Spectrum detection and analysis of the epidemiological characteristics of infectious pathogens in the feline respiratory tract.

Our study was designed to investigate the original spectrum of feline respiratory tract infection and to provide a scientific basis for the clinical diagnosis and treatment of feline respiratory infections and for precise prevention and control measures. A total of 400 cats with upper respiratory tract infections from animal hospitals in 12 provinces in China were examined from November 2022 to October 2023 to investigate the epidemiology of feline calicivirus (FCV), feline herpes virus type 1 (FHV-1), influenza A virus (IAV), Mycoplasma felis, Chlamydia felis, and Bordetella bronchiseptica through loop-mediated isothermal amplification (LAMP) with microfluidic chip detection. The results showed that 396 of the 400 samples tested were positive for at least one of these pathogens, with an overall detection rate of 99.00%. The detection rates were as follows: FCV, 36.00% (144/400); M. felis, 34.00% (136/400); FHV-1, 21.50% (86/400); C. felis, 15.75% (63/400); B. b, 13.00% (52/400); IAV, 4.50% (18/400). There were no statistically significant differences in the detection rates of respiratory pathogens between different sexes, ages, seasons, breeds, or regions (P > 0.05). There were 88 mixed infections, giving a total mixed infection rate of 22.00% (88/400). It is worth noting that the detection rate of FCV at different ages and of FHV-1 in different sexes showed significant differences (P < 0.05). The highest rate of FCV infection was found in animals that were 1 to 2 years old, and the rate of FHV-1 infection in male cats was higher than that in female cats. The results showed that the spectrum of feline respiratory pathogens is complex, with diverse epidemiological characteristics and mixed infections, and some differences among different respiratory pathogens were found with regard to the sex, age, and breed of the cat. Studies should be continued to provide a scientific basis for precise prevention and control of feline respiratory diseases.

The biological characteristics and infection dynamics of a novel H3N2 canine influenza virus genotype in beagles.

BACKGROUND: The canine influenza virus (CIV) outbreak has garnered considerable attention as it poses a significant threat to dog health. During the H3N2 CIV evolution in beagles, the virus formed a new clade after 2019 and gradually became more adaptable to other mammals. Therefore, successfully elucidating the biological characteristics and constructing a canine influenza infection model is required for CIV characterization. METHODS: We performed genetic analyses to examine the biological characteristics and infection dynamics of CIV. RESULTS: The genotype of our H3N2 CIV strain (from 2019 in Shanghai) belonged to the 5.1 clade, which is now prevalent in China. Using MDCK cells, we investigated viral cytopathic effects. Virus size and morphology were observed using transmission electron microscopy. Beagles were also infected with 104, 105, and 106 50% egg-infectious doses (EID50). When compared with the other groups, the 106 EID50 group showed the most obvious clinical symptoms, the highest virus titers, and typical lung pathological changes. Our results suggested that the other two treatments caused mild clinical manifestations and pathological changes. Subsequently, CIV distribution in the 106 EID50 group was detected by hematoxylin and eosin (H&E) and immunofluorescence (IF) staining, which indicated that CIV primarily infected the lungs. CONCLUSIONS: The framework established in this study will guide further CIV prevention strategies.

Epidemiological Surveillance of Respiratory Diseases in Urban Stray Cats in Shanghai.

