Interspecific differences between the DNA restriction profiles of canine adenoviruses

Difference Analysis Between Canine Adenovirus Types 1 And 2

Canine adenoviruses (CAdVs) include type 1 (CAdV-1, virulent strain) and type 2 (CAdV-2, attenuated strain). In recent years, the incidences of CAdV infections are increasing. However, they are difficult to distinguish when the symptoms are untypical. It is pivotal to find the differences between the two virus types for scientific, epidemiological, and specific treatment. CAdV-1 (virulent strain) and CAdV-2 (attenuated strain) induced canine hepatitis (ICH) and tracheobronchitis (ITB), respectively, but the clinical symptom is not obvious. CAdV-1 and CAdV-2 have the same genome structure, diameter, morphological features, and cytopathic features, but the same character hinder the diagnose time of the serotypes. CAdV-1 and CAdV-2 have a difference in the genome sequence, coding proteins, viral activity, hemagglutination patterns. After infection, pathogenicity and transmission route are different between the two serotypes. Sequence alignment, PCR, Real time-PCR assay are useful methods to distinguish the two serotypes. The attenuated live CAdV-2 vaccine is currently used to protect against CAdV-1, but it also has a risk. The further research should focus on the pathogenicity mechanism and the useful vaccine for the two serotypes of canine adenovirus.

Molecular analysis of a fragment of gene E1B 19K of canine adenovirus 2 (CAV-2) isolated from dogs with symptoms of cough

The aim of this study was to perform molecular analysis of canine adenovirus 2 (CAV-2) E1B 19K gene fragment isolated from 20 dogs of various breeds (12 males and 8 females aged 1-9 years), with clinical symptoms of upper respiratory tract infections, from the Lubelszczyzna region. Nasal swabs were taken from dogs. DNA of CAV-2 was detected using the PCR method in 16 swabs. All PCR products were sequenced, and the obtained sequences were compared with each other and with the sequence of the E1B 19K gene of the CAV-2 strain from an online database of NCBI GenBank: AC 000003. Based on analysis of the obtained sequences, three polymorphic variants of CAV-2 (No. 1-3) with homology of 78 - 100% were distinguished. The nucleotide and amino acid sequences of the most frequently represented polymorphic variant, No. 1, differed from the sequences of polymorphic variant No. 2 with one substitution. The nucleotide and amino acid sequence of the E1B 19K gene of CAV-2 AC 000003 differed from the analogous sequences of representatives of variant No. 1 with 44 nucleotide and 19 amino acid substitutions. The small number of nucleotide differences in the E1B 19K CAV-2 gene among the examined own isolates, compared with AC 000003, suggest that the infections in dogs were caused by a relatively genetically stable virus which occurs in eastern

Canine adenoviruses and herpesvirus

Canine adenoviruses (CAVs) and canine herpesvirus (CHV) are pathogens of dogs that have been known for several decades. The two distinct types of CAVs, type 1 and type 2, are responsible for infectious canine hepatitis and infectious tracheobronchitis, respectively. In the present article, the currently available literature on CAVs and CHV is reviewed, providing a meaningful update on the epidemiologic, pathogenetic, clinical, diagnostic, and prophylactic aspects of the infections caused by these important pathogens.

