Development and characterization of a novel specific monoclonal antibody against mink enteritis virus and its antigen epitope analysis.

This study prepared a novel monoclonal antibody (MAb) against mink enteritis parvovirus (MEV) and identified its antigen epitope. The antibody subclass is identified as IgG1, the titers of the MAb is up to 1:1 × 106 and keeps stably after low-temperature storage for 9 months or 11 passages of the MAb cells. The MAb can specifically recognize MEV in the cells in IFA, but not Aleutian disease virus (ADV) or canine distemper virus (CDV). Its antigen epitope was identified as a polypeptide containing 5 key amino acids (378YAFGR382) and the homology in 20 MEV strains, 4 canine parvovirus strains, and 4 feline panleukopenia virus strains was 100%. This study supplies a biological material for developing new methods to detect MEV.

Canine parvovirus type 2 (CPV-2) serological and molecular patterns in dogs with viral gastroenteritis from southern Brazil.

Canine Parvovirus type 2 (CPV-2) is a highly contagious virus that can cause severe systemic disease with gastroenteric symptoms in dogs, particularly in young puppies. Originating from the feline parvovirus in the late 1970s, it swiftly propagated globally, instigating a pandemic in dogs. Despite vaccination advancements, CPV-2 remains a substantial challenge for veterinary professionals and pet owners. This study aimed to contribute knowledge about the current situation of CPV-2 among dogs in southern Brazil. In this study, the sera of 125 dogs (mostly with gastroenteritis symptoms) were screened for antibodies against CPV-2 and their faeces for the virus itself. The results showed that 40% (50/125) of dogs were infected with CPV-2. Most animals (65.5%) had previously been exposed to CPV-2 (with serotitres equal or above 1:40), and only 37.6% had protective antibody titres equal or above 1:80. The findings have also demonstrated that vaccination against CPV-2 significantly reduced the risk of infection, with positive cases decreasing from 56.9% (unvaccinated) to 2.0% (fully vaccinated). Furthermore, the prevalence of CPV-2 decreased as dogs aged, with younger dogs and those with an incomplete or non-existent vaccination history at the highest risk of infection. In conclusion, this study provides valuable insight into the prevalence and risk factors associated with CPV-2 infection in dogs in southern Brazil, thereby providing valuable knowledge for the improvement of veterinary care and pet health.

Comparison of Eight Commercially Available Faecal Point-of-Care Tests for Detection of Canine Parvovirus Antigen.

A real-time polymerase chain reaction (qPCR) is considered the gold standard for the laboratory diagnosis of canine parvovirus (CPV) infection but can only be performed in specialized laboratories. Several point-of-care tests (POCT), detecting CPV antigens in faeces within minutes, are commercially available. The aim of this study was to evaluate eight POCT in comparison with qPCR. Faecal samples of 150 dogs from three groups (H: 50 client-owned, healthy dogs, not vaccinated within the last four weeks; S: 50 shelter dogs, healthy, not vaccinated within the last four weeks; p = 50 dogs with clinical signs of CPV infection) were tested with eight POCT and qPCR. Practicability, sensitivity, specificity, positive (PPV) and negative predictive values (NPV), as well as overall accuracy were determined. To assess the differences between and agreement among POCT, McNemar's test and Cohen's Kappa statistic were performed. Specificity and PPV were 100.0% in all POCT. Sensitivity varied from 22.9-34.3% overall and from 32.7-49.0% in group P. VetexpertRapidTestCPVAg® had the highest sensitivity (34.3% overall, 49.0% group P) and differed significantly from the 3 POCT with the lowest sensitivities (Fassisi®Parvo (27.7% overall, 36.7% group P), Primagnost®ParvoH+K (24.3% overall, 34.7% group P), FASTest®PARVOCard (22.9% overall, 32.7% group P)). The agreement among all POCT was at least substantial (kappa >0.80). A positive POCT result confirmed the infection with CPV in unvaccinated dogs, whereas a negative POCT result did not definitely exclude CPV infection due to the low sensitivity of all POCT.

