Rapid detection of infectious bovine Rhinotracheitis virus using recombinase polymerase amplification assays

Establishment of a real-time fluorescent quantitative PCR detection method and phylogenetic analysis of BoAHV-1

BACKGROUND

Infectious bovine rhinotracheitis (IBR), caused by Bovine alphaherpesvirus-1 (BoAHV-1), is an acute, highly contagious disease primarily characterized by respiratory tract lesions in infected cattle. Due to its severe pathological damage and extensive transmission, it results in significant economic losses in the cattle industry. Accurate detection of BoAHV-1 is of paramount importance. In this study, we developed a real-time fluorescent quantitative PCR detection method for detecting BoAHV-1 infections. Utilizing this method, we tested clinical samples and successfully identified and isolated a strain of BoAHV-1.1 from positive samples. Subsequently, we conducted a genetic evolution analysis on the isolate strain's gC, TK, gG, gD, and gE genes.

RESULTS

The study developed a real-time quantitative PCR detection method using SYBR Green II, achieving a detection limit of 7.8 × 101 DNA copies/μL. Specificity and repeatability analyses demonstrated no cross-reactivity with other related pathogens, highlighting excellent repeatability. Using this method, 15 out of 86 clinical nasal swab samples from cattle were found to be positive (17.44%), which was higher than the results obtained from conventional PCR detection (13.95%, 12/86). The homology analysis and phylogenetic tree analysis of the gC, TK, gG, gD, and gE genes of the isolated strain indicate that the JL5 strain shares high homology with the BoAHV-1.1 reference strains. Amino acid sequence analysis revealed that gC, gE, and gG each had two amino acid mutations, while the TK gene had one synonymous mutation and one H to Y mutation, with no amino acid mutations observed in the gD gene. Phylogenetic tree analysis indicated that the JL5 strain belongs to the BoAHV-1.1 genotype and is closely related to American strains such as C33, C14, and C28.

CONCLUSIONS

The established real-time fluorescent quantitative PCR detection method exhibits good repeatability, specificity, and sensitivity. Furthermore, genetic evolution analysis of the isolated BoAHV-1 JL-5 strain indicates that it belongs to the BoAHV-1.1 subtype. These findings provide a foundation and data for the detection, prevention, and control Infectious Bovine Rhinotracheitis.

Simultaneous detection of bovine viral diarrhea virus (BVDV) and bovine herpesvirus 1 (BoHV-1) using recombinase polymerase amplification

Bovine viral diarrhea virus (BVDV) is considered to be the most common agent of severe diarrhea in cattle worldwide, causing fever, diarrhea, ulcers, and abortion. Bovine herpesvirus 1 (BoHV-1) is also a major bovine respiratory disease agent that spreads worldwide and causes extensive damage to the livestock industry. Recombinase polymerase amplification (RPA) is a novel nucleic acid amplification method with the advantages of high efficiency, rapidity and sensitivity, which has been widely used in the diagnosis of infectious diseases. A dual RPA assay was developed for the simultaneous detection of BVDV and BoHV-1. The assay was completed at a constant temperature of 37 °C for 30 min. It was highly sensitive and had no cross-reactivity with other common bovine viruses. The detection rate of BVDV RPA in clinical samples (36.67%) was higher than that of PCR (33.33%), the detection rate of BoHV-1 RPA and PCR were equal. Therefore, the established dual RPA assay for BVDV and BoHV-1 could be a potential candidate for use as an immediate diagnostic.

Tegument protein UL3 of bovine herpesvirus 1 suppresses antiviral IFN-I signaling by targeting STING for autophagic degradation

Bovine herpesvirus 1 (BoHV-1) is a highly contagious pathogen which causes infectious bovine rhinotracheitis in cattle worldwide. Although it has the ability to evade the host's antiviral innate immune response and establish persistent latent infections, the mechanisms are not fully understood, especially the function of the tegument protein to escape innate immunity and participate in viral replication. In this study, we showed that overexpression of tegument protein UL3 facilitates BoHV-1 replication and suppresses the expression of type-I interferon (IFN-I) and IFN-stimulated genes. Then, STING was identified as the target by which UL3 inhibits the IFN-I signaling pathway, and STING was degraded through the UL3-induced autophagy pathway. Furthermore, overexpression of UL3 promotes the expression of the autophagy-related protein ATG101, thereby inducing autophagy. Further study showed that UL3 enhances the interaction between ATG101 and STING, and then the degradation of STING was reversed following ATG101 silencing in UL3-overexpressing cells during BoHV-1 infection. Our research results demonstrate a novel function of UL3 in regulating host's antiviral response and provide a potential mechanism for BoHV-1 immune evasion.

Integrated analysis of microRNA and messenger RNA expression profiles reveals functional microRNA in infectious bovine rhinotracheitis virus-induced mitochondrial damage in Madin-Darby bovine kidney cells

BACKGROUND

Studies have confirmed that Infectious bovine rhinotracheitis virus (IBRV) infection induces mitochondrial damage. MicroRNAs (miRNAs) are a class of noncoding RNA molecules, which are involved in various biological processes and pathological changes associated with mitochondrial damage. It is currently unclear whether miRNAs participate in IBRV-induced mitochondrial damage in Madin-Darby bovine kidney (MDBK) cells.

RESULTS

In the present study, we used high-throughput sequencing technology, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis to screen for mitochondria-related miRNAs and messenger RNAs (mRNAs). In total, 279 differentially expressed miRNAs and 832 differentially expressed mRNAs were identified in 6 hours (IBRV1) versus 24 hours (IBRV2) after IBRV infection in MDBK cells. GO and KEGG enrichment analysis revealed that 42 differentially expressed mRNAs and 348 target genes of differentially expressed miRNAs were correlated with mitochondrial damage, and the miRNA-mitochondria-related target genes regulatory network was constructed to elucidate their potential regulatory relationships. Among the 10 differentially expressed miRNAs, 8 showed expression patterns consistent with the high-throughput sequencing results. Functional validation results showed that overexpression of miR-10a and miR-182 aggravated mitochondrial damage, while inhibition of miR-10a and miR-182 alleviated mitochondrial damage.

CONCLUSIONS

This study not only revealed the expression changes of miRNAs and mRNAs in IBRV-infected MDBK cells, but also revealed possible biological regulatory relationship between them. MiR-10a and miR-182 may have the potential to be developed as biomarkers for the diagnosis and treatment of IBRV. Together, Together, these data and analyses provide additional insights into the roles of miRNA and mRNA in IBRV-induced mitochondria damage.

Development of an LFD-RPA Assay for Rapid Detection of Pentatrichomonas hominis Infection in Dogs

Pentatrichomonas hominis is a trichomonad protozoan that infects the cecum and colon of humans and other mammals. It is a zoonotic pathogen that causes diarrhea in both animals and humans. As companion animals, dogs infected with P. hominis pose a risk of transmitting it to humans. Current methods, such as direct smears and polymerase chain reaction (PCR), used for P. hominis detection have limitations, including low detection rates and the need for specialized equipment. Therefore, there is an urgent need to develop rapid, sensitive, and simple detection methods for clinical application. Recombinase polymerase amplification (RPA) has emerged as a technology for rapid pathogen detection. In this study, we developed a lateral flow dipstick (LFD)-RPA method based on the highly conserved SPO11-1 gene for detecting P. hominis infection by optimizing the primers, probes, and reaction conditions, and evaluating cross-reactivity with genomes of Giardia duodenalis and other parasites. The LFD-RPA method was then used to test 128 dog fecal samples collected from Changchun. The results confirmed the high specificity of the method with no cross-reactivity with the five other parasites. The lowest detection limit of the method was 102 copies/µL, and its sensitivity was 100 times higher than that of the conventional PCR method. Consistent with the positivity rate observed using nested PCR, 12 samples (out of 128) tested positive using this method (positivity rate, 9.38%). In conclusion, the LFD-RPA method developed in this study represents a simple and sensitive assay that allows for the rapid detection of P. hominis infection in dogs, especially in this field.

