Establishment of RPA-Cas12a-Based Fluorescence Assay for Rapid Detection of Feline Parvovirus

Feline parvovirus (FPV) is highly infectious for cats and other Felidae and often causes severe damage to young kittens. In this study, we incorporated recombinase polymerase amplification (RPA) and Cas12a-mediated detection and developed an RPA-Cas12a-based real-time or end-point fluorescence detection method to identify the NS1 gene of FPV. The total time of RPA-Cas12a-based fluorescence assay is approximately 25 min. The assay presented a limit of detection (LOD) of 1 copies/μl (25 copies/per reaction), with no cross-reactivity with several feline pathogens. The clinical performance of the assay was examined using total genomic DNA purified from 60 clinical specimens and then compared to results obtained with qPCR detection of FPV with 93.3% positive predictive agreement and 100% negative predictive agreement. Together, the rapid reaction, cost-effectiveness, and high sensitivity make the RPA-Cas12a-based fluorescence assay a fascinating diagnostic tool that will help minimize infection spread through instant detection of FPV.

FPLV: Enhancing recommender systems with fuzzy preference, vector similarity, and user community for rating prediction

Rating prediction is crucial in recommender systems as it enables personalized recommendations based on different models and techniques, making it of significant theoretical importance and practical value. However, presenting these recommendations in the form of lists raises the challenge of improving the list's quality, making it a prominent research topic. This study focuses on enhancing the ranking quality of recommended items in user lists while ensuring interpretability. It introduces fuzzy membership functions to measure user attributes on a multi-dimensional item label vector and calculates user similarity based on these features for prediction and recommendation. Additionally, the user similarity network is modeled to extract community information, leading to the design of a set of corresponding recommendation algorithms. Experimental results on two commonly used datasets demonstrate the effectiveness of the proposed algorithm in enhancing list ranking quality, reducing prediction errors, and maintaining recommendation diversity and accurate user preference classification. This research highlights the potential of integrating heuristic methods with complex network theory and fuzzy techniques to enhance recommendation system performance with interpretability in mind.

Feline Panleukopenia Virus Is Not Associated With Myocarditis or Endomyocardial Restrictive Cardiomyopathy in Cats

Canine parvovirus-2 (CPV-2) is nearly indistinguishable from feline panleukopenia virus (FPV) and is a well-known cause of viral myocarditis in young puppies; however, it is not known whether either FPV or CPV-2 naturally infects feline cardiomyocytes and causes myocarditis. Endomyocarditis (EMC) and left ventricular endomyocardial fibrosis (LVEF), clinically known as "endomyocardial restrictive cardiomyopathy," are important feline heart diseases suspected to have an infectious etiology. A continuum is suggested with EMC representing the acute reaction to an unknown infectious agent and LVEF the chronic manifestation of repair. The purpose of this study was to determine (1) whether there is natural parvovirus infection of the feline myocardium and (2) whether parvoviral infection is associated with feline EMC and/or LVEF. In a retrospective study, polymerase chain reaction and sequencing for the parvovirus VP1/2 gene was performed on archived heart tissue from cats with endomyocardial disease and controls. Similar methods were used prospectively on myocardial tissues from shelter-source kittens. Although 8 of 36 (22%; 95% confidence interval [CI], 11%-40%) shelter kittens had parvoviral DNA in myocardial tissue, VP1/2 DNA was not detected in 33 adult cases or 34 controls (95% CI, 0% to ∼11%). These findings were confirmed by in situ hybridization: adult cats did not have detectable parvovirus DNA, although rare intranuclear signal was confirmed in 7 of 8 shelter-source kittens. In kittens, parvovirus was not significantly associated with myocarditis, and in situ hybridization signal did not colocalize with inflammation. Although infection of cardiomyocytes was demonstrated in kittens, these data do not support a role for parvovirus in EMC-LVEF.

Co-infection with feline and canine parvovirus in a cat

In this study we reported a case of co-infection with canine parvovirus (CPV) type 2a and feline panleukopenia virus (FPV) in a 3-month-old male kitten, with the presence of a parvovirus variant which is a true intermediate between CPV and FPV. The report of a viral variant which contained FPV- and CPV-specific epitopes stresses the importance of the mechanism of multistep mutation in the production of new variants and in the emergence of new viruses. This type of multistep adaptation has already been documented during the emergence of CPV and on the basis of our results, it was hypothesized that CPV had presumably started a new process of readaptation in the feline host, confirming the importance of viral host switching as a mechanism for the emergence of new viruses.

Plant-derived vaccine protects target animals against a viral disease

The successful expression of animal or human virus epitopes on the surface of plant viruses has recently been demonstrated. These chimeric virus particles (CVPs) could represent a cost-effective and safe alternative to conventional animal cell-based vaccines. We report the insertion of oligonucleotides coding for a short linear epitope from the VP2 capsid protein of mink enteritis virus (MEV) into an infectious cDNA clone of cowpea mosaic virus and the successful expression of the epitope on the surface of CVPs when propagated in the black-eyed bean, Vigna unguiculata. The efficacy of the CVPs was established by the demonstration that one subcutaneous injection of 1 mg of the CVPs in mink conferred protection against clinical disease and virtually abolished shedding of virus after challenge with virulent MEV, demonstrating the potential utility of plant CVPs as the basis for vaccine development. The epitope used occurs in three different virus species-MEV, canine parvovirus, and feline panleukopenia virus- and thus the same vaccine could be used in three economically important viral hosts-mink, dogs, and cats, respectively.

Successful experimental challenge of dogs with canine parvovirus-2

Withholding food from dogs for 24 hours prior to, and for 48 hours following oral challenge with a gut mucosal homogenate of canine parvovirus-2, was a successful means of reproducing gastroenteric signs of canine parvovirus-2 infection. Twenty-one of 24 dogs, which had previously received various vaccine preparations of mink enteritis virus or were unvaccinated, and which were starved at challenge, developed soft or liquid feces with large or without large clots of mucus. Altered feces were most frequent on postexposure day 11. Seven dogs passed frank blood in their stools on one or more occasions and seven dogs vomited sporadically. Pyrexia was noted in 71.6% of the dogs on postexposure day 6 and lymphopenia was detected on postexposure day 5 or 6 in 50% of the dogs monitored. In contrast, four dogs not starved at the time of challenge remained free of gastrointestinal signs apart from one dog which passed a soft stool with scant mucus on one day, postexposure day 6. Also four dogs vaccinated with a killed canine parvovirus-2 vaccine preparation and subsequently starved at the time of challenge, remained clinically healthy. Apart from these last mentioned four dogs, all others shed canine parvovirus-2 in their feces following challenge.

IMMUNOFLUORESCENCE OF FELINE PANLEUCOPENIA VIRUS IN CELL CULTURE: DETERMINATION OF IMMUNOLOGICAL STATUS OF FELINES BY SERUM NEUTRALIZATION

Utilizing specific immunofluorescence as a viral indicator for a cell culture serum-neutralization system, the authors were able to demonstrate a relationship between specific antibody titer and susceptibility of felines to feline panleucopenia virus. This correlation was established by comparing prechallenge serum-neutralization titers to the clinical response of felines challenged with feline panleucopenia virus. The serological and clinical response of felines inoculated with commercial vaccines or related viruses was also studied.