of the nasal shedding kinetics of field and vaccine strains of Bordetella bronchiseptica

Groups of four two-week-old puppies were administered serial dilutions of an intranasal vaccine containing live Bordetella bronchiseptica and canine parainfluenza virus vaccine and housed individually in isolator cages. Three vaccinated...

Expression of β-defensins in the canine respiratory tract and antimicrobial activity against Bordetella bronchiseptica

β-Defensins are cationic peptides which form part of the innate immune response of the respiratory epithelium. Due to their antimicrobial properties and immunostimulatory activity, β-defensins are potential tools for the treatment and prevention of respiratory disease. In dogs, infectious respiratory disease is a common problem, particularly in housed animals. This study aimed to assess the presence of four β-defensins in the canine respiratory tract and to use quantitative real-time PCR to determine mRNA levels following microbial challenge. Three β-defensins, CBD1, CBD103 and CBD108, were detected in respiratory cells. All three defensins were also readily expressed in skin samples, while their expression in lymphoid tissues and the kidney was low and inconsistent. Treatment of primary tracheal epithelial cells with lipopolysaccharide (LPS) or infection with canine respiratory coronavirus led to decreased expression of CBD103 and CBD108, while cells infected with canine parainfluenza virus had lower levels of CBD1 and CBD108. Furthermore CBD103 was demonstrated to have antimicrobial activity against the respiratory pathogen Bordetella bronchiseptica.

Serosurvey of selected viruses in captive giant pandas (Ailuropoda melanoleuca) in China

Serum samples from 92 giant pandas in three captive facilities were tested for antibodies against five viruses of carnivores. Antibody titers against canine distemper virus (CDV) in two facilities in which giant pandas were vaccinated were variable. The canine adenovirus (CAV-1) and canine parvovirus (CPV) titers in vaccinated group were both positive, but titers were not high and varied among individual except one vaccinated panda had extremely high CAV-1 titer, indicating infection with the field virus following vaccination. Our results suggest that the vaccines used for these giant pandas do not elicit consistent antibody titers. Antibody titers against CDV, CPV and CAV-1 in unvaccinated giant pandas were highly variable, especially CPV titer. Almost half of sera were CPV antibody positive, and CPV titers were high enough to suggest infection with the virus. Canine coronavirus (CCV) and canine parainfluenza virus (CPIV) titers were not detected in all serum samples. The results of this study emphasize the need for research on infectious diseases of giant pandas and development of suitable vaccines for the species.

Antigenic detection of Canine Parainfluenza virus in urban dogs with respiratory disease in Ahvaz area, southwestern Iran

Canine parainfluenza virus (CPiV) is one of the most common organisms isolated from dogs with signs of infectious tracheobronchitis (ITB). Distribution is apparently worldwide. Although CPiV may cause mild clinical infections, clinical diseases is expected to be more severe in dogs co-infected with bordetella bronchiseptica than with any these agents alone. The present study was conducted to determine the prevalence of Canine parainfluenza virus infection in urban dogs of Ahvaz area, southwestern Iran. The urban dogs were selected between referred dogs (companion) to Veterinary Hospital of Ahvaz University. Sample of respiratory secretions was collected randomly from 76 affected dogs between June 2008 and May 2009. The studied dogs were divided into two age groups (6 months) and based of environment into two groups (close and open) also. The results were analyzed by using Chi-square analysis and Fischer's exact test. Prevalence to Canine parainfluenza virus antigens was 5.3% (4 of 76) by means of immunochromatography indicating that this antigen is present in the ecosystem. The infection had more prevalence in those dogs that were in open environment (17.65%; 3 of 17) in compared with close environment (1.69%; 1 of 59) and the difference was significant between different groups (P= 0.033). Prevalence was more in dogs less than 6 months (6.82%; 3 of 44) in compared with dogs above 6 months (3.12%; 1 of 32), but the difference was not significant between two groups (P= 0.436). Prevalence of infection was 4.44% (2 of 45) in male dogs and 6.45% (2 of 31) in female dogs. Prevalence was 6.06% (2 of 33) in Mixed breed, 5.55% (1 of 18) in Germanshepherds and 11.11% (1 0f 9) in Doberman pinchers. There was no significant difference between different sexes and breeds also (P>0.05). This study showed that Canine parainfluenza virus can be as a risk factor particularly for those dogs are in contact together in open environment and kennel dogs in Ahvaz area.

