An updated review of feline coronavirus: mind the two biotypes.

Feline coronavirus (FCoV) includes two biotypes: feline infectious peritonitis virus (FIPV) and feline enteric coronavirus (FECV). Although both biotypes can infect cats, their pathogenicities differ. The FIPV biotype is more virulent than the FECV biotype and can cause peritonitis or even death in cats, while most FECV biotypes do not cause lesions. Even pathogenic strains of the FECV biotype can cause only mild enteritis because of their very low virulence. This article reviews recent progress in FCoV research with regard to FCoV etiological characteristics; epidemiology; clinical symptoms and pathological changes; pathogenesis; and current diagnosis, prevention and treatment methods. It is hoped that this review will provide a reference for further research on FCoV and other coronaviruses.

A highly sensitive bead-based flow cytometric competitive binding assay to detect SARS-CoV-2 neutralizing antibody activity.

Accurate detection of SARS-CoV-2 neutralizing antibody (nAb) is critical for assessing the immunity levels after virus infection or vaccination. As fast, cost-effective alternatives to viral infection-based assays, competitive binding (CB) assays were developed to quantitate nAb by monitoring the ability of sera to inhibit the binding of viral spike (S) protein to the angiotensin converting enzyme 2 (ACE2) receptor. Herein, we established a bead-based flow cytometric CB assay and tested the detection performance of six combination models, i.e. immobilized ACE2 and soluble Fc-tagged S1 subunit of S protein (iACE2/S1-Fc), immobilized ACE2 and soluble Fc-tagged receptor binding domain (RBD) of S protein (iACE2/RBD-Fc), immobilized S1 and soluble Fc-tagged ACE2 (iS1/ACE2-Fc), immobilized S1 and soluble His-tagged ACE2 (iS1/ACE2-His), immobilized RBD and soluble Fc-tagged ACE2 (iRBD/ACE2-Fc), and immobilized RBD and soluble His-tagged ACE2 (iRBD/ACE2-His). Using SARS-CoV-2 monoclonal antibodies and sera of convalescent COVID-19 patients and vaccinated subjects, the combination models iACE2/RBD-Fc, iACE2/S1-Fc and iS1/ACE2-His were identified to be able to specifically detect SARS-CoV-2 nAb, among which iACE2/RBD-Fc model showed the highest sensitivity, superior to a commercial SARS-CoV-2 surrogate virus neutralization test (sVNT) ELISA kit. Further studies demonstrated that the sensitivity and specificity of CB assays were affected by the tag of ACE2, type of spike and method of measuring binding rate between ACE2 and spike. Moreover, the iACE2/RBD-Fc model showed good performance in detecting kinetic development of nAb against both the prototype SARS-CoV-2 strain and an omicron variant of SARS-CoV-2 in people immunized by an inactivated SARS-CoV-2 vaccine, and the results of iACE2/RBD-Fc model are correlated well with those of live virus-based and pseudovirus-based neutralization tests, demonstrating the potential to be developed into a highly sensitive, specific, versatile and high-throughput method for detecting SARS-CoV-2 nAb in clinical practice.

Preliminary experience of oral fruquintinib-capecitabine as a new maintenance treatment strategy for advanced colorectal cancer in the era of coronavirus disease 2019 (COVID-19): case report and literature review.

Background: Bevacizumab combined with fluorouracil is the currently recommended maintenance treatment for metastatic colorectal cancer, but the use of bevacizumab needs to be carried out in hospitals, which invisibly increases the risk of patients' exposure to coronavirus disease 2019 (COVID-19) during the COVID-19 epidemic. Therefore, except of the advantage of convenience, all oral drugs as the maintenance treatment can reduce hospitalization and potential exposure risk during the COVID-19 epidemic, which is worth further exploration. Case Description: First case was a 49-year-old male with stage IV colon adenocarcinoma and abnormal liver function who was given bevacizumab with FOLFOXIRI (8-cycles), following which his liver function recovered. Oxaliplatin was stopped upon thrombocytopenia development. The patient was finally maintained on oral fruquintinib and capecitabine therapy since November 2020, and has been progression-free for >15 months. Grade 2 leukopenia, neutropenia, and thrombocytopenia; grade 1 terminal nerve injury; and grade 1 hand and foot numbness were observed. The second case was a 48-year-old male with advanced colon cancer who underwent laparoscopic sigmoidectomy. Post-surgery, the patient was commenced on fluorouracil and leucovorin (1-cycle), followed by conversion therapy with cetuximab and chemotherapy (6-cycles). The patient underwent left hemi-hepatectomy, partial hepatectomy of the right lobe, and intraoperative radiofrequency ablation, following which he continued to receive cetuximab and chemotherapy. The patient was maintained on oral fruquintinib and capecitabine since December, 2020 and has been progression-free for >14 months. Grade1 myelosuppression, leukopenia, and neutropenia, grade 2 thrombocytopenia were observed. Conclusions: This case report based on preliminary evidence advocates oral fruquintinib-capecitabine maintenance treatment as an alternative to bevacizumab-capecitabine standard therapy for CRC patients, especially in the era of COVID-19 epidemic. This scheme can reduce hospitalization and potential COVID-19 contact, and is more convenient than intravenous administration. Which should be further explored in future studies.