Urban stray cats are cats without owners that survive in the wild for extended periods of time. They are one of the most common stray animals in cities, and as such, monitoring the pathogens carried by urban stray cats is an important component of urban epidemiological surveillance. In order to understand the prevalence of respiratory diseases in urban stray cats in Shanghai and provide scientific evidence for the development of targeted prevention and control strategies for respiratory diseases in stray cats, we collected 374 ocular, nasal, and oropharyngeal swabs from urban stray cats in Shanghai from January 2022 to December 2022. After RNA extraction, we used real-time PCR to detect six respiratory pathogens, including influenza A virus, feline calicivirus, feline herpesvirus type 1, Mycoplasma, Chlamydia, and Bordetella bronchiseptica. The results showed that among the 374 samples, 146 tested positive, with a positivity rate of 39.04%. The highest positivity rate was observed for Mycoplasma felis at 18.72% (70/374), followed by Chlamydia felis at 11.76% (44/374), feline calicivirus at 3.74% (14/374), feline herpesvirus 1 at 3.48% (13/374), Bordetella bronchiseptica at 1.34% (5/374), and influenza A virus was not detected. The highest positivity rate for Mycoplasma felis was in Minhang District at 31.94% (23/72), while Chlamydia felis and Bordetella bronchiseptica had the highest positivity rates in Jiading District at 23.53% (8/34) and 5.88% (2/34), respectively. The highest positivity rates for feline calicivirus and feline herpesvirus 1 were both observed in Qingpu District, at 14.46% (12/83) and 9.64% (8/83), respectively. A total of 36 samples showed mixed infections with two or more pathogens, with Mycoplasma felis being involved in 32 of these mixed infections, with the highest number of mixed infections being with Chlamydia felis at 25 samples. Respiratory pathogen positivity was detected throughout the year, with peak detection rates in summer and winter. The positivity rates of cat respiratory pathogens in different seasons showed statistical differences (χ2 = 27.73, p < 0.01). There was no statistical difference in the positivity rates of respiratory pathogens between cats of different genders (χ2 = 0.92, p > 0.05). The positivity rates of respiratory pathogens in cats of different age groups showed statistical differences (χ2 = 44.41, p < 0.01). Mycoplasma felis and Chlamydia felis were the main pathogens causing respiratory infections in stray cats, with Mycoplasma felis showing a much higher positivity rate than other respiratory pathogens and often co-infecting with Chlamydia felis and feline calicivirus. The positivity rate of Mycoplasma felis was high in summer, autumn, and winter, with no statistical difference between seasons. These results indicate a serious overall prevalence of respiratory pathogens in urban stray cats in the Shanghai area, showing seasonal trends and mixed infections with other pathogens. These findings suggest the need for comprehensive prevention and control measures to address respiratory pathogen infections in urban stray cats in the Shanghai area.

Comparison of dye-based and probe-based RT-LAMP in detection of canine astrovirus.

A rapid and sensitive assay is essential for reliable surveillance and diagnosis of canine astrovirus (CaAstV). In this study, two real-time reverse transcription loop-mediated isothermal amplification (RT-LAMP) assays with high sensitivity, rapidity, and reliability were developed using fluorescence dye and FRET-based assimilating probes for real-time detection of CaAstV. These assays specifically amplified the ORF2 gene of CaAstV and did not amplify any sequences from canine enterovirus. The limit of detection (LOD) of both the probe-based and dye-based RT-LAMPs was 100 copies/µL. Fluorescence signals were generated within 30 min for the lowest concentration of a standard RNA sample, which was significantly faster than that achieved by real-time fluorescence quantitative PCR (qRT-PCR) assay. When clinical samples were tested, the positive and negative agreement of the dye-based RT-LAMP assay with qRT-PCR was 87.5% (14/16) and 93.55% (29/31), respectively. The positive and negative agreement of the probe-based RT-LAMP assay with qRT-PCR was 94.11% (16/17) and 96.55% (28/29), respectively. The RT-LAMP assays developed in this study showed strong potential for use as an on-site diagnostic assay for rapid, specific, and reliable detection of CaAstV in clinical samples.

Recent advances in surface plasmon resonance imaging and biological applications.

Surface Plasmon Resonance Imaging (SPRI) is a robust technique for visualizing refractive index changes, which enables researchers to observe interactions between nanoscale objects in an imaging manner. In the past period, scholars have been attracted by the Prism-Coupled and Non-prism Coupled configurations of SPRI and have published numerous experimental results. This review describes the principle of SPRI and discusses recent developments in Prism-Coupled and Non-prism Coupled SPRI techniques in detail, respectively. And then, major advances in biological applications of SPRI are reviewed, including four sub-fields (cells, viruses, bacteria, exosomes, and biomolecules). The purpose is to briefly summarize the recent advances of SPRI and provide an outlook on the development of SPRI in various fields.

The fingerprints of nifedipine/isonicotinamide cocrystal polymorph studied by terahertz time-domain spectroscopy.

Cocrystal is constructed to improve physicochemical properties of active pharmaceutical ingredient and prevent polymorphism via intermolecular interactions. However, recent examples on cocrystal polymorphs display significantly different properties. Even though some analytical techniques have been used to characterize the cocrystal polymorphic system, it remains unclear how intermolecular interactions drive and stabilize the structure. In this work, we study the cocrystal polymorphs of nifedipine (NFD) and isonicotinamide (INA) using terahertz (THz) spectroscopy. Form I and form II of NFD-INA cocrystals show spectral fingerprints in THz region. Temperature-dependent THz spectra display distinguished frequency shifts of each fingerprint. Combined with solid-state density functional theory (DFT) calculations, the experimental fingerprints and their distinct responses to temperature are elucidated by specific collective vibrational modes. The vibrations of hydrogen bonding between dihydropyridine ring of NFD and INA are generally distributed below 1.5 THz, which play important roles in stabilizing cocrystal and preventing the oxidation of NFD. The rotations of methyl group in NFD are widely distributed in the range of 1.5-4.0 THz, which helps the steric recognition. The results demonstrate that THz spectroscopy is a sensitive tool to discriminate cocrystal polymorphs. It has the potential to be used as a non-invasive technique for pharmaceutical screening.