Predominance of canine parvovirus 2b in Japan: an epidemiological study during 2014-2019.

Canine parvovirus 2 (CPV-2) is an important pathogen of domestic dogs and wild canids. In Japan, CPV-2 infection is one of the most common infectious diseases of dogs. We analyzed samples collected between 2014 and 2019 to identify antigenic variants of CPV-2 in dogs in Japan. Our results demonstrated that the CPV-2b variant was predominant. The CPV-2c variant was not found among our samples. Our findings demonstrate that the distribution of CPV-2 antigenic variants in Japan was more similar to that in Australia than to that in neighboring countries in Asia.

Modified haemagglutination inhibition assay for the detection of canine parvovirus type 2 antibodies in dog sera.

Canine parvovirus type 2 (CPV-2) infection is associated with severe gastroenteritis in puppies. Quantification of CPV-2 specific antibodies before vaccination can reveal the presence of interfering maternal-derived immunity and facilitate timing of effective immunisation. Inhibition of haemagglutination (HI) is commonly used to measure CPV-2-specific antibody levels in serum. However, the presence of nonspecific agglutinins in canine serum and artefactual precipitation of red blood cells (RBC) are both limitations of the assay. In this study, we compared the standard HI protocol with a refined HI protocol, in which canine serum was pre-incubated with porcine RBC for 12 h to remove nonspecific agglutinins and a lower concentration (0.1% vs. 0.8%) of porcine RBC suspensions was used to limit artefactual precipitation of RBC. A panel of canine sera, collected from 80 dogs of different ages and with different neutralising antibody titres, was analysed. Nonspecific agglutinins were identified in most (97%) serum samples from puppies <4 months of age and in only 7% dogs 6 months old. Pre-treatment of serum samples was effective in removing nonspecific agglutinins from all samples and artefactual precipitation of RBCs was not noted when 0.1% RBC suspensions were used. Refinement of the HI protocol has increased the accuracy of interpretation and reduced the interference of nonspecific agglutinins, primarily seen in puppies. This reduces the likelihood of incorrect assessment of passive or active immunity in puppies when deciding whether to administer or defer vaccination, which could potentially leave them susceptible to CPV-2 infection.

Generation and evaluation of IgY-scFv based mimetics against canine parvovirus.

Antibody mimetics may be used for various biomedical applications, especially those for which conventional antibodies are ineffective. In this study, we developed a smaller molecular chicken IgY mimetic peptide (IgY-peptide) based on the complementarity-determining regions (CDRs) of the anti-canine parvovirus (CPV) IgY-scFv prepared previously. The mimetic peptide showed no cross-reactivity with canine distemper virus (CDV) and canine coronavirus (CCV) and showed excellent protective properties for Crandell-Rees Feline Kidney (CRFK) cells against CPV. This study is the first attempt to develop a mimetic IgY-peptide and demonstrates the ease and feasibility in generating such a novel antibody-like functional molecule for biomedical purposes.

[Prevention of canine parvovirosis - Part 1: Humoral and cellular immunity]. / Prophylaxe der kaninen Parvovirose.

Canine parvovirosis remains a common and highly infectious disease. Thus, adequate protection is essential for all dogs at any time. In this, humoral immunity plays an essential role. The presence of antibodies in adult dogs suggests immunity against the disease, and nearly all adult dogs possess antibodies (either due to previous vaccination or infection). Meanwhile, worldwide vaccination guidelines recommend measurement of pre-vaccination antibodies instead of regular triennial re-vaccinations in adult dogs. Studies have demonstrated a long lasting duration of immunity against canine parvovirus. Re-vaccination therefore possesses no beneficial effect when dogs already have pre-vaccination antibodies. Thus, when antibodies are present, unnecessary re-vaccinations that potentially cause vaccine-associated adverse events should be avoided. Hemagglutination inhibition and virus neutralization can be performed in specialized laboratories for quantitative antibody titer measurement. Semiquantitative point-of-care (POC) tests for detection of CPV antibodies are available. Since the presence of CPV antibodies in adult dogs that have been vaccinated or previously infected suggests adequate immunity against disease, these POC tests can be a useful tool in practice. They identify dogs that might potentially be unprotected and require re-vaccination during preventive health care appointments. Concerning the POC tests' quality assessment, a high specificity (low number of false positive test results) is considered the most important feature.

