Detection of Recombinant African Swine Fever Virus Strains of p72 Genotypes I and II in Domestic Pigs, Vietnam, 2023.

African swine fever virus (ASFV) genotype II is endemic to Vietnam. We detected recombinant ASFV genotypes I and II (rASFV I/II) strains in domestic pigs from 6 northern provinces in Vietnam. The introduction of rASFV I/II strains could complicate ongoing ASFV control measures in the region.

Label-Free and Colorimetric Detection of Influenza A Virus via Receptor-Mediated Viral Fusion with Plasmonic Vesicles.

The rapid transmission and numerous re-emerging human influenza virus variants that spread via the respiratory system have led to severe global damage, emphasizing the need for detection tools that can recognize active and intact virions with infectivity. Here, this work presents a plasmonic vesicle-mediated fusogenic immunoassay (PVFIA) comprising gold nanoparticle (GNP) encapsulating fusogenic polymeric vesicles (plasmonic vesicles; PVs) for the label-free and colorimetric detection of influenza A virus (IAV). The PVFIA combines two sequential assays: a biochip-based immunoassay for target-specific capture and a PV-induced fusion assay for color change upon the IAV-PV fusion complex formation. The PVFIA demonstrates excellent specificity in capturing the target IAV, while the fusion conditions and GNP induce a significant color change, enabling visual detection. The integration of two consecutive assays results in a low detection limit (100.7919 EID50 mL-1 ) and good reliability (0.9901), indicating sensitivity that is 104.208 times higher than conventional immunoassay. Leveraging the PV viral membrane fusion activity renders the PVFIA promising for point-of-care diagnostics through colorimetric detection. The innovative approach addresses the critical need for detecting active and intact virions with infectivity, providing a valuable tool with which to combat the spread of the virus.

Human-to-Animal Transmission of SARS-CoV-2, South Korea, 2021.

To investigate SARS-CoV-2 transmission from humans to animals in Seoul, South Korea, we submitted samples from companion animals owned by persons with confirmed COVID-19. Real-time PCR indicated higher SARS-CoV-2 viral infection rates for dogs and cats than previously reported from the United States and Europe. Host-specific adaptations could introduce mutant SARS-CoV-2 to humans.

Experimental Infection and Transmission of SARS-CoV-2 Delta and Omicron Variants among Beagle Dogs.

We assessed susceptibility of dogs to SARS-COV-2 Delta and Omicron variants by experimentally inoculating beagle dogs. Moreover, we investigated transmissibility of the variants from infected to naive dogs. The dogs were susceptible to infection without clinical signs and transmitted both strains to other dogs through direct contact.

Evaluation of a biotin-based surrogate virus neutralization test for detecting postvaccination antibodies against SARS-CoV-2 variants in sera.

A severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) surrogate virus neutralization test (sVNT) was used to determine the degree of inhibition of binding between human angiotensin converting enzyme 2 (hACE2) and the receptor binding domain (RBD) of spike protein by neutralizing antibodies in a biosafety level 2 facility. Here, to improve the sensitivity and specificity of the commercial sVNT, we developed a new biotin based sVNT using biotinylated RBD and HRP conjugated streptavidin instead of HRP conjugated RBD for direct detection in an ELISA assay that strongly correlated to the FDA approved cPass sVNT commercial kit (R2 = 0.8521) and pseudo virus neutralization test (R2 = 0.9006) (pVNT). The biotin based sVNT was evaluated in 535 postvaccination serum samples corresponding to second and third boosts of AZD1222 and BNT162b2 vaccines of the wild type strain. We confirmed that the neutralizing antibodies against SARS-CoV-2 variants in second vaccination sera decreased after a median of 141.5 days. Furthermore, vaccination sera from BNT162b2-BNT162b2 vaccines maintained neutralizing antibodies for longer than those of AZD1222 only vaccination. In addition, both vaccines maintained high neutralizing antibodies in third vaccination sera against Omicron BA.2 after a median of 27 days, but neutralizing antibodies significantly decreased after a median of 141.5 days. Along with the cPass sVNT commercial kit, biotin based sVNTs may also be suitable for specifically detecting neutralizing antibodies against multiple SARS-CoV-2 variants; however, to initially monitor the neutralizing antibodies in vaccinated sera using high throughput screening, conventional PRNT could be replaced by sVNT to circumvent the inconvenience of a long test time.

Rapid Visible Detection of African Swine Fever Virus Using Hybridization Chain Reaction-Sensitized Magnetic Nanoclusters and Affinity Chromatography.

