Background: Feline calicivirus (FCV), Feline panleukopenia virus (FPV), and Feline herpesvirus type I (FHV-1) are the three most common pathogens in cats, and also are the main pathogens leading to the death of kittens. Here, by a combination of gold nanoparticles and conventional PCR, we established a novel triple NanoPCR molecular detection method for clinical detection. Results: The triple NanoPCR molecular detection is able to detect 2.97 × 10¹copies/μL FCV recombinant copies plasmid per reaction, 2.64 × 10⁴copies/μL FPV recombinant copies plasmid per reaction, and 2.85copies/μL FHV-1 recombinant copies plasmid per reaction at the same time. The sensitivity of each plasmid is 100 times, 10 times, and 100 times higher than conventional PCR, respectively. The clinical results showed that among the 38 samples, the positive rates of FCV, FPV, and FHV-1 in a NanoPCR test were 63.16, 31.58, and 60.53%, while in a conventional PCR were 39.47, 18.42, and 34.21%. Conclusions: In this report, it is the first time that NanoPCR assays are applied in the detection of FCV, FPV, and FHV-1 as well. This sensitive and specific NanoPCR assay can be widely used in clinical diagnosis and field monitoring of FCV, FPV, and FHV-1 infections.

The molecular epidemiology and biological characteristics of Escherichia coli associated with hemorrhagic pneumonia (HP) mink from five Chinese Provinces were determined. From 2017 to 2019, 85 E. coli strains were identified from 115 lung samples of mink suffering from HP. These samples were subjected to serotyping, antimicrobial susceptibility, detection of virulence genes, phylogenetic grouping, whole-genome sequencing, drug resistant gene, multilocus sequence typing (MLST) and biofilm-forming assays. E. coli strains were divided into 18 serotypes. Thirty-nine E. coli strains belonged to the O11 serotype. Eighty-five E. coli strains were classified into seven phylogenetic groups: E (45.9%, 39/85), A (27.1%, 23/85), B1 (14.1%, 12/85), B2 (3.7%, 3/85), D (3.7%, 3/85), F (2.4%, 2/85) and clade I (1.2%, 1/85). MLST showed that the main sequence types (STs) were ST457 (27/66), All E. coli strains had ≥4 virulence genes. The prevalence of virulence was 98.8% for yijp and fimC, 96.5% for iucD, 95.3% for ompA, 91.8% for cnf-Ⅰ, 89.4% for mat, 82.3% for hlyF, and 81.2% for ibeB. The prevalence of virulence genes iss, cva/cvi, aatA, ibeA, vat, hlyF, and STa was 3.5–57.6%. All E. coli strains were sensitive to sulfamethoxazole, but high resistance was shown to tetracycline (76.5%), chloramphenicol (71.8%), ciprofloxacin (63.5%) and florfenicol (52.9%), resistance to other antibiotics was 35.3–16.5%. The types and ratios of drug-resistance genes were tet(A), strA, strB, sul2, oqxA, blaTEM-1B, floR, and catA1 had the highest frequency from 34%-65%, which were consistent with our drug resistance phenotype tetracycline, florfenicol, quinolones, chloramphenicol, the bla-NDM-I and mcr-I were presented in ST457 strains. Out of 85 E. coli strains, six (7.1%) possessed a strong ability, 12 (14.1%) possessed a moderate ability, and 64 (75.3%) showed a weak ability to form biofilm. Our data will aid understanding of the epidemiological background and provide a clinical basis for HP treatment in mink caused by E. coli.

Chlamydia (C.) abortus, a globally distributed obligate intracellular bacterium, has attracted increasing interest according to its veterinary importance and zoonotic nature. C. abortus can infect a variety of animals and cause foetal loss in livestock resulting in economic loss. In this study, the samples collected from two farms of foxes (n=20), raccoon dogs (n=15) and minks (n=20), were investigated by Chlamydiaceae- and Chlamydia species-specific real-time PCR. The results showed that all the tested foxes (20/20) and raccoon dogs (15/15) harbored Chlamydia spp., while 5% of minks (1/20) were positive for Chlamydia spp. C. abortus was identified in all positive samples as the dominant Chlamydia species, with C. pecorum DNA coexistence in some of the rectal samples (7/20) taken from foxes. Phylogenetic analysis based on specific gene fragments of 16S rRNA, IGS-23S rRNA, and ompA revealed that all sequences obtained in this study were assigned to the Chlamydiaceae family with high similarity to C. abortus S26/3 and B577 previously identified in ruminants. This is the first report confirming that farmed foxes, raccoon dogs, and minks carry C. abortus. Further studies are needed to fully elucidate the epidemiology and pathogenicity of this pathogen in farmed fur animals as well as the potential risks to public health.

As a key link between innate and adaptive immune responses, the interferon (IFN) system is the first line of defense against viral infection. IFN, and in particular, IFN-α, has been used clinically as an effective therapeutic agent for viral infections. However, different subtypes of IFN-α demonstrate distinct antiviral activity. Therefore, it is important to identify IFN-α subtypes with high antiviral activity for the development of genetically engineered antiviral drugs. In this study, we cloned the genes for 13 IFN-α subtypes from peripheral blood lymphocytes of the mink. The homologies of the 13 mink IFN-α genes were 93.6–99.3% and 88.8–98.4% at the nucleotide and amino acid sequence levels, respectively. In contrast to human and canine IFN-α subtypes, most mink IFN-α subtypes contained two N-glycosylation sites. We expressed and purified 13 mink IFN-α subtypes in Escherichia coli. The cytopathic effect inhibition assay showed that all the 13 recombinant mink IFN-α subtypes inhibited the propagation of vesicular stomatitis virus in WISH cells, with IFN-α2 and IFN-α12 demonstrating the highest activities. Furthermore, recombinant mink IFN-α2 and IFN-α12 significantly suppressed the propagation of canine distemper virus in Vero cells, with IFN-α2 demonstrating the highest activity. We identified the mink IFN-α2 subtype as a promising candidate for the development of effective antiviral drugs.

A novel neurological disorder, shaking mink syndrome (SMS), emerged in Denmark and Sweden in 2000. SMS has seldom been reported in China, but the causative agent has not been detected in the country. SMS outbreaks occurred in multiple provinces in 2020. A total of 44 brain samples from minks associated with SMS were collected from Heilongjiang, Liaoning and Shandong provinces of which 28 samples (63.3%) were SMS-astrovirus (SMS-AstV)-positive by reverse transcription PCR. Histopathological examination revealed non-suppurative encephalitis in three minks. Moreover, the complete coding region sequences (CDSs, 6559 bp) of a sample collected from a 2-month-old mink (termed SMS-AstV-H1, GSA accession No. SAMC816786) were amplified by PCR and Sanger sequencing. The complete CDS and open reading frame 2 sequences of SMS-AstV-H1 were 94.3% and 96.4% identical to an SMS-AstV strain (GenBank accession number: GU985458). Phylogenetically, SMS-AstV-H1 was closely related to an SMS-AstV strain (GU985458). Based on the above results, we describe SMS-AstV-associated encephalitis in farmed minks in China. Future studies need to focus on epidemiology, virus isolation and potential interspecies transmission of SMS-AstV.