Snapshot study of canine distemper virus in Bangladesh with on-site PCR detection and nanopore sequencing

Canine distemper virus (CDV) is a highly contagious virus that affects domestic and wild animals, causing severe illness with high mortality rates. Rapid monitoring and sequencing can provide valuable information about circulating CDV strains, which may foster effective vaccination strategies and the successful integration of these into conservation programs. During two site visits in Bangladesh in 2023, we tested a mobile, deployable genomic surveillance setup to explore the genetic diversity and phylogenetic patterns of locally circulating CDV strains. We collected and analysed 355 oral swab samples from stray dogs in Rajshahi and Chattogram cities, Bangladesh. CDV-specific real-time RT-PCR was performed to screen the samples. Out of the 355 samples, 7.4% (10/135) from Rajshahi city and 0.9% (2/220) from Chattogram city tested positive for CDV. We applied a real-time RT-PCR assay and a pan-genotype CDV-specific amplicon-based Nanopore sequencing technology to obtain the near-completes. Five near-complete genome sequences were generated, with phylogenetic relation to the India-1/Asia-5 lineage previously identified in India. This is the first study to provide genomic data on CDV in Bangladesh and the first demonstration of a mobile laboratory setup as a powerful tool in rapid genomic surveillance and risk assessment for CDV in low resource regions.

Molecular survey of selected viral pathogens in wild leopard cats (Prionailurus bengalensis) in Taiwan with an emphasis on the spatial and temporal dynamics of carnivore protoparvovirus 1

The leopard cat (Prionailurus bengalensis) was listed as an endangered species under the Wildlife Conservation Act in Taiwan in 2009. However, no study has evaluated the possible direct or indirect effects of pathogens on the Taiwanese leopard cat population. Here, we targeted viral pathogens, including carnivore protoparvovirus 1 (genus Protoparvovirus), feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), coronaviruses (CoVs), and canine distemper virus (CDV), through molecular screening. The spatial and temporal dynamics of the target pathogens were evaluated. Through sequencing and phylogenetic analysis, we clarified the phylogenetic relationship of viral pathogens isolated from leopard cats and domestic carnivores. Samples from 23 live-trapped leopard cats and 29 that were found dead were collected from 2015 to 2019 in Miaoli County in northwestern Taiwan. Protoparvoviruses and CoVs were detected in leopard cats, and their prevalence (95% confidence interval) was 63.5% (50.4%–76.6%) and 8.8% (0%–18.4%), respectively. Most of the protoparvovirus sequences amplified from Taiwanese leopard cats and domestic carnivores were identical. All of the CoV sequences amplified from leopard cats were identified as feline CoV. No spatial or temporal aggregation of protoparvovirus infection in leopard cats was found in the sampling area, indicating a wide distribution of protoparvoviruses in the leopard cat habitat. We consider sympatric domestic carnivores to be the probable primary reservoir for the identified pathogens. We strongly recommend management of protoparvoviruses and feline CoV in the leopard cat habitat, particularly vaccination programs and population control measures for free-roaming dogs and cats.

Two waves of canine distemper virus showing different spatio-temporal dynamics in Alpine wildlife (2006-2018)

Canine distemper virus (CDV) represents an important threat for both wild and domestic carnivores. Since 2006, the North-Eastern regions in Italy have been experiencing severe and widespread recurring outbreaks of CDV affecting the wild carnivore population. In this study we performed an extensive phylogeographic analysis of CDV strains belonging to the Wildlife-Europe genetic group identified between 2006 and 2018 in Veneto, Trentino Alto Adige and Friuli Venezia Giulia regions. Our analysis revealed that viruses from the first (2006-2009) and the second (2011-2018) epidemic wave cluster separately, suggesting the introduction of two distinct genetic variants. These two events were characterized by different diffusion rates and spatial distribution, thus suggesting the existence of a connection between infection spread and host population dynamics. We also report the first spillover event of this strain to a non-vaccinated dog in a rural area of Friuli Venezia Giulia. The increasing prevalence of the infection in wildlife population, the broad host range of CDV circulating in the Alpine wildlife and the first reported transmission of a wild-adapted strain to a domestic dog in this region raise concerns over the vulnerability of wildlife species and the exposure of our pets to new threatening strains. Understanding the dynamic of CDV epidemics will also improve preparedness for re-emerging diseases affecting carnivore species.

Seroprevalence of viral and vector-borne bacterial pathogens in domestic dogs (Canis familiaris) in northern Botswana

BACKGROUND

Domestic dogs (Canis familiaris) have the potential to act as disease reservoirs for wildlife and are important sentinels for common circulating pathogens. Therefore, the infectious disease seroprevalence among domestic dogs in northern Botswana may be indicative of pathogen exposure of various wildlife species. The objective of this study was to assess the seroprevalence of Ehrlichia spp., Borrelia burgdorferi, Anaplasma spp., Dirofilaria immitis, canine adenovirus, canine parvovirus, and canine distemper virus in domestic dogs as proxies of disease prevalence in the local wildlife in the Okavango Delta region of Botswana. Statistical analysis assessed crude and factor-specific seroprevalence proportions in relation to age, sex, and geographical location as predictors of seropositivity. Logistic regression was used to identify adjusted predictors of seropositivity for each of the pathogens of interest.

RESULTS

Samples from 233 dogs in a total of seven locations in Maun, Botswana, and surrounding villages were collected and serologically analyzed. No dogs were seropositive for B. burgdorferi, while low seroprevalence proportions were observed for Anaplasma spp. (2.2%) and D. immitis (0.9%). Higher seroprevalence proportions were observed for the tick-borne pathogen Ehrlichia spp. (21.0%), and 19.7% were seropositive for canine adenovirus (hepatitis). The highest seroprevalence proportions were for canine parvovirus (70.0%) and canine distemper virus (44.8%). The predictors of seropositivity revealed that adults were more likely to be seropositive for canine adenovirus, canine distemper virus, and canine parvovirus than juveniles, and location was a risk factor for canine adenovirus, canine distemper virus, canine parvovirus, and Ehrlichia spp.

CONCLUSIONS

Results indicate that increasing tick control and vaccination campaigns for domestic dogs may improve the health of domestic animals, and potentially wildlife and humans in the Okavango Delta since viral and vector-borne bacterial pathogens can be transmitted between them.

