Panleukopenia Research Articles

Correction: Isolation of a feline-derived feline panleukopenia virus with an A300P substitution in the VP2 protein and confirmation of its pathogenicity in dogs

Correction: Isolation of a feline-derived feline panleukopenia virus with an A300P substitution in the VP2 protein and confirmation of its pathogenicity in dogs

Preparation and preliminary application of fluorescent microsphere test strips for feline parvovirus antibodies

This study introduces a novel diagnostic modality for the detection of feline panleukopenia virus (FPV) antibodies in feline serum by using fluorescent microsphere immunochromatographic test strips (FM-ICTS). Leveraging the inherent specificity of antigen-antibody interactions, the FM-ICTS approach demonstrates considerable potential for efficient and accurate FPV antibody detection within a short timeframe. The FM-ICTS method demonstrates strong diagnostic performance, with consistent accuracy and stability over time. PBS buffer dilution enables detection across the range of FPV antibody haemagglutination inhibition (HI) titres in both healthy and immunized or infected cats. A high correlation (R² = 0.9733) between the T/C ratio and FPV antibody titres confirms the method’s effectiveness in quantifying these titres. Clinical validation with 84 samples supports its reliability by matching results with HI assays. Additionally, stability tests show that the test strips maintain performance during storage, with a coefficient of variation (CV) below 12% over three months at 25℃. This innovative FM-ICTS framework emerges as a promising avenue for expedient and dependable disease diagnosis within the realm of veterinary science, offering implications for timely disease management and surveillance.

Development of a recombinant Lactobacillus plantarum oral vaccine expressing VP2 protein for preventing feline panleukopenia virus

Feline panleukopenia virus (FPV) represents a significant health threat to the kittens. While traditional vaccines administered via subcutaneous or intramuscular injection are effective, they can induce stress and adverse reactions. Moreover, unvaccinated kittens visiting veterinary clinics risk exposure to FPV, increasing their susceptibility to infection. Therefore, there is an urgent need for a safer, more gentle vaccination method with streamlined administration. In this study, we developed a recombinant L. plantarum NC8/VP2 expressing the VP2 protein of the prevalent Chinese FPV strain, FPV-251. Our results show that L. plantarum NC8/VP2 effectively colonizes the feline intestinal tract and induces high levels of neutralizing antibodies through oral administration. Kittens exhibited significant protection against FPV-251 infection and associated illnesses or fatalities after 30 days of continuous dosing. These results highlight the potential of recombinant L. plantarum NC8/VP2 as a novel oral vaccine for FPV, presenting a promising approach for disease prevention in domestic cats.

Whole-genome sequence analysis of canine parvovirus reveals replacement with a novel CPV-2c strain throughout India.

Canine parvovirus (CPV) infection causes severe gastroenteritis in canines, with high mortality in puppies. This virus evolved from feline panleukopenia virus by altering its transferrin receptor (TfR), followed by the emergence of CPV-2 variants in subsequent years with altered immunodominant amino acid residues in the VP2 protein. While previous studies have focused on the VP2 gene, there have been fewer studies on non-structural protein (NS1 and NS2) genes. In the present study, CPV genome sequences from clinical samples collected from canines throughout India in 2023, previous Indian CPV isolates from 2009-2019, and the current Indian CPV vaccine strain were compared. The study showed that the CPV-2c (N426E) variant had almost completely replaced the previously dominant CPV-2a variant (N426) in India. The Q370R mutation of VP2 was the most common change in the recent CPV-2c strain (CPV-2c 370Arg variant). Phylogenetic analysis showed the existence of three clades among the recent CPV-2c strains, and sequence analysis identified several new sites of positive selection in the VP1 (N-terminus), VP2, NS1, and NS2 protein-encoding genes in recent CPV strains, indicating the emergence of new CPV-2c variants with varied antigenic and replication properties. The predominant 'CPV-2c 370Arg variants' were grouped with the Chinese and Nigerian CPV-2c strains but were separate from the CPV vaccine strain and earlier isolates from our repository. VP2 epitope analysis predicted nine amino acid variations (including two new variations) in four potential linear B-cell epitopes in the CPV-2c 370Arg variants that might make vaccine failure more likely. This pan-Indian study lays the foundation for further research concerning the dynamics of virus evolution and understanding genetic mutations.