A Rapid Nucleic Acid Visualization Assay for Infectious Bovine Rhinotracheitis Virus That Targets the TK Gene

Infectious bovine rhinotracheitis virus (IBRV) can cause various degrees of symptoms in the respiratory system, reproductive system, and whole body of cattle. It also can lead to persistent and latent infection in cattle, posing a challenge to timely control of infectious bovine rhinotracheitis (IBR) in farms and causing large financial losses in the global cattle industry. Therefore, the goal of this study was to establish a rapid, simple, and accurate method that can detect IBRV in order to facilitate the control and eradication of IBR in cattle. We combined recombinant polymerase amplification (RPA) with a closed vertical flow visualization strip (VF) and established an RPA-VF assay that targets the thymidine kinase (TK) gene to rapidly detect IBRV. This method (reaction at 42°C for 25 min) was able to detect a minimum of 3.8 × 101 copies/μL of positive plasmid and 1.09 × 101 50% tissue culture infective dose (TCID50) of the IBRV. This assay has high specificity for IBRV and does not cross-react with other respiratory pathogens in cattle. The concordance between the RPA-VF assay and the gold standard was 100%. In addition, this assay was also suitable for the detection of DNA from clinical samples extracted by a simple method (heating at 95°C for 5 min), which can achieve the rapid detection of clinical samples in the field. Overall, the present sensitivity, specificity, and clinical applicability assessments indicated that the RPA-VF assay we developed can be utilized as a quick and accurate on-site test for IBRV detection in farms. IMPORTANCE IBRV causes different degrees of clinical symptoms in cattle and poses a great threat to the cattle industry. The infection is persistent and latent, and the elimination of IBRV in infected herds is difficult. A rapid, simple, and accurate method to detect IBRV is therefore vital to control and eradicate IBR. Combining RPA with an VF, we established an RPA-VF assay for the rapid detection of IBRV, which can complete the test of clinical samples in 35 min. The assay shows good sensitivity, specificity, and clinical applicability and can be used as an on-site test for IBRV in farms.

Development of a reverse transcription recombinase polymerase amplification combined with lateral flow assay for equipment-free on-site field detection of tomato chlorotic spot virus

BACKGROUND

Tomato chlorotic spot virus (TCSV) is an economically important, thrips-transmitted, emerging member of the Orthotospovirus genus that causes significant yield loss mainly in tomatoes, but also in other vegetable and ornamental crops. Disease management of this pathogen is often challenging due to the limited availability of natural host resistance genes, the broad host range of TCSV, and the wide distribution of its thrips vector. Point-of-care detection of TCSV with a rapid, equipment-free, portable, sensitive, and species-specific diagnostic technique can provide prompt response outside the laboratory, which is critical for preventing disease progression and further spread of the pathogen. Current diagnostic techniques require either laboratory-dependent or portable electronic equipment and are relatively time-consuming and costly.

RESULTS

In this study, we developed a novel technique for reverse-transcription recombinase polymerase amplification combined with lateral flow assay (RT-RPA-LFA) to achieve a faster and equipment-free point-of-care detection of TCSV. The RPA reaction tubes containing crude RNA are incubated in the hand palm to obtain sufficient heat (∼36 °C) for the amplification without the need for equipment. Body-heat mediated RT-RPA-LFA is highly TCSV-specific with a detection limit as low as ∼6 pg/μl of total RNA from TCSV-infected tomato plants. The assay can be performed in 15 min in the field.

CONCLUSION

To the best of our knowledge, this is the first equipment-free, body-heat-mediated RT-RPA-LFA technique developed to detect TCSV. Our new system offers a time-saving advantage for the sensitive and specific diagnostic of TCSV that local growers and small nurseries in low-resource settings can use without skilled personnel.

Seroepidemiological study of bovine alphaherpesvirus 1 in the dairy cattle herds of Addis Ababa, Ethiopia

Bovine alphaherpesvirus 1(BoHV-1) causes respiratory disease, abortions, and genital disorders in cattle. Although BoHV-1 has been known to cause severe economic damage to the dairy industries, little is known about its epidemiology in dairy cattle of Addis Ababa, Ethiopia. The present study aimed to determine the seroprevalence and the risk factors associated with the occurrence of BoHV-1. A total of 369 blood samples from 115 dairy herds were collected using a proportional stratified random sampling method and examined antibodies against BoHV-1 using ELISA test. A questionnaire survey was done to gather information related to farm demographics and reproductive disorders. Univariate and multivariate mixed-effect logistic regression analyses were used. The overall seroprevalence of BoHV-1 was detected in 21 % (95%CI: 17-25%) and 32 % (95%CI: 24-42 %) at animal and herd levels, respectively. A multivariable mixed effect logistic regression model revealed that adult cattle had 14 times (OR = 14.32; 95 % CI: 2.53-81.5; P = 0.003) more likely to increase the risk of being BoHV-1 seropositive than young cattle. Purchased cattle had 4 times (OR = 4.15; 95 % CI: 1.36-12.66, P = 0.012) more likely to increase the risk of being BoHV-1 seropositive than homebred cattle. The risk of being BoHV-1 seropositive was 195 times higher in herds using bulls (OR = 195.51; 95 % CI: 3.62-1056.51; P = 0.010) than in herds using artificial insemination only for breeding. BoHV-1 seropositivity was significantly associated with cows that had a history of abortion (OR = 6.89; 95 % CI: 1.97-22.76; P = 0.002), retained placenta (OR = 3.26; 95 % CI: 1.32-8.07; P = 0.010), and repeat breeding (OR = 3.64; 95 % CI: 1.08-12.18; P = 0.036). This study demonstrated the gaps in the selection of BoHV-1 free bulls for breeding as well as limited farm biosecurity practices. Thus, awareness creation for dairy farmers on good farm biosecurity practices including vaccination should be initiated.

Development of Two Recombinase Polymerase Amplification EXO (RPA-EXO) and Lateral Flow Dipstick (RPA-LFD) Techniques for the Rapid Visual Detection of Aeromonas salmonicida

Aeromonas salmonicida is the pathogen underlying furunculosis, causing a septicemic infection that influences both salmonid and non-salmonid fish. Early diagnosis of these contagions is essential for disease surveillance and prevention, so a rapid and sensitive approach is needed. Herein, a recombinase polymerase amplification EXO (RPA-EXO) assay and RPA with a lateral flow dipstick (RPA-LFD) were produced for testing A. salmonicida. The RPA-EXO and RPA-LFD primer sets were devised based on the conserved fragment sequence of the vapA gene. Then, RPA-EXO and RPA-LFD reaction systems were established, and the reaction temperature and time were optimized. After optimization, the RPA-EXO method was capable of testing A. salmonicida within 10 min, and the RPA-LFD method could detect A. salmonicida in only 5 min. The RPA-EXO and RPA-LFD methods exhibited high specificity with no cross-reaction with other strains. To assess sensitivity, a partial vapA gene was cloned, and serial plasmid dilutions were created ranging from 1 × 10⁶ to 1 × 10^-1 copies/μL. The detection limit of RPA-EXO was 1 × 10² copies/μL, and the detection limit of RPA-LFD was 1 copy/μL. For spiked turbot tissue samples, the sensitivity detection of A. salmonicida was 1.2 × 10¹ CFU/mL and 1.2 CFU/mL by RPA-EXO and RPA-LFD, respectively. In comparative analyses of clinical samples, the diagnostic results of RPA-EXO and RPA-LFD were compared with those of the standard conventional PCR test and showed nearly 100% consistency. Therefore, our RPA-EXO and RPA-LFD assays exhibited excellent specificity and sensitivity, which provided two simple, fast and dependable methods to conduct large-scale field investigations of A. salmonicida in resource-limited settings.

