Background We aim to investigate the profile of acute antibody response in COVID-19 patients, and provide proposals for the usage of antibody test in clinical practice.Methods A multi-center cross-section study (285 patients) and a single-center follow-up study (63 patients) were performed to investigate the feature of acute antibody response to SARS-CoV-2. A cohort of 52 COVID-19 suspects and 64 close contacts were enrolled to evaluate the potentiality of the antibody test. ResultsThe positive rate for IgG reached 100% around 20 days after symptoms onset.The median day of seroconversion for both lgG and IgM was 13 days after symptoms onset. Seroconversion of IgM occurred at the same time, or earlier, or later than that of IgG. IgG levels in 100% patients (19/19) entered a platform within 6 days after seroconversion. The criteria of "IgG seroconversion" and "≥ 4-fold increase in the IgG titers in sequential samples" together diagnosed 82.9% (34/41) of the patients.Antibody test aided to confirm 4 patients with COVID-19 from 52 suspects who failed to be confirmed by RT-PCR and 7 patients from 148 close contacts with negative RT-PCR. ConclusionIgM and IgG should be detected simultaneously at the early phase of infection. The serological diagnosis criterion of seroconversion or the "≥ 4-fold increase in the IgG titer" is suitable for a majority of COVID-19 patients. Serologic test is helpful for the diagnosis of SARS-CoV-2 infection in suspects and close contacts.

This study investigated the role of the sugar transporter OsSWEET11 during the early stage of rice caryopsis development using β-glucoronidase (GUS) to represent its expression, together with clustered regularly interspaced short palindromic repeats-CRISPR-associated protein 9 (CRISPR-Cas9)-mediated knockout, cross-fertilization and RNA sequencing (RNA-seq) analyses. The results showed that OsSWEET11 was expressed strongly in developing caryopsis, particularly in the ovular vascular trace, nucellar epidermis and cross cells. The knockout of OsSWEET11 significantly decreased the sucrose concentration in the mutant embryo sacs and led to defective grain filling compared with that of the wild-type (WT) plant. Moreover, the expression of 2,549 genes in the mutant caryopsis was affected. The grain weight and seed setting percentage were also decreased in the mutants. The cross-fertilization of the mutant and WT rice revealed that the mutated maternal donor induced defective grain filling. These results strongly suggested that OsSWEET11 played an important role in sucrose release from maternal tissue to the maternal-filial interface during the early stage of caryopsis development. It might also induce sucrose release from the ovular vascular trace and cross cells of developing caryopsis. These findings bridge the gap in the understanding of post-phloem sugar transport during the early stage of rice caryopsis development.

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To assess the diagnostic accuracy of 1,3-β-D-glucan (BDG) assay for diagnosing invasive fungal infections (IFI), we searched the Medline and Embase databases, and studies reporting the performance of BDG assays for the diagnosis of IFI were identified. Our analysis was mainly focused on the cutoff level. Meta-analysis was performed using conventional meta-analytical pooling and bivariate analysis. Our meta-analysis covered 28 individual studies, in which 896 out of 4214 patients were identified as IFI positive. The pooled sensitivity, specificity, diagnostic odds ratio, and area under the summary receiver operating characteristic (AUC-SROC) curve were 0.78 [95% confidence interval (CI), 0.75-0.81], 0.81 (95% CI, 0.80-0.83), 21.88 (95% CI, 12.62-37.93), and 0.8855, respectively. Subgroup analyses indicated that in cohort studies, the cutoff value of BDG at 80 pg/mL had the best diagnostic accuracy, whereas in case-control studies the cutoff value of 20 pg/mL had the best diagnostic accuracy; moreover, the AUC-SROC in cohort studies was lower than that in case-control studies. The cutoff value of 60 pg/mL has the best diagnostic accuracy with the European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria as a reference standard. The 60 pg/mL cutoff value has the best diagnostic accuracy with the Fungitell assay compared to the BDG detection assay. The cutoff value of 20 pg/mL has the best diagnostic accuracy with the Fungitec G-test assay, and the cutoff value of 11 pg/mL has the best diagnostic accuracy with the Wako assay. Serum BDG detection is highly accurate for diagnosing IFIs. As such, 60 pg/mL of BDG level can be used as the best cutoff value to distinguish patients with IFIs from patients without IFI (mainly due to Candida and Aspergillus).

Dongxiang wild rice is phylogenetically close to temperate japonica and contains multiple cold resistance loci conferring its adaptation to high-latitude habitat. Understanding the nature of adaptation in wild populations will benefit crop breeding in the development of climate-resilient crop varieties. Dongxiang wild rice (DXWR), the northernmost common wild rice known, possesses a high degree of cold tolerance and can survive overwintering in its native habitat. However, to date, it is still unclear how DXWR evolved to cope with low-temperature environment, resulting in limited application of DXWR in rice breeding programs. In this study, we carried out both QTL mapping and phylogenetic analysis to discern the genetic mechanism underlying the strong cold resistance. Through a combination of interval mapping and single locus analysis in two genetic populations, at least 13 QTLs for seedling cold tolerance were identified in DXWR. A phylogenetic study using both genome-wide InDel markers and markers associated with cold tolerance loci reveals that DXWR belongs to the Or-III group, which is most closely related to cold-tolerant Japonica rice rather than to the Indica cultivars that are predominant in the habitat where DXWR grows. Our study paves the way toward an understanding of the nature of adaptation to a northern habitat in O. rufipogon. The QTLs identified in DXWR in this study will be useful for molecular breeding of cold-tolerant rice.