Status in clinical and molecular characteristics of differentiated thyroid carcinoma in children and adolescents / 中华外科杂志

The epidemiological, clinical, and molecular characteristics of differentiated thyroid carcinoma (DTC) in children and adolescents are different from those in adults. The incidence of DTC in children and adolescents is very low, with high rates of lymph node metastasis, extra-thyroidal extension and recurrence, but mortality is lower than that in adults. Younger children with DTC tend to show a higher rate of recurrence, more lymph node metastases, and more extra-thyroidal extension. Furthermore, studies on molecular characteristics suggest that the diversity of gene mutations causes the clinical manifestations of DTC in children and adolescents that are different from those in adults. The incidence of gene fusion is significantly higher than in adults, while the incidence of point mutations is lower than in adults, which may be closely related to clinicopathological characteristics such as high tumor aggressiveness and poor prognosis.

Effect of Echinococcus multilocularis infection on Tim3 expression in spleen natural killer cells of mice / 中国血吸虫病防治杂志

OBJECTIVE@#To investigate the effect of Echinococcus multilocularis infection on Tim3 expression and its co-expression with immune checkpoint molecules 2B4 and LAG3 in spleen natural killer (NK) cells of mice.@*METHODS@#C57BL/6 mice, each weighing (20 ± 2) g, were randomly divided into a high-dose infection group (15 mice), a low-dose infection group (13 mice), and a control group (11 mice). Mice in the high- and low-dose infection groups were inoculated with 2 000 and 50 Echinococcus multilocularis protoscolices via the hepatic portal vein, while animals in the control group was injected with an equivalent amount of physiological saline via the hepatic portal vein. Mouse spleen cells were harvested 12 and 24 weeks post-infection, and Tim3 expression and its co-expression with 2B4 and LAG3 in NK cells were detected using flow cytometry.@*RESULTS@#There were significant differences in the proportions of Tim3 expression (F = 13.559, P < 0.001) and Tim3 and 2B4 co-expression (F = 12.465, P < 0.001) in mouse spleen NK cells among groups 12 weeks post-infection with E. multilocularis, and the proportion of Tim3 expression was significantly higher in mouse spleen NK cells in the low-dose infection group [(23.84 ± 2.28)%] than in the high-dose infection group [(15.72 ± 3.67)%] and the control group [(16.14 ± 3.83)%] (both P values < 0.01), while the proportion of Tim3 and 2B4 co-expression was significantly higher in mouse spleen NK cells in the low-dose infection group [(22.20 ± 2.13)%] than in the high-dose infection group [(14.17 ± 3.81)%] and the control group [(15.20 ± 3.77)%] (both P values < 0.01). There were significant differences in the proportions of Tim3 expression (F = 5.243, P < 0.05) and Tim3 and 2B4 co-expression (F = 4.659, P < 0.05) in mouse spleen NK cells among groups 24 weeks post-infection with E. multilocularis infection, and the proportions of Tim3 expression and Tim3 and 2B4 co-expression were significantly lower in mouse spleen NK cells in the high-dose infection group [(20.55 ± 7.04)% and (20.98 ± 7.12)%] than in the control group [(31.38 ± 3.19)% and (31.25 ± 3.06)%] (both P values < 0.05), and there were no significantly difference between the proportions of Tim3 expression and Tim3 and 2B4 co-expression in splenic NK cells in the low-dose infection group [(26.80 ± 6.47)% and (26.48 ± 6.48)%] and the control group (both P > 0.05). There were no significant differences in the proportions of Tim3 and LAG3 co-expression in mouse spleen NK cells among groups 12 (F = 2.283, P > 0.05) and 24 weeks post-infection (F = 0.375, P > 0.05). In the low-dose infection group, there were no significant differences in the proportions of Tim3 expression or Tim3 and 2B4 co-expression in mouse spleen NK cells 12 (t = -1.137, P > 0.05) or 24 weeks post-infection (t = -1.658, P > 0.05), and the proportion of Tim3 and LAG3 co-expression increased in mouse spleen NK cells 24 weeks post-infection relative to 12 weeks post-infection (t = -5.261, P < 0.01). In the highdose infection group, there was no significant difference in the proportion of Tim3 expression in mouse spleen NK cells 12 and 24 weeks post-infection (t = -1.546, P > 0.05); however, the proportions of Tim3 co-expression with 2B4 and LAG3 increased in mouse splenic NK cells 24 weeks post-infection relative to 12 weeks post-infection (t = -2.425 and -4.745, both P values < 0.05).@*CONCLUSIONS@#The Tim3 expression and Tim3 co-expression with LAG3 and 2B4 on spleen NK cells is affected by doses of E. multilocularis infection and disease stages, and present different phenotypes during the course of alveolar echinococcosis. NK cells tend to form an immunosuppressive phenotype with the progression of E. multilocularis infection, which facilitates immune escape and chronic parasitism of E. multilocularis.