Point-of-care testing in companion and food animal disease diagnostics

Laboratory diagnoses of animal diseases has advanced tremendously in recent decades with the advent of cutting-edge technologies such as real-time polymerase chain reaction, next generation sequencing (NGS), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and others However, most of these technologies need sophisticated equipment, laboratory space and highly skilled workforce. Therefore, there is an increasing market demand for point-of-care testing (POCT) in animal health and disease diagnostics. A wide variety of assays based on antibodies, antigens, nucleic acid, and nanopore sequencing are currently available. Each one of these tests have their own advantages and disadvantages. However, a number of research and developmental activities are underway in both academia and industry to improve the existing tests and develop newer and better tests in terms of sensitivity, specificity, turnaround time and affordability. In both companion and food animal disease diagnostics, POCT has an increasing role to play, especially in resource-limited settings. It plays a critical role in improving animal health and wellbeing in rural communities in low- and middle-income countries. At the same time, ensuring high standard of quality through proper validation, quality assurance and regulation of these assays are very important for accurate diagnosis, surveillance, control and management of animal diseases. This review addresses the different types of POCTs currently available for companion and food animal disease diagnostics, tests in the pipeline and their advantages and disadvantages.

Photo-Cross-Linked Probe-Modified Magnetic Particles for the Selective and Reliable Recovery of Nucleic Acids

Polymerase chain reaction (PCR) assays are used to diagnose various infectious diseases such as Coronavirus disease 2019 by detecting the nucleic acids of the pathogen. However, in practice, the yield of the extraction process and the inhibition of the reverse transcription reaction and PCR by foreign substances reduce the sensitivity and may yield false negative results. The sensitivity of the PCR test can be improved by using technologies that can reliably capture the target nucleic acid and remove foreign substances. In this study, we developed photo-cross-linkable probe-modified magnetic particles (PPMPs) for the sequence-specific recovery of target nucleic acids using photo-cross-linkable artificial nucleic acid probes and magnetic particles. Nucleic acid probes modified with photo-cross-linkable artificial nucleic acids can hybridize with the target nucleic acids in a sequence-specific manner and then securely capture the target nucleic acids by UV irradiation-mediated covalent bonding. Then the target nucleic acid is detected by trapping the target-bound probe on the surface of the magnetic particles and subjecting these collected magnetic particles to PCR. Recovery of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) N gene pseudo-DNA (120 bp) was performed using PPMPs. We confirmed that the PPMPs captured the target consistently even after washes were done with denaturing agents and surfactants. Even in the presence of foreign DNA fragments, PPMPs were able to specifically recover the target DNA. This method allows for a more accurate detection by recovering only the target DNA for PCR. Hence, PPMPs can be successfully used for PCR-mediated detection of SARS-CoV-2 and other pathogens whose nucleic acid sequences are known.

Recombinase polymerase amplification in the molecular diagnosis of microbiological targets and its applications

Since the introduction of the polymerase chain reaction (PCR) technique in 1983, nucleic acid amplification has permeated all fields of biological science, particularly clinical research. Despite its importance, PCR has been restricted to specialized centers and its use in laboratories with few resources is limited. In recent decades, there has been a notable increase in the development of new isothermal technologies for molecular diagnosis with the hope of overcoming the traditional limitations of the laboratory. Among these technologies, recombinase polymerase amplification (RPA) has a wide application potential because it does not require thermocyclers and has high sensitivity, specificity, simplicity, and detection speed. This technique has been used for DNA and RNA amplification in various pathogenic organisms such as viruses, bacteria, and parasites. In addition, RPA has been successfully implemented in different detection strategies, making it a promising alternative for performing diagnoses in environments with scarce resources and a high burden of infectious diseases. In this study, we present a review of the use of RPA in clinical settings and its implementation in various research areas.

Point of care diagnostics and non-invasive sampling strategy: a review on major advances in veterinary diagnostics

The use of point of care diagnostics (POCD) in animal diseases has steadily increased over the years since its introduction. Its potential application to diagnose infectious diseases in remote and resource limited settings have made it an ideal diagnostic in animal disease diagnosis and surveillance. The rapid increase in incidence of emerging infectious diseases requires urgent attention where POCD could be indispensable tools for immediate detection and early warning of a potential pathogen. The advantages of being rapid, easily affordable and the ability to diagnose an infectious disease on spot has driven an intense effort to refine and build on the existing technologies to generate advanced POCD with incremental improvements in analytical performance to diagnose a broad spectrum of animal diseases. The rural communities in developing countries are invariably affected by the burden of infectious animal diseases due to limited access to diagnostics and animal health personnel. Besides, the alarming trend of emerging and transboundary diseases with pathogen spill-overs at livestock-wildlife interfaces has been identified as a threat to the domestic population and wildlife conservation. Under such circumstances, POCD coupled with non-invasive sampling techniques could be successfully deployed at field level without the use of sophisticated laboratory infrastructures. This review illustrates the current and prospective POCD for existing and emerging animal diseases, the status of non-invasive sampling strategies for animal diseases, and the tremendous potential of POCD to uplift the status of global animal health care.

Development of a One-Step Multiplex Real-Time PCR Assay for the Detection of Viral Pathogens Associated With the Bovine Respiratory Disease Complex

Bovine respiratory disease complex (BRDC) occurs widely in cattle farms. The main viral pathogens include bovine viral diarrhea virus (BVDV), Bovine herpesvirus 1 (BoHV-1), bovine parainfluenza virus type 3 (BPIV3), and bovine respiratory syncytial virus (BRSV), and the newly emerged influenza D virus (IDV). In this study, we have developed a one-step multiplex real-time Polymerase Chain Reaction (PCR) capable of simultaneously detecting these five viral pathogens causing BRDC. The established assay could specifically detect targeted viruses without cross-reaction with others. The detection limit was ~10 copies/reaction for single real-time PCR and 100 copies/ reaction for multiplex real-time PCR assay. A total of 213 nasal samples from cattle with signs of respiratory tract disease were then collected for performance evaluation of the established platform, proving that the method has good specificity and sensitivity. The surveillance data suggested that BVDV and BoHV-1 infections are the dominant cause of BRDC in the herd, whereas the detection rate of IDV, BIPV3, and BRSV is relatively lower. In summary, the established assay provides technical support for rapid clinical detection of BRDC associated viral pathogens to guide the formulation of BRDC prevention and control measures.

