Molecular diagnosis of COVID-19 primarily relies on the detection of RNA of the SARS-CoV-2 virus, the causative infectious agent of the pandemic. Reverse transcription polymerase chain reaction (RT-PCR) enables sensitive detection of specific sequences of genes that encode the RNA dependent RNA polymerase (RdRP), nucleocapsid (N), envelope (E), and spike (S) proteins of the virus. Although RT-PCR tests have been widely used and many alternative assays have been developed, the current testing capacity and availability cannot meet the unprecedented global demands for rapid, reliable, and widely accessible molecular diagnosis. Challenges remain throughout the entire analytical process, from the collection and treatment of specimens to the amplification and detection of viral RNA and the validation of clinical sensitivity and specificity. We highlight the main issues surrounding molecular diagnosis of COVID-19, including false negatives from the detection of viral RNA, temporal variations of viral loads, selection and treatment of specimens, and limiting factors in detecting viral proteins. We discuss critical research needs, such as improvements in RT-PCR, development of alternative nucleic acid amplification techniques, incorporating CRISPR technology for point-of-care (POC) applications, validation of POC tests, and sequencing of viral RNA and its mutations. Improved assays are also needed for environmental surveillance or wastewater-based epidemiology, which gauges infection on the community level through analyses of viral components in the community's wastewater. Public health surveillance benefits from large-scale analyses of antibodies in serum, although the current serological tests do not quantify neutralizing antibodies. Further advances in analytical technology and research through multidisciplinary collaboration will contribute to the development of mitigation strategies, therapeutics, and vaccines. Lessons learned from molecular diagnosis of COVID-19 are valuable for better preparedness in response to other infectious diseases.

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Hypericum perforatum L., also known as Saint John’s Wort, has been well studied for its chemical composition and pharmacological activity. In this study, the antiviral activities of H. perforatum on infectious bronchitis virus (IBV) were evaluated in vitro and in vivo for the first time. The results of in vitro experiments confirmed that the antiviral component of H. perforatum was ethyl acetate extraction section (HPE), and results showed that treatment with HPE significantly reduced the relative messenger ribonucleic acid (mRNA) expression and virus titer of IBV, and reduced positive green immunofluorescence signal of IBV in chicken embryo kidney (CEK) cells. HPE treatment at doses of 480–120 mg/kg for 5 days, reduced IBV induced injury in the trachea and kidney, moreover, reduced the mRNA expression level of IBV in the trachea and kidney in vivo. The mRNA expression levels of IL-6, tumor necrosis factor alpha (TNF-α), and nuclear factor kappa beta (NF-κB) significantly decreased, but melanoma differentiation-associated protein 5 (MDA5), mitochondrial antiviral signaling gene, interferon alpha (IFN-α), and interferon beta (IFN-β) mRNA levels significantly increased in vitro and in vivo. Our findings demonstrated that HPE had significant anti-IBV effects in vitro and in vivo, respectively. In addition, it is possible owing to up-regulate mRNA expression of type I interferon through the MDA5 signaling pathway and down-regulate mRNA expression of IL-6 and TNF-α via the NF-κB signaling pathway. Moreover, the mainly active compositions of HPE analyzed by high-performance liquid chromatography/electrospray ionization–mass spectroscopy (ESI-MS) are hyperoside, quercitrin, quercetin, pseudohypericin, and hypericin, and a combination of these compounds could mediate the antiviral activities. This might accelerate our understanding of the antiviral effect of H. perforatum and provide new insights into the development of effective therapeutic strategies.

A study was conducted to evaluate the effect of 3 different levels (1.25, 2.5 or 5.0%) of black cumin seeds (BCS) on five hundred chicks. A basal diet was supplemented with either 0 (negative control), or 0.1% antibiotic (positive control), or 3 levels of BCS. At day 28 and 42 of age, the 2.5 and 5.0% BCS groups had significantly greater body weight gain (BWG) than the 1.25% BCS and the antibiotic group. The same groups had feed efficiency significantly improved (P<0.05) compared to the 1.25% BCS group and the controls. At both ages, measurement of the dressing percentage showed no marked variation between BCS supplementation and antibiotic. The 2.5 and 5.0% BCS groups showed an increase (P<0.05) in total protein and higher (P<0.05) haematological values than the 1.25%, antibiotic or unsupplemented diet group. The activities of blood enzymes were lower (P<0.05) and caecal coliform and Escherichia coli populations decreased (P<0.05) in BCS and antibiotic groups. Serum and tissue cholesterol concentration decreased (P<0.05) as the levels of BCS increased. The geometric means haemagglutination inhibition (HI) titres of the BCS and the antibiotic group were always higher than the negative control. The mean lymphoid organs weight/body weight ratio of the negative control was significantly (P<0.05) lower than BCS and antibiotic groups. In conclusion, including up to 2.5 or 5.0% BSC in the diets of broilers has no deleterious effects on their performance, immunity, serum biochemical constituents nor haematological indices. In fact, it may lead to the development of low-cholesterol chicken meat