Perivascular epithelioid cell tumor of the lung: a clinicopathological analysis of eight cases / 中华病理学杂志

Objective: To investigate the clinicopathological features of perivascular epithelioid cell tumor (PEComa) of the lung. Methods: Eight PEComa cases of the lung diagnosed at the First Affiliated Hospital of Soochow University, Suzhou, China from July 2008 to December 2021 were collected and subject to immunohistochemical staining, fluorescence in situ hybridization and next generation sequencing. The relevant literature was reviewed and the clinicopathological features were analyzed. Results: There were 5 males and 3 females, aged from 18 to 70 years (mean 39 years). There were 3 cases of the right upper lung, 3 cases of the left lower lung, 1 case of the left upper lung and 1 case of the right middle lung. Seven cases were solitary and 1 case was multifocal (4 lesions). Seven cases were benign while one was malignant. The tumors were all located in the peripheral part of the lung, with a maximum diameter of 0.2-4.0 cm. Grossly, they were oval and well circumscribed. Microscopically, the tumor cells were oval, short spindle-shaped, arranged in solid nests, acinar or hemangiopericytoma-like patterns, with clear or eosinophilic cytoplasm. The stroma was rich in blood vessels with hyalinization. Coagulated necrosis and high-grade nuclei were seen in the malignant case, and calcification was seen in 2 cases. Immunohistochemically, the tumor cells were positive for Melan A (8/8), HMB45 (7/8), CD34 (6/8), TFE3 (4/7), and SMA (3/8). All cases were negative for CKpan and S-100. TFE3 (Xp11.2) gene fusion was examined using the TFE3 break-apart fluorescence in situ hybridization in 5 cases, in which only the malignant case was positive. The next generation sequencing revealed the SFPQ-TFE3 [t(X;1)(p11.2;p34)] fusion. Follow-up of the patients ranged from 12 to 173 months while one patient was lost to the follow-up. The malignant case had tumor metastasis to the brain 4 years after the operation and then received radiotherapy. Other 6 cases had no recurrence and metastasis, and all the 7 patients survived. Conclusions: Most of the PEComas of the lung are benign. When there are malignant morphological features such as necrosis, high-grade nuclei or SFPQ-TFE3 gene fusion, close follow-up seems necessary.

Activation of HIF-1α/ACLY signaling axis promotes progression of clear cell renal cell carcinoma with VHL inactivation mutation / 中华病理学杂志

