Naturally Acquired Canine Herpesvirus-Associated Meningoencephalitis.

Canid alphaherpesvirus 1 (CHV) causes morbidity and mortality in susceptible puppies. While the neuropathology of experimentally infected puppies has been detailed, characterization of naturally acquired infections is limited. The aim of this study was to describe the histologic, immunohistochemical, and in situ hybridization features of CHV encephalitis in the dog. Six female and 11 male puppies ranging in age from stillborn to 57 days old were included. Histologically, lesions included multifocal glial nodules (16/17, 94%), meningeal infiltrates (15/17, 88%), and cerebellar cortical necrosis (6/9, 67%); however, robust inflammation was not a significant feature in any of the cases. Immunohistochemistry for CD3, CD20, MAC387, and Iba1 was performed. Although T cells predominated over B cells, the overall number of cells was small in all cases both within the glial nodules and the meninges. In 16 of 16 (100%) cases, glial nodules were diffusely immunoreactive for Iba1; however, limited or no immunoreactivity for MAC387 was present. In situ hybridization directed at the CHV thymidine kinase gene revealed CHV nucleic acid in the granule neurons of the cerebellar folia (8/9; 89%), endothelial cells in the meninges and parenchyma (12/17, 71%), and individual randomly distributed neurons (6/17, 35%). These results clarify the pathology of naturally acquired CHV infection and indicate that developing cerebellar granule neurons are an important site of viral replication.

Fatal Canid Herpesvirus 1 Respiratory Infections in 4 Clinically Healthy Adult Dogs.

Four healthy adult dogs (Golden Retrievers aged 6 years and 9 years, Dalmatian aged 13 years, and Mastiff aged 5 years) developed clinical signs of acute respiratory disease and died within 2 to 7 days of onset of clinical signs. The lungs of the 3 dogs submitted for necropsy were diffusely and severely reddened due to hyperemia and hemorrhage. Microscopic lesions in all dogs were suggestive of acute viral or toxic respiratory damage and varied from acute severe fibrinonecrotic or hemorrhagic bronchopneumonia to fibrinous or necrotizing bronchointerstitial pneumonia. Necropsied dogs also had hemorrhagic rhinitis and tracheitis with necrosis. Virus isolation, transmission electron microscopy, and polymerase chain reaction were used to confirm the presence of canid herpesvirus 1 (CaHV-1) in the lung samples of these dogs. Lung tissues were negative for influenza A virus, canine distemper virus, canine parainfluenza virus, canine respiratory coronavirus, and canine adenovirus 2. Canid herpesvirus 1 has been isolated from cases of acute infectious respiratory disease in dogs but has only rarely been associated with fatal primary viral pneumonia in adult dogs. The cases in the current report document lesions observed in association with CaHV-1 in 4 cases of fatal canine herpesvirus pneumonia in adult dogs.

Seroprevalence of canid alphaherpesvirus-1 and associated risk factors in domestic dogs in North Queensland, Australia.

Canid alphaherpesvirus-1 (CaHV-1) may cause a highly fatal haemorrhagic disease in neonatal pups and is associated with reproductive, respiratory and ocular disease in older dogs. Although assumed to have a world-wide distribution, there have been few reports of CaHV-1 in Australia. The aim of this study was to investigate the seroprevalence of CaHV-1 in household dogs in a residential suburb in Townsville, as well as in dogs attending two dog shows in the region. Study participants were recruited through door-to-door non-probability sampling (Douglas dogs, n = 185) or invited to participate (Show dogs; n = 76). Dog owners completed a questionnaire that investigated possible risk factors for recent exposure to CaHV-1. A serum sample from each dog was assayed for anti-CaHV-1 antibodies using a commercially available ELISA. Associations between seropositive dogs and owner-reported risk factors were analysed using univariable analysis and multivariable logistic regression models. The seroprevalence of CaHV-1 was 11.4 % (95 % CI 6.8-15.9 %) and 17.1 % (95 % CI 5.5-28.8) for the Douglas and Show dogs, respectively, with a pooled seroprevalence of 13 % (95 % CI 8.3-17.7 %). Dogs that had suffered from conjunctivitis within the previous 3 months or were involved in breeding were more likely to be seropositive to CaHV-1. No other significant risk factors were identified. In conclusion, CaHV-1 is circulating in dogs in North Queensland and may be contributing to foetal and neonatal losses in this region.