Evaluation of feline mesenchymal stem cell susceptibility to feline viruses

Feline mesenchymal stem cells (fMSCs) are well known for their robust differentiation capabilities and are commonly used in studying immune-related diseases in cats. Despite their importance, the susceptibility of fMSCs to viral infections remains uncertain. This study aimed to assess the susceptibility of feline adipose-derived mesenchymal stem cells (fAD-MSCs) and feline umbilical cord-derived mesenchymal stem cells (fUC-MSCs) to common feline viruses, including feline coronavirus (FCoV), feline herpesvirus type 1 (FHV-1), and feline panleukopenia virus (FPV). The results demonstrated that both FCoV and FHV-1 were able to infect both types of cells, while FPV did not exhibit cytopathic effects on fUC-MSCs. Furthermore, all three viruses were successfully isolated from fAD-MSCs. These findings suggest that certain feline viruses can replicate in fMSCs, indicating potential limitations in using fMSCs for treating viral diseases caused by these specific viruses. This study has important clinical implications for veterinarians, particularly in the management of viral diseases.

Antibody response after feline panleukopenia virus vaccination in kittens with and without intestinal parasites.

Vaccinations should only be given to healthy cats, and deworming before vaccination is generally recommended; however, so far, no study has investigated the influence of intestinal parasitic infection on the immune response in kittens. The aim of this prospective study was to compare the antibody response to feline panleukopenia virus (FPV) vaccination in kittens with and without intestinal parasites. Overall, 74 healthy kittens were included. Of these, 17 had intestinal parasites (12/17 Toxocara cati, 6/17 Cystoisospora felis, 1/17 Capillaria species). Both kittens with and without (n = 57) parasites received two primary kitten vaccinations with modified live FPV vaccines in a 4-week interval starting at the age of 8-12 weeks. Anti-FPV antibodies were determined at the beginning of the study (week 0) and at week 8 (4 weeks after the second vaccination) by haemagglutination inhibition. A ⩾four-fold titre increase (week 8 vs week 0) was defined as a response to vaccination. Comparison of the immune response in the kittens with and without intestinal parasites was performed using Pearson's χ2 test. Pre-vaccination antibodies were present in 4/17 (23.5%) kittens with intestinal parasites and in 24/57 (42.1%) without parasites. A ⩾four-fold titre increase was seen in 13/17 (76.5%) kittens with parasites compared with 32/57 (56.1%) kittens without parasites. There was neither a significant difference in pre-vaccination antibodies (P = 0.17), nor in vaccination response (P = 0.13) between kittens with and without parasites. The results indicate that asymptomatic intestinal infections with endoparasites do not interfere with the immune response to kitten vaccination series. Parasitic infection (at least with T cati, C felis and Capillaria species) is therefore not a reason to postpone important vaccinations.

Illegal Wildlife Trade gives insights into suspected Feline Panleukopenia Virus (FPV) Occurrence in Puma concolor

Illegal Wildlife Trade gives insights into suspected Feline Panleukopenia Virus (FPV) Occurrence in Puma concolor

Identificación de genogrupos de protoparvovirus y sus variantes en leucocitos de gatos domésticos del Valle Central de Costa Rica

Carnivore protoparvovirus 1 (CPPV-1) includes feline parvovirus (or feline panleukopenia virus, FPV) and canine parvovirus 2 (CPV-2). Currently, although CPV-2 is not found in nature, its variants CPV-2a, CPV-2b, and CPV-2c are found and can infect cats as well. The objective of this research was to identify CPPV-1 and its variants as antibodies against CPPV-1 in the blood of domestic cats from the Central Valley of Costa Rica. Blood samples were collected from 155 cats, along with the following data: sex, age, breed, vaccination information, the environment where the animal lives (urban or rural), coexistence with other cats, health status, any chronic diseases, lifestyle (indoor or outdoor cat), and place of origin. Blood samples were analyzed by hemagglutination inhibition assay (HIA) and molecular techniques (polymerase chain reaction (PCR) and sequencing). Antibodies against CPPV-1 were detected using HIA in all cats; a total of 112 (72.3%) had protective titers (≥1:80). Using real-time PCR, CPPV-1 was detected in the blood of 42 (27.1%) cats, none of which presented anemia, leukopenia, or any chronic disease; five (11.9%) were vaccinated, and three (7.1%) had low body condition but showed appetite and had no other symptom or sign associated with CPPV-1. The group of qPCR-positive cats did not show significant differences compared to the qPCR-negative group regarding age, sex, lifestyle, coexistence with other cats, and antibody titers. Ten asymptomatic and healthy cats showed FPV (n=2) and CPV-2c (n=8) in blood with nucleotide similarities of 100% (GenBank M38246) and 99.8%-100% (GenBank AF401519), respectively.