Objective: To explore the potential pathogenesis of clear cell renal cell carcinoma (ccRCC) based on the HIF-1α/ACLY signaling pathway, as well as to provide new ideas for the treatment of ccRCC. Methods: Seventy-eight ccRCC cases diagnosed at the First Affiliated Hospital of Soochow University, Suzhou, China were collected. The VHL mutation was examined using exon sequencing. The expression of HIF-1α/ACLY in VHL-mutated ccRCC was evaluated using immunohistochemical staining and further validated in VHL-mutated ccRCC cell lines (786-O, A498, UM-RC-2, SNU-333, and Caki-2) using Western blot. The mRNA and protein levels of ACLY were detected using real-time quantitative PCR and Western blot after overexpression or interference with HIF-1α in ccRCC cell lines. HeLa cells were treated with CoCl2 and hypoxia (1%O2) to activate HIF-1α and then subject to the detection of the ACLY mRNA and protein levels. The potential molecular mechanism of HIF-1α-induced ACLY activation was explored through JASPAR database combined with chromatin immunoprecipitation assay (ChIP) and luciferase reporter gene assay. The effect of HIF-1α/ACLY regulation axis on lipid accumulation was detected using BODIPY staining and other cell biological techniques. The expression of ACLY was compared between patients with ccRCC and those with benign lesions, and the feasibility of ACLY as a prognostic indicator for ccRCC was explored through survival analysis. Results: Exon sequencing revealed that 55 (70.5%) of the 78 ccRCC patients harbored a VHL inactivation mutation, and HIF-1α expression was associated with ACLY protein levels. The protein levels of ACLY and HIF-1α in ccRCC cell lines carrying VHL mutation were also correlated to various degrees. Overexpression of HIF-1α in A498 cells increased the mRNA and protein levels of ACLY, and knockdown of HIF-1α in Caki-2 cells inhibited the mRNA and protein levels of ACLY (P<0.001 for all). CoCl2 and hypoxia treatment significantly increased the mRNA and protein levels of ACLY by activating HIF-1α (P<0.001 for all). The quantification of transcriptional activity of luciferase reporter gene and ChIP-qPCR results suggested that HIF-1α could directly bind to ACLY promoter region to transcriptionally activate ACLY expression and increase ACLY protein level (P<0.001 for all). The results of BODIPY staining suggested that the content of free fatty acids in cell lines was associated with the levels of HIF-1α and ACLY. The depletion of HIF-1α could effectively reduce the accumulation of lipid in cells, while the overexpression of ACLY could reverse this process. At the same time, cell function experiments showed that the proliferation rate of ccRCC cells with HIF-1α knockdown was significantly decreased, and overexpression of ACLY could restore proliferation of these tumor cells (P<0.001). Survival analysis further showed that compared with the ccRCC patients with low ACLY expression, the ccRCC patients with high ACLY expression had a poorer prognosis and a shorter median survival (P<0.001). Conclusions: VHL mutation-mediated HIF-1α overexpression in ccRCC promotes lipid synthesis and tumor progression by activating ACLY. Targeting the HIF-1α/ACLY signaling axis may provide a theoretical basis for the clinical diagnosis and treatment of ccRCC.

Alarming antibody evasion properties of rising SARS-CoV-2 BQ and XBB subvariants

The SARS-CoV-2 Omicron variant continues to evolve, with new BQ and XBB subvariants now rapidly expanding in Europe/US and Asia, respectively. As these new subvariants have additional spike mutations, they may possess altered antibody evasion properties. Here, we report that neutralization of BQ.1, BQ.1.1, XBB, and XBB.1 by sera from vaccinees and infected persons was markedly impaired, including sera from individuals who were boosted with a WA1/BA.5 bivalent mRNA vaccine. Compared to the ancestral strain D614G, serum neutralizing titers against BQ and XBB subvariants were lower by 13-81-fold and 66-155-fold, respectively, far beyond what had been observed to date. A panel of monoclonal antibodies capable of neutralizing the original Omicron variant, including those with Emergency Use Authorization, were largely inactive against these new subvariants. The spike mutations that conferred antibody resistance were individually studied and structurally explained. Finally, the ACE2-binding affinities of the spike proteins of these novel subvariants were found to be similar to those of their predecessors. Taken together, our findings indicate that BQ and XBB subvariants present serious threats to the efficacy of current COVID-19 vaccines, render inactive all authorized monoclonal antibodies, and may have gained dominance in the population because of their advantage in evading antibodies.