Metaherpetic corneal disease in a dog associated with partial limbal stem cell deficiency and neurotrophic keratitis.

OBJECTIVE: To describe clinical, in vivo confocal microscopic, histopathologic, and immunohistochemical features of a dog with metaherpetic corneal disease that developed subsequent to a protracted episode of canine herpesvirus-1 (CHV-1) dendritic ulcerative keratitis. CASE DESCRIPTION: A 7-year-old, spayed-female, Miniature Schnauzer was treated for bilateral CHV-1 dendritic ulcerative keratitis. Following resolution of ulcerative keratitis, sectoral peripheral superficial corneal gray opacification, vascularization, and pigmentation slowly migrated centripetally to the axial cornea of both eyes. Corneal sensitivity measured with a Cochet-Bonnet esthesiometer was dramatically and persistently reduced. In vivo corneal confocal microscopic examination revealed regions of epithelium with a conjunctival phenotype. In these areas, the surface epithelium was thin, disorganized, and composed of hyper-reflective epithelial cells. Goblet cells and Langerhans cells were frequent, and the subbasal nerve plexus was completely absent or markedly diminished. Histopathologic abnormalities in the globes were restricted to the superficial cornea and included sectoral corneal conjunctivalization, increased anterior stromal spindle cells, and vascularization. Immunohistochemical evaluation of the corneas with anti-neurotublin antibody demonstrated attenuation of the epithelial and subbasal nerve plexuses with marked stromal hyperinnervation and increased numbers of morphologically abnormal neurites. CONCLUSIONS: Similar to herpes simplex virus keratitis in humans, CHV-1 ulcerative keratitis may be associated with the development of chronic degenerative corneal disease in dogs. In the described dog, this chronic corneal disease included progressive corneal opacification because of partial limbal stem cell deficiency and neurotrophic keratitis. Long-term monitoring of dogs following resolution of active CHV-1 keratitis may be indicated, particularly when ulcerations persist for an extended period.

Canine herpesvirus during pregnancy and non-pregnant luteal phase.

Canine herpesvirus (CHV) is a widespread infection among dogs that typically get latently infected after exposure and can reactivate the infection after stress. The aim of the present study was to study the effects of latent CHV infection during pregnancy on pregnancy outcome, and to study if there are signs of genital viral reactivation during pregnancy or during non-pregnant luteal phase. Twelve mated bitches and eight control bitches were followed and sampled regularly during pregnancy or non-pregnant luteal phase. Blood samples were taken for antibody analysis and vaginal swabs for real-time PCR analysis. Three of the pregnant bitches were vaccinated against CHV during pregnancy. All bitches had antibodies to CHV. Two pregnant bitches that were not vaccinated had a twofold or larger increase in CHV titre, with no negative effects detected on pregnancy. Higher titres were not associated with smaller litters or with vaccination. There was no consistent variation in antibody titres due to pregnancy or non-pregnant luteal phase. Vaginal excretion of CHV was not detected from any of the bitches.

Acute primary canine herpesvirus-1 dendritic ulcerative keratitis in an adult dog.

We present a report of dendritic ulcerative keratitis in a 4-year old locally immunosuppressed dog suspected to result from acute primary canine herpesvirus-1 (CHV-1) infection. The dog was presented for evaluation of mild blepharospasm and conjunctival hyperemia in the right eye (OD) shortly after attending a public boarding facility. For approximately 3 months, the dog had been receiving topical prednisolone acetate 1.0% and tacrolimus 0.02% in both eyes (OU) q12h for treatment of follicular conjunctivitis. Ophthalmic examination revealed three regions of corneal fluorescein retention OD. The lesions had a dendritic pattern, were approximately 2-3 mm in length, and were located at the dorsomedial, lateral, and ventromedial aspects of the cornea. No additional abnormalities were noted on complete ophthalmic and physical examinations. CHV-1 was identified in conjunctival samples OD by polymerase chain reaction, and paired CHV-1 serum virus neutralization antibody titers were positive and consistent with acute infection. Topical prednisolone acetate and tacrolimus were discontinued. The dog was treated with cidofovir 0.5% OU q12h for a period of 4 weeks, with resolution of corneal disease noted within 1 week of treatment. In conjunction with previous studies, this case report supports a central role for alterations in host immune status in the pathogenesis and clinical manifestations of CHV-1 ocular disease in dogs.