African swine fever virus (ASFV) is a severe and persistent threat to the global swine industry. As there are no vaccines against ASFV, there is an immense need to develop easy-to-use, cost-effective, and rapid point-of-care (POC) diagnostic platforms to detect and prevent ASFV outbreaks. Here, a novel POC diagnostic system based on affinity column chromatography for the optical detection of ASFV is presented. This system employs an on-particle hairpin chain reaction to sensitize magnetic nanoclusters with long DNA strands in a target-selective manner, which is subsequently fed into a column chromatography device to produce quantitatively readable and colorimetric signals. The detection approach does not require expensive analytical apparatus or immobile instrumentation. The system can detect five genes constituting the ASFV whole genome with a detection limit of ≈19.8 pm in swine serum within 30 min at laboratory room temperature. With an additional pre-amplification step using polymerase chain reaction (PCR), the assay is successfully applied to detect the presence of ASFV in 30 suspected swine samples with 100% sensitivity and specificity, similar to quantitative PCR. Thus, this simple, inexpensive, portable, robust, and customizable platform for the early detection of ASFV can facilitate the timely surveillance and implementation of control measures.

Identification of the multiple roles of enolase as an plasminogen receptor and adhesin in Mycoplasma hyopneumoniae.

Mycoplasma hyopneumoniae is the etiological agent underlying porcine enzootic pneumonia, a chronic respiratory disease worldwide. The recruitment of plasminogen to the surface and subsequently promotion of plasmin conversion by the surface-located receptor, have been reported to assist the adhesion and invasion of Mycoplasmas. The surface localization and plasminogen-binding ability of M. hyopneumoniae enolase were previously confirmed; however, the biological functions were not be determined, especially the role as a plasminogen receptor. Here, using ELISA and SPR analyses, we confirmed the stable binding of M. hyopneumoniae enolase to plasminogen in a dose-dependent manner. The facilitation of the activation of plasminogen in the presence of tPA and direct activation of plasminogen at low efficiency without tPA addition by M. hyopneumoniae enolase were also determined using a plasmin-specific chromogenic substrate. Notably, the C-terminal and N-terminal regions located in M. hyopneumoniae enolase play an important role in plasminogen binding and activation. Additionally, we demonstrate that M. hyopneumoniae enolase can competitively inhibit the adherence of M. hyopneumoniae to PK15 cells. These results provide insight into the role of enolase in M. hyopneumoniae infection, a mechanism that manipulates the proteolytic system of the host.

Development of a neutralization monoclonal antibody with a broad neutralizing effect against SARS-CoV-2 variants.

BACKGROUND: The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has challenged the effectiveness of current therapeutic regimens. Here, we aimed to develop a potent SARS-CoV-2 antibody with broad neutralizing effect by screening a scFv library with the spike protein receptor-binding domain (RBD) via phage display. METHODS: SKAI-DS84 was identified through phage display, and we performed pseudovirus neutralization assays, authentic virus neutralization assays, and in vivo neutralization efficacy evaluations. Furthermore, surface plasmon resonance (SPR) analysis was conducted to assess the physical characteristics of the antibody, including binding kinetics and measure its affinity for variant RBDs. RESULTS: The selected clones were converted to human IgG, and among them, SKAI-DS84 was selected for further analyses based on its binding affinity with the variant RBDs. Using pseudoviruses, we confirmed that SKAI-DS84 was strongly neutralizing against wild-type, B.1.617.2, B.1.1.529, and subvariants of SARS-CoV-2. We also tested the neutralizing effect of SKAI-DS84 on authentic viruses, in vivo and observed a reduction in viral replication and improved lung pathology. We performed binding and epitope mapping experiments to understand the mechanisms underlying neutralization and identified quaternary epitopes formed by the interaction between RBDs as the target of SKAI-DS84. CONCLUSIONS: We identified, produced, and tested the neutralizing effect of SKAI-DS84 antibody. Our results highlight that SKAI-DS84 could be a potential neutralizing antibody against SARS-CoV-2 and its variants.

Establishment of multicenter COVID-19 therapeutics preclinical test system in Republic of Korea.