Antibody Evasion Properties of SARS-CoV-2 Omicron Sublineages

The identification of the Omicron variant (B.1.1.529.1 or BA.1) of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) in Botswana in November 20211 immediately raised alarms due to the sheer number of mutations in the spike glycoprotein that could lead to striking antibody evasion. We2 and others3-6 recently reported results in this Journal confirming such a concern. Continuing surveillance of Omicron evolution has since revealed the rise in prevalence of two sublineages, BA.1 with an R346K mutation (BA.1+R346K) and B.1.1.529.2 (BA.2), with the latter containing 8 unique spike mutations while lacking 13 spike mutations found in BA.1. We therefore extended our studies to include antigenic characterization of these new sublineages. Polyclonal sera from patients infected by wild-type SARS-CoV-2 or recipients of current mRNA vaccines showed a substantial loss in neutralizing activity against both BA.1+R346K and BA.2, with drops comparable to that already reported for BA.12,3,5,6. These findings indicate that these three sublineages of Omicron are antigenically equidistant from the wild-type SARS-CoV-2 and thus similarly threaten the efficacies of current vaccines. BA.2 also exhibited marked resistance to 17 of 19 neutralizing monoclonal antibodies tested, including S309 (sotrovimab)7, which had retained appreciable activity against BA.1 and BA.1+R346K2-4,6. This new finding shows that no presently approved or authorized monoclonal antibody therapy could adequately cover all sublineages of the Omicron variant.

Structural basis for antibody resistance to SARS-CoV-2 omicron variant

The recently reported B.1.1.529 Omicron variant of SARS-CoV-2 includes 34 mutations in the spike protein relative to the Wuhan strain that initiated the COVID-19 pandemic, including 15 mutations in the receptor binding domain (RBD). Functional studies have shown omicron to substantially escape the activity of many SARS-CoV-2-neutralizing antibodies. Here we report a 3.1 [A] resolution cryo-electron microscopy (cryo-EM) structure of the Omicron spike protein ectodomain. The structure depicts a spike that is exclusively in the 1-RBD-up conformation with increased mobility and inter-protomer asymmetry. Many mutations cause steric clashes and/or altered interactions at antibody binding surfaces, whereas others mediate changes of the spike structure in local regions to interfere with antibody recognition. Overall, the structure of the omicron spike reveals how mutations alter its conformation and explains its extraordinary ability to evade neutralizing antibodies. HighlightsO_LISARS-CoV-2 omicron spike exclusively adopts 1-RBD-up conformation C_LIO_LIOmicron substitutions alter conformation and mobility of RBD C_LIO_LIA subset of omicron mutations change the local conformation of spike C_LIO_LIThe structure reveals the basis of antibody neutralization escape C_LI

Striking Antibody Evasion Manifested by the Omicron Variant of SARS-CoV-2

The Omicron (B.1.1.529) variant of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) was only recently detected in southern Africa, but its subsequent spread has been extensive, both regionally and globally1. It is expected to become dominant in the coming weeks2, probably due to enhanced transmissibility. A striking feature of this variant is the large number of spike mutations3 that pose a threat to the efficacy of current COVID-19 (coronavirus disease 2019) vaccines and antibody therapies4. This concern is amplified by the findings from our study. We found B.1.1.529 to be markedly resistant to neutralization by serum not only from convalescent patients, but also from individuals vaccinated with one of the four widely used COVID-19 vaccines. Even serum from persons vaccinated and boosted with mRNA-based vaccines exhibited substantially diminished neutralizing activity against B.1.1.529. By evaluating a panel of monoclonal antibodies to all known epitope clusters on the spike protein, we noted that the activity of 17 of the 19 antibodies tested were either abolished or impaired, including ones currently authorized or approved for use in patients. In addition, we also identified four new spike mutations (S371L, N440K, G446S, and Q493R) that confer greater antibody resistance to B.1.1.529. The Omicron variant presents a serious threat to many existing COVID-19 vaccines and therapies, compelling the development of new interventions that anticipate the evolutionary trajectory of SARS-CoV-2.

A "Made-in-Canada" serology solution for profiling humoral immune responses to SARS-CoV-2 infection and vaccination