Effectiveness of Lianhua Qingwen Capsule in Treatment of Asymptomatic COVID-19 Patients: A Randomized, Controlled Multicenter Trial.

Background: Asymptomatic patients are unneglected sources in propagating transmission chain due to their high viral loads. However, treatments available based on symptoms seem not applicable to asymptomatic patients. In this study, the authors want to estimate the effectiveness of Lianhua Qingwen (LH) capsule on asymptomatic coronavirus disease 2019 (COVID-19) patients. Methods: A randomized controlled trial (RCT) was performed to explore the effectiveness and safety of LH capsule in treating asymptomatic COVID-19 patients. Patients were randomized to control group (isolated observation) and treatment group (LH, 4 capsules, thrice daily) for 14 days. The primary endpoints were the rate and time of nucleic acid turning negative during the isolation observation. Results: A total of 120 participants were included in the full analysis set (60 each in the control and treatment groups). Data showed that the rate of nucleic acid turning negative during the isolation observation in the treatment group was higher than that in the control group (rate difference: 21.66%, 95% confidence interval [CI]: 4.34 to 37.27, p = 0.0142). Patients in the treatment group have a shorter time of nucleic acid turning negative (7.5 vs. 14.5 days, p = 0.018). Moreover, the rate of clinical symptoms appearance in the treatment group was lower compared with that in the control group (rate difference: -31.67, 95% CI: -46.83 to -13.82, p = 0.0005). The proportion of confirmed mild and common cases in the treatment group was also lower (35.00% vs. 66.67%, p = 0.0005). No serious adverse events were documented. Conclusions: In this study, the authors illustrated that LH capsule is beneficial to asymptomatic COVID-19 patients. Considering the lack of interventions for treating asymptomatic COVID-19 patients at this stage, LH capsule could be considered as a choice. Chinese Clinical Trial Registry: ChiCTR2100042066.

Novel coronavirus mutations: Vaccine development and challenges.

The ongoing global pandemic of novel coronavirus pneumonia (COVID-19) caused by the SARS-CoV-2 has a significant impact on global health and economy system. In this context, there have been some landmark advances in vaccine development. Over 100 new coronavirus vaccine candidates have been approved for clinical trials, with ten WHO-approved vaccines including four inactivated virus vaccines, two mRNA vaccines, three recombinant viral vectored vaccines and one protein subunit vaccine on the "Emergency Use Listing". Although the SARS-CoV-2 has an internal proofreading mechanism, there have been a number of mutations emerged in the pandemic affecting its transmissibility, pathogenicity and immunogenicity. Of these, mutations in the spike (S) protein and the resultant mutant variants have posed new challenges for vaccine development and application. In this review article, we present an overview of vaccine development, the prevalence of new coronavirus variants and their impact on protective efficacy of existing vaccines and possible immunization strategies coping with the viral mutation and diversity.

Evaluation of humoral immune responses induced by different SARS-CoV-2 spike trimers from wild-type and emerging variants with individual, sequential, and combinational delivered strategies.