Intensive ocular sampling for the detection of subclinical canine herpesvirus-1 shedding in dogs with experimentally-induced latent infection.

Latent canine herpesvirus-1 (CaHV-1) infections are common in domestic dogs, but viral shedding patterns in dogs are poorly understood. Previous research failed to detect spontaneous subclinical ocular CaHV-1 shedding in dogs following ocular infection, a situation that is fundamentally distinct from many of the alphaherpesviruses closely related to CaHV-1. One possible explanation for this finding is that the sampling interval in the prior studies evaluating ocular shedding patterns was too infrequent to detect rapidly cleared, brief ocular viral shedding episodes. To evaluate for this potential viral shedding scenario, 10 laboratory beagles recovered from experimental primary ocular CaHV-1 infection and with latent CaHV-1infection were intensively monitored for viral reactivation and shedding for 28 days. Clinical ophthalmic examinations were performed daily. Ocular swab samples were collected for CaHV-1 polymerase chain reaction 3 times daily and CaHV-1 virus neutralizing antibody assays were evaluated at 2-week intervals. No abnormalities suggestive of recurrent CaHV-1 ocular disease were observed during clinical ophthalmic examination in the dogs during the study. Ocular CaHV-1 shedding was not detected by polymerase chain reaction and CaHV-1 virus neutralizing antibody titers remained stable in all dogs for the study duration. In the present study utilizing frequent multiple daily sample collections, no evidence of subclinical ocular CaHV-1 shedding was detected in mature dogs with experimentally-induced latent CaHV-1 infection.

Nosocomial outbreak of serious canine infectious tracheobronchitis (kennel cough) caused by canine herpesvirus infection.

Canine herpesvirus (CHV; Canid herpesvirus 1) is principally a perinatal pathogen of pregnant bitches and newborn pups and secondarily a respiratory tract pathogen of older pups and dogs. Infectious disease of the canine respiratory tract frequently occurs among dogs in groups, in which it is called " infectious tracheobronchitis" (ITB). Mortality from ITB is generally negligible, and the clinical importance of CHV as an ITB pathogen is considered to be low. The present report describes a novel ITB outbreak accompanied by death among aged dogs in an animal medical center. Most inpatient dogs had received medications that could induce immunosuppression. CHV was the only pathogen identified, and several CHV isolates were recovered in cell culture. No other viral pathogens or significant bacterial pathogens were found. Molecular and serological analyses revealed that the causative CHV isolates were from a single source but that none was a peculiar strain when the strains were compared with previous CHV strains. The virus had presumably spread among the dogs predisposed to infection in the center. The present results serve as a warning to canine clinics that, under the specific set of circumstances described, such serious CHV outbreaks may be expected wherever canine ITB occurs.

Virologic survey of dogs with naturally acquired idiopathic conjunctivitis.