Isolation and genetic characterization of parvoviruses from domestic cats reveals emergence of CPV-2c in India: A first report.

The objective of the present study was to isolate and characterize the VP2 gene of parvoviruses from domestic cats in India. For that, 38 fecal samples were screened by PCR with 36.84% positivity. Sequence analysis of those isolates showed canine parvovirus type-2c (CPV-2c) as the predominant variant, followed by feline panleukopenia virus (FPV) and 2a. Phylogenetic analysis of the CPV-2c sequences revealed clustering with Singaporean, South Korean, Mongolian and Bangladeshi dog 2c sequences. Phylogenetic analysis of the 2a isolate (MZC 2) was found to be clustered with Indian, Thai and Singaporean dog 2a isolates. Similarly, all the four FPV sequences were ancestrally related to Indian dog and cat FPV sequences hinting towards interspecies transmission between dogs and cats. Both synonymous and non-synonymous mutations were evident in CPV-2c, 2a and FPV sequences indicative of active evolution. In cell culture medium, CPV-2 showed cytopathogenic effects at the third passage level. In conclusion, the study provided the first report of CPV-2c in cats from India, which demands for extensive epidemiological surveillance to monitor interspecies spread and to shed more light on viral phylogenomics, their distribution in the country and in the Southeast Asian region and usage of current vaccines.

Causes of shelter cats mortality in the Czech Republic

Awareness of the causes of mortality in shelter cats can contribute to its effective reduction. The aim of this study was to investigate the causes of mortality in cat shelters in the Czech Republic, taking into account the age of the animals and their length of stay in the shelter facilities until natural death or euthanasia. A cooperation with two private no-kill shelters in the Czech Republic was established. The subject of the study were records of 3047 cats admitted to the selected shelters in the period from 2013 to 2023. A total of 357 (11.7 %) out of 3047 cats died or had to be euthanized in two monitored shelters. No significant difference (p > 0.05) in the cat mortality was found between the two shelters (11.5 % and 12 %). The median length of stay of cats in the shelter until death or euthanasia was 23 days. The highest mortality was recorded in the youngest cats (≤ 6 months). The most common causes of death or euthanasia of cats in both shelters were feline infectious peritonitis (21.6 %), panleukopenia (18.5 %) and upper and lower respiratory tract infections (17.5 %). Adult and older cats were significantly (p < 0.05) more prone to death due to renal failure and cancer than young animals and kittens. The results of the study contribute to the knowledge on the health of cat population in shelters in the Czech Republic and can serve as a basis for further work that will target mortality reduction strategies in at-risk categories.

The coding complete genomic sequence of a feline panleukopenia virus detected from a domestic cat (Felis catus) in Chattogram, Bangladesh.

The coding complete genome sequence of the feline panleukopenia virus (FPLV), detected from an indigenous cat in Bangladesh, has been determined. The genome spans 4,842 bp and contains four protein-coding genes. The genome will contribute to a comprehensive understanding of the genetic traits and evolutionary trends of FPLV.

Molecular Detection of Viral and Bacterial Pathogens in Red Foxes (Vulpes vulpes) from Italy.

Animals, including wildlife, are part of One-Health concept since many infectious diseases can affect both humans and animals. In this study, 126 red foxes (Vulpes vulpes) from Northern Italy in 2022-2023 were tested by molecular assays for Protoparvovirus carnivoran 1 (PPVC-1), Canine adenovirus type 1 and 2 (CAdV-1 and CAdV-2), Circovirus canine (CanineCV), Canine distemper virus (CDV), and Leptospira spp. A total of 39 of 126 (30.9%) red foxes were infected with at least one pathogen and five of these were coinfected: 20/126 (15.9%) red foxes tested positive for PPVC-1, 3/126 (2.4%) for CAdV, 20/126 (15.9%) for CanineCV, and 2/126 (1.6%) for Leptospira spp. DNA. No foxes tested positive for CDV RNA. The pathogens identified were genetically analysed. New findings were reported such as a fox with multiple feline panleukopenia virus (FPV) and canine parvovirus type 2b (CPV-2b) infection associated with quasispecies dynamics, typical genetic characteristics of the identified CanineCV, and the first detection in red foxes of Leptospira ST198 related to L. interrogans serogroup Australis. Further studies are necessary to investigate the transmission between domestic animals and wildlife and to understand the role of red foxes in the maintenance of these pathogens not only in the wild but also in urban and peri-urban environments.