Determination of parvovirus antigen in the vaccine using time-resolved fluorescence immunoassay.

As a highly contagious and potentially fatal disease of dogs, canine parvovirus type 2 (CPV-2) usually causes severe myocarditis and gastroenteritis, while vaccine injection has greatly reduced the incidence of CPV-2 diseases. However, there is currently a lack of simple and effective method for quantitative detection of CPV-2 in vaccine. Therefore, this study aims to prepare an accurate method to determine the CPV-2 antigen (CPV-2-Ag) in vaccine. Here, a sandwich time-resolved fluorescence immunoassay (TRFIA) was established and optimized. Anti-CPV-2 antibodies were immobilized on 96-well plates to capture CPV-2-Ag, and then bound together with the detection antibodies labeled with Europium(III) (Eu3+ ) chelates; finally, time-resolved fluorometry was employed to measure the fluorescence intensity. Vaccination was performed to evaluate the relationship between CPV-2-Ag concentration and antibody titer. The sensitivity is 1.15 mEU/mL (LogY = 1.524 + 0.8667 × LogX, R2  = 0.9933), and the average recovery is among 91.00% to 106.39% without cross-reactions with the other canine viral antigen. The correlation between ELISA assay and this method is up to 0.9861. And, there is high correlation between the CPV-2-Ag concentration and antibody titers (R2  = 0.9234). This immunoassay established has high sensitivity, accuracy, and specificity, which indicate that this method could be suitable for quantitative detection of CPV-2-Ag in vaccine evaluation.

Analysis of canine parvoviruses circulating in Australia reveals predominance of variant 2b and identifies feline parvovirus-like mutations in the capsid proteins.

Canine parvovirus (CPV) is a major enteric pathogen of dogs worldwide that emerged in the late 1970s from a feline parvovirus (FPV)-like ancestral virus. Shortly after its emergence, variant CPVs acquired amino acid (aa) mutations in key capsid residues, associated with biological and/or antigenic changes. This study aimed to identify and analyse CPV variants and their capsid mutations amongst Australian dogs, to gain insights into the evolution of CPV in Australia and to investigate relationships between the disease and vaccination status of dogs from which viruses were detected. CPV VP2 sequences were amplified from 79 faecal samples collected from dogs with parvoviral enteritis at 20 veterinary practices in five Australian states. The median age at diagnosis was 4 months (range 1-96 months). Only 3.7% of dogs with vaccination histories had completed recommended vaccination schedules, while 49% were incompletely vaccinated and 47.2% were unvaccinated. For the first time, CPV-2b has emerged as the dominant antigenic CPV variant circulating in dogs with parvoviral enteritis in Australia, comprising 54.4% of viruses, while CPV-2a and CPV-2 comprised 43.1% and 2.5%, respectively. The antigenic variant CPV-2c was not identified. Analysis of translated VP2 sequences revealed a vast repertoire of amino acid (aa) mutations. Several Australian CPV strains displayed signatures in the VP2 protein typical of Asian CPVs, suggesting possible introduction of CPV strains from Asia, and/or CPV circulation between Asia and Australia. Canine parvoviruses were identified containing aa residues typical of FPV at key capsid (VP2) positions, representing reverse mutations or residual mutations retained from CPV-2 during adaptation from an FPV-like ancestor, suggesting that evolutionary intermediates between CPV-2 and FPV are circulating in the field. Similarly, intermediates between CPV-2a-like viruses and CPV-2 were also identified. These findings help inform a better understanding of the evolution of CPV in dogs.