Throughout the recent COVID-19 pandemic, South Korea led national efforts to develop vaccines and therapeutics for SARS-CoV-2. The project proceeded as follows: 1) evaluation system setup (including Animal Biosafety Level 3 (ABSL3) facility alliance, standardized nonclinical evaluation protocol, and laboratory information management system), 2) application (including committee review and selection), and 3) evaluation (including expert judgment and reporting). After receiving 101 applications, the selection committee reviewed pharmacokinetics, toxicity, and efficacy data and selected 32 final candidates. In the nonclinical efficacy test, we used golden Syrian hamsters and human angiotensin-converting enzyme 2 transgenic mice under a cytokeratin 18 promoter to evaluate mortality, clinical signs, body weight, viral titer, neutralizing antibody presence, and histopathology. These data indicated eight new drugs and one repositioned drug having significant efficacy for COVID-19. Three vaccine and four antiviral drugs exerted significant protective activities against SARS-CoV-2 pathogenesis. Additionally, two anti-inflammatory drugs showed therapeutic effects on lung lesions and weight loss through their mechanism of action but did not affect viral replication. Along with systematic verification of COVID-19 animal models through large-scale studies, our findings suggest that ABSL3 multicenter alliance and nonclinical evaluation protocol standardization can promote reliable efficacy testing against COVID-19, thus expediting medical product development.

Magnetic-bead-based DNA-capture-assisted real-time polymerase chain reaction and recombinase polymerase amplification for the detection of African swine fever virus.

African swine fever (ASF) is a deadly disease in swine caused by African swine fever virus (ASFV). The global spread of ASFV has resulted in significant economic losses worldwide. Improved early detection has been the most important first line of defense for preventing ASF outbreaks and for activating control measures. Despite the availability of rapid amplification methods, nucleic acid extraction from specimens still needs to be performed in a laboratory. To facilitate this step, we exploited the strong affinity of biotin-streptavidin binding by functionalizing streptavidin-coated magnetic beads with biotinylated oligonucleotide capture probes to efficiently capture genotype II ASFV DNA directly from crude clinical samples. The captured DNA is suitable for detection using real-time quantitative PCR (qPCR) and recombinase polymerase amplification (RPA). In this study, ASFV DNA was efficiently captured from swine feces, serum, and tissue samples. Both DNA-capture-assisted qPCR and RPA-based detection methods have a limit of detection (LOD) of 102 copies/µl, which is comparable to those of commercially available kits. In addition, an RPA-SYBR Green I method was developed for the immediate visual detection of ASFV DNA, which is time-saving and efficient for resource-limited field settings. In summary, a rapid, versatile, sequence-specific DNA capture method was developed to efficiently capture ASFV DNA from swine clinical samples and subsequent detection by qPCR and RPA, which has the potential to be used for robust screening and surveillance of ASFV and in point-of-care (POC) diagnostics.

A flap endonuclease 1-assisted universal viral nucleic acid sensing system using surface-enhanced Raman scattering.

The continued uncertainty of emerging infectious viral diseases has led to an extraordinary urgency to develop advanced molecular diagnostic tests that are faster, more reliable, simpler to use, and readily available than traditional methods. This study presents a system that can accurately and rapidly trace viral nucleic acids by employing flap endonuclease 1 (FEN1)-assisted specific DNA cleavage reactions and surface-enhanced Raman scattering (SERS)-based analysis. The designed Raman tag-labeled 5'- and 3'-flap provider DNA yielded structurally defined DNA substrates on magnetic nanoparticle surfaces when a target was present. The FEN1 enzyme subsequently processes the substrates formed via an invasive cleavage reaction, producing 5'-flap DNA products. Magnetic separation allows efficient purification of flap products from reaction mixtures. The isolated solution was directly applied onto high aspect-ratio plasmonic silver nanopillars serving as SERS-active substrates to induce amplified SERS signals. We verified the developed SERS-based sensing system using a synthetic target complementary to an avian influenza A (H9N2) virus gene and examined the detection performance of the system using complementary DNA (cDNA) derived from H9N2 viral RNA. As a result, we could detect a synthetic target with a detection limit of 41.1 fM with a single base-pair discrimination ability and achieved multiplexed detection capability for two targets. Using cDNA samples from H9N2 viruses, we observed a high concordance of R2 = 0.917 between the data obtained from SERS and the quantitative polymerase chain reaction. We anticipate that this enzyme-assisted SERS sensor may provide insights into the development of high-performance molecular diagnostic tools that can respond rapidly to viral pathogens.

Characterization of replication and variations in genome segments of a bat reovirus, BatMRV/B19-02, by RNA-seq in infected Vero-E6 cells.