OBJECTIVE: To determine the frequency of viral detection in conjunctival samples from client-owned domestic dogs with naturally acquired idiopathic conjunctivitis and to identify signalment, historical, and clinical findings positively associated with viral detection. DESIGN: Case-control study. ANIMALS: 30 dogs with naturally acquired idiopathic conjunctivitis and a control population of 30 dogs without ocular disease. PROCEDURES: Complete physical and ophthalmic examinations were performed for each dog. Conjunctival swab specimens were analyzed by use of virus isolation and PCR assays for the following viruses: canine adenovirus-2 (CAV-2), canine distemper virus, canine herpesvirus-1 (CHV-1), canine parainfuenza virus, canine respiratory coronavirus, infuenza A virus, and West Nile virus. Signalment, clinical, and historical information was recorded and compared between study groups. RESULTS: Viruses were detected by either virus isolation or PCR methods significantly more frequently in conjunctival samples from dogs with conjunctivitis (7/30 [23.3%]) than dogs without conjunctivitis (0/30 [0%]). Canine herpesvirus-1 was isolated from 2 conjunctival samples and detected by use of PCR assay in 5 conjunctival samples. Canine adenovirus-2 was isolated from 1 conjunctival sample and detected by use of PCR assay in 2 conjunctiva samples. Sexually intact dogs and frequent exposure to dogs outside the household were positively associated with viral detection in the conjunctivitis group. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that CHV-1 and CAV-2 are common etiologic agents of conjunctivitis in domestic dogs. Risk factors for viral conjunctivitis in dogs reflected increased exposure to other dogs and opportunities for contact with infectious secretions.

Seroprevalence of canine herpesvirus in breeding kennels in the Gauteng Province of South Africa.

Canine herpesvirus (CHV-1) causes neonatal deaths as well as infertility due to embryonal death, abortion and stillbirths in breeding kennels. The aim of this study was to determine the prevalence of antibodies against canine herpesvirus in the serum of dogs older than 1 year in breeding kennels in the Gauteng Province of South Africa. A serum neutralization test (SNT) and a newly developed enzyme linked immunosorbent assay (ELISA) were used to test the serum samples of 328 dogs in 38 breeding kennels. With SNT as well as ELISA, 22% of sera were positive (P>0.9). Seventeen kennels (45% of total kennels) each had at least one positive dog on SNT compared with twenty kennels (53% of total kennels) that each had at least one positive dog on ELISA (P=0.6). The prevalence of positive dogs in positive kennels was 42+/-26% (n=17 kennels) for SNT and 39+/-26% (n=20 kennels) for ELISA. Pairwise comparison of kennels showed that the prevalence of SNT positive dogs was similar to the prevalence of ELISA positive dogs (P=0.3, n=38 kennels). Seroprevalence was independent of age, gender or colony size. This study suggests that canine herpesvirus is sufficiently common in breeding dogs in the Gauteng Province of South Africa to pose a threat to neonatal survival and fertility.

Long-term shedding of Canine alphaherpesvirus 1 in naturally infected newborn pups.

The long-term shedding of Canine alphaherpesvirus 1 (CaHV-1) by neonatal pups with natural infection is reported. The pups belonged to a litter of 11 pointers of a breeding kennel in southern Italy, 9 of which developed a fatal form of systemic infection, as resulted by the detection of CaHV-1 in internal organs (kidney, liver, lung and brain) of one of this dogs and in the vaginal swab of their mother. The two remaining animals displayed a milder form of disease, with one pup showing ocular involvement, and underwent a progressive recovery. These pups were monitored from 11 to 36  days of age, showing a long-term shedding of the virus through the nasal and ocular secretions and the faeces. CaHV-1 shedding, as assessed by means of a specific and sensitive real-time PCR assay, occurred mainly through the nasal secretions, although the pup displaying ocular disease shed the virus at high titres and for a long period even in the ocular secretions.

New Paradigms for the Study of Ocular Alphaherpesvirus Infections: Insights into the Use of Non-Traditional Host Model Systems.

Ocular herpesviruses, most notably human alphaherpesvirus 1 (HSV-1), canid alphaherpesvirus 1 (CHV-1) and felid alphaherpesvirus 1 (FHV-1), infect and cause severe disease that may lead to blindness. CHV-1 and FHV-1 have a pathogenesis and induce clinical disease in their hosts that is similar to HSV-1 ocular infections in humans, suggesting that infection of dogs and cats with CHV-1 and FHV-1, respectively, can be used as a comparative natural host model of herpesvirus-induced ocular disease. In this review, we discuss both strengths and limitations of the various available model systems to study ocular herpesvirus infection, with a focus on the use of these non-traditional virus-natural host models. Recent work has demonstrated the robustness and reproducibility of experimental ocular herpesvirus infections in dogs and cats, and, therefore, these non-traditional models can provide additional insights into the pathogenesis of ocular herpesvirus infections.