Canine distemper in Nepal's Annapurna Conservation Area - Implications of dog husbandry and human behaviour for wildlife disease

Dogs are often commensal with human settlements. In areas where settlements are adjacent to wildlife habitat, the management of dogs can affect risk of spillover of disease to wildlife. We assess dog husbandry practices, and measure the prevalence of Canine Distemper Virus (CDV) in dogs, in 10 villages in Nepal's Annapurna Conservation Area (ACA), an important region for Himalayan wildlife. A high proportion (58%) of owned dogs were allowed by their owners to roam freely, and many village dogs originated from urban areas outside the region. CDV antibodies, indicating past exposure, were detected in 70% of dogs, and 13% were positive for P-gene, suggesting current circulation of CDV. This is the first detection of canine distemper virus in a National Park in Nepal Himalaya. Dogs were generally in good condition, and none exhibited clinical signs of CDV infection, which suggests that infections were asymptomatic. CDV exposure varied with village location and age of dogs, but this variation was minor, consistent with high rates of movement of dogs across the region maintaining high seroprevalence. Residents reported the occurrence of several species of wild carnivores in or close to villages. These results suggest a high potential for transmission of CDV from village dogs to wild carnivores in ACA. We suggest that control of dog immigration, along with vaccination and neutering of dogs could mitigate the risk of CDV spillover into wild carnivore populations.

Evolution and Interspecies Transmission of Canine Distemper Virus-An Outlook of the Diverse Evolutionary Landscapes of a Multi-Host Virus

Canine distemper virus (CDV) is a worldwide distributed virus which belongs to the genus Morbillivirus within the Paramyxoviridae family. CDV spreads through the lymphatic, epithelial, and nervous systems of domestic dogs and wildlife, in at least six orders and over 20 families of mammals. Due to the high morbidity and mortality rates and broad host range, understanding the epidemiology of CDV is not only important for its control in domestic animals, but also for the development of reliable wildlife conservation strategies. The present review aims to give an outlook of the multiple evolutionary landscapes and factors involved in the transmission of CDV by including epidemiological data from multiple species in urban, wild and peri-urban settings, not only in domestic animal populations but at the wildlife interface. It is clear that different epidemiological scenarios can lead to the presence of CDV in wildlife even in the absence of infection in domestic populations, highlighting the role of CDV in different domestic or wild species without clinical signs of disease mainly acting as reservoirs (peridomestic and mesocarnivores) that are often found in peridomestic habits triggering CDV epidemics. Another scenario is driven by mutations, which generate genetic variation on which random drift and natural selection can act, shaping the genetic structure of CDV populations leading to some fitness compensations between hosts and driving the evolution of specialist and generalist traits in CDV populations. In this scenario, the highly variable protein hemagglutinin (H) determines the cellular and host tropism by binding to signaling lymphocytic activation molecule (SLAM) and nectin-4 receptors of the host; however, the multiple evolutionary events that may have facilitated CDV adaptation to different hosts must be evaluated by complete genome sequencing. This review is focused on the study of CDV interspecies transmission by examining molecular and epidemiological reports based on sequences of the hemagglutinin gene and the growing body of studies of the complete genome; emphasizing the importance of long-term multidisciplinary research that tracks CDV in the presence or absence of clinical signs in wild species, and helping to implement strategies to mitigate the infection. Integrated research incorporating the experience of wildlife managers, behavioral and conservation biologists, veterinarians, virologists, and immunologists (among other scientific areas) and the inclusion of several wild and domestic species is essential for understanding the intricate epidemiological dynamics of CDV in its multiple host infections.

Rabies and Distemper Outbreaks in Smallest Ethiopian Wolf Population

Widespread deaths recently devastated the smallest known population of Ethiopian wolves. Of 7 carcasses found, all 3 tested were positive for rabies. Two wolves were subsequently vaccinated for rabies; 1 of these later died from canine distemper. Only 2 of a known population of 13 wolves survived.

How the Canine Distemper Virus Infects Human Cells at the Molecular Level in Vitro

Infection by the canine distemper virus (CDV) results in a fulminating infectious disease that causes serious harm to dogs. With breaking 'of the CDV into primates, some researchers wonder if the CDV will cause a serious infection in humans. To better understand the potential of the CDV to infect humans, the molecular characteristics of the CDV, how it infects target cells in the host, the key receptors involved in infection, and infection of human cells in vitro were assessed in this review. There is no direct evidence that CDV can colonize and grow in humans. Two key receptors, SLAM and nectin-4, in hunans and primates have high identity, and the CDV can infect human cells in vitro. Therefore, we must pay close attention to the potential threat of infection by the CDV in humans.

The 2000 Canine Distemper Epidemic in Caspian Seals (Phoca caspica): Pathology and Analysis of Contributory Factors

More than 10,000 Caspian seals ( Phoca caspica) were reported dead in the Caspian Sea during spring and summer 2000. We performed necropsies and extensive laboratory analyses on 18 seals, as well as examination of the pattern of strandings and variation in weather in recent years, to identify the cause of mortality and potential contributory factors. The monthly stranding rate in 2000 was up to 2.8 times the historic mean. It was preceded by an unusually mild winter, as observed before in mass mortality events of pinnipeds. The primary diagnosis in 11 of 13 seals was canine distemper, characterized by broncho-interstitial pneumonia, lymphocytic necrosis and depletion in lymphoid organs, and the presence of typical intracytoplasmic inclusion bodies in multiple epithelia. Canine distemper virus infection was confirmed by phylogenetic analysis of reverse transcriptase-polymerase chain reaction products. Organochlorine and zinc concentrations in tissues of seals with canine distemper were comparable to those of Caspian seals in previous years. Concurrent bacterial infections that may have contributed to the mortality of the seals included Bordetella bronchiseptica (4/8 seals), Streptococcus phocae (3/8), Salmonella dublin (1/8), and S. choleraesuis (1/8). A newly identified bacterium, Corynebacterium caspium, was associated with balanoposthitis in one seal. Several infectious and parasitic organisms, including poxvirus, Atopobacter phocae, Eimeria- and Sarcocystis-like organisms, and Halarachne sp. were identified in Caspian seals for the first time.

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.