Mammalian orthoreoviruses (MEVs) that can cause enteric, respiratory, and encephalitic infections have been identified in a wide variety of mammalian species. Here, we report a novel MRV type 1 strain detected in Miniopterus schreibersii that may have resulted from reassortment events. Using next-generation RNA sequencing (RNA-seq), we found that the ratios of the RNA levels of the 10 reovirus segments in infected cells were constant during the late stages of infection. We also discovered that the relative abundance of each segment differed. Notably, the relative abundance of M2 (encoding the µ1 protein) and S4 (encoding the σ3 protein) RNAs was higher than that of the others throughout the infection. Additionally, massive junctions were identified. These results support the hypothesis that defective genome segments are generated and that cross-family recombination occurs. These data may further the study of gene function, viral replication, and virus evolution.

Practical scale evaluation of a photocatalytic air purifier equipped with a Titania-zeolite composite bead filter for VOC removal and viral inactivation.

A practical scale photocatalytic air purifier equipped with a TiO2/H-ZSM-5 composite bead filter was demonstrated to be able to effectively remove indoor volatile organic compounds (VOCs) and viruses with sustainable performances under UVA-LED illumination. TiO2 hybridized with 5 wt% H-ZSM-5 zeolite significantly enhanced its photocatalytic activity for degrading VOCs including formaldehyde, acetaldehyde, and toluene, than bare TiO2. H-ZSM-5 provided strong adsorption sites for these compounds, thus accelerating their photocatalytic conversion into CO2 by adjacent TiO2 photocatalyst. Moreover, owing to its superior adsorption capacity, the composite bead filter completely prevented the emission of formaldehyde produced by photocatalytic oxidation of toluene. The sustainability of this composite bead filter for VOC removal was confirmed by regeneration and accelerated durability tests. In addition, the photocatalytic air purifier was effective in removing aerosolized viral particles of bacteriophage Phi-X 174. It was confirmed that the viruses on filter surfaces were completely inactivated by photocatalytic oxidation. TiO2/H-ZSM-5 composite beads also exhibited excellent efficacies for inactivation of pathogenic coronaviruses including SARS-CoV-2. The photocatalytic process degraded viral RNAs of SARS-CoV-2 by more than 99.999% in 1 h, eliminating the viral infectivity. Results of this study suggest that the air purifier equipped with the composite bead filter is ready for practical applications for home and hospital uses.

Molecular profile of African swine fever virus (ASFV) circulating in Vietnam during 2019-2020 outbreaks.

African swine fever (ASF) is a highly infectious disease of pigs caused by African swine fever virus (ASFV). In order to identify potential genetic variations among ASFV strains circulating in Vietnam, 26 ASFV isolates from organs and blood samples collected from domestic pigs from 23 different provinces of northern, central and southern Vietnam during 2019-2020 ASF outbreaks were genetically characterized. Nucleotide sequences were determined for a portion of the B646L (p72) gene, the complete E183L (p54) gene, the variable region of EP402R (CD2v), the central variable region (CVR) of pB602L, and a tandem repeat sequence (TRS) between the I73R and I329L genes. Analysis of the partial B646L (p72) and EP402R (CD2v) gene sequences and the full-length E183L (p54) gene sequence showed that all 26 ASFV isolates belonged to genotype II and serotype VIII and that they were identical to the strain Georgia/2007/1 and all ASFV strains sequenced in China. The TRS between the I73R and I329L genes contained a 10-nucleotide insertion that was observed in the Chinese ASFV strain CN201801 isolated from domestic pigs in 2018, but not in the Georgia/2007/1 and China/Jilin/2018/boar strains isolated from wild boar in China. This is the first intra-epidemic genome analysis reported for the ASFV strains circulating in Vietnam.

Porous gold nanoparticles for attenuating infectivity of influenza A virus.

BACKGROUND: Influenza viruses (IVs) have become increasingly resistant to antiviral drugs that target neuraminidase and matrix protein 2 due to gene mutations that alter their drug-binding target protein regions. Consequently, almost all recent IV pandemics have exhibited resistance to commercial antiviral vaccines. To overcome this challenge, an antiviral target is needed that is effective regardless of genetic mutations. MAIN BODY: In particular, hemagglutinin (HA), a highly conserved surface protein across many IV strains, could be an effective antiviral target as it mediates binding of IVs with host cell receptors, which is crucial for membrane fusion. HA has 6 disulfide bonds that can easily bind with the surfaces of gold nanoparticles. Herein, we fabricated porous gold nanoparticles (PoGNPs) via a surfactant-free emulsion method that exhibited strong affinity for disulfide bonds due to gold-thiol interactions, and provided extensive surface area for these interactions. A remarkable decrease in viral infectivity was demonstrated by increased cell viability results after exposing MDCK cells to various IV strains (H1N1, H3N2, and H9N2) treated with PoGNP. Most of all, the viability of MDCK cells infected with all IV strains increased to 96.8% after PoGNP treatment of the viruses compared to 33.9% cell viability with non-treated viruses. Intracellular viral RNA quantification by real-time RT-PCR also confirmed that PoGNP successfully inhibited viral membrane fusion by blocking the viral entry process through conformational deformation of HA. CONCLUSION: We believe that the technique described herein can be further developed for PoGNP-utilized antiviral protection as well as metal nanoparticle-based therapy to treat viral infection. Additionally, facile detection of IAV can be achieved by developing PoGNP as a multiplatform for detection of the virus.