RPA-SYBR Green I based instrument-free visual detection for pathogenic Yersinia enterocolitica in meat

Pathogenic Yersinia (Y.) enterocolitica is the primary causative agent of Yersiniosis, with outbreaks in numerous countries around the world, and causes diarrhea and vomiting in animals and humans. Therefore, an instrument-free and convenient nucleic acid visualization method, RPA-SYBR Green I, was established, which combines recombinase polymerase amplification (RPA) with the fluorescent dye SYBR Green I for the detection of the adhesion gene ail in pathogenic Y. enterocolitica. After optimization of a series of conditions such as primer concentration, the detection of pathogenic Y. enterocolitica could be finally completed within about 20 min (from DNA extraction to observation of results) at an isothermal temperature of 39°C. RPA-SYBR Green I had no cross-reactivity with other bacteria and the detection limit was 10¹ CFU/μL, with sensitivity equal to that of conventional PCR. The method established in this paper and conventional PCR identified a total of 5 spiked samples and 15 meat samples stored in refrigerated, and it was concluded that there was 100% consistency between the two methods. Overall, RPA-SYBR Green I is a visual and facilitate detection assay that can accurately discover pathogenic Y. enterocolitica.

Nucleic acid visualization assay for Middle East Respiratory Syndrome Coronavirus (MERS-CoV) by targeting the UpE and N gene

Since its first emergence in 2012, cases of infection with Middle East respiratory syndrome coronavirus (MERS-CoV) have continued to occur. At the end of January 2020, 2519 laboratory confirmed cases with a case-fatality rate of 34.3% have been reported. Approximately 84% of human cases have been reported in the tropical region of Saudi Arabia. The emergence of MERS-CoV has highlighted need for a rapid and accurate assay to triage patients with a suspected infection in a timely manner because of the lack of an approved vaccine or an effective treatment for MERS-CoV to prevent and control potential outbreaks. In this study, we present two rapid and visual nucleic acid assays that target the MERS-CoV UpE and N genes as a panel that combines reverse transcription recombinase polymerase amplification with a closed vertical flow visualization strip (RT-RPA-VF). This test panel was designed to improve the diagnostic accuracy through dual-target screening after referencing laboratory testing guidance for MERS-CoV. The limit of detection was 1.2×101 copies/μl viral RNA for the UpE assay and 1.2 copies/μl viral RNA for the N assay, with almost consistent with the sensitivity of the RT-qPCR assays. The two assays exhibited no cross-reactivity with multiple CoVs, including the bat severe acute respiratory syndrome related coronavirus (SARSr-CoV), the bat coronavirus HKU4, and the human coronaviruses 229E, OC43, HKU1 and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Furthermore, the panel does not require sophisticated equipment and provides rapid detection within 30 min. This panel displays good sensitivity and specificity and may be useful to rapidly detect MERS-CoV early during an outbreak and for disease surveillance.

Rapid and simple detection of Phytophthora cactorum in strawberry using a coupled recombinase polymerase amplification-lateral flow strip assay

Phytophthora cactorum is a devastating pathogen that infects a wide range of plants and causes Phytophthora rot disease, which has resulted in great economic losses in crop production. Therefore, the rapid and practicable detection of P. cactorum is important for disease monitoring and forecasting. In this study, we developed a lateral flow recombinase polymerase amplification (LF-RPA) assay for the sensitive visual detection of P. cactorum. Specific primers for P. cactorum were designed based on the ras-related protein gene Ypt1; all 10 P. cactorum isolates yielded positive detection results, whereas no cross-reaction occurred in related oomycete or fungal species. The detection limit for the LF-RPA assay was 100 fg of genomic DNA under optimized conditions. Combined with a simplified alkaline lysis method for plant DNA extraction, the LF-RPA assay successfully detected P. cactorum in naturally diseased strawberry samples without specialized equipment within 40 min. Thus, the LF-RPA assay developed in this study is a rapid, simple, and accurate method for the detection of P. cactorum, with the potential for further application in resource-limited laboratories.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1186/s42483-021-00089-8.

Mini review: immunologic functions of dual oxidases in mucosal systems of vertebrates

Abstract Mucosal epithelial cells act as the first immunologic barrier of organisms, and contact directly with pathogens. Therefore, hosts must have differential strategies to combat pathogens efficiently. Reactive oxygen species (ROS), as a kind of oxidizing agents, participates in the early stage of killing pathogens quickly. Recent reports have revealed that dual oxidase (DUOX) plays a key role in mucosal immunity. And the DUOX is a transmembrane protein which produces ROS as their primary enzymatic products. This process is an important pattern for eliminating pathogens. In this review, we highlight the DUOX immunologic functions in the respiratory and digestive tract of vertebrates.

Application of Electrochemical Sensors Based on Carbon Nanomaterials for Detection of Flavonoids

Flavonoids have a variety of physiological activities such as anti-free radicals, regulating hormone levels, antibacterial factors, and anti-cancer factors, which are widely present in edible and medicinal plants. Real-time detection of flavonoids is a key step in the quality control of diverse matrices closely related to social, economic, and health issues. Traditional detection methods are time-consuming and require expensive equipment and complicated working conditions. Therefore, electrochemical sensors with high sensitivity and fast detection speed have aroused extensive research interest. Carbon nanomaterials are preferred material in improving the performance of electrochemical sensing. In this paper, we review the progress of electrochemical sensors based on carbon nanomaterials including carbon nanotubes, graphene, carbon and graphene quantum dots, mesoporous carbon, and carbon black for detecting flavonoids in food and drug homologous substances in the last four years. In addition, we look forward to the prospects and challenges of this research field.

Annexin A2 gene interacting with viral matrix protein to promote bovine ephemeral fever virus release

Bovine ephemeral fever virus (BEFV) causes bovine ephemeral fever, which can produce considerable economic damage to the cattle industry. However, there is limited experimental evidence regarding the underlying mechanisms of BEFV. Annexin A2 (AnxA2) is a calcium and lipid-conjugated protein that binds phospholipids and the cytoskeleton in a Ca²⁺-dependent manner, and it participates in various cellular functions, including vesicular trafficking, organization of membrane domains, and virus proliferation. The role of the AnxA2 gene during virus infection has not yet been reported. In this study, we observed that AnxA2 gene expression was up-regulated in BHK-21 cells infected with the virus. Additionally, overexpression of the AnxA2 gene promoted the release of mature virus particles, whereas BEFV replication was remarkably inhibited after reducing AnxA2 gene expression by using the small interfering RNA (siRNA). For viral proteins, overexpression of the Matrix (M) gene promotes the release of mature virus particles. Moreover, the AnxA2 protein interaction with the M protein of BEFV was confirmed by GST pull-down and co-immunoprecipitation assays. Experimental results indicate that the C-terminal domain (268-334 aa) of AxnA2 contributes to this interaction. An additional mechanistic study showed that AnxA2 protein interacts with M protein and mediates the localization of the M protein at the plasma membrane. Furthermore, the absence of the AnxA2-V domain could attenuate the effect of AnxA2 on BEFV replication. These findings can contribute to elucidating the regulation of BEFV replication and may have implications for antiviral strategy development.

Induction of the Unfolded Protein Response during Bovine Alphaherpesvirus 1 Infection

Bovine herpesvirus 1 (BoHV-1) is an alphaherpesvirus that causes great economic losses in the cattle industry. Herpesvirus infection generally induces endoplasmic reticulum (ER) stress, and the unfolded protein response (UPR) in infected cells. However, it is not clear whether ER stress and UPR can be induced by BoHV-1 infection. Here, we found that ER stress induced by BoHV-1 infection could activate all three UPR sensors (the activating transcription factor 6 (ATF6), the inositol-requiring enzyme 1 (IRE1), and the protein kinase RNA-like ER kinase (PERK)) in MDBK cells. During BoHV-1 infection, the ATF6 pathway of UPR did not affect viral replication. However, both knockdown and specific chemical inhibition of PERK attenuated the BoHV-1 proliferation, and chemical inhibition of PERK significantly reduced the viral replication at the post-entry step of the BoHV-1 life cycle. Furthermore, knockdown of IRE1 inhibits BoHV-1 replication, indicating that the IRE1 pathway may promote viral replication. Further study revealed that BoHV-1 replication was enhanced by IRE1 RNase activity inhibition at the stage of virus post-entry in MDBK cells. Furthermore, IRE1 kinase activity inhibition and RNase activity enhancement decrease BoHV1 replication via affecting the virus post-entry step. Our study revealed that BoHV-1 infection activated all three UPR signaling pathways in MDBK cells, and BoHV-1-induced PERK and IRE1 pathways may promote viral replication. This study provides a new perspective for the interactions of BoHV-1 and UPR, which is helpful to further elucidate the mechanism of BoHV-1 pathogenesis.