Molecular Characterization of Feline Parvovirus from Domestic Cats in Henan Province, China from 2020 to 2022.

Carnivore protoparvovirus-1, feline parvovirus (FPV), and canine parvovirus (CPV) continue to spread in companion animals all over the world. As a result, FPV and CPV underwent host-to-host transfer in carnivorous wild-animal hosts. Here, a total of 82 fecal samples of suspected cat FPV infections were collected from Henan Province from 2020 to 2022. The previously published full-length sequence primers of VP2 and NS1 genes were used to amplify the targeted genes of these samples, and the complete gene sequences of 11 VP2 and 21 NS1 samples were obtained and analyzed. Analysis showed that the amino acid homology of the VP2 and NS1 genes of these isolates was 96.1-100% and 97.6-100%, respectively. The phylogenetic results showed that the VP2 and NS1 genes of the local isolates were mainly concentrated in the G1 subgroup, while the vaccine strains were distributed in the G3 subgroup. Finally, F81 cells were inoculated with the local endemic isolate Luoyang-01 (FPV-LY strain for short) for virus amplification, purification, and titer determination, and the pathogenesis of FPV-LY was detected. After five generations of blind transmission in F81 cells, cells infected with FPV-LY displayed characteristic morphological changes, including a round, threadlike, and wrinkled appearance, indicative of viral infection. The virus titer associated with this cytopathic effect (CPE) was measured at 1.5 × 106 TCID50/mL. Subsequent animal regression tests confirmed that the virus titer of the PFV-LY isolate remained at 1.5 × 106 TCID50/mL, indicating its highly pathogenic nature. Cats exposed to the virus exhibited typical clinical symptoms and pathological changes, ultimately succumbing to the infection. These results suggest that the gene mutation rate of FPV is increasing, resulting in a complex pattern of gene evolution in terms of host preference, geographical selection, and novel genetic variants. The data also indicate that continuous molecular epidemiological surveillance is required to understand the genetic diversity of FPV isolates.

Clinical efficacy studies of the vaccine against feline panleukopenia, calicivirus infection and viral rhinotracheitis Carnifel PCH in kittens

Clinical efficacy studies of the vaccine against feline panleukopenia, calicivirus infection and viral rhinotracheitis Carnifel PCH in kittens

Rapid lateral flow immunoassay for fluorescence detection of canine distemper virus (CDV).

Canine distemper virus (CDV) is a highly contagious and potentially lethal virus that affects dogs and other members of the Canidae family, including wolves, foxes, and coyotes. Here, we present a fluorescent lateral flow immunoassay (FLFA) platform for the detection of CDV, which utilizes fluorescent microspheres - fusion protein monoclonal antibody (mAb)-labeled monoclonal antibody. The assay detected CDV within 5 min, with a detection limit threshold of 3 × 102 TCID50/mL. Notably, the assay demonstrated no cross-reactivity with canine parvovirus, canine coronavirus, canine adenovirus, feline calicivirus, feline herpesvirus, or feline parvovirus. Field and clinical applicability of the assay was evaluated using 63 field samples, including 30 canine fecal samples, 18 swab samples, and 15 blood samples. The coincidence rate between the detection results of clinical samples obtained through FLFA and reverse transcription polymerase chain reaction (RT-PCR) was 96.83%. Thus, this assay offers a significant advancement for the rapid diagnosis of CDV at the point of care.

Viral pathogens in domestic cats in southern Italy: A retrospective analysis in Sicily, 2020–2022

A retrospective study was carried out on selected feline viral pathogens detected in domestic cat in Sicily, southern Italy. Samples from 64 cats, collected from 2020 to 2022, were analysed for the presence of feline panleukopenia virus, canine parvovirus type 2 (CPV-2), feline coronavirus (FCoV), feline calicivirus (FCV), feline herpesvirus type 1, norovirus (NoV), and rotavirus (RoV). Single (45 %) or mixed (38 %) viral infections were detected. FPV, related with other Italian FPV strains, remains the main viral cause of infection (66 %). CPV-2c Asian lineage strains (3 %) were detected for the first time in domestic cats in Europe. FCoV (29.6 %), either enteric or systemic, and systemic FCV (18.7 %) infections were detected in positive cats. Less commonly reported viruses (GIV.2/GVI.2 NoVs, RoV), potentially related to the animal/human interface, were detected at lower rates as well (5 %). The present epidemiological data suggest the need to improve disease prevention, immunization, and biosecurity strategies.