Genetic characterization of an isolate of canine distemper virus from a Tibetan Mastiff in China

Canine distemper (CD) is a highly contagious, often fatal, multisystemic, and incurable disease in dogs and other carnivores, which is caused by canine distemper virus (CDV). Although vaccines have been used as the principal means of controlling the disease, CD has been reported in vaccinated animals. The hemoagglutinin (H) protein is one of the most important antigens for inducing protective immunity against CD, and antigenic variation of recent CDV strains may explain vaccination failure. In this study, a new CDV isolate (TM-CC) was obtained from a Tibetan Mastiff that died of distemper, and its genome was characterized. Phylogenetic analysis of the H gene revealed that the CDV-TM-CC strain is unique among 20 other CDV strains and can be classified into the Asia-1 group with the Chinese strains, Hebei and HLJ1-06, and the Japanese strain, CYN07-hV. The H gene of CDV-TM-CC shows low identity (90.4 % nt and 88.9 % aa) with the H gene of the classical Onderstepoort vaccine strain, which may explain the inability of the Tibetan Mastiff to mount a protective immune response. We also performed a comprehensive phylogenetic analysis of the N, P, and F protein sequences, as well as potential N-glycosylation sites and cysteine residues. This analysis shows that an N-glycosylation site at aa 108-110 within the F protein of CDV-TM-CC is specific for the wild-type strains (5804P, A75/17, and 164071) and the Asia-1 group strains, and may be another important factor for the poor immune response. These results provide important information for the design of CD vaccines in the China region and elsewhere.

Uncommon acute neurologic presentation of canine distemper in 4 adult dogs

Four uncommon cases of canine distemper (CD) were diagnosed in vaccinated adult dogs. All dogs had acute onset of neurologic signs, including seizures, abnormal mentation, ataxia, and proprioceptive deficits. Polymerase chain reaction for CD virus was positive on cerebrospinal fluid in 2 cases. Due to rapid deterioration the dogs were euthanized and CD was confirmed by postmortem examination.

Emergence of canine distemper virus strains with two amino acid substitutions in the haemagglutinin protein, detected from vaccinated carnivores in North-Eastern China in 2012-2013

A total of 16 strains of canine distemper virus (CDV) were detected from vaccinated minks, foxes, and raccoon dogs in four provinces in North-Eastern China between the end of 2011 and 2013. Upon sequence analysis of the haemagglutinin gene and comparison with wild-type CDV from different species in the same geographical areas, two non-synonymous single nucleotide polymorphisms were identified in 10 CDV strains, which led to amino acid changes at positions 542 (isoleucine to asparagine) and 549 (tyrosine to histidine) of the haemagglutinin protein coding sequence. The change at residue 542 generated a potentially novel N-glycosylation site. Masking of antigenic epitopes by sugar moieties might represent a mechanism for evasion of virus neutralising antibodies and reduced protection by vaccination.

Sandwich-dot enzyme-linked immunosorbent assay for the detection of canine distemper virus

A sandwich-dot enzyme-linked immunosorbent assay (dot ELISA) was developed for the detection of canine distemper virus (CDV). In 56 dogs suspected to have CD the rates of detection of CDV antigen in samples of blood lymphocytes and palpebral conjunctiva by dot ELISA and ELISA were, respectively, 91% (49/54) and 81% (44/54) for the lymphocyte samples and 88% (28/32) and 75% (24/32) for the conjunctival samples. The CDV detection limits were 10 ng/50 μL for dot ELISA and 40 ng/50 μL for ELISA. The reliability of dot ELISA relative to electron microscopy was 96% with 22 samples: all 21 samples in which CDV particles were observed by electron microscopy yielded positive results with dot ELISA; the single sample in which particles were not observed yielded false-positive results with dot ELISA. The results indicate that the dot ELISA developed can serve as a reliable rapid diagnostic test in suspected cases of CD and also be useful for epidemiologic surveillance of the disease.

Canine distemper virus (CDV) in another big cat: should CDV be renamed carnivore distemper virus?

One of the greatest threats to the conservation of wild cat populations may be dogs or, at least, one of their viruses. Canine distemper virus (CDV), a single-stranded RNA virus in the Paramyxoviridae family and genus Morbillivirus, infects and causes disease in a variety of species, not just canids. An outbreak of CDV in wild lions in the Serengeti, Tanzania, in 1994 was a wake-up call for conservationists, as it demonstrated that an infectious disease could swiftly impact a previously healthy felid population. To understand how this virus causes disease in noncanid hosts, researchers have focused on specific mutations in the binding site of the CDV hemagglutinin gene. Now, Seimon et al. provide information on CDV in its latest feline victim, the endangered wild Amur tiger (Panthera tigris altaica) [T. A. Seimon et al., mBio 4(4):e00410-13, 2013, doi:10.1128/mBio.00410-13]. Their findings of CDV strains infecting tigers, in combination with recent information from other felids, paints a different picture, one in which CDV strains from a variety of geographic lineages and with a variety of amino acid residues in the hemagglutinin gene binding site can infect cats and cause disease. Although CDV has been known as a multihost disease since its discovery in domestic dogs in 1905, perhaps it is time to reconsider whether these noncanid species are not just incidental or "spillover" hosts but, rather, a normal part of the complex ecology of this infectious disease.

The fusion protein signal-peptide-coding region of canine distemper virus: a useful tool for phylogenetic reconstruction and lineage identification

Canine distemper virus (CDV; Paramyxoviridae, Morbillivirus) is the etiologic agent of a multisystemic infectious disease affecting all terrestrial carnivore families with high incidence and mortality in domestic dogs. Sequence analysis of the hemagglutinin (H) gene has been widely employed to characterize field strains, permitting the identification of nine CDV lineages worldwide. Recently, it has been established that the sequences of the fusion protein signal-peptide (Fsp) coding region are extremely variable, suggesting that analysis of its sequence might be useful for strain characterization studies. However, the divergence of Fsp sequences among worldwide strains and its phylogenetic resolution has not yet been evaluated. We constructed datasets containing the Fsp-coding region and H gene sequences of the same strains belonging to eight CDV lineages. Both datasets were used to evaluate their phylogenetic resolution. The phylogenetic analysis revealed that both datasets clustered the same strains into eight different branches, corresponding to CDV lineages. The inter-lineage amino acid divergence was fourfold greater for the Fsp peptide than for the H protein. The likelihood mapping revealed that both datasets display strong phylogenetic signals in the region of well-resolved topologies. These features indicate that Fsp-coding region sequence analysis is suitable for evolutionary studies as it allows for straightforward identification of CDV lineages.