OBJECTIVESAntibody testing against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been instrumental in detecting previous exposures and analyzing vaccine-elicited immune responses. Here, we describe a scalable solution to detect and quantify SARS-CoV-2 antibodies, discriminate between natural infection- and vaccination-induced responses, and assess antibody-mediated inhibition of the spike-angiotensin converting enzyme 2 (ACE2) interaction. METHODSWe developed methods and reagents to detect SARS-CoV-2 antibodies by enzyme-linked immunosorbent assay (ELISA). The main assays focus on the parallel detection of immunoglobulin (Ig)Gs against the spike trimer, its receptor binding domain (RBD), and nucleocapsid (N). We automated a surrogate neutralization (sn)ELISA that measures inhibition of ACE2-spike or -RBD interactions by antibodies. The assays were calibrated to a World Health Organization reference standard. RESULTSOur single-point IgG-based ELISAs accurately distinguished non-infected and infected individuals. For seroprevalence assessment (in a non-vaccinated cohort), classifying a sample as positive if antibodies were detected for [≥] 2 of the 3 antigens provided the highest specificity. In vaccinated cohorts, increases in anti-spike and -RBD (but not -N) antibodies are observed. We present detailed protocols for serum/plasma or dried blood spots analysis performed manually and on automated platforms. The snELISA can be performed automatically at single points, increasing its scalability. CONCLUSIONSMeasuring antibodies to three viral antigens and identify neutralizing antibodies capable of disrupting spike-ACE2 interactions in high-throughput enables large-scale analyses of humoral immune responses to SARS-CoV-2 infection and vaccination. The reagents are available to enable scaling up of standardized serological assays, permitting inter-laboratory data comparison and aggregation.

Mucosal antibody response to SARS-CoV-2 in paediatric and adult patients: a longitudinal study

Conjunctival and nasal mucosal antibody responses in thirty-four paediatric and forty-seven adult COVID-19 patients were measured. The mucosal antibody was IgA dominant. In the nasal epithelial lining fluid (NELF) of asymptomatic paediatric patients, SARS-CoV-2 spike protein 1 (S1) specific immunoglobulin A (IgA) was induced early. Their plasma S1-specific IgG levels were higher than symptomatic patients. More adult with mild disease had NELF S1-specific IgA than those with severe/critical illness. Within the first week of diagnosis, higher S1-specific antibodies in NELF and plasma and lower vial loads were detected in paediatric than adult patients with mild disease. The IgA and IgG levels correlated positively with the surrogate neutralization readout. The detectable NELF neutralizing S1-specific IgA in the first week after diagnosis correlated with a rapid decline in viral load. This study highlights the effect of nasal IgA in limiting the SARS-CoV-2 replication and provides complementary information to the serum antibody measurements.

A Third Dose of SARS-CoV-2 Vaccine Increases Neutralizing Antibodies Against Variants of Concern in Solid Organ Transplant Recipients

Vaccine-induced SARS-CoV-2 antibody responses are attenuated in solid organ transplant recipients (SOTRs) and breakthrough infections are more common. Additional SARS-CoV-2 vaccine doses increase anti-spike IgG in some SOTRs, but it is uncertain whether neutralization of variants of concern (VOCs) is enhanced. We tested 47 SOTRs for clinical and research anti-spike IgG, pseudoneutralization (ACE2 blocking), and live-virus neutralization (nAb) against VOCs before and after a third SARS-CoV-2 vaccine dose (70% mRNA, 30% Ad26.COV2.S) with comparison to 15 healthy controls after two mRNA vaccine doses. We used correlation analysis to compare anti-spike IgG assays and focused on thresholds associated with neutralizing activity. A third SARS-CoV-2 vaccine dose increased median anti-spike (1.6-fold) and receptor-binding domain (1.5-fold) IgG, as well as pseudoneutralization against VOCs (2.5-fold versus Delta). However, IgG and neutralization activity were significantly lower than healthy controls (p<0.001); 32% of SOTRs had zero detectable nAb against Delta after third vaccination. Correlation with nAb was seen at anti-spike IgG >4 AU on the clinical assay and >10^4 AU on the research assay. These findings highlight benefits of a third vaccine dose for some SOTRs and the need for alternative strategies to improve protection in a significant subset of this population.