Therapeutic Effects of Propionibacterium acnes and Lipopolysaccharide from Escherichia coli in Cats with Feline Panleukopenia.

The objective of this study was to investigate the therapeutic effects of inactivated Propionibacterium acnes and lipopolysaccharide derived from Escherichia coli cells in cats affected by feline panleukopenia virus (FPV). A retrospective study of 80 FPV-positive cats was divided into two groups: a treatment group receiving inactivated Propionibacterium acnes and lipopolysaccharide derived from Escherichia coli cells along with supportive treatment and a no-treatment group receiving only supportive treatment. There was no significant difference in the total white blood cell counts between the two groups. However, the total white blood cell counts of both groups were low on day 0 and increased significantly on days 3 and 6 of treatment. Additionally, the white blood cell counts in the treatment group significantly increased during days 3 to 6 compared with those of the no-treatment group (p < 0.01). The mortality rate was not significantly different between the two groups. In a prospective study, the serum and fecal immunoglobulin A (IgA) levels were measured in both groups. There were no significant differences in IgA levels between the two groups in either the serum or feces.

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.

One-step triplex TaqMan quantitative reverse transcription polymerase chain reaction for the detection of feline coronavirus, feline panleukopenia virus, and feline leukemia virus.

Feline coronavirus (FCoV), feline panleukopenia virus (FPV), and feline leukemia virus (FeLV) are prevalent throughout China and significantly threaten cat health. These viruses cause similar manifestations and pathological damage. Rapid and accurate diagnosis depends on detection in the laboratory. This study aimed to establish a reliable and rapid method for accurate detection of FCoV, FPV, and FeLV so that a definite diagnosis can be made and effective measures can be taken to prevent and control viral infection. We designed three pairs of specific primers and probes for the detection of FCoV 5' untranslated region, FPV viral protein 2, and FeLV pol genes. Recombinant plasmid constructs were generated for use as standard plasmid constructs. Optimal reaction conditions, including primer and probe concentrations, reaction cycles, and annealing temperatures, were obtained on the basis of optimization tests. One-step triplex real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was successfully established to simultaneously detect FCoV, FPV, and FeLV. The specificity, sensitivity, and repeatability of the assay were analyzed, and its applicability was validated by testing 1175 clinical samples. One-step triplex RT-qPCR had a high degree of specificity only for the detection of FCoV, FPV, and FeLV; it had high sensitivity with limits of detection of 139.904, 143.099, and 152.079 copies/reaction for p-FCoV, p-FPV, and p-FeLV standard plasmid constructs, respectively, and it had reliable repeatability with 0.06%-0.87% intra-assay coefficients of variations. A total of 1175 clinical samples were examined for FCoV, FPV, and FeLV using triplex RT-qPCR, and the FCoV, FPV, and FeLV positivity rates were 18.47%, 19.91%, and 47.57%, respectively. The clinical sensitivity and specificity of one-step triplex RT-qPCR were 93.07% and 97.99%, respectively. We developed a rapid and reliable one-step triplex RT-qPCR method for the detection of FCoV, FPV, and FeLV, which could be used as a diagnostic tool for clinical monitoring and diagnosis.

Investigation of canine parvovirus occurrence in cats with clinical signs of feline panleukopenia in Slovakia - pilot study.

Feline panleukopenia is a contagious viral disease caused by the feline panleukopenia virus (FPV). A closely related pathogen is canine parvovirus (CPV), and amino acid substitutions in this virus allow it to acquire a feline host range. In feline hosts, the disease induced by CPV manifests with similar symptoms to those caused by FPV or milder ones, leading to its underdiagnosis. The aim of this study was to determine the presence of CPV type 2 (CPV-2) in cats with clinical symptoms of panleukopenia and to assess the use of commercial CPV antigen tests for the clinical diagnosis of FPV. Samples from 59 cats from central Slovakia were included in the study. Rectal swabs were collected and clinically tested for parvovirus infection using a commercial antigen test. Antigen-positive samples were confirmed by PCR targeting the viral VP2 gene. The sequences of the PCR products were established with the Sanger method. Of 59 samples, 23 were revealed to be positive for parvovirus infection by both antigen and PCR test (38.9%). Analysis with the National Center for Biotechnology Information BLASTn application showed 99.78-100% pairwise identity with FPV. The mortality rate of parvovirus-infected cats included in this study was 8.69% (2/23). Although feline disease with CPV-2 was not confirmed, the CPV antigen test was able to detect FPV infection.