The spike trimer of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an effective target for inducing neutralizing antibodies by coronavirus disease 2019 (COVID-19) vaccines. However, the diversity of spike protein from emerging SASR-CoV-2 variants has become the major challenge for development of a universal vaccine. To investigate the immunogenicity of spike proteins from various circulating strains including wild type, Delta, and Omicron variants, we produced various natural spike trimers and designed three vaccination strategies, that is, individual, sequential, and bivalent regimens to assess autologous and heterogenous antibody responses in a mouse model. The results indicated that monovalent vaccine strategy with individual spike trimer could only induce binding and neutralizing antibodies against homologous viruses. However, sequential and bivalent immunization with Delta and Omicron spike trimers could induce significantly broader neutralizing antibody responses against heterogenous SARS-CoV-2. Interestingly, the spike trimer from Omicron variant showed superior immunogenicity in inducing antibody response against recently emerging XE variant. Taken together, our data supported the development of novel vaccination strategies or multivalent vaccine against emerging variants.

Research advances and clinical management of bronchiectasis: Chinese perspective.

Bronchiectasis is a debilitating chronic suppurative airway disease that confers a substantial burden globally. Despite the notable prevalence, research on bronchiectasis in mainland China remains in its infancy. Nevertheless, there has been a significant leap in the quantity and quality of research, which has contributed to the ever-improving clinical practice. A nationwide collaborative platform has been established to foster multicentre studies, which will help increase the level of evidence further. Here, we summarise the status quo of clinical management and consider the research priorities for bronchiectasis that have been published previously. We also highlight the efforts of the Chinese medical communities to outline the core tasks that need to be addressed within the next decade.

Mind the feline coronavirus: Comparison with SARS-CoV-2.

Both feline coronavirus (FCoV) and SARS-CoV-2 are coronaviruses that infect cats and humans, respectively. However, cats have been shown to be susceptible to SARS-CoV-2, and FCoV also had been shown to infect human. To elucidate the relationship between FCoV and SARS-CoV-2, we highlight the main characteristics of the genome, the receptor usage, and the correlation of the receptor-binding domain (RBD) of spike proteins in FCoV and SARS-CoV-2. It is demonstrated that FCoV and SARS-CoV-2 are closely related to the main characteristics of the genome, receptor usage, and RBD of spike proteins with similar furin cleavage sites. In particular, the affinity of the conserved feline angiotensin-converting enzyme 2 (fACE2) receptor to the RBD of SARS-CoV-2 suggests that cats are susceptible to SARS-CoV-2. In addition, cross-species of coronaviruses between cats and humans or other domesticated animals are also discussed. This review sheds light on cats as potential intermediate hosts for SARS-CoV-2 transmission, and cross-species transmission or zoonotic infection of FCoV and SARS-CoV-2 between cats and humans was identified.

Mind the feline coronavirus: comparison with SARS-CoV-2

Both feline coronavirus (FCoV) and SARS-CoV-2 are coronaviruses that infect cats and humans, respectively. However, cats have been shown to be susceptible to SARS-CoV-2, and FCoV also had been shown to infect human. To elucidate the relationship between FCoV and SARS-CoV-2, we highlight the main characteristics of the genome, the receptor usage, and the correlation of the receptor-binding domain (RBD) of spike proteins in FCoV and SARS-CoV-2. It is demonstrated that FCoV and SARS-CoV-2 are closely related to the main characteristics of the genome, receptor usage, and RBD of spike proteins with similar furin cleavage sites. In particular, the affinity of the conserved feline angiotensin-converting enzyme 2 (fACE2) receptor to the RBD of SARS-CoV-2 suggests that cats are susceptible to SARS-CoV-2. In addition, cross-species of coronaviruses between cats and humans or other domesticated animals are also discussed. This review sheds light on cats as potential intermediate hosts for SARS-CoV-2 transmission, and cross-species transmission or zoonotic infection of FCoV and SARS-CoV-2 between cats and humans was identified.

Traditional Uses, Phytochemistry, Pharmacology and Toxicology of Rhizoma phragmitis: A Narrative Review.

Rhizoma phragmitis is a common Chinese herbal medicine whose effects are defined as 'clearing heat and fire, promoting fluid production to quench thirst, eliminating irritability, stopping vomiting, and disinhibiting urine'. During the Novel Coronavirus epidemic in 2020, the Weijing Decoction and Wuye Lugen Decoction, with Rhizoma phragmitis as the main herbal component, were included in The Pneumonia Treatment Protocol for Novel Coronavirus Infection (Trial Version 5) due to remarkable antiviral effects. Modern pharmacological studies have shown that Rhizoma phragmitis has antiviral, antioxidative, anti-inflammatory, analgesic, and hypoglycemic functions, lowers blood lipids and protects the liver and kidney. This review aims to provide a systematic summary of the botany, traditional applications, phytochemistry, pharmacology and toxicology of Rhizoma phragmitis.