SEROLOGIC SURVEY FOR SELECTED VIRAL PATHOGENS IN FREE-RANGING ENDANGERED EUROPEAN MINK (MUSTELA LUTREOLA) AND OTHER MUSTELIDS FROM SOUTH-WESTERN FRANCE

To investigate the possible role of selected pathogens in the decline of endangered European mink (Mustela lutreola) populations and the potential for these pathogens to affect mink survival, a serologic survey was conducted using serum samples collected from March 1996 to March 2003 in eight departments of south-western France. In total, 481 free-ranging individuals of five mustelid species (including the European mink) were tested. Sympatric mustelids can serve as sentinels to determine the presence of antibodies to viruses in the study area that could potentially infect mink. Antibodies to Canine distemper virus (CDV) were detected in all species; 9% of 127 European mink, 20% of 210 polecats (Mustela putorius), 5% of 112 American mink (Mustela vison), 33% of 21 stone marten (Martes foina) and 5% of 20 pine marten (Martes martes). Antibody prevalence was significantly higher in stone marten and polecats, possibly because their ranges overlap more closely with that of domestic species than that of the other species tested. Antibodies to Canine adenovirus were detected in all species but the pine marten; antibody prevalence estimates ranging from 2% to 10%. Antibodies to canine parainfluenza virus were detected in 1% of European mink, 1% of American mink and 5% of tested polecats but were not detected in Martes species. Antibodies to Rabies virus (RV) were detected in three animals, possibly because of interspecies transmission of bat lyssaviruses as the sampling area is considered to be free of RV, or to a lack of test specificity, as antibody titers were low. The high antibody prevalence to potentially lethal CDV suggests that this pathogen could have significant effects on the free-ranging populations and has implications for the conservation efforts for the endangered European mink.

A Hyperfusogenic F Protein Enhances the Oncolytic Potency of a Paramyxovirus Simian Virus 5 P/V Mutant without Compromising Sensitivity to Type I Interferon

Viral fusogenic membrane proteins have been proposed as tools to increase the potency of oncolytic viruses, but there is a need for mechanisms to control the spread of fusogenic viruses in normal versus tumor cells. We have previously shown that a mutant of the paramyxovirus simian virus 5 (SV5) that harbors mutations in the P/V gene from the canine parainfluenza virus (P/V-CPI(-)) is a potent inducer of type I interferon (IFN) and apoptosis and is restricted for spread through normal but not tumor cells in vitro. Here, we have used the cytopathic P/V-CPI(-) as a backbone vector to test the hypothesis that a virus expressing a hyperfusogenic glycoprotein will be a more effective oncolytic vector but will retain sensitivity to IFN. A P/V mutant virus expressing an F protein with a glycine-to-alanine substitution in the fusion peptide (P/V-CPI(-)-G3A) was more fusogenic than the parental P/V-CPI(-) mutant. In two model prostate tumor cell lines which are defective in IFN production (LNCaP and DU145), the hyperfusogenic P/V-CPI(-)-G3A mutant had normal growth properties at low multiplicities of infection and was more effective than the parental P/V-CPI(-) mutant at cell killing in vitro. However, in PC3 cells which produce and respond to IFN, the hyperfusogenic P/V-CPI(-)-G3A mutant was attenuated for growth and spread. Killing of PC3 cells was equivalent between the parental P/V-CPI(-) mutant and the hyperfusogenic P/V-CPI(-)-G3A mutant. In a nude mouse model using LNCaP cells, the hyperfusogenic P/V-CPI(-)-G3A mutant was more effective than P/V-CPI(-) at reducing tumor burden. In the case of DU145 tumors, the two vectors based on P/V-CPI(-) were equally effective at limiting tumor growth. Together, our results provide proof of principle that a cytopathic SV5 P/V mutant can serve as an oncolytic virus and that the oncolytic effectiveness of P/V mutants can be enhanced by a fusogenic membrane protein without compromising sensitivity to IFN. The potential advantages of SV5-based oncolytic vectors are discussed.

