ABSTRACT
Background:Swine acute diarrhea syndrome coronavirus (SADS-CoV) causes acute vomiting and diarrhea of piglets, leading to significant financial losses in pig industry. Recombinase polymerase amplification (RPA) technology is the second method for nucleic acid amplification under constant temperature conditions besides loop-mediated isothermal amplification (LAMP). The study established a real-time reverse transcription (RT)-RPA assay for early confirmatory diagnoses to detection SADS-CoV.Results:The detection limit of the real-time RT-RPA was 74 copies/µL of SADS-CoV genomic RNA standard in 95% of cases. The assay was performed in less than 30 min and no cross-reactions were observed with 8 other common viruses that affect swine, namely, CSFV, PRRSV, PRV, SIV, SVA, TGEV, PEDV, or PDCoV. The coefficient of variation (C.V.) values of the two standards dilutions and a positive clinical sample ranged from 0 to 4.5%. A total of 72 clinical fecal samples from swine with diarrheal symptoms were analyzed via the developed RT-RPA and qRT-PCR. There was 98.61% agreement between the RT-RPA and the qRT-PCR results. Conclusions:These results indicate that the developed RT-RPA assay has good specificity, sensitivity, stability, and repeatability. In summary, the established RT-RPA assay could satisfy the demand for infield diagnoses, and is suitable for use in remote areas as it is fast, portable, and cost-effective.
ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes the COVID-19 pandemic, is rapidly evolving. Due to the limited efficacy of vaccination in prevention of SARS-CoV-2 transmission and continuous emergence of variants of concern (VOC), including the currently most prevalent Delta variant, orally bioavailable and broadly efficacious antiviral drugs are urgently needed. Previously we showed that adenosine analogue 69-0 (also known as GS-441524), possesses potent anti-SARS-CoV-2 activity. Herein, we report that esterification of the 5-hydroxyl moieties of 69-0 markedly improved the antiviral potency. The 5-hydroxyl -isobutyryl prodrug, ATV006, showed excellent oral bioavailability in rats and cynomolgus monkeys and potent antiviral efficacy against different VOCs of SARS-CoV-2 in cell culture and three mouse models. Oral administration of ATV006 significantly reduced viral loads, alleviated lung damage and rescued mice from death in the K18-hACE2 mouse model challenged with the Delta variant. Moreover, ATV006 showed broad antiviral efficacy against different mammal-infecting coronaviruses. These indicate that ATV006 represents a promising oral drug candidate against SARS-CoV-2 VOCs and other coronaviruses.