Respiratory Mucosal Immunity: Kinetics of Secretory Immunoglobulin A in Sputum and Throat Swabs From COVID-19 Patients and Vaccine Recipients.

While IgM and IgG response to SARS-CoV-2 has been extensively studied, relatively little is known about secretory IgA (sIgA) response in respiratory mucosa. Here we report IgA response to the SARS-CoV-2 in sputum, throat swabs, and serum with nucleocapsid protein (NP) enzyme-linked immunosorbent assays (ELISA) in a cohort of 28 COVID-19 patients and 55 vaccine recipients. The assays showed sIgA in respiratory mucosa could be detected on the first day after illness onset (AIO), and the median conversion time for sIgA in sputum, throat swabs, and serum was 3, 4, and 10 days, respectively. The positive rates of sIgA first week AIO were 100% (24/28) and 85.7% (24/28) in sputum and throat swabs, respectively, and were both 100% during the mid-onset (2-3 weeks AIO). During the recovery period, sIgA positive rates in sputum and throat swabs gradually decreased from 60.7% (17/28) and 57.1% (16/28) 1 month AIO and the sIgA antibodies were all undetectable 6 months AIO. However, serum IgA positive rate was still 100% at 4 months and 53.6% (15/28) at 6 months. Throat swabs obtained from volunteers who received inactivated SARS-CoV-2 vaccines by intramuscular delivery all showed negative results in IgA ELISA. These findings will likely improve our understanding of respiratory mucosal immunity of this emerging disease and help in containing the pandemic and developing vaccines.

Efficacy and Safety of Lianhua Qingke Tablets in the Treatment of Mild and Common-Type COVID-19: A Randomized, Controlled, Multicenter Clinical Study.

BACKGROUND: Lianhua Qingke (LH) tablets is an effective traditional Chinese medicine against various viral infections, especially in relieving coughing. However, its effects on COVID-19 are unknown. METHODS: To examine the therapeutic effectiveness of LH tablets in COVID-19 patients with mild and common types, a randomized, multicenter, controlled study was carried out. COVID-19 cases were randomized to undergo routine treatment with or without LH tablets (4 tablets, three times a day) for 14 days. The primary endpoints were the rate of achieving clinical symptom resolution and the corresponding time. RESULTS: There were 144 participants in the full analysis set (72 each in the LH and control groups). The LH group participants had elevated symptom alleviation rate at 14 days compared with control cases (FAS: 98.61% vs. 84.72%, p = 0.0026). In comparison with control group participants, the LH group participants had reduced median time to clinical symptom alleviation (median: 4 vs. 7 days, p < 0.0001). Higher resolution rates of coughing (98.44% vs. 84.51%, p = 0.0045) and expectoration (100% vs. 82.35%, p = 0.0268) were observed in the LH group. Times to recovery of fever (median: 2 vs. 3 days, p = 0.0007), coughing (median: 4 vs. 7 days, p < 0.0001), and expectoration (median: 3 vs. 6 days, p < 0.0001) were also notably shorter in the LH group. Moreover, the LH group had elevated improvement rates in chest computed tomography signs (FAS: 86.11% vs. 72.22%, p = 0.0402) and clinical cure at day 28 (FAS: 83.33% vs. 68.06%, p = 0.0326). However, no differences were found in the laboratory test and viral assay. Serious adverse events were not detected. CONCLUSION: These preliminary findings indicate LH tablets may be effective in symptomatic COVID-19, especially in relieving coughing. This trial was registered in Chinese Clinical Trial Registry (ChiCTR2100042069).

Novel Monoclonal Antibodies and Recombined Antibodies Against Variant SARS-CoV-2.