Canine respiratory viruses

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

Forty years of canine vaccination

During the last 40 years vaccines have been developed that have greatly reduced the incidence of infectious diseases of dogs. In general, modified live products have been superior to inactivated vaccines for dogs. It can be expected that recombinant and/or DNA vaccines may dominate the market in the future. Although most vaccines on the market are safe and efficacious, there have been exceptions where disease was induced by vaccination or dogs were not protected. The failure of protection may in part be due to variations in individual vaccine batches. Only potency tests but not efficacy tests are required, which may not be sufficient. For example, a virus titer in a vaccine may be meaningless if the minimum protective dose is not known. Overattenuated virus (e.g., CDV-Ond or parvovirus in cat cells) may have a high titer in tissue culture but is not immunogenic. The question of frequency of vaccination of dogs should be addressed. Annual revaccinations for CDV, CPV, and CAV are probably not needed. However, it would be desirable to collect more data to support less frequent vaccinations. Annual immunization for bacterial diseases such as kennel cough, Lyme disease, and leptospirosis should continue. It also would be desirable to develop more oro/nasal vaccines, perhaps combined with newly developed vectors that are less likely to induce undesirable side effects that may be seen after parenteral vaccination. Finally a word of warning against homeopathic "nosodes" to replace tested canine vaccines. They will appear highly effective as long as the majority of dogs remain vaccinated. As soon as a nonvaccinated dog population is large enough to allow virulent agents to spread, disease outbreaks will occur and we will be back where we began 40 years ago.

Isolation and identification of canine adenovirus type-2 from the upper respiratory tract of a dog

AIM

To report on the isolation and identification of canine adenovirus type-2 (CAV-2) from a greyhound dog with tracheitis/tonsillitis.

METHODS

Virus isolation was performed with Madin and Darby canine kidney (MDCK) cell monolayers using standard virological techniques. The isolated virus was identified by haemagglutination inhibition and serum neutralisation tests. Viral DNA was extracted from infected MDCK cells and subjected to restriction endonuclease analysis using the endonuclease enzymes Bam HI, Bgl II, Eco RI and Hind III.

RESULTS

A virus, designated 5 113-87, was isolated in MDCK cells yielding typical cytopathic effect. The virus could be neutralised with a CAV-2 specific reference antiserum and also showed some cross neutralisation with CAV-1 specific reference antiserum. The virus 5 113-87 had a high haemagglutination inhibition titre with CAV-2 antiserum using human group 0 red blood-cells and CAV-1 and CAV-2 reference antisera. This virus also had DNA restriction profiles identical to those of the reference CAV-2 (Toronto A26/61), whereas previously isolated strains of adenovirus from dogs in New Zealand had DNA restriction patterns identical to the prototype CAV-1 strain (Utrecht).

CONCLUSION

The findings show that the virus 5 113-87 isolated from the upper respiratory tract of a dog in New Zealand is CAV-2.

Two genomic variations in the E1 region of canine adenovirus type 2 strains

We amplified the E1 region of canine adenovirus type 2 genomes by the polymerase chain reaction (PCR) and analyzed the PCR products by using eight restriction endonucleases. Restriction patterns of the E1 region cleaved with HaeIII and RsaI revealed two genomic variations among the canine adenovirus type 2 strains. Although the clinical significance of two distinct genotypes among the canine adenovirus type 2 strains is currently unknown, these genomic variations are well conserved among different strains in each genotype and suggest that the Japanese field strains, with reference to the E1 region, are different from the non-Japanese strains examined.

Genotypic differences between the mouse adenovirus strains FL and K87

Restriction endonuclease analysis was used to compare the genome of mouse adenovirus (MAd) strains FL and K87. Large differences were found between the Kpn I, PaeR7, Pvu I, Sal I and Sma I restriction profiles of the prototype strains. MAd-FL and MAd-K87 thus represent two distinct species of mouse adenovirus.

Cloning, physical mapping and cross-hybridization of the canine adenovirus types 1 and 2 genomes

Cloned HindIII fragments of the type 1 and type 2 canine adenovirus (canAd) genomes were mapped with respect to the BamHI, EcoRI, HincII, PaeR7 and PstI restriction endonuclease cleavage sites. Considering the large differences found between the canAd-1 and canAd-2 DNA molecules, in terms of number and location of restriction sites, cross-hybridization experiments were performed. Homologous DNA sequences were located on the canAd-1 and canAd-2 physical maps. Both viruses are genetically related to the extent of 57%. Our results confirm the existence of two distinct Ad species in the dog.