Three-year serologic immunity against canine parvovirus type 2 and canine adenovirus type 2 in dogs vaccinated with a canine combination vaccine

A group of client-owned dogs and a group of dogs at a commercial kennel were evaluated for duration of antibody responses against canine parvovirus type 2 (CPV-2) and canine adenovirus type 1 (CAV-1) after receiving a combination vaccine containing recombinant canarypox-vectored canine distemper virus (CDV) and modified-live CPV-2, CAV-2, and canine parainfluenza virus, with (C6) or without (C4) two serovars of Leptospira (Recombitek C4 or C6, Merial). Duration of antibody, which correlates with protective immunity, was found to be at least 36 months in both groups. Recombitek combination vaccines can confidently be given every 3 years with assurance of protection in immunocompetent dogs against CPV-2 and CAV-1 as well as CDV. This allows this combination vaccine, like other, similar modified- live virus combination products containing CDV, CAV-2, and CPV-2, to be administered in accordance with the recommendations of the American Animal Hospital Association Canine Vaccine Task Force.     

Occurrence of canine parvovirus type 2c in the dogs with haemorrhagic enteritis in India

Canine parvovirus 2 (CPV-2) causes a highly contagious and often fatal disease in dogs. Since its sudden emergence in the early 1970s, CPV-2 has been evolving through the generation of novel genetic and antigenic variants (CPV-2a/b/c) that are unevenly distributed throughout the world. In the present study we have examined 36 clinical cases of dogs suspected of CPV collected during year 2006. A fragment of the VP2 gene of the virus was analyzed using polymerase chain reaction (PCR), restriction endonuclease (RE) and DNA sequence analysis. Out of the 36 samples analyzed, 16 were found positive for CPV-2a/2b by conventional PCR. DNA sequencing was done for 6 PCR positive samples, out of which three were characterized as CPV-2c, indicating that this CPV type 2c is currently circulating in India.     

Chronological analysis of canine parvovirus type 2 isolates in Japan

Fifty-five canine parvovirus type 2 (CPV) samples, 12 fecal specimens and 43 cell culture isolates, were examined for their genetic characteristics of VP2 gene. They were collected from the diseased dogs at various districts of Japan during 27 years from 1980 to 2006. A fragment of VP2 gene was analyzed by restriction fragment length polymorphism assay and DNA sequencing. The original antigenic type 2 of CPV (CPV-2) was no longer found in the samples since 1984, and two antigenic variants CPV-2a and CPV-2b replaced CPV-2 as predominant types for about 5 years from 1982. A new genetic variant of prototype CPV-2a with non-synonymous substitution at the VP2 amino acid residue 297 from Ser to Ala was first detected in 1987. New CPV-2b with the same amino acid substitution at position 297 as new CPV-2a was also detected from the samples collected in 1997. Since then new CPV-2b has been the predominant CPV over the field of Japan. Several additional amino acid substitutions were detected in the VP2 gene of some recent CPV strains. Neither CPV-2c(a), CPV-2c(b), nor "Glu-426" of the antigenic variants previously found outside the country was detected in any samples tested. Reactivity of new CPV-2a and 2b variants against antibodies produced by the current vaccine products was determined by a cross hemagglutination-inhibition test. The recent field CPV isolates reacted more efficiently to the antibodies produced in dogs vaccinated with the new CPV-2b vaccine strain than the conventional CPV-2 vaccine strain.     

A real-time PCR assay for rapid detection and quantitation of canine parvovirus type 2 in the feces of dogs

We describe a rapid, sensitive and reproducible real-time PCR assay for detecting and quantifying canine parvovirus type 2 (CPV-2) DNA in the feces of dogs with diarrhea. An exogenous internal control was added to control the assay performance from extraction to amplification. The method was demonstrated to be highly specific and sensitive, allowing a precise CPV-2 DNA quantitation over a range of eight orders of magnitude (from 10(2) to 10(9) copies of standard DNA). The reproducibility of the CPV-2 real-time PCR assay was assessed by calculating the coefficients of variation (CV) intra-assay and inter-assay for samples containing amounts of CPV-2 DNA spanning the whole range of the real-time PCR standard curve. Then, fecal specimens from diarrheic dogs were analyzed by hemagglutination (HA), conventional PCR and real-time amplification. Comparison between these different techniques revealed that real-time PCR is more sensitive than HA and conventional gel-based PCR, allowing to detect low viral titers of CPV-2 in infected dogs.     