The mutants resulted from the ongoing SARS-CoV-2 epidemic have showed resistance to antibody neutralization and vaccine-induced immune response. The present study isolated and identified two novel SARS-CoV-2 neutralizing antibodies (nAbs) from convalescent COVID-19 patients. These two nAbs (XG81 and XG83) were then systemically compared with nine nAbs that were reconstructed by using published data, and revealed that, even though these two nAbs shared targeting epitopes on spike protein, they were different from any of the nine nAbs. Compared with XG81, XG83 exhibited a higher RBD binding affinity and neutralization potency against wild-typed pseudovirus, variant pseudoviruses with mutated spike proteins, such as D614G, E484Q, and A475V, as well as the authentic SARS-CoV-2 virus. To explore potential broadly neutralizing antibodies, heavy and light chains from all 18 nAbs (16 published nAbs, XG81 and XG83) were cross-recombined, and some of the functional antibodies were screened and studied for RBD binding affinity, and neutralizing activity against pseudovirus and the authentic SARS-CoV-2 virus. The results demonstrated that several recombined antibodies had a more potent neutralization activity against variant pseudoviruses compared with the originally paired Abs. Taken together, the novel neutralizing antibodies identified in this study are a likely valuable addition to candidate antibody drugs for the development of clinical therapeutic agents against SARS-CoV-2 to minimize mutational escape.

Crucial Mutations of Spike Protein on SARS-CoV-2 Evolved to Variant Strains Escaping Neutralization of Convalescent Plasmas and RBD-Specific Monoclonal Antibodies.

Small number of SARS-CoV-2 epidemic lineages did not efficiently exhibit a neutralization profile, while single amino acid mutation in the spike protein has not been confirmed in altering viral antigenicity resulting in immune escape. To identify crucial mutations in spike protein that escape humoral immune response, we evaluated the cross-neutralization of convalescent plasmas and RBD-specific monoclonal antibodies (mAbs) against various spike protein-based pseudoviruses. Three of 24 SARS-CoV-2 pseudoviruses containing different mutations in spike protein, including D614G, A475V, and E484Q, consistently showed an altered sensitivity to neutralization by convalescent plasmas. A475V and E484Q mutants are highly resistant to neutralization by mAb B38 and 2-4, suggesting that some crucial mutations in spike protein might evolve SARS-CoV-2 variants capable of escaping humoral immune response.

Structural Basis and Function of the N Terminus of SARS-CoV-2 Nonstructural Protein 1.

Nonstructural protein 1 (Nsp1) of severe acute respiratory syndrome coronaviruses (SARS-CoVs) is an important pathogenic factor that inhibits host protein translation by means of its C terminus. However, its N-terminal function remains elusive. Here, we determined the crystal structure of the N terminus (amino acids [aa] 11 to 125) of SARS-CoV-2 Nsp1 at a 1.25-Å resolution. Further functional assays showed that the N terminus of SARS-CoVs Nsp1 alone loses the ability to colocalize with ribosomes and inhibit protein translation. The C terminus of Nsp1 can colocalize with ribosomes, but its protein translation inhibition ability is significantly weakened. Interestingly, fusing the C terminus of Nsp1 with enhanced green fluorescent protein (EGFP) or other proteins in place of its N terminus restored the protein translation inhibitory ability to a level equivalent to that of full-length Nsp1. Thus, our results suggest that the N terminus of Nsp1 is able to stabilize the binding of the Nsp1 C terminus to ribosomes and act as a nonspecific barrier to block the mRNA channel, thus abrogating host mRNA translation.

Evaluation of laboratory application of two RT-PCR detection kits for SARS-CoV-2 nucleic acid

Objective: The kits produced by the two manufacturers were used to detect samples of patients with pneumonia infected by new coronavirus in parallel, and their detection effects were evaluated for limited application.

Digital PCR assay for the effective detection of COVID-19 patients with SARS-CoV-2 low viral load.

OBJECTIVE: Viral nucleic acid detection by real-time reverse transcription polymerase chain reaction (qPCR) is the current standard method for diagnosis of SARS-CoV-2 infection. However, due to low viral load in some COVID-19 patients, false negative results from this method have been repeatedly reported. METHOD: In this study, we compared the sensitivity and specificity of digital PCR (dPCR) in simulated samples and clinical samples with qPCR assay through a series of vigorous tests. RESULTS: The results showed that dPCR was more sensitive than qPCR especially for samples with low viral load (≤3 copies). In addition, dPCR had similar specificity as qPCR and could effectively distinguish other human coronaviruses and influenza virus from SARS-CoV-2. More importantly, dPCR was more sensitive than qPCR in detecting the virus in the "negative" samples from recurrent COVID-19 patients. CONCLUSIONS: In summary, dPCR could serve as a powerful complement to the current qPCR method for SARS-CoV-2 detection, especially for the samples with extremely low viral load, such as recurrent COVID-19 patients.