Interval-locked dual-frequency φ-OFDR with an enhanced strain dynamic range and a long-term stability.

We report on an interval-locked dual-frequency phase-sensitive optical frequency-domain reflectometry relying on a common-reference optical phase-locked loop. With a shared unbalanced interferometry, this design allows for synchronizing the frequency drift of two lasers, leading to a steadily stabilized dual frequency with an arbitrary interval. Equivalently to a longer synthetic wavelength, their phase difference is utilized to demodulate the ambient changes of interest with an enhanced dynamic range and long-term stability. With a stabilized interval of 1 THz, it allows for an enhancement in a strain measurement range of up to 193-fold in theory. Demonstration in terms of distributed strain sensing covering a distance of 500 m with a 10 cm spatial resolution has been verified, showing a significant extension in the achievable strain dynamic range with a preserved sensitivity over 1 h.

Porcine deltacoronavirus and its prevalence in China: a review of epidemiology, evolution, and vaccine development.

Porcine deltacoronavirus (PDCoV) is one of the most important enteropathogenic pathogens, and it causes enormous economic losses to the global commercial pork industry. PDCoV was initially reported in Hong Kong (China) in 2012 and subsequently emerged in swine herds with diarrhea in Ohio (USA) in 2014. Since then, it has spread to Canada, South Korea, mainland China, and several Southeast Asian countries. Information about the epidemiology, evolution, prevention, and control of PDCoV and its prevalence in China has not been comprehensively reported, especially in the last five years. This review is an update of current information on the general characteristics, epidemiology, geographical distribution, and evolutionary relationships, and the status of PDCoV vaccine development, focusing on the prevalence of PDCoV in China and vaccine research in particular. Together, this information will provide us with a greater understanding of PDCoV infection and will be helpful for establishing new strategies for controlling this virus worldwide.

A Novel Human Acute Encephalitis Caused by Pseudorabies Virus Variant Strain.

BACKGROUND: Pseudorabies virus (PRV) is a common pathogen in multiple animal species, particularly in pigs. However, PRV infection in humans is rare and, to the best of our knowledge, PRV has never been isolated from human cases before. METHODS: Four acute encephalitis cases in humans were confirmed as PRV infection based on clinical symptoms, laboratory diagnosis, and metagenomic next-generation sequencing (mNGS). Cerebrospinal fluid (CSF) samples were collected and applied for virus isolation. Etiological and genetic characteristics of this PRV human isolate were further determined. RESULTS: The patients manifested respiratory dysfunction and acute neurological symptoms. The mNGS revealed PRV-specific nucleotide sequences in patients' CSF samples (7-6198 reads and 0.2446%-80.58% coverage). The PRV envelope glycoprotein B antibody, glycoprotein E antibody, and neutralizing antibody were positively detected. For the first time, a PRV strain, designated hSD-1/2019, was isolated and identified from a CSF sample, and transmission electron microscopy revealed that hSD-1/2019 had typical morphology similar to that of swine PRV. Phylogenetic analysis illustrated that hSD-1/2019 was genetically closest to those PRV variant strains currently circulating in pigs in China, and this strain showed similar etiological characteristics to Chinese PRV variant strains, while different from Chinese classical strain. Moreover, hSD-1/2019 showed high pathogenicity and induced acute neurological symptoms in pigs. CONCLUSIONS: A PRV strain was isolated from an acute human encephalitis case. This isolate showed close phylogenetic relationships and similar etiological characteristics to Chinese PRV variant strains, implying the great risk of PRV transmission from pigs to humans.

Isolation of Moraxella bovoculi from racehorses with keratoconjunctivitis.

Moraxella bovoculi was isolated and identified in ocular fluid samples collected from 9 racehorses with infectious keratoconjunctivitis in China in 2013. All 9 M. bovoculi isolates were hemolytic, Gram-negative diplococci that were phenylalanine deaminase positive. The sequence of the 16S ribosomal DNA (rDNA) gene of the isolates matched the 16S rDNA sequence of M. bovoculi. Amplification of the 16S-23S intergenic spacer region followed by AfaI digestion produced a 600-base pair product, a result characteristic of M. bovoculi isolates. The phylogenetic analysis based on the 16S rDNA sequence confirmed the strain isolated in the current study had genetic homology with M. bovoculi.

Mycobacteriosis associated with Mycobacterium peregrinum infection in Red-crowned Cranes (Grus japonensis) in China.

We describe mycobacteriosis caused by Mycobacterium peregrinum in Red-crowned Cranes (Grus japonensis) in China. Isolates were identified by bacteriology, molecular identification methods, and phylogenetic analysis. This study shows that M. peregrinum is an important pathogen for mycobacteriosis and could represent a threat to conservation efforts of endangered species.

Genome Sequence of a Circulating Human-Like Swine-Origin Influenza A Virus H3N2 Strain.

The full-genome sequence of A/swine/Henan/1/2010, a strain of influenza A virus isolated in central China, was determined. Phylogenetic analyses show that its eight genomic segments are human-like, and some of its segments have appeared in swine H1N2, swine H1N1, and human H1N2 influenza viruses.

Immunogenicity of two FMDV nonameric peptides encapsulated in liposomes in mice and the protective efficacy in guinea pigs.

It has been predicted that nonameric peptides I (VP1(26-34), RRQHTDVSF), II (VP1(157-165), RTLPTSFNY) and III (VP1(45-53), KEQVNVLDL) from the VP1 capsid protein of the foot-and-mouth disease virus (FMDV) are T cell epitopes. To investigate whether these peptides have immunological activity, BALB/c mice were immunized with peptide I, II or III conjugated with immunostimulating complexes (ISCOMs). A cytotoxic T lymphocyte assay was used to evaluate the cytotoxic activity induced by peptides along with by measuring peptide-specific T-cell proliferation and CD8(+) T lymphocyte numbers in whole blood and interferon (IFN)-γ production in peripheral blood mononuclear cells induced by peptides. To further identify the protective efficacy of peptides, an FMDV challenge assay was done in guinea pigs. Peptides I and II stimulated significant increases in T-cell proliferation, CD8(+) T lymphocytes, and IFN-γ secretion and cytotoxic activity compared to controls. The FMDV challenge assay indicated peptides I and II can protect over 60% of animals from virus attack. The results demonstrate that peptides I and II encapsulated in liposomes should be CTL epitopes of FMDV and can protect animals from virus attack to some extent.