Electrochemical Sensors Based on Carbon Nanomaterial Used in Diagnosing Metabolic Disease

Metabolic diseases have become common diseases with the improvement of living standards because of changed dietary habits and living habits, which seriously affect health. Currently, related biomarkers have been widely used as important indicators for clinical diagnosis, treatment, and prognosis of metabolic diseases. Among all detection methods for biomarkers of metabolic diseases, electrochemical sensor technology has the advantages of simplicity, real-time analysis, and low cost. Carbon nanomaterials were preeminent materials for fabricating electrochemical sensors in order to enhance the performance. In this paper, we summarize the research progress in the past 3 years of electrochemical sensors based on carbon nanomaterials in detecting markers of metabolic diseases, which include carbon nanotubes, graphene, carbon quantum dots, fullerene, and carbon nitride. Additionally, we discuss the future prospects for this field.

Detection of bovine viral diarrhea virus genotype 1 in aerosol by a real time RT-PCR assay

BACKGROUND

As a pestivirus of the Flaviviridae family, bovine viral diarrhea virus (BVDV), has imposed a large burden on animal husbandry worldwide, and such virus can be transmitted mainly through direct contact with other infected animals and probably via aerosols. In the present study, we aimed to develop a real-time RT-PCR method for detection of BVDV-1 in aerosol samples.

METHODS

A pair of primers specific for highly conserved regions of the BVDV-1 5'-UTR was designed. The standard curve and sensitivity of the developed assay were assessed based on 10-fold serial dilutions of RNA molecular standard. The specificity of the assay was evaluated with other pestiviruses and infectious bovine viruses. The clinical performance was examined by testing 169 aerosol samples.

RESULTS

The results showed that a good linear relationship existed between the standard curve and the concentration of template. The lowest detection limit was 5.2 RNA molecules per reaction. This assay was specific for detection of BVDV-1, and no amplification was found for other pestiviruses such as classical swine fever virus (CSFV), border disease virus (BDV), and common infectious bovine viruses, including BVDV-2, infectious bovine rhinotracheitis virus (IBRV), bovine parainfluenza virus type 3 (BPIV-3), bovine respiratory syncytial virus (BRSV), bovine ephemeral fever virus (BEFV) and bovine coronavirus (BcoV). The assay was highly reproducible with low variation coefficient values (CVs) for intra-assay and inter-assay. A total of 169 aerosol samples collected from six dairy herds were tested using this method. The results showed that the positive detection rate of BVDV-1 was 17.2% (29/169), which was significantly higher compared with the conventional RT-PCR. Additionally, the positive samples (n = 29) detected by real-time RT-PCR were verified by BVDV RPA-LFD, and a concordance rate of 100% was obtained between them.

CONCLUSIONS

Taken together, we developed a real-time RT-PCR assay for quantitative analysis of BVDV-1 in aerosol samples, and our finding provided valuable insights into the risk on aerosol transmission of BVDV-1.

Cell Cycle Regulation in the Plant Response to Stress

As sessile organisms, plants face a variety of environmental challenges. Their reproduction and survival depend on their ability to adapt to these stressors, which include water, heat stress, high salinity, and pathogen infection. Failure to adapt to these stressors results in programmed cell death and decreased viability, as well as reduced productivity in the case of crop plants. The growth and development of plants are maintained by meiosis and mitosis as well as endoreduplication, during which DNA replicates without cytokinesis, leading to polyploidy. As in other eukaryotes, the cell cycle in plants consists of four stages (G1, S, G2, and M) with two major check points, namely, the G1/S check point and G2/M check point, that ensure normal cell division. Progression through these checkpoints involves the activity of cyclin-dependent kinases and their regulatory subunits known as cyclins. In order for plants to survive, cell cycle control must be balanced with adaption to dynamic environmental conditions. In this review, we summarize recent advances in our understanding of cell cycle regulation in plants, with a focus on the molecular interactions of cell cycle machinery in the context of stress tolerance.

Identification of modules and hub genes associated with platinum-based chemotherapy resistance and treatment response in ovarian cancer by weighted gene co-expression network analysis

High-grade serous ovarian carcinoma (HGSOC) is the most prevalent and malignant ovarian tumor.To identify co-expression modules and hub genes correlated with platinum-based chemotherapy resistant and sensitive HGSOC, we performed weighted gene co-expression network analysis (WGCNA) on microarray data of HGSOC with 12 resistant samples and 16 sensitive samples of GSE51373 dataset.A total of 5122 genes were included in WGCNA, and 16 modules were identified. Module-trait analysis identified that the module salmon (cor = 0.50), magenta (cor = 0.49), and black (cor = 0.45) were discovered associated with chemotherapy resistant, and the significance for these platinum-resistant modules were validated in the GSE63885 dataset. Given that the black module was validated to be the most related one, hub genes of this module, alcohol dehydrogenase 1B, cadherin 11, and vestigial like family member 3were revealed to be expressional related with platinum resistance, and could serve as prognostic markers for ovarian cancer.Our analysis might provide insight for molecular mechanisms of platinum-based chemotherapy resistance and treatment response in ovarian cancer.

A portable detection assay for Apple stem pitting virus using reverse transcription-recombinase polymerase amplification

A molecular diagnostic assay for the rapid, sensitive and specific detection of Apple stem pitting virus (ASPV) in infected samples, utilizing reverse transcription-recombinase polymerase amplification (RT-RPA) at an isothermal constant temperature of 42 °C and the designed target-specific primers, was developed. The RT-RPA assay was able to be used in ASPV-infected leaves, rootstocks and fruits. Sensitivity tests, using ASPV transcripts, showed that the RT-RPA with the ASPV-specific primers was more sensitive than the conventional RT-PCR, with a detection limit of 1 fg/μL of RNA. In addition, the reaction time for the amplification of ASPV was shortened to as little as 1 min. The assay was highly specific and did not give a positive reaction to other viruses infecting pears. Moreover, the amplified genomic fragment of ASPV produced by the assay could be determined within 4 min using a portable capillary gel electrophoresis system. The entire process, excluding the extraction of total RNA, could be completed in 5 min using portable equipment in the field. This is the first report of utilizing an RT-RPA assay to detect a pear tree virus and the assay could be used both in the laboratory and in the field for ASPV detection.

A novel reassortant influenza A (H1N1) virus infection in swine in Shandong Province, eastern China

Influenza A (H1N1) viruses are distributed worldwide and pose a threat to public health. Swine, as a natural host and mixing vessel of influenza A (H1N1) virus, play a critical role in the transmission of this virus to humans. Furthermore, swine influenza A (H1N1) viruses have provided all eight genes or some genes to the genomes of influenza strains that historically have caused human pandemics. Hence, persistent surveillance of influenza A (H1N1) virus in swine herds could contribute to the prevention and control of this virus. Here, we report a novel reassortant influenza A (H1N1) virus generated by reassortment between 2009 pandemic H1N1 viruses and swine viruses. We also found that this virus is prevalent in swine herds in Shandong Province, eastern China. Our findings suggest that surveillance of the emergence of the novel reassortant influenza A (H1N1) virus in swine is imperative.