Deduced sequences of the membrane fusion and attachment proteins of canine distemper viruses isolated from dogs and wild animals in Korea

Canine distemper virus (CDV) causes highly contagious respiratory, gastrointestinal, and neurological diseases in wild and domestic animal species. Despite a broad vaccination campaign, the disease is still a serious problem worldwide. In this study, six field CDV strains were isolated from three dogs, two raccoon dogs, and one badger in Korea. The full sequence of the genes encoding fusion (F) and hemagglutinin (H) proteins were compared with those of other CDVs including field and vaccine strains. The phylogenetic analysis for the F and H genes indicated that the two CDV strains isolated from dogs were most closely related to Chinese strains in the Asia-1 genotype. Another four strains were closely related to Japanese strains in the Asia-2 genotype. The six currently isolated strains shared 90.2-92.1% and 88.2-91.8% identities with eight commercial vaccine strains in their nucleotide and amino acid sequences of the F protein, respectively. They also showed 90.1-91.4% and 87.8-90.7% identities with the same vaccine strains in their nucleotide and deduced amino acid sequences of the H protein, respectively. Different N-linked glycosylation sites were identified in the F and H genes of the six isolates from the prototype vaccine strain Onderstepoort. Collectively, these results demonstrate that at least two different CDV genotypes currently exist in Korea. The considerable genetic differences between the vaccine strains and wild-type isolates would be a major factor of the incomplete protection of dogs from CDV infections.

Concomitant canine distemper, infectious canine hepatitis, canine parvoviral enteritis, canine infectious tracheobronchitis, and toxoplasmosis in a puppy

The concomitant infections of Canine distemper virus (CDV), Canine adenovirus A types 1 (CAdV-1) and 2 (CAdV-2), Canine parvovirus type 2 (CPV-2), and Toxoplasma gondii are described in a 43-day-old mixed-breed puppy. Clinically, there were convulsions and blindness with spontaneous death; 14 siblings of this puppy, born to a 10-month-old dam, which was seropositive (titer: 1,024) for T. gondii, also died. Necropsy revealed unilateral corneal edema (blue eye), depletion of intestinal lymphoid tissue, non-collapsible lungs, congestion of meningeal vessels, and a pale area in the myocardium. Histopathology demonstrated necrotizing myocarditis associated with intralesional apicomplexan protozoa; necrotizing and chronic hepatitis associated with rare intranuclear inclusion bodies within hepatocytes; necrotizing bronchitis and bronchiolitis; interstitial pneumonia associated with eosinophilic intracytoplasmic inclusion bodies within epithelial cells; atrophy and fusion of intestinal villi with cryptal necrosis; and white matter demyelination of the cerebrum and cerebellum associated with intranuclear inclusion bodies within astrocytes. Polymerase chain reaction (PCR) amplified the partial fragments (bp) of the CDV N gene (290 bp), CPV-2c VP2 capsid protein gene (583 bp), and CAdV-1 (508 bp) and CAdV-2 (1,030 bp) E gene from urine and tissue samples. The PCR assays demonstrated that the apicomplexan protozoa observed within several organs contained DNA specific for T. gondii; genotyping revealed T. gondii type III. The findings support the characterization of concomitant infections of CDV, CAdV-1, CAdV-2, CPV-2, and T. gondii in this puppy. Further, seroreactivity to T. gondii of the dam in association with the systemic disease observed in the puppy described herein is suggestive of congenital toxoplasmosis.

[Establishment and application of a Vero cell line stably expressing raccoon dog SLAM, the cellular receptor of canine distemper virus]

OBJECTIVE

The signaling lymphocyte activation molecule (SLAM, also known as CD150), is used as a cellular receptor by canine distemper virus (CDV). Wild-type strains of CDVs can be isolated and propagated efficiently in non-lymphoid cells expressing this protein. Our aim is to establish a Vero cells expressing raccoon dog SLAM (rSLAM) to efficiently isolate CDV from pathological samples.

METHODS

A eukaryotic expression plasmid, pIRES2-EGFP-rSLAMhis, containing rSLAM gene fused with six histidine-coding sequence, EGFP gene, and neomycin resistance gene was constructed. After transfection with the plasmid, a stable cell line, Vero-rSLAM, was screened from Vero cells with the identification of EGFP reporter and G418 resistance. Three CD positive specimens from infected foxes and raccoon dogs were inoculated to Vero-rSLAM cells for CDV isolation. Foxes and raccoon dogs were inoculated subcutaneously LN (10)fl strain with 4 x 10(2.39)TCID50 dose to evaluate pathogenicity of CDV isolations.

RESULTS

The rSLAMh fused gene was shown to transcript and express stably in Vero-rSLAM cells by RT-PCR and Immunohistochemistry assay. Three CDV strains were isolated successfully in Vero-rSLAM cells 36 -48 hours after inoculation with spleen or lung specimens from foxes and raccoon dogs with distemper. By contrast, no CDV was recovered from those CD positive specimens when Vero cells were used for virus isolation. Infected foxes and raccoon dogs with LN(10)f1 strain all showed typical CD symptoms and high mortality (2/3 for foxes and 3/3 for raccoon dogs) in 22 days post challenge.

CONCLUSION

Our results indicate that Vero-rSLAM cells stably expressing raccoon dog SLAM are highly sensitive to CDV in clinical specimens and the CDV isolation can maintain high virulence to its host animals.

Rabies virus and canine distemper virus in wild and domestic carnivores in Northern Kenya: are domestic dogs the reservoir?

Rabies virus (RV) and canine distemper virus (CDV) can cause significant mortality in wild carnivore populations, and RV threatens human lives. We investigated serological patterns of exposure to CDV and RV in domestic dogs (Canis familiaris), African wild dogs (Lycaon pictus), black-backed jackals (Canis mesomelas), spotted hyenas (Crocuta crocuta), striped hyenas (Hyaena hyaena) and African lions (Panthera leo), over a 10-year period, in a Kenyan rangeland to assess the role domestic dogs may play in the transmission dynamics of these two important canid pathogens. Observed patterns of RV exposure suggested that repeated introduction, rather than maintenance, occurred in the wild carnivore species studied. However, RV appeared to have been maintained in domestic dogs: exposure was more likely in domestic dogs than in the wild carnivores; was detected consistently over time without variation among years; and was detected in juveniles (≤1-year-old) as well as adults (>1-year-old). We conclude that this domestic dog population could be a RV reservoir. By contrast, the absence of evidence of CDV exposure for each carnivore species examined in the study area, for specific years, suggested repeated introduction, rather than maintenance, and that CDV may require a larger reservoir population than RV. This reservoir could be a larger domestic dog population; another wildlife species; or a "metareservoir" consisting of multiple interconnected carnivore populations. Our findings suggest that RV risks to people and wild carnivores might be controlled by domestic dog vaccination, but that CDV control, if required, would need to target the species of concern.

