Point-of-Care Tests for Rapid Detection of Porcine Epidemic Diarrhea Virus: A Systematic Review and Meta-Analysis

Microfluidic systems for infectious disease diagnostics

Microorganisms, encompassing both uni- and multicellular entities, exhibit remarkable diversity as omnipresent life forms in nature. They play a pivotal role by supplying essential components for sustaining biological processes across diverse ecosystems, including higher host organisms. The complex interactions within the human gut microbiota are crucial for metabolic functions, immune responses, and biochemical signalling, particularly through the gut-brain axis. Viruses also play important roles in biological processes, for example by increasing genetic diversity through horizontal gene transfer when replicating inside living cells. On the other hand, infection of the human body by microbiological agents may lead to severe physiological disorders and diseases. Infectious diseases pose a significant burden on global healthcare systems, characterized by substantial variations in the epidemiological landscape. Fast spreading antibiotic resistance or uncontrolled outbreaks of communicable diseases are major challenges at present. Furthermore, delivering field-proven point-of-care diagnostic tools to the most severely affected populations in low-resource settings is particularly important and challenging. New paradigms and technological approaches enabling rapid and informed disease management need to be implemented. In this respect, infectious disease diagnostics taking advantage of microfluidic systems combined with integrated biosensor-based pathogen detection offers a host of innovative and promising solutions. In this review, we aim to outline recent activities and progress in the development of microfluidic diagnostic tools. Our literature research mainly covers the last 5 years. We will follow a classification scheme based on the human body systems primarily involved at the clinical level or on specific pathogen transmission modes. Important diseases, such as tuberculosis and malaria, will be addressed more extensively.

Antiviral activity of chrysin and naringenin against porcine epidemic diarrhea virus infection

Porcine epidemic diarrhea virus (PEDV) is one of the critical pathogens causing diarrhea in piglets and has caused huge economic losses to the swine industry in worldwide. However, there is currently no effective therapeutic medication available for the treatment of PEDV. Natural compounds are a hot topic for researching and screening antiviral lead compounds due to their abundant sources, varied activities, and low toxicity. In this study, a total of 6 compounds from different plant sources were selected for in vitro anti-PEDV screening, including chrysin, naringenin, soy isoflavone, glycyrrhetinic acid, oleanolic acid, and geniposide. Then two active compounds, chrysin and naringenin, were further evaluated on PEDV infected cells at different stage. And the anti-PEDV mechanism was analyzed by molecule docking and molecular dynamics. The results showed that both chrysin and naringenin showed the most significant anti-PEDV activity by increasing the cell viability and decreasing the virus copy number. Both natural compounds could inhibit viral titer, mRNA and protein levels in the prophylactic and post-viral entry stages of PEDV infection. Furthermore, chrysin and naringenin mainly interacted with viral replicase proteins such as 3CLpro and PLP-2 through hydrogen bonds and hydrophobic forces. The complexes formed by chrysin and naringenin with the two PEDV replication proteases had high stability. These results suggested that chrysin and naringenin may exert antiviral effects by interacting with the virus 3CLpro protein or PLP2 protein, thereby affecting their role in the formation of PEDV non-structural proteins or interfering with virus replication. This study lays the foundation for developing chrysin and naringenin as novel anti-PEDV therapeutic drugs.

Relative diagnostic accuracy of point-of-care tests to rule-in Dirofilaria immitis infection in clinically suspect dogs: A systematic review and meta-analysis

Canine heartworm, Dirofilaria immitis, can cause severe disease and sometimes death of the host. Associated clinical signs, lack of preventative usage and regional endemicity are unlikely sufficient by themselves to reach a definitive diagnosis. Several point-of-care (POC) diagnostic tests are commercially available to aid in-clinic diagnosis, however, there is variable diagnostic accuracy reported and no synthesis of published evidence. This systematic review aims at meta-analysing the likelihood ratio of a positive result (LR⁺) to inform the selection and interpretation of POC tests in practice to rule-in heartworm infection when there is clinical suspicion. Three literature index interfaces (Web of Science, PubMed, Scopus) were searched on November 11th, 2022, for diagnostic test evaluation (DTE) articles assessing at least one currently commercialised POC test. Risk of bias was assessed adapting the QUADAS-2 protocol and articles with no evidence of high risk of bias were meta-analysed if deemed applicable to our review objective. Substantial between DTE heterogeneity was investigated including potential threshold or covariate effects. A total of 324 primary articles were sourced and 18 were retained for full text review of which only three had low risk of bias in all four QUADAS-2 domains. Of the nine heartworm POC tests evaluated, only three, IDEXX SNAP (n DTEs = 6), Zoetis WITNESS (n DTEs = 3) and Zoetis VETSCAN (n DTEs = 5) could be analysed. Both WITNESS and VETSCAN DTEs showed substantial heterogeneity due to a putative threshold effect and no summary point estimates could be reported. SNAP DTEs showed acceptable heterogeneity, and a summary LR⁺ was estimated at 559.0 (95%CI: 24.3-12,847.4). The quality and heterogeneity of heartworm POC test DTEs was highly variable which restricted our summary of the diagnostic accuracy to only the SNAP test. A positive result from the SNAP test provides strong evidence of the presence of an infection with adult heartworm(s) in a dog patient and this test is warranted to rule-in clinical suspicion(s) in clinics. However, our review did not appraise the literature to assess the fitness of SNAP test, or any other POC tests, to rule-out heartworm infection in dogs without clinical suspicion or following heartworm therapy.

Development of Duplex LAMP Technique for Detection of Porcine Epidemic Diarrhea Virus (PEDV) and Porcine Circovirus Type 2 (PCV 2)

Porcine epidemic diarrhea virus (PEDV) and porcine circovirus type 2 (PCV2) are both important global pathogenic viruses which have a significant impact on the swine industry. In this study, a duplex loop-mediated isothermal amplification (duplex LAMP) method was developed in combination with lateral flow dipstick (LFD) for simultaneous detection of PEDV and PCV2 using specific sets of primers and probes designed based on the conserved regions of a spike gene (KF272920) and an ORF gene (EF493839), respectively. The limit of detection (LOD) values of the duplex LAMP-LFD for the detection of PEDV and PCV2 were 0.1 ng/µL and 0.246 ng/µL, respectively. The LOD of duplex LAMP-LFD was 10-times more sensitive than conventional PCR and RT-PCR-agarose gel-electrophoresis (PCR-AGE and RT-PCR-AGE). No cross-reaction to each other and to other pathogenic viruses that can infect pigs were observed according to analytical specificity tests. The duplex LAMP-LFD method for the simultaneous detection of PEDV and PCV2 co-infection could be completed within approximately 1.5 h, and only a simple heating block was required for isothermal amplification. The preliminary validation using 50 swine clinical samples with positive and negative PEDV and/or PCV2 revealed that the sensitivity, specificity, and accuracy of duplex LAMP-LFD were all 100% in comparison to conventional PCR and RT-PCR. Hence, this study suggests that duplex LAMP-LFD is a promising tool for the early detection and initial screening of PEDV and PCV2, which could be beneficial for prevention, planning, and epidemiological surveys of these diseases.