Two mutations in viral protein enhance the adaptation of waterfowl-origin H3N2 virus in murine model

After serial passage of a waterfowl-origin H3N2 subtype avian influenza virus in BALB/c mice, we obtained H3N2 mouse-adapted variants and identified eight amino acid substitutions in five viral proteins in our previous study. Here, we analyze the key mutations determining viral pathogenicity in mammals. We found that both PB2-D701N mutation and M1-M192V mutation were implicated in the viral pathogenic phenotypic variation of H3N2 avian influenza virus in mice. Furthermore, we found that PB2-D701N could enhance viral replication in vitro and in vivo and expanded viral tissue tropism. Our data suggest that PB2-D701N and M1-M192V are the virulence markers of H3N2 avian influenza virus, and these markers can be used in the trans-species transmission surveillance for the H3N2 avian influenza virus.

PB2 and hemagglutinin mutations confer a virulent phenotype on an H1N2 avian influenza virus in mice

We previously obtained mouse-adapted variants of H1N2 avian influenza virus that contained PB2-L134H, PB2-I647L, PB2-D701N, HA-G228S, and M1-D231N mutations. Here, we analyzed the effects of these mutations on viral pathogenicity in a mammalian model. By evaluating the virulence of mouse-adapted H1N2 variants at different generations, we found that the PB2-D701N and HA-G228S mutations both contribute to the virulence of this virus in mammals. Furthermore, we found that the PB2-D701N and HA-G228S mutations both enhance the ability of the virus to replicate in vivo and in vitro and that the PB2-D701N substitution results in an expansion of viral tissue tropism. These results suggest that the PB2-D701N mutation and the HA-G228S mutation are the major mammalian determinants of H1N2 virus. These results help us to understand more about the mechanisms by which influenza viruses adapt to mammals, and monitoring of these mutations can be used in continuous influenza surveillance to assess the pandemic potential of avian influenza virus variants.

Use of a recombinase polymerase amplification commercial kit for rapid visual detection of Pasteurella multocida

Background

Pasteurella multocida (P. multocida) is a bacterium that causes bovine respiratory disease (BRD) and haemorrhagic septicaemia (HS) in cattle, buffaloes and bison. Rapid point-of-care diagnosis or regular testing of Pasteurellosis, therefore, could contribute greatly to early detection, and screening infected animal is important. Up to now, there are no published reports on the use of recombinase polymerase amplification (RPA) combined with a lateral flow dipstick (LFD) for P. multocida detection.

Results

This study proposes a promising isothermal detection method for P. multocida with the potential to be developed as an on-site test for Pasteurellosis. The method includes an RPA combined with LFD. First, the analytical sensitivity and specificity of P. multocida RPA-LFD were tested. The RPA-LFD, performed at 39 °C, successfully detected P. multocida DNA in 30 min, with a detection limit of up to 120 copies per reaction. Then, the practicability of RPA-LFD was analysed using 62 nasal swabs and 33 fresh lungs samples from 17 different dairy farms. Compared to real-time quantitative PCR (qPCR), the RPA-LFD assay yielded a clinical specificity of 95.15%, positive predictive value (PPV) of 95.15% and 0.958 kappa coefficient. Compared with the culture method, it achieved 100% sensitivity, 67.20% specificity and a 0.572 kappa coefficient.

Conclusions

These results combined with the simple conditions required for the performance of the RPA-LFD assay, have demonstrated the effectiveness and practicability of the method for development into a regular on-site protocol for the diagnosis of Pasteurellosis.

Rapid and Sensitive Recombinase Polymerase Amplification Combined With Lateral Flow Strip for Detecting African Swine Fever Virus

African swine fever virus (ASFV), the etiological agent of African swine fever (ASF), a hemorrhagic fever of domestic pigs, has devastating consequences for the pig farming industry. More than 1,000,000 pigs have been slaughtered since 3 August 2018 in China. However, vaccines or drugs for ASF have yet to be developed. As such, a rapid test that can accurately detect ASFV on-site is important to the timely implementation of control measures. In this study, we developed a rapid test that combines recombinase polymerase amplification (RPA) of the ASFV p72 gene with lateral flow detection (LFD). Results showed that the sensitivity of recombinase polymerase amplification with lateral flow dipstick (RPA-LFD) for ASFV was 150 copies per reaction within 10 min at 38°C. The assay was highly specific to ASFV and had no cross-reactions with other porcine viruses, including classical swine fever virus (CSFV). A total of 145 field samples were examined using our method, and the agreement of the positive rate between RPA-LFD (10/145) and real-time PCR (10/145) was 100%. Overall, RPA-LFD provides a novel alternative for the simple, sensitive, and specific identification of ASFV and showed potential for on-site ASFV detection.

Cellular microRNA bta-miR-2361 inhibits bovine herpesvirus 1 replication by directly targeting EGR1 gene

Bovine herpesvirus 1 (BHV-1) is an economically important pathogen of cattle and has led to significant consequences on the cattle industry worldwide. MicroRNAs (miRNAs) are a class of regulators that play critical roles in virus and host interaction. However, the roles of host miRNAs in BHV-1 infection remain largely unclear. In this study, a set of differentially expressed miRNAs by small RNA deep sequencing were analyzed in the Madin-Darby Bovine Kidney Cells (MDBK) infected with BHV-1 after 12 h, 24 h and 48 h post-infection compared to mock infection, and it was confirmed that bta-miR-2361 was significantly down-regulated. Moreover, bta-miR-2361 mimics transfection could inhibit BHV-1 replication. Combined with up-regulated genes from BHV-1-infected MDBK cells by deep RNA-sequencing and predicted by bioinformatics tools, early growth response 1 (EGR1) was putative target of bta-miR-2361. Furthermore, EGR1 was up-regulated during BHV-1 infection, and overexpression of EGR1 promoted BHV-1 replication whereas knockdown of EGR1 had the opposite effects. Subsequently, the target association between bta-miR-2361 and 3'UTR of EGR1 was further validated using a dual-luciferase reporter assay. In addition, overexpression of bta-miR-2361 resulted in decreased EGR1 mRNA and protein levels. Further mechanistic study showed that EGR1 stimulated BHV-1 UL46 promoter activity, but overexpression of bta-miR-2361 suppressed the production of UL46 gene. Collectively, this is the first study to reveal that bta-miR-2361 as a novel host factor regulates BHV-1 replication via directly targeting the EGR1 gene, which is a transcription factor that regulates viral UL46 gene of BHV-1. These results provide further insight into the study of BHV-1 pathogenesis.

Electrochemical Biosensors for Detection of Foodborne Pathogens

Foodborne safety has become a global public health problem in both developed and developing countries. The rapid and precise monitoring and detection of foodborne pathogens has generated a strong interest by researchers in order to control and prevent human foodborne infections. Traditional methods for the detection of foodborne pathogens are often time-consuming, laborious, expensive, and unable to satisfy the demands of rapid food testing. Owing to the advantages of simplicity, real-time analysis, high sensitivity, miniaturization, rapid detection time, and low cost, electrochemical biosensing technology is more and more widely used in determination of foodborne pathogens. Here, we summarize recent developments in electrochemical biosensing technologies used to detect common foodborne pathogens. Additionally, we discuss research challenges and future prospects for this field of study.