Antibody levels and protection to canine parvovirus type 2

The relationship between maternally derived antibody (MDA) levels and protection to canine parvovirus (CPV) infection in pups is reported. Twelve pups with a wide range of haemagglutination inhibiting (HI) titres of MDA to CPV were divided into four groups, with each group balanced for antibody titres. The dogs were inoculated with a field CPV-2b strain and clinical signs, virus shedding and antibody response were assessed. The CPV was not detected in the faeces of dogs with HI titres of 320 at any time. In dogs with HI titres up to 160, active CPV replication after challenge was demonstrated by real-time polymerase chain reaction. The successful infection of dogs with HI titres of 80 and 160 was confirmed by seroconversion, evaluated at day 14 post-infection. These findings demonstrated that CPV infection could also occur in the presence of MDA HI titres (> or =80) usually considered fully protective.     

Stray dogs as sentinels for canine parvovirus

An attempt to determine the prevalence of canine parvovirus in the stray dog population of Franklin County, Ohio (U.S.A.) was made by sampling dogs during the first 6 months of 1981. Serum and fecal samples, which were collected from 209 strays at time of euthanasia, were tested by serum hemagglutination inhibition (HI) and fecal hemagglutination (HA) techniques to determine canine parvovirus experience (seropositive) or fecal virus shedding, respectively. Sera collected from 93 strays for an unrelated study conducted in 1979 were used as the comparison group. All of the 1979 sera were HI negative (< 1:80) whereas, 139 of 201 (69.2%) sera suitable for testing from the 1981 group of strays were HI positive (? 1:80). The fecal HA results from the 1981 group revealed 26 of the 209 (12.4%) dogs were shedding parvovirus at time of euthanasia (HA titers ? 1:64). Of these 26 of the 209 (12.4%) dogs were shedding parvovirus at time of euthanasia were found to be seropositive. These results indicate that the stray population of Franklin County, Ohio, was not exposed in 1979, but by 1981 had experienced and for the most part, had recovered from canine parvovirus as indicated by a 69.2% seropositive dog population with 12.4% active virus shedders. The stray dog population, if sampled regularly, could thus serve as a sentinel for canine parvovirus activity in a community.     

Occurrence of canine parvovirus type 2c in the United States.

Canine parvovirus (CPV) type 2 (CPV-2) emerged around 1978 as a major pathogen of dogs worldwide. In the mid-1980s, the original CPV-2 had evolved and was completely replaced by 2 variants, CPV-2a and CPV-2b. In 2000, a new variant of CPV (named CPV-2c) was detected in Italy and now cocirculates with types 2a and 2b in that country. The CPV-2c has also been reported from single outbreaks in Vietnam and Spain. This study was conducted to determine if CPV-2c occurs in the United States. Thirty-three fecal samples were collected from dogs in 16 states between April 2006 and April 2007 and were tested for CPV using real-time polymerase chain reaction (PCR). Positive samples were further tested using conventional PCR and minor-groove binding TaqMan PCR assays to determine the viral type and to differentiate vaccine strains from field strains. Twenty-seven samples were positive for CPV, 7 of which were CPV-2c from 5 states: Arizona, California, Georgia, Oklahoma, and Texas. Of the 7 isolates, 4 differed from European CPV-2c isolates by 2 additional single-nucleotide mutations at positions 4076 and 4104, the latter of which produces a ThrAla change at residue 440 located near a major antigenic site. The coast-to-coast geographic distribution of the states in which CPV-2c was detected strongly suggests that this new CPV variant is probably widespread in the United States. The continuous evolution of CPV requires that monoclonal antibody-based and nucleic acid-based diagnostic assays should be periodically checked for sensitivity on prevalent CPV strains.     