Corneal ulceration associated with naturally occurring canine herpesvirus-1 infection in two adult dogs.

CASE DESCRIPTION: An 8-year-old Labrador Retriever with diabetes mellitus in which bilateral phacoemulsification had been performed 3 weeks earlier was evaluated for acute onset of blepharospasm, and a 7-year-old Miniature Schnauzer with chronic immune-mediated thrombocytopenia was reevaluated for keratoconjunctivitis sicca that had been diagnosed 4 weeks earlier. CLINICAL FINDINGS: Dendritic corneal ulcerations were detected in both dogs. Canine herpesvirus-1 (CHV-1) was isolated from corneal swab specimens obtained during the initial evaluation of each dog and during recheck examinations performed until the ulcerations were healed. Canine herpesvirus-1 serum neutralization titers were detected in both dogs. Results of virus isolation from oropharyngeal and genital swab specimens were negative for both dogs. The isolated viruses were identified as CHV-1 via immunofluorescence, transmission electron microscopy, PCR assay, and gene sequencing. Negative controls for PCR assay and virus isolation included conjunctival swab specimens from 50 dogs without extraocular disease and corneal swab specimens from 50 dogs with corneal ulcers, respectively. TREATMENT AND OUTCOME: Lesions resolved in both dogs after topical administration of idoxuridine or trifluridine and discontinuation of topically administered immunosuppressive medications. CLINICAL RELEVANCE: To the authors' knowledge, this is the first report of corneal ulcerations associated with naturally occurring CHV-1 infection and may represent local ocular recrudescence of latent CHV-1 infection. The viruses isolated were identified as CHV-1, and the morphology, antigenicity, and genotype were similar to those for CHV-1 isolates obtained from a puppy that died from systemic CHV-1 infection.

Patterns of Exposure of Iberian Wolves (Canis lupus) to Canine Viruses in Human-Dominated Landscapes.

Wildlife inhabiting human-dominated landscapes is at risk of pathogen spill-over from domestic species. With the aim of gaining knowledge in the dynamics of viral infections in Iberian wolves (Canis lupus) living in anthropized landscapes of northern Spain, we analysed between 2010 and 2013 the samples of 54 wolves by serology and polymerase chain reaction (PCR) for exposure to four pathogenic canine viruses: canine distemper virus (CDV), canine parvovirus-2 (CPV), canine adenovirus 1 and 2 (CAV-1 and CAV-2) and canine herpesvirus. Overall, 76% of the studied wolves presented evidence of exposure to CPV (96% by HI, 66% by PCR) and 75% to CAV (75% by virus neutralization (VN), 76% by PCR, of which 70% CAV-1 and 6% CAV-2). This represents the first detection of CAV-2 infection in a wild carnivore. CPV/CAV-1 co-infection occurred in 51% of the wolves. The probability of wolf exposure to CPV was positively and significantly correlated with farm density in a buffer zone around the place where the wolf was found, indicating that rural dogs might be the origin of CPV infecting wolves. CPV and CAV-1 appear to be enzootic in the Iberian wolf population, which is supported by the absence of seasonal and inter-annual variations in the proportion of positive samples detected. However, while CPV may depend on periodical introductions by dogs, CAV-1 may be maintained within the wolf population. All wolves were negative for exposure to CDV (by VN and PCR) and CHV (by PCR). The absence of acquired immunity against CDV in this population may predispose it to an elevated rate of mortality in the event of a distemper spill-over via dogs.

Prevalence of serum antibodies to canine adenovirus and canine herpesvirus in the European red fox (Vulpes vulpes) in Australia.