Phylostratigraphic analysis of gene co-expression network reveals the evolution of functional modules for ovarian cancer

Ovarian cancer (OV) is an extremely lethal disease. However, the evolutionary machineries of OV are still largely unknown. Here, we used a method that combines phylostratigraphy information with gene co-expression networks to extensively study the evolutionary compositions of OV. The present co-expression network construction yielded 18,549 nodes and 114,985 edges based on 307 OV expression samples obtained from the Genome Data Analysis Centers database. A total of 20 modules were identified as OV related clusters. The human genome sequences were divided into 19 phylostrata (PS), the majority (67.45%) of OV genes was already present in the eukaryotic ancestor. There were two strong peaks of the emergence of OV genes screened by hypergeometric test: the evolution of the multicellular metazoan organisms (PS5 and PS6, P value = 0.002) and the emergence of bony fish (PS11 and PS12, P value = 0.009). Hence, the origin of OV is far earlier than its emergence. The integrated analysis of the topology of OV modules and the phylogenetic data revealed an evolutionary pattern of OV in human, namely, OV modules have arisen step by step during the evolution of the respective lineages. New genes have evolved and become locked into a pathway, where more and more biological pathways are fixed into OV modules by recruiting new genes during human evolution.

Viral metagenomics reveals significant viruses in the genital tract of apparently healthy dairy cows

The virome in genital tract secretion samples collected from 80 dairy cattle in Shanghai, China, was characterized. Viruses detected included members of the families Papillomaviridae, Polyomaviridae, Hepeviridae, Parvoviridae, Astroviridae, Picornaviridae, and Picobirnaviridae. A member of a new species within the genus Dyoxipapillomavirus and six circular Rep-encoding single-stranded DNA (ssDNA) (CRESS-DNA) viral genomes were fully sequenced and phylogenetically analyzed. The prevalence of bovine polyomaviruses 1 and 2 was measured by PCR to be 10% (8/80) and 6.25% (5/80), respectively. PCR screening also indicated that the novel papillomavirus ujs-21015 and bovine herpesvirus 6 were present in three and two out of the 80 samples, respectively.

Targeted inhibition of histone deacetylase 6 in inflammatory diseases

Targeting epigenetic modification of gene expression represents a promising new approach under investigation for the treatment of inflammatory diseases. Accumulating evidence suggests that epigenetic mechanisms, such as histone modification, play a crucial role in a number of inflammatory diseases, including rheumatoid arthritis, asthma, and contact hypersensitivity. Consistent with this role, histone deacetylase (HDAC) inhibitors have shown efficacy in the treatment of inflammatory diseases. In particular, selective inhibitors of HDAC6, a cytoplasmic member of the HDAC family that contains two deacetylase domains, are under investigation as a potential treatment strategy for inflammatory diseases due to their ability to regulate inflammatory cells and cytokines. Here, we review recent findings highlighting the critical roles of HDAC6 in a variety of inflammatory diseases, and discuss the therapeutic potential of HDAC6 inhibitors in these settings.

Genetic characterization of an H13N2 low pathogenic avian influenza virus isolated from gulls in China

Low pathogenic avian influenza viruses circulate in wild birds but are occasionally transmitted to other species, including poultry, mammals and humans. To date, infections with low pathogenic avian influenza viruses of HA subtype 6, HA subtype 7, HA subtype 9 and HA subtype 10 among humans have been reported. However, the epidemiology, genetics and ecology of low pathogenic avian influenza viruses have not been fully understood thus far. Therefore, persistent surveillance of low pathogenic avian influenza virus infections in wild birds and other species is needed. Here, we found a low pathogenic avian influenza virus of the subtype H13N2 (abbreviated as WH42) in black-tailed gulls in China. All gene sequences of this H13N2 virus were determined and used for subsequent analysis. Phylogenetic analysis of the HA gene and NA gene indicated that WH42 was derived from the Eurasian lineage. We analysed the timing of the reassortment events and found that WH42 was a reassortant whose genes were transferred from avian influenza viruses circulating in Asia, Europe and North America. Additionally, WH42 possessed several molecular markers associated with mammalian virulence and mammalian transmissibility. Interestingly, we also found low but detectable haemagglutination inhibition antibodies against H13N2 low pathogenic avian influenza virus in serum samples collected from chickens. Taken together, our findings show that the H13 virus may have been introduced into poultry and that sustainable surveillance in gulls and poultry is required.

MiR-3470b promotes bovine ephemeral fever virus replication via directly targeting mitochondrial antiviral signaling protein (MAVS) in baby hamster Syrian kidney cells

BACKGROUND

Bovine ephemeral fever virus (BEFV), the causative agent of bovine ephemeral fever, is an economically important pathogen of cattle and water buffalo. MicroRNAs (miRNAs) are endogenous 21-23 nt small non-coding RNA molecules that binding to a multiple of target mRNAs and functioning in the regulation of viral replication including the miRNA-mediated antiviral defense. However, the reciprocal interaction between bovine ephemeral fever virus replication and host miRNAs still remain poorly understood. The aim of our study herein was to investigate the exact function of miR-3470b and its molecular mechanisms during BEFV infection.

RESULTS

In this study, we found a set of microRNAs induced by BEFV infection using small RNA deep sequencing, and further identified BEFV infection could significantly up-regulate the miR-3470b expression in Baby Hamster Syrian Kidney cells (BHK-21) after 24 h and 48 h post-infection (pi) compared to normal BHK-21 cells without BEFV infection. Additionally, the target association between miR-3470b and mitochondrial antiviral signaling protein (MAVS) was predicted by target gene prediction tools and further validated using a dual-luciferase reporter assay, and the expression of MAVS mRNA and protein levels was negatively associated with miR-3470b levels. Furthermore, the miR-3470b mimic transfection significantly contributed to increase the BEFV N mRNA, G protein level and viral titer, respectively, whereas the miR-3470b inhibitor had the opposite effect on BEFV replication. Moreover, the overexpression of MAVS or silencing of miR-3470b by its inhibitors suppressed BEFV replication, and knockdown of MAVS by small interfering RNA also promoted the replication of BEFV.

CONCLUSIONS

Our findings is the first to reveal that miR-3470b as a novel host factor regulates BEFV replication via directly targeting the MAVS gene in BHK-21 cells and may provide a potential strategy for developing effective antiviral therapy.

Development of a recombinase polymerase amplification combined with a lateral flow dipstick assay for rapid detection of the Mycoplasma bovis

BACKGROUND

Mycoplasma bovis (M. bovis) is a major etiological agent of bovine mycoplasmosis around the world. Point-of-care testing in the field is lacking owing to the requirement for a simple, robust field applicable test that does not require professional laboratory equipment. The recombinase polymerase amplification (RPA) technique has become a promising isothermal DNA amplify assay for use in rapid and low-resource diagnostics.

RESULTS

Here, a method for specific detection of M. bovis DNA was established, which was RPA combined with lateral flow dipstick (LFD). First, the analytical specificity and sensitivity of the RPA primer and LF-probe sets were evaluated. The assay successfully detected M. bovis DNA in 30 min at 39 °C, with detection limit of 20 copies per reaction, which it was compared the real-time quantitative PCR (qPCR) assay. This method was specific because it did not detect a selection of other bacterial pathogens in cattle. Both qPCR and RPA-LFD assays were used to detect M. bovis 442 field samples from 42 different dairy farms in Shandong Province of China, also the established RPA-LFD assay obtained 99.00% sensitivity, 95.61% specificity, and 0.902 kappa coefficient compared with the qPCR.