Optic neuritis caused by canine distemper virus in a Jack Russell terrier

An atypical case of canine distemper (CD) was diagnosed in a vaccinated healthy adult dog. The patient was presented circling, seizuring, and blind. Postmortem examination resulted in a diagnosis of CD. Optic neuritis was diagnosed, a finding not previously described in the context of CD virus infection presenting solely with neurological signs.

Molecular detection of Canine distemper virus and the immunohistochemical characterization of the neurologic lesions in naturally occurring old dog encephalitis

The current article describes a spontaneous case of old dog encephalitis (ODE) in a 7-year-old, intact, female Miniature Schnauzer dog from Londrina, Paraná, southern Brazil. Unlike conventional distemper encephalomyelitis, ODE is a poorly understood and extremely rare manifestation of Canine distemper virus (CDV) infection. The dog was presented with progressive clinical manifestations consistent with cerebral dysfunction. Briefly, histopathologic lesions were restricted to the forebrain and included chronic multifocal lymphoplasmacytic encephalitis with extensive perivascular cuffing, astrocytosis, and intranuclear inclusions within astrocytes and giant cells, with both intracytoplasmic and intranuclear inclusions. Immunohistochemistry (IHC) was used to identify the antigens of the nucleoprotein (NP) of CDV and to detect cluster of differentiation (CD)3, CD79a, macrophage (MAC) 387, glial fibrillary acidic protein, and vimentin to characterize the neuroparenchymal lesions. By IHC, CDV NP was demonstrated predominantly within neurons and astrocytes. Cells that formed perivascular cuffs and some astrocyte-like cells reacted intensely to vimentin. Reverse transcription polymerase chain reaction assay from brain sections further confirmed a role for CDV in this disease by the amplification and partial sequence analysis of the NP gene. These findings confirmed simultaneous detection of CDV in ODE by IHC and molecular assays. In addition, results of the current study could contribute to the neuropathologic characterization of this rare manifestation of CDV.

First evidence of canine distemper in Brazilian free-ranging felids

Serum samples from 19 jaguars (Panthera onca), nine pumas (Puma concolor), and two ocelots (Leopardus pardalis) were collected between January 1999 and March of 2005 and tested for presence of canine distemper virus (CDV). All cats were free-ranging animals living in two protected areas in the Brazilian Atlantic Forest. In addition, 111 domestic dogs from nearby areas were sampled for CDV. Our results show the first evidence of CDV exposure in Brazilian free-ranging felids. From the 30 samples analyzed, six jaguars and one puma were tested seropositive for CDV. All seropositive large felids were from Ivinhema State Park, resulting in 31.5% of the sampled jaguars or 60% of the total jaguar population in Ivinhema State Park, and 11.28% of the sampled pumas. From the total 111 domestic dogs sampled, 45 were tested seropositive for CDV. At Morro do Diabo State Park, 34.6% of the dogs sampled were positive for CDV, and 100% at Ivinhema State Park. Canine distemper virus in wild felids seems to be related with home range use and in close association with domestic dogs living in nearby areas.

Detection by RT-PCR and genetic characterization of canine distemper virus from vaccinated and non-vaccinated dogs in Argentina

RT-PCR was used to detect canine distemper virus (CDV) RNA in clotted blood from Argentine domestic dogs. The NP gene was detected in 73 out of 99 blood samples analyzed. The deduced amino acid sequence of these gene fragments showed 100% identity with the sequence of other wild-type and vaccine strains. A fragment of the hemagglutinin gene was amplified from 24 (32.9%) of the NP-RNA-positive clinical specimens. These H fragments were further analyzed by restriction fragment length polymorphism (RFLP) and sequencing. A single NdeI site was detected in all 24 wild-type strains but was absent in the vaccine strains. Phylogenetic analysis of the partial hemagglutinin amino acid sequences showed close clustering for local strains, clearly distinct from vaccine strains and other wild-type foreign CDV strains. One of the local strains, Arg 23, branched out of the root of the Argentine clade, close to the European strains, suggesting that two different pathogenic CDV genotypes are currently circulating in Argentina, one of them clearly predominant.

Combined distemper-adenoviral pneumonia in a dog

A 3 1/2-month-old pug with oculonasal discharge and seizures was submitted for postmortem examination. Grossly, the lungs had cranioventral consolidation, and microscopically, 2 distinct types of inclusion bodies compatible with Canine distemper virus and Canine adenovirus type 2. Presence of both viruses was confirmed via immunohistochemical staining.

Multicenter blinded analysis of RT-PCR detection methods for paramyxoviruses in relation to Paget's disease of bone

Conflicting results have been reported on the detection of paramyxovirus transcripts in Paget's disease, and a possible explanation is differences in the sensitivity of RT-PCR methods for detecting virus. In a blinded study, we found no evidence to suggest that laboratories that failed to detect viral transcripts had less sensitive RT-PCR assays, and we did not detect measles or distemper transcripts in Paget's samples using the most sensitive assays evaluated.

INTRODUCTION

There is conflicting evidence on the possible role of persistent paramyxovirus infection in Paget's disease of bone (PDB). Some workers have detected measles virus (MV) or canine distemper virus (CDV) transcripts in cells and tissues from patients with PDB, but others have failed to confirm this finding. A possible explanation might be differences in the sensitivity of RT-PCR methods for detecting virus. Here we performed a blinded comparison of the sensitivity of different RT-PCR-based techniques for MV and CDV detection in different laboratories and used the most sensitive assays to screen for evidence of viral transcripts in bone and blood samples derived from patients with PDB.

MATERIALS AND METHODS

Participating laboratories analyzed samples spiked with known amounts of MV and CDV transcripts and control samples that did not contain viral nucleic acids. All analyses were performed on a blinded basis.

RESULTS

The limit of detection for CDV was 1000 viral transcripts in three laboratories (Aberdeen, Belfast, and Liverpool) and 10,000 transcripts in another laboratory (Manchester). The limit of detection for MV was 16 transcripts in one laboratory (NIBSC), 1000 transcripts in two laboratories (Aberdeen and Belfast), and 10,000 transcripts in two laboratories (Liverpool and Manchester). An assay previously used by a U.S.-based group to detect MV transcripts in PDB had a sensitivity of 1000 transcripts. One laboratory (Manchester) detected CDV transcripts in a negative control and in two samples that had been spiked with MV. None of the other laboratories had false-positive results for MV or CDV, and no evidence of viral transcripts was found on analysis of 12 PDB samples using the most sensitive RT-PCR assays for MV and CDV.