OBJECTIVES: To determine the seroprevalence and aspects of the epidemiology of canine adenovirus (CAdV) and canine herpesvirus (CaHV-1) in European red foxes (Vulpes vulpes) in Australia. DESIGN: Serum samples were collected opportunistically from foxes in 1991-1994 in Western Australia (WA) and South Australia (SA) and in 1980-1984 and 1990-1994 in New South Wales (NSW) and the Australian Capital Territory (ACT). The sera were examined for antibody to CAdV and CaHV-1 using ELISAs. Seroprevalence in the different regions was determined for both viruses and the CAdV data were analysed for interactions between decade of collection, age, season, region and gender using logistic regression. RESULTS: The overall prevalence of antibody to CAdV was 23.2% (308/1326) but was significantly higher in sera collected in the eastern states of Australia (47%: 233/498) than in WA (9%: 75/828). Overall, in NSW and the ACT, there was a significantly lower prevalence in juveniles than in adults and the prevalence in juveniles in the 1990s was significantly lower than in the 1980s. The prevalence was also significantly lower in the autumn than in the winter for juveniles but the reverse held for adults. The NSW and ACT data were subdivided into eastern (including the ACT) and western regions. This revealed a significantly higher prevalence in the winter than in the autumn for the west and the reverse in the east. In WA, the northern rangeland regions of WA had lower prevalence (1.9%) than the southern agriculture regions (10.7%). Seasonally, there was a peak prevalence in the spring dropping through the summer and autumn and rising again in the winter. This seasonal pattern was also found in the combined data for all sites in the 1990s. There was no gender difference in prevalence of CAdV either overall or in different regions. The overall prevalence of antibody to CaHV-1 was 2.2% (28/1300). The small number of positives allowed only limited statistical analysis that did not reveal any differences in decade of collection, age, season or region. CONCLUSIONS: CAdV infection is common in the Australian fox population whereas CaHV-1 infection is rare. For CAdV, the age and seasonal patterns of seroprevalence were generally consistent with the recruitment of young susceptible foxes into the population in the spring and the accumulation of infections with age. The differences in regional prevalences correlated with fox density. The low prevalence of antibody to CaHV-1 suggests that CaHV-1 may be a more suitable vector than CAdV for bait delivery of immunocontraceptive antigens to foxes in Australia.

Prevalence of canid herpesvirus-1 infection in stillborn and dead neonatal puppies in Denmark.

BACKGROUND: Canid herpesvirus-1 (CaHV-1) infection in puppies less than three weeks of age is often reported to be associated with a lethal generalized necrotizing inflammation and since the discovery of the virus in 1965 several reports of neonatal infections have been published. However, the significance of CaHV-1 for peri- and neonatal mortality in puppies remains unclear. Therefore, we examined stillborn and dead neonatal puppies in Denmark to determine the prevalence of infection and further to correlate infection levels with necropsy findings to assess the possible significance of the infection. RESULTS: From a cross-sectional study of 57 dead puppies, 22.8% (n = 13) were confirmed positive for CaHV-1 by real-time polymerase chain reaction (PCR) of tissue pools of lung/liver and/or spleen/kidney. Specimens from PCR positive cases were further investigated by histology and in situ hybridization (ISH). High levels of CaHV-1 DNA were present in only one case in which lesions and ISH staining consistent with CaHV-1 infection were found as well. CaHV-1 concentrations in the other cases were low and a range of lesions not consistent with CaHV-1 were found. Similar, ISH staining was mostly negative in these except for one case with a few positive cells. CONCLUSION: CaHV-1 infection in stillborn and dead neonatal puppies in Denmark seems to be common, but the direct significance for puppy mortality remains unclear as only one of 13 PCR positive puppies (7.7%) had pathognomonic lesions.

Experimental infection of European red foxes (Vulpes vulpes) with canine herpesvirus.

We report on the pathogenicity of canine herpesvirus (CHV) for European red foxes. In the first experiment, we inoculated 10 adult foxes intravenously with a canine isolate of CHV. All foxes became infected and shed CHV in saliva and genital secretions for up to 14 days post-inoculation (p.i.) as evaluated by PCR and/or by virus isolation. All foxes developed clinical signs such as fever, lethargy and evidence of respiratory tract disease. Two foxes died on day 6 p.i., one on day 7 p.i., and one fox was euthanased on day 6 p.i. Tissues taken from the four dead foxes were positive for CHV by PCR. The remaining six foxes recovered after approximately 14 days p.i. Virus particles with morphology typical of herpesviruses were found by electron microscopy in the liver of an infected animal. All surviving foxes developed serum anti-CHV antibodies. In a second experiment, six foxes were dosed perorally with CHV and paired with six untreated controls. Neither the perorally dosed nor the in-contact control foxes developed clinical signs of disease. Infectious CHV was not isolated from any of the dosed or the in-contact foxes but all perorally-infected foxes and one of the in-contact foxes tested PCR-positive for CHV on several occasions p.i. All perorally-infected foxes, but none of the in-contact foxes, seroconverted. In summary, intravenous CHV inoculation caused a clinical disease in adult foxes much more severe than observed in experimentally-infected adult dogs. No clinical disease or virus spread was observed after peroral dosing although viral infection occurred as evidenced by seroconversion.