CONCLUSIONS

To the author's knowledge, this is the first report using an RPA-FLD assay to visualise and detect M. bovis. Comparative analysis with qPCR indicates the potential of this assay for rapid diagnosis of bovine mycoplasmosis in resource limited settings.

Oncolytic herpes simplex virus and immunotherapy

BACKGROUND

Oncolytic viruses have been proposed to be employed as a potential treatment of cancer. Well targeted, they will serve the purpose of cracking tumor cells without causing damage to normal cells. In this category of oncolytic viral drugs human pathogens herpes simplex virus (HSV) is especially suitable for the cause. Although most viral infection causes antiviral reaction in the host, HSV has multiple mechanisms to evade those responses. Powerful anti-tumor effect can thus be achieved via genetic manipulation of the HSV genes involved in this evading mechanism, namely deletions or mutations that adapt its function towards a tumor microenvironment. Currently, oncolytic HSV (oHSV) is widely use in clinical; moreover, there's hope that its curative effect will be further enhanced through the combination of oHSV with both traditional and emerging therapeutics.

RESULTS

In this review, we provide a summary of the HSV host antiviral response evasion mechanism, HSV expresses immune evasion genes such as ICP34.5, ICP0, Us3, which are involved in inducing and activating host responses, so that the virus can evade the immune system and establish effective long-term latent infection; we outlined details of the oHSV strains generated by removing genes critical to viral replication such as ICP34.5, ICP0, and inserting therapeutic genes such as LacZ, granulocyte macrophage colony-stimulating factor (GM-CSF); security and limitation of some oHSV such G207, 1716, OncoVEX, NV1020, HF10, G47 in clinical application; and the achievements of oHSV combined with immunotherapy and chemotherapy.

CONCLUSION

We reviewed the immunotherapy mechanism of the oHSV and provided a series of cases. We also pointed out that an in-depth study of the application of oHSV in cancer treatment will potentially benefits cancer patients more.

Development and evaluation of serotype-specific recombinase polymerase amplification combined with lateral flow dipstick assays for the diagnosis of foot-and-mouth disease virus serotype A, O and Asia1

Background

Foot-and-mouth disease (FMD) caused by foot-and-mouth disease virus (FMDV) is one of the most highly infectious diseases in livestock, and leads to huge economic losses. Early diagnosis and rapid differentiation of FMDV serotype is therefore integral to the prevention and control of FMD. In this study, a series of serotype-specific reverse transcription recombinase polymerase amplification assays combined with lateral flow dipstick (RPA-LFD) were establish to differentiate FMDV serotypes A, O or Asia 1, respectively.

Results

The serotype-specific primers and probes of RPA-LFD were designed to target conserved regions of the FMDV VP1 gene sequence, and three primer and probe sets of serotype-specific RPA-LFD were selected for amplification of FMDV serotypes A, O or Asia 1, respectively. Following incubation at 38 °C for 20 min, the RPA amplification products could be visualized by LFD. Analytical sensitivity of the RPA assay was then determined with ten-fold serial dilutions of RNA of VP1 gene and the recombinant vector respectively containing VP1 gene from FMDV serotypes A, O or Asia1, the detection limits of these assays were 3 copies of plasmid DNA or 50 copies of viral RNA per reaction. Moreover, the specificity of the assay was assessed, and there was no cross reactions with other viruses leading to bovine vesicular lesions. Furthermore, 126 clinical samples were respectively detected with RPA-LFD and real-time PCR (rPCR), there was 98.41% concordance between the two assays, and two samples were positive by RPA-LFD but negative in rPCR, these were confirmed as FMDV-positive through viral isolation in BHK-21 cells. It showed that RPA-LFD assay was more sensitive than the rPCR method in this study.

Conclusion

The development of serotype-specific RPA-LFD assay provides a rapid, sensitive, and specific method for differentiation of FMDV serotype A, O or Asia1, respectively. It is possible that the serotype-specific RPA-LFD assay may be used as a integral protocol for field detection of FMDV.

Prevalence of bovine viral diarrhea virus in dairy cattle herds in eastern China

Bovine viral diarrhea virus (BVDV) is a worldwide spreading pestivirus affecting cattle and other ruminants; however, there have been few reports on epidemiologic investigation of BVDV in eastern China. In this study, bulk tank milk from 36 herds of dairy cattle in eastern China was submitted to serological investigations, 77.8% of herds was BVDV antibody positive. Individual animal status in two herds was further investigated collecting blood samples, the positive ratio was 49.74% and 24.64%, and the average positive ratio of calves, heifers, and lactating cows was 15.94%, 40.16%, and 41.7%, respectively. Moreover, clinical survey was carried out among 8170 dairy cattle from 36 herds, for diarrhea syndrome, respiratory problems and reproductive failure, and pathogens of all clinical cattle were further investigated. The results showed that BVDV was one of the main pathogen, which infected animals combining with various other viruses. Then, nine BVDV strains were isolated; phylogenetic analysis showed that BVDV subtypes currently circulating in eastern China were BVDV 1a and BVDV 1c. In addition, out of 377 cows tested, the 1.86% detected positive to the BVDV antigen. This study provided the foundation of further study on vaccination and control strategies of BVDV in eastern China.

Isolation and genetic characterization of H13N8 low pathogenic avian influenza virus from migratory birds in eastern China

Low pathogenic avian influenza virus (LPAIV) is an important zoonotic pathogen. Migratory birds are the natural reservoir for all 16 haemagglutinin (HA) and nine neuraminidase (NA) subtypes of LPAIV. Surveillance of LPAIV in migratory waterfowl and poultry is important for animal and public health. An understanding of the ecology and epidemiology of LPAI viruses in their reservoirs is beneficial for routine surveillance projects. Here, we report the isolation of an H13N8 LPAIV from black-tailed gulls in eastern China. Full genome sequences of this isolate were determined. Genetic analysis of the HA and NA segments of this isolate showed that this H13N8 LPAIV was derived from the Eurasian lineage. Additionally, we speculate that this H13N8 LPAIV was a reassortant between the North American and Eurasian lineages. Interestingly, we identified amino acid motifs responsible for increased virulence or transmission of influenza viruses in mammals. We also found weak but measurable haemagglutination inhibition antibody titers against H13N8 virus in serum samples collected from chickens. These results suggest that continued surveillance for LPAI viruses in migratory birds and poultry is required.

Applications of SERS in the Detection of Stress-Related Substances

A wide variety of biotic and abiotic stresses continually attack plants and animals, which adversely affect their growth, development, reproduction, and yield realization. To survive under stress conditions, highly sophisticated and efficient tolerance mechanisms have been evolved to adapt to stresses, which consist of the variation of effector molecules playing vital roles in physiological regulation. The development of a sensitive, facile, and rapid analytical methods for stress factors and effector molecules detection is significant for gaining deeper insight into the tolerance mechanisms. As a nondestructive analysis technique, surface-enhanced Raman spectroscopy (SERS) has unique advantages regarding its biosensing applications. It not only provides specific fingerprint spectra of the target molecules, conformation, and structure, but also has universal capacity for simultaneous detection and imaging of targets owing to the narrow width of the Raman vibrational bands. Herein, recent progress on biotic and abiotic stresses, tolerance mechanisms and effector molecules is summarized. Moreover, the development and promising future trends of SERS detection for stress-related substances combined with nanomaterials as substrates and SERS tags are discussed. This comprehensive and critical review might shed light on a new perspective for SERS applications.