CONCLUSIONS

We found that RT-PCR assays used by different laboratories differed in their sensitivity to detect CDV and MV transcripts but found no evidence to suggest that laboratories that previously failed to detect viral transcripts had less sensitive RT-PCR assays than those that detected viral transcripts. False-positive results were observed with one laboratory, and we failed to detect paramyxovirus transcripts in PDB samples using the most sensitive assays evaluated. Our results show that failure of some laboratories to detect viral transcripts is unlikely to be caused by problems with assay sensitivity and highlight the fact that contamination can be an issue when searching for pathogens by sensitive RT-PCR-based techniques.

Identification of a genetic variant of canine distemper virus from clinical cases in two vaccinated dogs in Mexico

Canine distemper virus (CDV) is a highly contagious viral pathogen of worldwide distribution that can cause lethal disease in dogs and other mammals. Genetic diversity is found among reference strains and isolates of CDV, mainly in the haemagglutinin protein (H), fusion protein (F) and nucleoprotein (N), and this may be associated with the increasing incidence of distemper in dogs. CDV was identified by RT-PCR in serum samples taken from two clinically diseased, previously vaccinated Mexican dogs. Subsequently, in both samples, a fragment of the CDV N gene was sequenced revealing a 100% identity between nucleotide sequences. However, the sequence obtained was different to that found in virus strains used in vaccines and in isolates reported elsewhere, but was closely related to A75/17, 1127/Gi95, and 2495/Gi95 sequences from USA and Germany, and clustered with 1127/Gi95 and 2495/Gi95 strains. The results suggest that a novel CDV lineage may be present in Mexico.

Genetic diversity of Hungarian canine distemper virus strains

To achieve proper diagnosis of dogs based on acute clinical symptoms and poorly preserved field samples taken from animals that died due to canine distemper (CD), a new differential diagnostic test has been developed based on polymerase chain reaction (PCR). In this study, more than 150 samples collected from dogs showing respiratory, gastrointestinal and neurological signs suggesting canine distemper virus (CDV) infection were examined. The samples consisted of urine, blood and nasal swabs collected from clinically ill patients, sent to our laboratory by clinicians from various veterinary clinics throughout Hungary. Various organs collected during the necropsy of dogs with pathological changes that suggested CDV infection were also included. Three distinct PCRs were designed. For diagnostic purposes, a primer pair specific to a 409 bases-long segment within the conservative part of the large polymerase region (L) of the CDV genome was designed. Using this test, out of the 150 analyzed samples, 46 (30.66%) proved to be positive for CDV, indicating that CDV still represents a high risk to the canine population in Hungary. For the phylogenetical analysis, a primer pair that completely encompasses the hemagglutinin (H) gene of the CDV genome was designed. The amplicons of this region were sequenced in both directions using the appropriate primers. Our results indicate that several different CDV genotypes are currently present in Hungary. Nine of the analyzed Hungarian strains turned out to belong to the so-called Arctic group of CDVs, and were most closely related to non-European strains from North America, China and Greenland, as well as to the phocine distemper virus 2 (PDV-2) isolated from Baikal seals (Phoca sibirica). One of the Hungarian strains showed high similarity to other European isolates from Denmark, Germany, Italy and Turkey, as well as to other isolates from geographically more distant regions, such as the USA. Three Hungarian strains seem to join a new cluster that is formed by only a couple of strains, one isolated from a mink in Denmark, and another from a dog in North America. Using a third set of primers, a restriction fragment length polymorphism (RFLP) assay has also been designed for the fast and reliable differentiation of the wild-type CDVs from the vaccine strains.

Genotyping canine distemper virus (CDV) by a hemi-nested multiplex PCR provides a rapid approach for investigation of CDV outbreaks

CDV is a highly contagious viral pathogen causing a lethal systemic disease in dogs and other carnivores. Several lineages or genotypes of CDV exist that are variously distributed throughout several continents. Legal or uncontrolled trading of animals may modify the epidemiology of CDV, introducing novel strains in CDV-naïve areas or accounting for the resurgence of CDV in areas where vaccine prophylaxis was effective and successful to control the disease. A hemi-nested PCR system was developed to genotype strains of the major CDV lineages, America-1, Europe, Asia-1, Asia-2 and Arctic. The assay was tested using a collection of 27 laboratory and vaccine strains and of 36 field CDV strains. Distinct lineages could be differentiated by specific primers targeted to the H gene. The method could be useful for molecular epidemiological studies of CDV, providing a tool for large-scale studies, and for the diagnosis of vaccine-related disease.

Infectious canine hepatitis: an "old" disease reemerging in Italy

Four outbreaks of infectious canine hepatitis (ICH) occurring in Italy between 2001 and 2006 are reported. Three outbreaks were observed in animal shelters of southern Italy, whereas a fourth outbreak involved two purebred pups imported from Hungary few days before the onset of clinical symptoms. In all outbreaks canine adenovirus type 1 (CAV-1) was identified by virus isolation and PCR. In three outbreaks, other canine viral pathogens were detected, including canine distemper virus, canine parvovirus or canine coronavirus. The present study shows that CAV-1 is currently circulating in the Italian dog population and that vaccination is still required.

Antemortem Diagnosis of CDV Infection by RT-PCR in Distemper Dogs with Neurological Deficits without the Typical Clinical Presentation

In dogs with neurological disturbances without myoclonus and extraneural signs, the clinical diagnosis of distemper is difficult perform. Considering the great infectious potential of the disease, the possibility of carrying out an antemortem diagnosis of distemper is important, particularly in hospitalized patients with neurological disease. The present study was carried out to evaluate RT-PCR for antemortem CDV detection in hospitalized dogs with neurological disturbances without the typical findings of distemper. We investigated five dogs with canine distemper virus (CDV) encephalomyelitis, in which the clinical diagnosis was not performed owing to the absence of characteristic signs of the disease, such as myoclonus and systemic signs. We observed an apparent high sensitivity of RT-PCR in urine samples for detection of CDV: four out of five urine samples were RT-PCR positive. The results of the present study suggest that urine is a good biological sample for antemortem CDV detection by RT-PCR in dogs with distemper encephalomyelitis in which the clinical diagnosis is likely to be difficult owing to the absence of suggestive distemper signs. The use of two different body fluids (urine and CSF) may increase the RT-PCR sensitivity for antemortem diagnosis of distemper in such cases.