Outbreak of African Swine Fever, Vietnam, 2019.

African swine fever is one of the most dangerous diseases of swine. We confirmed the 2019 outbreak in Vietnam by real-time reverse transcription PCR. The causative strain belonged to p72 genotype II and was 100% identical with viruses isolated in China (2018) and Georgia (2007). International prevention and control collaboration is needed.

Detection of antibodies against hepatitis E virus in pet veterinarians and pet dogs in South Korea.

Hepatitis E virus (HEV) is a zoonotic pathogen commonly considered an important foodborne virus. Pet dogs are important reservoirs of zoonotic agents. In the present study, the seroprevalence of HEV in pet dogs and pet veterinarians were found to be 28.2 and 5.0%, respectively. It remains unclear whether pet veterinarians are at higher risk of HEV transmission. However, pet animals and individuals who have contact with infected animals must be continually monitored for public health concerns.

Host Cell Mimic Polymersomes for Rapid Detection of Highly Pathogenic Influenza Virus via a Viral Fusion and Cell Entry Mechanism.

Highly pathogenic avian influenza virus (HPAIV) infections have occurred continuously and crossed the species barrier to humans, leading to fatalities. A polymerase chain reaction based molecular test is currently the most sensitive diagnostic tool for HPAIV; however, the results must be analyzed in centralized diagnosis systems by a trained individual. This requirement leads to delays in quarantine and isolation. To control the spread of HPAIV, rapid and accurate diagnostics suitable for field testing are needed, and the tests must facilitate a differential diagnosis between HPAIV and low pathogenic avian influenza virus (LPAIV), which undergo cleavage specifically by trypsin- or furin-like proteases, respectively. In this study, a differential avian influenza virus rapid test kit is developed and evaluated in vitro and using clinical specimens from HPAIV H5N1-infected animals. It is demonstrated that this rapid test kit provides highly sensitive and specific detection of HPAIV and LPAIV and is thus a useful field diagnostic tool for H5N1 HPAIV outbreaks and for rapid quarantine control of the disease.

Correction to: Simultaneous detection of severe acute respiratory syndrome, Middle East respiratory syndrome, and related bat coronaviruses by real-time reverse transcription PCR.

Unfortunately, the concentration unit of plasmids was published incorrectly in the original publication of the article. The concentration unit, 'copies/ml' should be corrected to 'copies/µl'. This changes do not affect to the analytic sensitivity of the method because the detection limits of 50-100 copies/µL and 5-100 copies/µL using pUC57-SARS-pS2 (a template for SARS-CoV) and pGEM-MERS-S2 (a template for MERS-CoV), respectively, were as sensitive as other real-time PCR methods [1].

Virological and pathological characterization of an avian H1N1 influenza A virus.

Gene segments from avian H1N1 influenza A viruses have reassorted with other influenza viruses to generate pandemic strains over the past century. Nevertheless, little effort has been invested in understanding the characteristics of avian H1N1 influenza viruses. Here, we present the genome sequence and a molecular and virological characterization of an avian influenza A virus, A/wild bird/Korea/SK14/2014 (A/SK14, H1N1), isolated from migratory birds in South Korea during the winter season of 2014-2015. Full-genome sequencing and phylogenetic analysis revealed that the virus belongs to the Eurasian avian lineage. Although it retained avian-receptor binding preference, A/SK14 virus also exhibited detectable human-like receptor binding and was able to replicate in differentiated primary normal human bronchial epithelial cells. In animal models, A/SK14 virus was moderately pathogenic in mice, and virus was detected in nasal washes from inoculated guinea pigs, but not in direct-contact guinea pigs. Although A/SK14 showed moderate pathogenicity and no evidence of transmission in a mammalian model, our results suggest that the dual receptor specificity of A/SK14-like virus might allow for a more rapid adaptation to mammals, emphasizing the importance of further continuous surveillance and risk-assessment activities.