Comparison of Four Commercially Available Point-of-Care Tests to Detect Antibodies against Canine Parvovirus in Dogs.

Measuring antibodies to evaluate dogs' immunity against canine parvovirus (CPV) is useful to avoid unnecessary re-vaccinations. The study aimed to evaluate the quality and practicability of four point-of-care (POC) tests for detection of anti-CPV antibodies. The sera of 198 client-owned and 43 specific pathogen-free (SPF) dogs were included; virus neutralization was the reference method. Specificity, sensitivity, positive and negative predictive value (PPV and NPV), and overall accuracy (OA) were calculated. Specificity was considered to be the most important indicator for POC test performance. Differences between specificity and sensitivity of POC tests in the sera of all dogs were determined by McNemar, agreement by Cohen's kappa. Prevalence of anti-CPV antibodies in all dogs was 80% (192/241); in the subgroup of client-owned dogs, it was 97% (192/198); and in the subgroup of SPF dogs, it was 0% (0/43). FASTest® and CanTiCheck® were easiest to perform. Specificity was highest in the CanTiCheck® (overall dogs, 98%; client-owned dogs, 83%; SPF dogs, 100%) and the TiterCHEK® (overall dogs, 96%; client-owned dogs, 67%; SPF dogs, 100%); no significant differences in specificity were observed between the ImmunoComb®, the TiterCHEK®, and the CanTiCheck®. Sensitivity was highest in the FASTest® (overall dogs, 95%; client-owned dogs, 95%) and the CanTiCheck® (overall dogs, 80%; client-owned dogs, 80%); sensitivity of the FASTest® was significantly higher compared to the one of the other three tests (McNemars p-value in each comparison: <0.001). CanTiCheck® would be the POC test of choice when considering specificity and practicability. However, differences in the number of false positive results between CanTiCheck®, TiterCHEK®, and ImmunoComb® were minimal.

Diagnostic Challenges in Canine Parvovirus 2c in Vaccine Failure Cases.

In this study, three different diagnostic tests for parvovirus were compared with vaccination status and parvovirus genotype in suspected canine parvovirus cases. Faecal samples from vaccinated (N17) and unvaccinated or unknown vaccination status (N41) dogs that had clinical signs of parvovirus infection were tested using three different assays of antigen tests, conventional and quantitative PCR tests. The genotype of each sample was determined by sequencing. In addition to the suspected parvovirus samples, 21 faecal samples from apparently healthy dogs were tested in three diagnostic tests to evaluate the sensitivity and specificity of the tests. The antigen test was positive in 41.2% of vaccinated dogs and 73.2% of unvaccinated diseased dogs. Conventional PCR and qPCR were positive for canine parvovirus (CPV) in 82.4% of vaccinated dogs and 92.7% of unvaccinated dogs. CPV type-2c (CPV-2c) was detected in 82.75% of dogs (12 vaccinated and 36 unvaccinated dogs), CPV-2b was detected in 5.17% dogs (one vaccinated and two unvaccinated) and CPV-2a in 1.72% vaccinated dog. Mean Ct values in qPCR for vaccinated dogs were higher than the unvaccinated dogs (p = 0.049), suggesting that vaccinated dogs shed less virus, even in clinical forms of CPV. CPV-2c was the dominant subtype infecting dogs in both vaccinated and unvaccinated cases. Faecal antigen testing failed to identify a substantial proportion of CPV-2c infected dogs, likely due to low sensitivity. The faecal samples from apparently healthy dogs (n = 21) showed negative results in all three tests. Negative CPV faecal antigen results should be viewed with caution until they are confirmed by molecular methods.

Molecular characterisation of canine parvoviruses from clinical samples and vaccines in Nigeria.