Epidemiological survey and genetic evolution of H3N2 subtype influenza viruses from stray dogs in Shanghai, China.

An avian-origin canine influenza virus (CIV) has recently emerged in dogs and is spreading in China. Given that humans have frequent contact with dogs, this has prompted an increased emphasis on biosafety. In this study, we collected 693 nasal swab samples and 800 blood samples from stray dogs in animal shelters to survey canine influenza epidemiology and characterize the evolution of CIV H3N2 in Shanghai. We tested samples for canine influenza antibodies and canine influenza RNA in January-May, 2019, and the results showed that the positive rate was 17.62% by ELISA, 15.75% by microneutralization (MN) assay, and 18.51% by real time RT-PCR, respectively. We also performed phylogenetic and genomic analysis on six H3N2 CIV isolates. The H3N2 viruses which prevailed in Shanghai originated from Beijing and Jiangsu isolates. Phylogenetic analysis showed that the sequences of CIV isolates have multiple amino acid antigenic drifts, deletions, and substitutions. The time of the most recent common ancestor (TMRCA) of HA and NA was 2004 and 2005, respectively. Notably, the substitution, 146S, in hemagglutinin and the deletion in the neuraminidase (NA) stalk region we found in this study warrant attention because they have frequently been identified in human influenza viruses. The potential adaptation of this CIV H3N2 clade to mammals and its public health threat should be further evaluated.

A Refractive Index Sensor Based on H-Shaped Photonic Crystal Fibers Coated with Ag-Graphene Layers.

An Ag-graphene layers-coated H-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor with a U-shaped grooves open structure for refractive index (RI) sensing is proposed and numerically simulated by the finite element method (FEM). The designed sensor could solve the problems of air-holes material coating and analyte filling in PCF. Two big air-holes in the x-axis produce a birefringence phenomenon leading to the confinement loss and sensitivity of x-polarized light being much stronger than y-polarized. Graphene is deposited on the layer of silver in the grooves; its high surface to volume ratio and rich π conjugation make it a suitable dielectric layer for sensing. The effect of structure parameters such as air-holes size, U-shaped grooves depth, thickness of the silver layer and number of graphene layers on the sensing performance of the proposed sensor are numerical simulated. A large analyte RI range from 1.33 to 1.41 is calculated and the highest wavelength sensitivity is 12,600 nm/RIU. In the linear RI sensing region of 1.33 to 1.36; the average wavelength sensitivity we obtained can reach 2770 nm/RIU with a resolution of 3.61 × 10-5 RIU. This work provides a reference for developing a high-sensitivity; multi-parameter measurement sensor potentially useful for water pollution monitoring and biosensing in the future.

High-sensitivity magnetic field sensor based on a dual-core photonic crystal fiber.

A high-sensitivity magnetic field sensor based on a dual-core photonic crystal fiber has been designed with an extremely short device length of 2000 µm in this paper. The two cores of the fiber are separated by one air hole filled with magnetic fluid. The sensitive properties are investigated by the full-vector finite element method. Simulation results illustrate that the highest sensitivity can reach -442.7 pm/Oe in the magnetic field strength range of 30-520 Oe. The photonic crystal fiber filled with magnetic fluid, serving as an excellent platform for magnetic field sensing, has great potential applications in complex environments, remote sensing, and real-time monitoring fields.

Square-lattice alcohol-filled photonic crystal fiber temperature sensor based on a Sagnac interferometer.

A square-lattice alcohol-filled photonic crystal fiber temperature sensor based on a Sagnac interferometer (SI) is designed and analyzed by the finite element method. Alcohol is filled in all air holes in the cladding. The temperature-sensing properties of the proposed fiber sensor are investigated. Simulation results exhibit the transmission spectrums of the fiber SI will shift with the change of temperature, because the birefringence of the alcohol-filled fiber will change under different temperatures. The temperature sensitivity is obtained from the fitting line of the temperature and resonant wavelength. The average sensitivity can reach to 16.55 nm/°C in the range from 45°C to 75°C. This designed fiber temperature sensor has advantages in simple structure and high sensitivity. It can be used to detect temperature in complex environments.