Detection of canine distemper virus in dogs by real-time RT-PCR

Canine distemper virus is the etiological agent of a severe disease in dogs and many other carnivores. Clinical diagnosis of canine distemper is difficult due to the broad spectrum of signs that may be confounded with other respiratory and enteric diseases of dogs. Accordingly, a laboratory confirmation is required for suspected cases. In this study a real-time RT-PCR assay was developed for detection and quantitation of canine distemper virus. The assay exhibited high specificity as all the negative controls (no-template-controls and samples from healthy sero-negative dogs) and other canine pathogens were not misdetected. Up to 1 x 10(2) copies of RNA were detected by the TaqMan assay, thus revealing a high sensitivity. Quantitative TaqMan was validated on clinical samples, including various tissues and organs collected from dogs naturally infected by canine distemper virus. Urines, tonsil, conjunctival swabs and whole blood were found to contain high virus loads and therefore proved to be suitable targets for detection of canine distemper virus RNA.

Heterogeneity within the hemagglutinin genes of canine distemper virus (CDV) strains detected in Italy

Canine distemper virus (CDV) is a highly contagious viral pathogen causing lethal disease in dogs and other mammalians. A high degree of genetic variation is found between recent CDV strains and the old CDV isolates used in the vaccines and such genetic variation is regarded as a possible cause of the increasing number of CDV-related diseases in dogs. The H gene shows the greatest extent of genetic variation that allows for distinction of various lineages, according to a geographical pattern of distribution and irrespective of the species of identification. In the present study, hemagglutinin (H) genes obtained from field strains detected from clinical specimens of Italian dogs were analyzed genetically. Phylogenetic analysis revealed that a homogeneous group of CDV strains is widespread in Italian dogs, all which are included into the European lineage. Unexpectedly, strains 179/04 and 48/05 clustered along with CDVs of the Arctic lineage, the highest identity being to strain GR88 (98.0 and 98.4%aa, respectively). The full-length sequence of a red fox CDV strain, 207/00 was also determined and analyzed. The H protein of the fox CDV strain was unrelated to strains within the major European lineage. These results suggest that at least three different CDV lineages are present in Italy.

Detection of canine distemper virus by reverse transcriptase-polymerase chain reaction in the urine of dogs with clinical signs of distemper encephalitis

In a prospective study we evaluated the use of the reverse transcriptase-polymerase chain reaction (RT-PCR) in urine samples to diagnose canine distemper virus in dogs with progressive neurological disease. A fragment of the nucleoprotein gene of canine distemper virus was amplified from the urine of 22 distemper dogs. The body fluids and leukocytes of 12 asymptomatic dogs were RT-PCR negative. RT-PCR of urine samples was more sensitive than serum and leukocytes and at least as sensitive as cerebrospinal fluid to screen for distemper in dogs with neurological signs and extraneural systemic signs.

Cerebrospinal fluid from a 7-month-old dog with seizure-like episodes

A 7-month-old dog was presented to the Veterinary Teaching Hospital of the Universidade Estadual de Londrina, Paraná, Brazil with a 1-week history of seizure-like activity and compulsive walking. Neurological deficits included seizures, nystagmus, absence of a menace reaction, depressed postural reactions, spastic tetraparesis, opisthotonos, and spasticity of the thoracic limbs. Cerebrospinal fluid (CSF) evaluation showed severe lymphocytic pleocytosis (554 cells/microL, with 70% lymphocytes) and a protein concentration of 17 mg/dL. The histopathologic findings in cerebrum, cerebellum, and brainstem obtained at necropsy were compatible with acute encephalomyelitis caused by canine distemper virus (CDV). Using reverse transcription-polymerase chain reaction (RT-PCR), CDV RNA was detected in both CSF and fragments of fresh brain tissue. The results indicated that CDV was the agent responsible for the clinical and laboratory presentation. Severe pleocytosis with lymphocyte predominance is an unusual finding in canine distemper and must be differentiated from granulomatous meningoencephalitis. RT-PCR on CSF is a useful, fast, and specific method to diagnose CDV infection in dogs.

Comparative analyses of canine distemper viral isolates from clinical cases of canine distemper in vaccinated dogs

Sequence and phylogenetic analyses of three isolates of canine distemper virus (CDV) isolated from three dogs with a vaccination history were compared with the same analyses of vaccine virus isolated from a vaccine used for dogs. The three dogs showed clinical signs of a recent major type of CD in Japan, including oculonasal discharge and diarrhea, and pathological findings including non-suppurative encephalitis, pneumonia, mild gastroenteritis and lymphoid depletion. Inclusion bodies were in the stomach without inflammation and encephalitis was without clinical signs. One of the highest titers of CDV in different organs of the three dogs was commonly systemic lymphatic organs, including the spleen, lymph nodes and tonsils. New isolates of CDV joined to the clades of the Asia 1 group that is far from the vaccine group. These results surely indicate that wild strains of CDV from dogs with a vaccination history were not reversed vaccine virus, and that the dogs showed characteristics of recent CD in Japan.

Detection of canine distemper virus in blood samples by reverse transcription loop-mediated isothermal amplification

Reverse transcription loop‐mediated isothermal amplification (RT‐LAMP) was used to detect canine distemper virus (CDV) genomic RNA. A set of four primers, two outer and two inner, were designed from CDV genomic RNA targeting the nucleocapsid protein gene. The optimal reaction time and temperature for LAMP were determined to be 60 min at 65°C. The relative sensitivity and specificity of RT‐LAMP was found to be 100% and 93.3%, respectively, based on 50 canine blood samples and using RT‐PCR as the gold standard. The detection limit of the RT‐LAMP method was 100 times lower than with RT‐PCR (10‐1TCID50 ml⁻¹ versus 10TCID50 ml⁻¹). In addition to the advantage resulting from the visual detection of the end‐product, the LAMP method is fast, requiring only 1 h to complete the assay. The LAMP method is a viable alternative to RT‐PCR for diagnosing CDV infection in dogs. The LAMP method might be useful as an on site diagnostic assay for detecting CDV.