First detection of canine parvovirus type 2c in South America

Since its sudden emergence in the early 1970s, canine parvovirus type-2 (CPV-2) has been evolving through the generation of novel genetic and antigenic variants (CPV-2a/b/c and a number of additional mutations) that are unevenly distributed throughout the world. In order to develop strategies to control the spread of these variants and to understand virus evolution is fundamental to genotype field isolates from different geographic locations. In the present paper we have examined 25 isolates of CPV from clinical samples of Uruguayan dogs collected during year 2006. A fragment of the VP2 gene of the virus was analyzed using polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) and DNA sequence analysis. Out of the 25 isolates analyzed, only one was characterized as CPV-2a and 24 were characterized as CPV-2c, indicating that this type is currently the prevalent field CPV circulating in Uruguay. This is the first report of CPV-2c in the American continent and it also represents the highest frequency of this type observed in a dog population so far. Its presence in South American supports the assumption that CPV-2c is reaching a worldwide distribution as occurred with 2a/2b antigenic types.     

Genetic analysis of canine parvovirus from dogs in Australia

OBJECTIVE: To determine the genetic variants of canine parvovirus-2 (CPV) present in domestic dogs in Australia and to investigate 26 cases of apparent vaccine failure. DESIGN: Thirty-three samples of faeces or intestinal tissues and 16 cell culture virus isolates collected over a period from 1980 to 2005 from five Australian states were analysed. Procedure DNA was extracted from the samples and a 1975 bp fragment of the VP1/2 gene of CPV was amplified by polymerase chain reaction (PCR) and sequenced. Sequences were compared to published strains of CPV-2, CPV-2a, CPV-2b and CPV-2c. RESULTS: Forty-one of 43 PCR-positive samples contained CPV-2a viruses. One sample collected in 2002 from a pup in northern NSW contained a CPV-2b virus. One sample that had been included in the study as a CPV-antigen negative control sample contained a CPV-2 virus. CONCLUSION: CPV-2a remains the predominant genetic variant of CPV in dogs in Australia and has not been replaced by CPV-2b or CPV-2c as in many other countries. The vaccine failures investigated in the study were likely caused not by genetic variation of field viruses but by maternal antibody interference in the response of pups to vaccination.     

Phylogenetic analysis of canine parvovirus CPV-2 strains and its variants isolated in Poland

Canine parvovirus disease appeared in the world and in Europe during the second half of the 1970s. Over the course of 40 years the original CPV-2 strains mutated and variants 2a, 2b and 2c appeared. Their appearance is connected with specific amino acid changes, mainly in the capsid protein VP2. Strains isolated by the authors were adapted for in vitro cell culture. Phylogenetic analysis revealed differences between strains isolated in Poland in 1982-1985 and in 1995-2009. Strains from the 1980s were shown to belong to variant CPV-2a (11 strains) and variant 2b (2 strains), while no fundamental differences were found among the genetic profiles of the strains from 1995-2009, which were classified as belonging to variant 2c.     

New approaches for the molecular characterization of canine parvovirus type 2 strains

Characterization of the canine parvovirus type 2 (CPV-2) is sometimes ambiguous, frequently requiring more than one technique for definitive prediction of the viral type. Taking into account the single-nucleotide polymorphisms encountered in the VP2-protein gene between types 2a and 2b and between type 2b and Glu-426 mutant (type 2c), two different minor groove binder (MGB) probe assays were developed for rapid identification of the CPV-2 variants. A total of 315 samples collected from dogs with diarrhoea were screened for CPV-2 by a real-time polymerase chain reaction (PCR) assay capable of detecting all CPV-2 types. In order to compare the type-specific assays with the traditional techniques [haemagglutination inhibition with monoclonal antibodies, PCR-restriction fragment-length polymorphism (RFLP), sequence analysis] for prediction of CPV-2 antigen specificity, the 203 samples tested CPV-2 positive were analysed using the different methods. The results showed a 100% concordance between the MGB probe assays and the combined conventional methods, with 116 samples characterized as type 2a, 32 as type 2b and 55 as type 2c. Therefore, the MGB probe assays represent a quick, reliable tool for prediction of CPV-2 antigen specificity, with regard to the more time-consuming assays currently used.     