High-Resolution Temperature Sensor Based on Single-Frequency Ring Fiber Laser via Optical Heterodyne Spectroscopy Technology.

We demonstrate a high-resolution temperature sensor based on optical heterodyne spectroscopy technology by virtue of the narrow linewidth characteristic of a single-frequency fiber laser. When the single-frequency ring fiber laser has a Lorentzian-linewidth <1 kHz and the temperature sensor operates in the range of 3-85 °C, an average sensitivity of 14.74 pm/°C is obtained by an optical spectrum analyzer. Furthermore, a resolution as high as ~5 × 10-3 °C is demonstrated through optical heterodyne spectroscopy technology by an electrical spectrum analyzer in the range of 18.26⁻18.71 °C with the figure of merit up to 3.1 × 105 in the experiment.

Relative Humidity Sensor Based on No-Core Fiber Coated by Agarose-Gel Film.

A relative humidity (RH) sensor based on single-mode-no-core-single-mode fiber (SNCS) structure is proposed and experimentally demonstrated. The agarose gel is coated on the no-core fiber (NCF) as the cladding, and multimode interference (MMI) occurs in the SNCS structure. The transmission spectrum of the sensor is modulated at different ambient relative humidities due to the tunable refractive index property of the agarose gel film. The relative humidity can be measured by the wavelength shift and intensity variation of the dip in the transmission spectra. The humidity response of the sensors, coated with different concentrations and coating numbers of the agarose solution, were experimentally investigated. The wavelength and intensity sensitivity is obtained as -149 pm/%RH and -0.075 dB/%RH in the range of 30% RH to 75% RH, respectively. The rise and fall time is tested to be 4.8 s and 7.1 s, respectively. The proposed sensor has a great potential in real-time RH monitoring.

Simultaneous measurement of refractive index and temperature based on SPR in D-shaped MOF.

A surface plasmon resonance (SPR) sensor based on D-shaped microstructured optical fiber (MOF) is proposed to realize the simultaneous measurement of refractive index (RI) and temperature. The D-shaped flat surface coated with a gold layer is in direct contact with analyte as a sensing channel of RI, and one of the air holes near the fiber core is filled with chloroform to detect temperature. Two separate channels and birefringence caused by the asymmetric structure can distinguish the variations of RI and temperature independently, thus completely solving the cross-sensitivity problem. This is the first time to realize the simultaneous measurement of multiple parameters without matrix equations, to the best of our knowledge. Results show that the y-polarized peak supported by channel I only shifts with RI variation and is unaffected by the temperature floating. Similarly, the x-polarized peak supported by channel II is only influenced by the change of temperature in the external environment. The effect of gold layer thickness is investigated numerically, and the sensor sensitivity is identified both in wavelength and amplitude interrogations. This work is very helpful for the design and implementation of a highly sensitive, real-time, and distributed SPR sensor for multi-parameter measurement applications.

Improved Numerical Calculation of the Single-Mode-No-Core-Single-Mode Fiber Structure Using the Fields Far from Cutoff Approximation.

Multimode interferometers based on the single-mode-no-core-single-mode fiber (SNCS) structure have been widely investigated as functional devices and sensors. However, the theoretical support for the sensing mechanism is still imperfect, especially for the cladding refractive index response. In this paper, a modified model of no-core fiber (NCF) based on far from cut-off approximation is proposed to investigate the spectrum characteristic and sensing mechanism of the SNCS structure. Guided-mode propagation analysis (MPA) is used to analyze the self-image effect and spectrum response to the cladding refractive index and temperature. Verified by experiments, the performance of the SNCS structure can be estimated specifically and easily by the proposed method.

Influenza virus-like particles harboring H9N2 HA and NA proteins induce a protective immune response in chicken.