Neutralizing antibody responses to SARS-CoV-2 variants in vaccinated Ontario long-term care home residents and workers

Prioritizing Ontarios long-term care home (LTCH) residents for vaccination against severe acute respiratory syndrome coronavirus 2 has drastically reduced their disease burden; however, recent LTCH outbreaks of variants of concern (VOCs) have raised questions regarding their immune responses. In 198 residents, mRNA vaccine dose 1 elicited partial spike and receptor binding domain antibody responses, while the second elicited a response at least equivalent to convalescent individuals in most residents. Residents administered mRNA-1273 (Moderna) mounted stronger total and neutralizing antibody responses than those administered BNT162b2 (Pfizer-BioNTech). Two to four weeks after dose 2, residents (n = 119, median age 88) produced 4.8-6.3-fold fewer neutralizing antibodies than staff (n = 78; median age 47) against wild-type (with D614G) pseudotyped lentivirus, and residents administered BNT162b2 produced 3.89-fold fewer neutralizing antibodies than those who received mRNA-1273. These effects were exacerbated upon serum challenge with pseudotyped VOC spike, with up to 7.94-fold reductions in B.1.351 (Beta) neutralization. Cumulatively, weaker vaccine stimulation, age/comorbidities, and the VOC produced an [~]130-fold reduction in apparent neutralization titers in LTCH residents and 37.9% of BNT162b2-vaccinated residents had undetectable neutralizing antibodies to B.1.351. Continued immune response surveillance and additional vaccine doses may be required in this population with known vulnerabilities.

Genetic mismatch explains sizable variation of COVID-19 vaccine efficacy in clinical trials

Timely evaluation of the protective effects of COVID-19 vaccines is challenging but urgently needed to inform the pandemic control planning. Based on vaccine efficacy/effectiveness (VE) data of 11 vaccine products and 297,055 SARS-CoV-2 sequences collected in 20 regions, we analyzed the relationship between genetic mismatch of circulating viruses against the vaccine strain and VE. Variations from technology platforms are controlled by a mixed-effects model. We found that the genetic mismatch measured on the RBD is highly predictive for vaccine protection and accounted for 72.0% (p-value < 0.01) of the VE change. The NTD and S protein also demonstrate significant but weaker per amino acid substitution association with VE (p-values < 0.01). The model is applied to predict vaccine protection of existing vaccines against new genetic variants and is validated by independent cohort studies. The estimated VE against the delta variant is 79.3% (95% prediction interval: 67.0 - 92.1) using the mRNA platform, and an independent survey reported a close match of 83.0%; against the beta variant (B.1.351) the predicted VE is 53.8% (95% prediction interval: 39.9 - 67.4) using the viral-vector vaccines, and an observational study reported a close match of 48.0%. Genetic mismatch provides an accurate prediction for vaccine protection and offers a rapid evaluation method against novel variants to facilitate vaccine deployment and public health responses.

Temporal patterns in the evolutionary genetic distance of SARS-CoV-2 during the COVID-19 pandemic

BackgroundDuring the pandemic of coronavirus disease 2019 (COVID-19), the genetic mutations occurred in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cumulatively or sporadically. In this study, we employed a computational approach to identify and trace the emerging patterns of the SARS-CoV-2 mutations, and quantify accumulative genetic distance across different periods and proteins. MethodsFull-length human SARS-CoV-2 strains in United Kingdom were collected. We investigated the temporal variation in the evolutionary genetic distance defined by the Hamming distance since the start of COVID-19 pandemic. FindingsOur results showed that the SARS-CoV-2 was in the process of continuous evolution, mainly involved in spike protein (S protein), the RNA-dependent RNA polymerase (RdRp) region of open reading frame 1 (ORF1) and nucleocapsid protein (N protein). By contrast, mutations in other proteins were sporadic and genetic distance to the initial sequenced strain did not show an increasing trend.

Demographic and psychological correlates of SARS-CoV-2 vaccination intentions in a sample of Canadian families

The COVID-19 pandemic has been ongoing for close to a year, with second waves occurring presently and many viewing a vaccine as the most likely way to curb successive waves and promote herd immunity. Reaching herd immunity status likely necessitates that children, as well as their parents, receive a vaccine targeting SARS-CoV-2. In this exploratory study, we investigated the demographic, experiential, and psychological factors associated with the anticipated likelihood and speed of having children receive a SARS-CoV-2 vaccine in a sample of 455 Canadian families (857 children). Using linear mixed effects and proportional odds logistic regression models, we demonstrated that older parental age, living in the Prairies (relative to Central Canada), more complete child and parental vaccination history, more positive attitudes towards vaccines generally, higher psychological avoidance of the pandemic and a greater tendency to prioritize the risks of the disease relative to the risks of side effects (i.e., lower omission bias), were associated with higher likelihoods of intention to vaccinate participants children. In some models, subjective evaluations of proximal COVID-19 risk and higher levels of state anxiety were associated with increased likelihood of having children vaccinated. Faster speed of intended vaccination was predicted by a similar constellation of variables, with higher SES emerging as a trend-level predictor of vaccination speed. Results are discussed with respect to public health knowledge mobilization.