犬细小病毒新2b型分离株的分离鉴定

为了更好的了解我国东北地区犬细小病毒的流行情况,采用F81细胞从来自长春某宠物医院疑似患有肠炎的犬粪便样品中分离出1株病毒,经形态学、血清学、动物回归试验和分子生物学鉴定,分离的病毒为犬细小病毒new CPV-2b型,命名为CPV JL13-1。对该病毒主要结构蛋白VP2基因进行克隆测序和基因进化分析表明,CPV JL13-1分离株VP2基因与GenBank上提交的其他41株犬细小病毒株核苷酸和氨基酸均有较高的同源性,分别为98.6%~99.5%和97.6%~99.5%,其中核苷酸和氨基酸同源性最高的均为B-2004株。本研究为犬细小病毒分子流行病学调查和疫苗的研究奠定基础。     

Antibody titers for canine parvovirus type-2, canine distemper virus, and canine adenovirus type-1 in adult household dogs

Serum antibody titers for canine parvovirus type-2 (CPV-2), canine distemper virus (CDV) and canine adenovirus type-1 (CAV-1) were investigated in 1031 healthy adult household dogs (2 to 18 years old) given an annual inoculation in the previous 11 to 13 months. The number of dogs retaining significant titers of antibodies against CPV-2, CDV, and CAV-1 were 888 (86%), 744 (72%), and 732 (71%), respectively. There were no differences between males and females in antibody titers against the 3 viruses. Antibody titer for CPV-2 was significantly higher in younger dogs than in older dogs, CDV antibody was significantly higher in older dogs than in younger dogs, and CAV titer was not associated with age.     

辽宁省警犬犬瘟热犬细小病毒和犬冠状病毒感染情况调查

犬传染病是危害养犬业健康发展的主要疾病,来自警犬方面的统计资料证实,全国每年免疫警犬的发病率为14％,其中传染病占60％以上,因传染病而死亡的犬超过死亡犬总数的80％。从近几年的临床实践和国外的有关报道来看,危害严重的犬病毒病主要有犬瘟热、犬细小病毒感染、犬传染性肝炎、犬冠状病毒病、犬副流感及狂犬病等6种疾病,     

Peptide nucleic acid-based (PNA) array for the antigenic discrimination of canine parvovirus

A novel peptide nucleic acid (PNA)-based array was developed for use in ante-mortem antigenic typing discrimination in dogs with canine parvovirus (CPV). Cyclic benzothiazole-2-sulfonyl PNA monomers were synthesized that recognized GTA (CPV-2) and TAT (CPV-2a, -2b and -2c) at the nt 913–915 positions, and AAT (CPV-2 and CPV-2a), GAT (CPV-2b), and GAA (CPV-2c) at the nt 1276–1278 positions of the VP2 gene. The detection limits for aa 305 and aa 426 of the VP2 proteins belonging to the four CPV antigenic types were determined optically to be 40–2000 DNA copies, and the optimal cut-off fluorescence signaling value was fixed at 5000. The PNA array described here was developed from 135 field dog fecal specimens and had 89.8% (62/69) sensitivity and 90.4% (66/73) specificity compared with a real-time PCR using the TaqMan assay, a gold standard method. This CPV PNA array could be used together with MGB probe assays as an attractive novel tool for ante-mortem antigenic typing discrimination.     

Current status and risk factors of canine parvovirus type 2 in North Central Nigeria

Since its emergence in Nigeria, canine parvovirus type 2 (CPV-2) infection has posed problems to dog breeding and requires constant awareness and monitoring. In this study, the status, the assessment of extrinsic risk factors of parvoviral infection in dog kennels in North Central Nigeria, and isolation of the CPV-2 were carried out. Potential risk factors were considered during sampling: age, breed, sex, location, vaccination and health status, using well-structured questionnaires on dog owners with experience of CPV-2 infection. There was high prevalence which depended on age, breed, location, clinical status of the dog while vaccination status of the dogs did not influence the prevalence. CPV-2 vaccination compliance by the breeders and management system of the kennels were also observed as risk factors. Isolation of CPV-2a and -2c strains from Nigeria for further study has been reported. The spread of CPV-2 in Nigeria is increasing, hence needs for continual epidemiological monitoring and review.