BACKGROUND: Avian influenza viruses represent a growing threat of an influenza pandemic. The co-circulation of multiple H9N2 genotypes over the past decade has been replaced by one predominant genotype-G57 genotype, which displays a changed antigenicity and improved adaptability in chickens. Effective H9N2 subtype avian influenza virus vaccines for poultry are urgently needed. OBJECTIVE: In this study, we constructed H9N2 subtype avian influenza virus-like particle (VLP) and evaluated its protective efficacy in specific pathogen-free (SPF) chickens to lay the foundation for developing an effective vaccine against influenza viruses. METHODS: Expression of influenza proteins in VLPs was confirmed by Western blot, hemagglutination inhibition (HI), and neuraminidase inhibition (NI). The morphology was observed by electron microscopy. A group of 15 three-week-old SPF chickens was divided into three subgroups of five chickens immunized with VLP, commercial vaccine, and PBS. Challenge study was performed to evaluate efficacy of VLP vaccine. RESULTS AND CONCLUSIONS: The hemagglutinin (HA) and neuraminidase (NA) proteins were co-expressed in the infected cells, self-assembled, and were released into the culture medium in the form of VLPs of diameter ~80 nm. The VLPs exhibited some functional characteristics of a full influenza virus, including hemagglutination and neuraminidase activity. In SPF chickens, the VLPs elicited serum antibodies specific for H9N2 and induced a higher HI titer (as detected by a homologous antigen) than did a commercial H9N2 vaccine (A/chicken/Shanghai/F/1998). Viral shedding from VLP vaccine subgroup was reduced compared with commercial vaccine subgroup and control subgroup.

Analysis of Hollow Fiber Temperature Sensor Filled with Graphene-Ag Composite Nanowire and Liquid.

A hollow fiber temperature sensor filled with graphene-Ag composite nanowire and liquid is presented and numerically characterized. The coupling properties and sensing performances are analyzed by finite element method (FEM) using both wavelength and amplitude interrogations. Due to the asymmetrical surface plasmon resonance sensing (SPR) region, the designed sensor exhibits strong birefringence, supporting two separate resonance peaks in orthogonal polarizations. Results show that x-polarized resonance peak can provide much better signal to noise ratio (SNR), wavelength and amplitude sensitivities than y-polarized, which is more suitable for tempertature detecting. The graphene-Ag composite nanowire filled into the hollow fiber core can not only solve the oxidation problem but also avoid the metal coating. A wide temperature range from 22 ∘C to 47 ∘C with steps of 5 ∘C is calculated and the temperature sensitivities we obtained are 9.44 nm/ ∘C for x-polarized and 5.33 nm/ ∘C for y-polarized, much higher than other sensors of the same type.

Genotypic evolution and antigenicity of H9N2 influenza viruses in Shanghai, China.

H9N2 influenza viruses have been circulating in China since 1994, but a systematic investigation of H9N2 in Shanghai has not previously been undertaken. Here, using 14 viruses we isolated from poultry and pigs in Shanghai during 2002 and 2006-2014, together with the commercial vaccine A/chicken/Shanghai/F/1998 (Ck/SH/F/98), we analyzed the evolution of H9N2 influenza viruses in Shanghai and showed that all 14 isolates originated from Ck/SH/F/98 antigenically. We evaluated the immune protection efficiency of the vaccine. Our findings demonstrate that H9N2 viruses in Shanghai have undergone extensive reassortment. Various genotypes emerged in 2002, 2006 and 2007, while during 2009-2014 only one genotype was found. Four antigenic groups, A-D, could be identified among the 14 isolates and a variety of antigenically distinct H9N2-virus-derived avian influenza viruses (AIVs) circulated simultaneously in Shanghai during this period. Challenge experiments using vaccinated chickens indicated that the vaccine prevented shedding of antigenic group A and B viruses, but not those of the more recent groups C and D. Genetic analysis showed that compared to the vaccine strain, representative viruses of antigenic groups C and D possess greater numbers of amino acid substitutions in the hemagglutinin (HA) protein than viruses in antigenic groups A and B. Many of these substitutions are located in antigenic sites. Our results indicate that the persistence of H9N2 AIV in China might be due to incomplete vaccine protection and that the avian influenza vaccine should be regularly evaluated and updated to maintain optimal protection.

An Exposed-Core Grapefruit Fibers Based Surface Plasmon Resonance Sensor.

To solve the problem of air hole coating and analyte filling in microstructured optical fiber-based surface plasmon resonance (SPR) sensors, we designed an exposed-core grapefruit fiber (EC-GFs)-based SPR sensor. The exposed section of the EC-GF is coated with a SPR, supporting thin silver film, which can sense the analyte in the external environment. The asymmetrically coated fiber can support two separate resonance peaks (x- and y-polarized peaks) with orthogonal polarizations and x-polarized peak, providing a much higher peak loss than y-polarized, also the x-polarized peak has higher wavelength and amplitude sensitivities. A large analyte refractive index (RI) range from 1.33 to 1.42 is calculated to investigate the sensing performance of the sensor, and an extremely high wavelength sensitivity of 13,500 nm/refractive index unit (RIU) is obtained. The silver layer thickness, which may affect the sensing performance, is also discussed. This work can provide a reference for developing a high sensitivity, real-time, fast-response, and distributed SPR RI sensor.