Etiologic Study on Upper Respiratory Infections of Household Dogs

Infectious tracheobronchitis (ITB), also known as the kennel cough, is a respiratory syndrome of dogs and usually appears to be contagious among dogs housed in groups. Etiologic agent of ITB is multiple and sometimes complex. In the present study, 68 household dogs showing clinical signs of respiratory infection were examined, and 20 dogs (29.4%) were found to be positive for either of following agents. Bordetella bronchiseptica (B.b.) was most frequently detected from nasal and oropharynx sites of 7 dogs (10.3%). Among the viruses examined, canine parainfluenza virus (CPIV) was detected with the highest frequency (7.4%). Other pathogens included in the order of frequency group 1 canine coronavirus (4.4%), canine adenovirus type 2 (2.9%), group 2 canine respiratory coronavirus (1.5%), and canine distemper virus (1.5%). Only 2 cases showed mixed infections. Neither influenza A virus nor canine bocavirus (minute virus of canines) was found in any dogs examined. These results indicate that both B.b. and CPIV are likely to be the principal etiologic agents of canine ITB in Japan, and they may be considered as the target for prophylaxis by vaccination.

SEROSURVEY OF EX SITU GIANT PANDAS (AILUROPODA MELANOLEUCA) AND RED PANDAS (AILURUS FULGENS) IN CHINA WITH IMPLICATIONS FOR SPECIES CONSERVATION

Conservation strategies for the giant panda (Ailuropoda melanoleuca) include the development of a self-sustaining ex situ population. This study examined the potential significance of infectious pathogens in giant pandas ex situ. Serologic antibody titers against canine distemper virus (CDV), canine parvovirus (CPV), canine adenovirus (CAV), canine coronavirus (CCV), canine herpesvirus, canine parainfluenza virus (CPIV), Toxoplasma gondii, Neospora caninum, and Leptospira interrogans were measured in 44 samples taken from 19 giant pandas between 1998 and 2003 at the Chengdu Research Base of Giant Panda Breeding in Sichuan, China. Seroassays also included samples obtained in 2003 from eight red pandas (Ailurus fulgens) housed at the same institution. All individuals had been vaccinated with a Chinese canine vaccine that included modified live CDV, CPV, CAV, CCV, and CPIV. Positive antibody titers were found only against CDV, CPV, and T. gondii. Sera were negative for antibodies against the other six pathogens. Results indicate that the quality of the vaccine may not be reliable and that it should not be considered protective or safe in giant pandas and red pandas. Positive antibody titers against T. gondii were found in seven of the 19 giant pandas. The clinical, subclinical, or epidemiologic significance of infection with these pathogens via natural exposure or from modified live vaccines in giant pandas is unknown. Research in this area is imperative to sustaining a viable population of giant pandas and other endangered species.

Anticorpos neutralizantes contra os vírus da cinomose e da parainfluenza em cães de canis dos municípios de Novo Hamburgo e Porto Alegre, RS, Brasil

No presente estudo, foi realizada uma pesquisa em busca de anticorpos neutralizantes contra os vírus da cinomose (CDV) e da parainfluenza (CPIV) caninos em amostras de soro de 173 cães recolhidos a canis municipais em Novo Hamburgo (n=82) e Porto Alegre (n=91), RS. A pesquisa de anticorpos neutralizantes foi realizada pela técnica de soroneutralização frente a duas amostras vacinais de CDV (Rockborn e Snyder Hill) e frente a uma amostra de CPIV (V660). Em relação ao CDV, 95,9% das amostras de soros foram negativas para anticorpos neutralizantes contra a amostra Snyder Hill e 90,7% soronegativas para a amostra Rockborn. Entre os soropositivos (n=20; 11,6%), somente três deles apresentaram anticorpos neutralizantes frente às duas amostras de CDV testadas, indicando pouca reatividade cruzada entre as mesmas. Quanto ao CPIV, a prevalência de anticorpos neutralizantes encontrada frente à amostra V660 foi de 51,4%. Esses achados indicam que a maioria dos cães examinados não teve contato prévio com o CDV, seja por infecção natural ou por imunização prévia. O CPIV, porém, parece estar amplamente difundido na população canina examinada, provavelmente por exposição natural ao vírus.

Canine respiratory viruses

Acute contagious respiratory disease (kennel cough) is commonly described in dogs worldwide. The disease appears to be multifactorial and a number of viral and bacterial pathogens have been reported as potential aetiological agents, including canine parainfluenza virus, canine adenovirus and Bordetella bronchiseptica, as well as mycoplasmas, Streptococcus equi subsp. zooepidemicus, canine herpesvirus and reovirus-1,-2 and -3. Enhancement of pathogenicity by multiple infections can result in more severe clinical forms. In addition, acute respiratory diseases associated with infection by influenza A virus, and group I and II coronaviruses, have been described recently in dogs. Host species shifts and tropism changes are likely responsible for the onset of these new pathogens. The importance of the viral agents in the kennel cough complex is discussed.