Prevalence of antibodies against canine herpesvirus 1 in dogs in The Netherlands in 1997-1998.

Canine herpesvirus (CHV1) is found in dogs all over the world and may spread by oronasal or sexual contact. We developed an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against CHV1 in dogs. The antigen used for this ELISA was prepared by purifying CHV1 virions from the medium of infected A72 cells. To investigate the prevalence of CHV1 in The Netherlands, a panel of 145 sera of dogs boarding at a kennel in Lelystad, The Netherlands, was screened using this ELISA. The dogs originated from all parts of The Netherlands and represented many different breeds. The sera were collected both at the start and at the end of the boarding period. Of the 145 paired sera 61 (42.1%) were positive, 79 (54.5%) were negative and 5 (3.4%) could not be attributed to either group. None of the negative dogs became seropositive during the boarding period, which lasted normally two to three weeks. We also tested 79 individual sera taken from dogs at various other places in The Netherlands and found that 27 (34.2%) were positive. Hence, in total 224 dog sera, collected from April 1997 to March 1998, were tested and 88 (39.3%) were found positive. We conclude that the prevalence of CHV1 seropositive dogs in The Netherlands in this period was about 40%, and that boarding at a dogs kennel did not contribute to the spread of CHV1. In addition, CHV1 has been isolated from two clinical cases of fatal haemorrhagic disease in The Netherlands.

Detection of canine herpesvirus 1 in a wide range of tissues using the polymerase chain reaction.

Canine herpesvirus 1 (CHV-1), a member of the alphaherpesvirus sub-family, is known to cause fatal infections in litters of puppies and may also be involved in infertility, abortion, and stillbirths in adult dogs. The purpose of this study was to determine the presence of CHV-1 DNA using the polymerase chain reaction (PCR) in twelve key sites that have been associated with latency for the other herpesviruses. A 605 base pair portion of the viral glycoprotein B (gB) gene was amplified using degenerate primers, cloned, and sequenced. Conventional 20 mer primers were designed using this sequence information to amplify a 120 bp fragment of gB situated between the original degenerate primers. The specificity of amplification was confirmed by Southern Blot hybridisation using an internal oligonucleotide probe. DNA was extracted from tissue samples taken from twelve dogs at post mortem and from twenty-four blood samples. Nine out of twelve dogs showed evidence of infection with CHV-1; the tissues most commonly affected were lumbo-sacral ganglia (5/12 dogs), tonsil (5/12), parotid salivary gland (4/9), and liver (4/9). No positive results were detected within the twenty-four blood samples. These results indicate that exposure to CHV-1 may be much more common than previously suggested.

Detection of high levels of canine herpes virus-1 neutralising antibody in kennel dogs using a novel serum neutralisation test.

It is widely held that only cells of canine origin support canine herpesvirus-1 (CHV-1) replication and, that cytopathic effect (CPE) develops relatively slowly. Here we show that mink fetal lung cells (NBL-7 cell line) are permissive for CHV-1 and can be used to produce a sensitive test for neutralising antibody by plaque reduction in the presence of complement. The test was applied to the investigation of CHV-1 virus neutralising antibody levels in three kennel populations. The results showed that 26 out of 28 dogs were neutralising antibody positive (titre >/=2), and, 11 out of 28 had titres of >/=1024. The serum samples were analysed by enzyme linked immunoassay (ELISA); 27 out of 28 were graded as ELISA IgG positive (titre >/=500) and 26 of 28 were graded as ELISA IgM positive (titre >/=50).