Pathogenesis and phylogenetic analyses of canine distemper virus strain 007Lm, a new isolate in dogs

The pathogenesis of a new isolate of canine distemper virus (CDV), strain 007Lm, was investigated from lymph node tissue by using Vero cells that express canine signalling lymphocyte activation molecules with a tag (Vero-DST) in dogs. Two CDV sero-negative Beagle dogs were inoculated intranasally and intraconjunctively with a virus suspension. Both infected dogs showed clinical signs of severe bloody diarrhea, conjunctivitis, ocular discharge, nasal discharge and coughing, lymphopenia, fever and weight loss. Titers of CDV-IgM and CDV-IgG in the blood were measured. CDV was detected by using reverse transcriptase-PCR and was recovered in swabs from one dog from 9 days and from the other dogs from 10 days after inoculation. Molecular and phylogenetic analyses of H and P genes showed that nucleotide and amino acid sequences of these genes of strain 007Lm after isolation in Vero-DST cells are identical to those of the original virus from fresh tissue and that strain 007Lm joins to the Asia 2 group cluster of CDV strains that is distinct from other clusters. These results indicate that (1) CDV strain 007Lm isolated in Vero-DST cells is virulent, (2) nucleotide and amino acid sequences of H and P genes of strain 007Lm do not change after isolation in Vero-DST cells compared with the original virus from fresh tissue and (3) strain 007Lm isolated from a vaccinated dog belongs to a cluster far from the vaccine strains in the phylogenetic trees of H and P genes.

Phylogenetic characterization of canine distemper viruses detected in naturally infected dogs in North America

In 2004, six puppies and one adult dog from a total of four premises were subjected to necropsy evaluation. For five of the seven dogs, disease caused by canine distemper virus (CDV) infection was suspected based on clinical signs. In all of the dogs, a diagnosis of CDV infection was established by the presence of compatible gross and histologic lesions, immunohistochemical labeling for CDV antigen, and detection of CDV RNA by reverse transcription-PCR. To further characterize the CDV strains detected in the four cases, complete gene sequences were determined for the hemagglutinin (H) and fusion (F) protein genes, while partial gene sequencing was performed for the phosphoprotein gene. A total of 4,508 bases were sequenced for the CDV strains detected from each of the four cases. Two cases were found to have identical sequences except for 2 bases in the intergenic region of the F and H genes. Phylogenetic analysis strongly suggested an evolutionary relationship between sequences detected in these two cases and those of phocine distemper virus 2 and two other strains of CDV not previously detected in the continental United States. Clear phylogenetic relationships were not established for viruses detected in the two additional cases; however, one strain showed similarity to CDV strains detected in a panda from China. Importantly, the three CDV strains detected were demonstrated to be genetically distinct from known vaccine strains and strains previously reported in the continental United States.

Immunohistochemical detection of antigens of distemper, adenovirus and parainfluenza viruses in domestic dogs with pneumonia

The lungs of 35 dogs that died in Mexico from acute or subacute pneumonia were examined immunohistochemically for canine distemper virus (CDV), canine adenovirus (CAV) and canine parainfluenza virus (CpiV), to determine their frequency and occurrence and possible associations. CDV was identified in 27 (77%) cases, CAV in 20 (57%) and CpiV in 18 (51%). The most frequent dual association was that between CDV and CpiV (five cases; 14%). All three viruses, however, were identified in the same lung in 10 cases. Immunolabelling occurred in alveolar macrophages, monocytes, pneumocytes, epithelial cells and syncytial cells. It was concluded that immunohistochemistry is a useful diagnostic tool in canine respiratory disease to complement histopathological examination.

Comparison of the immunofluorescence assay with RT-PCR and nested PCR in the diagnosis of canine distemper

Two pairs of primers were prepared, both localized within the sequences of the nucleoprotein gene (NP) of canine distemper virus (CDV). A number of experiments were done to optimize the conditions of RT-PCR and nested PCR methods. The nucleic acids of the Onderstepoort, Rockborn, Snyder Hill and Lederle strains of CDV could be detected with these primers. However, they did not react with the sequences of the Edmonston strain of the measles virus. The detection limit for RT-PCR was 10 TCID50 and for nested PCR 0.1 TCID50 of CDV. The RT-PCR was able to demonstrate the nucleic acid of CDV in the blood of all seven puppies vaccinated with a modified live virus. Blood samples of 23 dogs clinically suspected of distemper were examined by RT-PCR combined with nested PCR, and the results were compared with the detection of the CDV antigen in the smears from the mucous membranes by the direct immunofluorescence (IF) test. Of the 23 dogs, 12 were positive in nested PCR, six in the IF assay, and only two in single RT-PCR. It is concluded that nested PCR seems to be the most sensitive method for ante-mortem diagnosis of canine distemper, especially in its subacute or chronic forms.

[Can obesity be infectious?]

Currently the presence of obesity is increasing and it has become the basic civilisation illness of our times. Up to date no attention has been paid to the possibility of etiology of infectious obesity. Recently some publications have appeared whose authors suggest a possibility of an infectious derivation of some forms of obesity. Six pathogens causing obesity in animals have been described: canine distemper virus (CDV), avian adenovirus, Borna disease virus (BDV), SMAM-1, human adenovirus Ad-36, scrapie agent, Rous-associated virus-7 (RAV-7). Among them two viruses occur in humans: human adenovirus Ad-36 and avian adenovirus SMAM-1.

Nucleotide sequence analysis of nucleocapsid protein gene of canine distemper virus isolates in Thailand

The C-terminal part of the nucleocapsid protein gene of 13 canine distemper virus (CDV) isolates from Thailand, were analyzed. The nucleotide sequences were assigned to two clusters; cluster A exhibited a high degree of homology with the vaccine strain Onderstepoort, 99.10 and 97.61%, respectively, in the two isolates examined. Cluster B appeared closely related to virulent strains registered in the GeneBank database and to the virulent reference strain (A75/17); a total of 11 samples were analyzed, with 94.63-99.10% homology at the same position. The deduced amino acid sequences correlated with the two-nucleotide sequence clusters. However, there was no association among the CDV groups with histories of vaccination, sex, ages, clinical findings and evidence of viral antigen in tissues.

Phylogenetic and restriction fragment length polymorphism analyses of hemagglutinin (H) protein of canine distemper virus isolates from domestic dogs in Japan

We conducted phylogenetic and restriction fragment length polymorphism (RFLP) analyses of 995 nucleotides within the hemagglutinin (H) gene open reading frame (ORF) of field isolates of 23 canine distemper virus (CDV) strains isolated from domestic dogs in Japan between 1982 and 1998. The phylogenetic analysis showed that Japanese field isolates could be separated into three groups. Eighteen out of the twenty-three strains constituted one cluster consisting of Japanese CDVs, four strains formed a second Japanese CDV group, and only one strain belonged to a group containing foreign CDV strains. By RFLP analysis using SspI, we could distinguish all the Japanese field isolates from the vaccine strains. Thus, the RFLP method is useful for differentiating the infections with field CDV strains from the vaccine strains in clinical cases.