Canine parvovirus (CPV) the causative agent of canine parvovirus enteritis is an intractable pathogen of dogs characterised by mutations, evolutionary changes and eventual vaccine failure. The disease is a serious problem in dogs with limited studies conducted in Nigeria. Therefore, this study was designed to characterise the subtypes of CPV isolates in six commonly used vaccines and 157 clinical samples collected from seven states in Nigeria from June 2016 to March 2018. Faecal samples collected from the clinical cases were subjected to in-clinic immunoassay to detect viral antigens. Polymerase chain reaction (PCR) was used to amplify viral VP2 gene in the samples and commonly used vaccines in Nigeria. Thereafter, PCR products were sequenced and analysed. The result showed that 93.0% of the dogs tested positive for CPV in both assays; 72.8% were puppies less than six months old, with 58.3% of them vaccinated. Partial VP2 gene sequence and phylogenetic analysis of 11 random clinical samples showed that CPV-2c 7(63.6%) and CPV-2a 4(36.4%) were the predominant subtypes in Nigeria; with genetic signatures that are 98.7% to 99.9% closely related to Asian and European strains, respectively. No CPV-2b was detected. Amino acid mutation analysis divulged some imperative transmutation sites: D305Y, Y324I, Q370R, N375D, T440A, Y444S, I447M and Y451C in the isolates. The viruses in the vaccines were characterised as the wild-type CPV. The genetic variability, viral population heterogeneity and phylogenetic linkage with isolates from other countries probably suggest transboundary migrations and local differentiations are contributing to continuous CPV evolution and vaccine failure in Nigeria.

Canine Parvovirus is diagnosed and neutralized by chicken IgY-scFv generated against the virus capsid protein.

Canine parvovirus (CPV) can cause acute and highly contagious bloody enteritis in dog. To obtain antibodies against CPV, hens were immunized with virus-like particles (VLP) of CPV-VP2. The IgY single chain fragment variables (scFv) were generated by T7 phage display system and expressed in E. coli system. The titer of the primary scFv library reached to 1.5 × 106 pfu/mL, and 95% of the phages contained the target fragments. The CPV-VLP and CPV-VP2 protein showed similar reaction values to the purified scFv in the ELISA test, and the results of ELISA analysis using IgY-scFv toward CPV clinical samples were consistent with commercial immunochromatographic assay (ICA) and PCR detection, the scFv did not show cross reactivity with canine distemper virus (CDV) and canine coronavirus (CCV). IgY-scFv was successfully expressed in CRFK cells, and in the virus suppression assay, 55% of CPV infections were eliminated within 24 h. Docking results demonstrated that the number of amino acids of the binding sides between scFv and VP2 were AA37 and AA40, respectively. This study revealed the feasibility of a novel functional antibody fragment development strategy by generating diversified avian IgY-scFv libraries towards the pathogenic target of interest for both detection and therapeutic purposes in veterinary medicine.

Canine parvovirus vaccination and immunisation failures: Are we far from disease eradication?

Despite extensive vaccination, canine parvovirus (CPV) remains a leading infectious cause of canine mortality, especially among juveniles. This review provides an update on CPV vaccine types and vaccination protocols. The design of CPV prevention strategies and vaccination programs with a goal of herd immunity has been hampered by deficiencies of studies that model companion animal viral infections and inform an understanding of the basic reproduction number. However, the most important issue in eradication of CPV disease is represented by immunisation failures including: i) the presence of interfering titres of maternally-derived antibodies; ii) the presence of non-responders; and iii) possible reversion to virulence. In contrast, the role of the CPV variants in immunisation failures is widely debated. Taking into account the reduced circulation of canine distemper virus and canine adenovirus type 1 in countries where extensive vaccination is carried out, more effort should be made to aim for CPV eradication, including antibody testing to determine the optimal time for vaccinations of pups and adults and homogeneous vaccine coverage of dog population.

Development of a monoclonal antibody against canine parvovirus NS1 protein and investigation of NS1 dynamics and localization in CPV-infected cells.

Canine parvovirus (CPV) non-structural protein-1 (NS1) plays crucial roles in CPV replication and transcription, as well as pathogenic effects to the host. However, the mechanism was not fully understood. Lack of NS1 antibody is one of the restricting factors for NS1 function investigation. To prepare NS1 monoclonal antibody (mAb), the NS1 epitope (AA461 ~ AA650) gene was amplified by PCR, and inserted into pGEX-4T-1vector to construct the prokaryotic expression vector of GST-tag-fused NS1 epitope gene. The NS1 fusion protein was expressed in E. coli, and purified with GSH-magnetic beads, and then used to immunize BALB/c mice. The mouse splenic lymphocytes were isolated and fused with myeloma cells (SP 2/0) to generate hybridoma cells. After several rounds of screening by ELISA, a hybridoma cell clone (1B8) stably expressing NS1 mAb was developed. A large amount of NS1 mAb was prepared from mouse ascites fluid. The isotype of NS1 mAb was identified as IgG1, which can specifically bind NS1 protein in either CPV-infected cells or NS1 vector-transfected cells, indicating the NS1 mAb is effective in detecting NS1 protein. Meanwhile, we used the NS1 mAb to investigate NS1 dynamic changes by qRT-PCR and location by confocal imaging in CPV-infected host cells and showed that NS1 began to appear in the cells at 12 h after CPV infection and reached the highest level at 42 h, NS1 protein was mainly located in nucleus of the cells. This study provided a necessary condition for further investigation on molecular mechanism of NS1 function and pathogenicity.

Phylogenetic, Evolutionary and Structural Analysis of Canine Parvovirus (CPV-2) Antigenic Variants Circulating in Colombia.

Canine parvovirus (CPV-2) is the causative agent of haemorrhagic gastroenteritis in canids. Three antigenic variants-CPV-2a, CPV-2b and CPV-2c-have been described, which are determined by variations at residue 426 of the VP2 capsid protein. In Colombia, the CPV-2a and CPV-2b antigenic variants have previously been reported through partial VP2 sequencing. Mutations at residues Asn428Asp and Ala514Ser of variant CPV-2a were detected, implying the appearance of a possible new CPV-2a variant in Colombia. The purpose of the present study was to characterise the full VP2 capsid protein in samples from Antioquia, Colombia. We conducted a cross-sectional study with 56 stool samples from dogs showing clinical symptoms of parvoviral disease. Following DNA extraction from the samples, VP2 amplification was performed using PCR and positive samples were sequenced. Sequence and phylogenetic analyses were performed by comparison with the VP2 gene sequences of the different CPV-2 worldwide. VP2 was amplified in 51.8% of the analysed samples. Sequencing and sequence alignment showed that 93.1% of the amplified samples belonged to the new CPV-2a antigenic variant previously. Analysing the amino acid sequences revealed that all CPV-2a contain Ala297Asn mutations, which are related to the South America I clade, and the Ala514Ser mutation, which allows characterization as a new CPV-2a sub-variant. The Colombian CPV-2b variant presented Phe267Tyr, Tyr324Ile and Thr440Ala, which are related to the Asia-I clade variants. The CPV-2c was not detected in the samples. In conclusion, two antigenic CPV-2 variants of two geographically distant origins are circulating in Colombia. It is crucial to continue characterising CPV-2 to elucidate the molecular dynamics of the virus and to detect new CPV-2 variants that could be becoming highly prevalent in the region.

Administration with Vaccinia Virus Encoding Canine Parvovirus 2 vp2 Elicits Systemic Immune Responses in Mice and Dogs.

Canine parvovirus type 2 (CPV2) is a highly contagious cause of serious and often fatal disease in young dogs. Despite the widespread availability of attenuated vaccines, safer, more stable, and more effective CPV2 vaccine candidates are still under exploration. Vaccinia virus (VV) has already been proved to be a safe, stable, and effective vaccine vector. In this study, we generated a VV-based CPV2 vaccine candidate (VV-CPV-VP2) and then evaluated its immunogenicity in mice and dogs. The exogenous vp2 gene of CPV2, which replaced the major virulence gene hemagglutinin (ha) of VV, expressed efficiently and stably in vitro. Subsequently, intramuscular immunization of mice induced robust and lasting systemic immune responses, including neutralizing antibody against both CPV2a and CPV2b, and CPV2-VP2-specific interferon gamma (IFN-γ) secreting T cell. In addition, administration with a high-dose of VV-CPV-VP2 did not cause significant side effects for mice, thus indicating marked safety of this vaccine candidate. Most importantly, a single-dose vaccination of VV-CPV2-VP2 elicited substantial antibody responses and provided comparable protection for dogs with attenuated CPV2 vaccine. Collectively, this study demonstrated that VV-CPV2-VP2 could be used as a promising vaccine candidate preventing CPV2 from infection for dogs.

Comparison of immunity against canine distemper, adenovirus and parvovirus after vaccination with two multivalent canine vaccines.

BACKGROUND: Viral diseases are a major cause of morbidity and mortality in puppies. There is a belief among veterinary practitioners and even educational institutions that the vaccines made in Brazil against canine distemper virus (CDV), canine parvovirus (CPV) and canine adenovirus (CAV) are ineffective or only partially effective. OBJECTIVES: This study aimed at comparing the immunity of two multivalent vaccines in adult dogs in the city of Uberlândia, Minas Gerais state, Brazil. METHODS: The study was carried out at the Animal Protection Association and a total of 60 adult mongrel dogs were selected and divided into two groups. Group A was immunized with two doses of Elevencell® vaccine and Group B received two doses of imported vaccine from the United States; each group was made up of 14 females and 14 males. RESULTS: In group A, the Elevencell vaccine generated a protective antibody titre against CDV in 26 out of 28 subjects (92.85%), CPV in 24 out of 28 subjects (85.71%) and CAV in 26 out of 28 subjects (92.85%). In group B, the imported US vaccine generated a protective antibody titre against CDV in 22 out of 28 subjects (78.57), CPV in 21 out of 28 subjects (75%) and CAV in 25 out of 28 subjects (89.28%). There was no statistical difference between titres generated between vaccine types for any of the three diseases tested. CONCLUSION: Elevencell vaccine titres were not inferior to the imported US vaccine in conferring protective titres against CDV, CPV and CAH, which confirms the efficacy of this product.

Construction and Immunogenicity of Virus-Like Particles of Feline Parvovirus from the Tiger.

Feline panleukopenia, caused by feline parvovirus (FPV), is a highly infectious disease characterized by leucopenia and hemorrhagic gastroenteritis that severely affects the health of large wild Felidae. In this study, tiger FPV virus-like particles (VLPs) were developed using the baculovirus expression system. The VP2 gene from an infected Siberian tiger (Panthera tigris altaica) was used as the target gene. The key amino acids of this gene were the same as those of FPV, whereas the 101st amino acid was the same as that of canine parvovirus. Indirect immunofluorescence assay (IFA) results demonstrated that the VP2 protein was successfully expressed. SDS-PAGE and Western blotting (WB) results showed that the target protein band was present at approximately 65 kDa. Electron micrograph analyses indicated that the tiger FPV VLPs were successfully assembled and were morphologically similar to natural parvovirus particles. The hemagglutination (HA) titer of the tiger FPV VLPs was as high as 1:218. The necropsy and tissue sections at the cat injection site suggested that the tiger FPV VLPs vaccine was safe. Antibody production was induced in cats after subcutaneous immunization, with a >1:210 hemagglutination inhibition (HI) titer that persisted for at least 12 months. These results demonstrate that tiger FPV VLPs might provide a vaccine to prevent FPV-associated disease in the tiger.