Biological strategies for the prevention of periodontal disease: Probiotics and vaccines.

Probiotics have been considered as an adjunct to prevent and treat a variety of diseases. The ease of administration of probiotics and the fact that no adverse outcomes have been reported in the literature has promoted increasing interest from the research community for this preventive approach in a number of diseases, including periodontal diseases. Several preliminary human clinical trials have been conducted and have yielded promising results. Vaccination is another biological strategy considered for use in the prevention of periodontal diseases. To date, no vaccine trials have been conducted in humans to determine if this strategy would prevent alveolar bone loss or bacterial colonization by target pathogens. Although the available research appears promising, the current body of evidence is incomplete for both strategies. This review attempts to summarize the present status of these 2 biological strategies for the prevention of periodontal diseases.

Evidence for sustained mucosal and systemic antibody responses to SARS-CoV-2 antigens in COVID-19 patients

While the antibody response to SARS-CoV-2 has been extensively studied in blood, relatively little is known about the mucosal immune response and its relationship to systemic antibody levels. Since SARS-CoV-2 initially replicates in the upper airway, the antibody response in the oral cavity is likely an important parameter that influences the course of infection, but how it correlates to the antibody response in serum is not known. Here, we profile by enzyme linked immunosorbent assays (ELISAs) IgG, IgA and IgM responses to the SARS-CoV-2 spike protein (full length trimer) and its receptor binding domain (RBD) in serum (n=496) and saliva (n=90) of acute and convalescent patients with laboratory-diagnosed COVID-19 ranging from 3-115 days post-symptom onset (PSO), compared to negative controls. Anti-CoV-2 antibody responses were readily detected in serum and saliva, with peak IgG levels attained by 16-30 days PSO. Whereas anti-CoV-2 IgA and IgM antibodies rapidly decayed, IgG antibodies remained relatively stable up to 105 days PSO in both biofluids. In a surrogate neutralization ELISA (snELISA), neutralization activity peaks by 31-45 days PSO and slowly declines, though a clear drop is detected at the last blood draw (105-115 days PSO). Lastly, IgG, IgM and to a lesser extent IgA responses to spike and RBD in the serum positively correlated with matched saliva samples. This study confirms that systemic and mucosal humoral IgG antibodies are maintained in the majority of COVID-19 patients for at least 3 months PSO. Based on their correlation with each other, IgG responses in saliva may serve as a surrogate measure of systemic immunity. One Sentence SummaryIn this manuscript, we report evidence for sustained SARS-CoV-2-specific IgG and transient IgA and IgM responses both at the site of infection (mucosae) and systemically in COVID-19 patients over 3 months and suggest that saliva could be used as an alternative biofluid for monitoring IgG to SARS-CoV-2 spike and RBD antigens.

Epidemiological parameters of coronavirus disease 2019: a pooled analysis of publicly reported individual data of 1155 cases from seven countries

BackgroundThe outbreak of coronavirus disease 2019 (COVID-19) has been declared a pandemic by the World Health Organization, while several key epidemiological parameters of the disease remain to be clarified. This study aimed to obtain robust estimates of the incubation period, upper limit of latent period (interval between infectors exposure and infectees exposure), serial interval, time point of exposure (the day of infectees exposure to infector relative to the latters symptom onset date) and basic reproduction number (R0) of COVID-19. MethodsBetween late February and early March of 2020, the individual data of laboratory confirmed cases of COVID-19 were retrieved from 10728 publicly available reports released by the health authorities of and outside China and from 1790 publications identified in PubMed and CNKI. To be eligible, a report had to contain the data that allowed for estimation of at least one parameter. As relevant data mainly came from clustering cases, the clusters for which no evidence was available to establish transmission order were all excluded to ensure accuracy of estimates. Additionally, only the cases with an exposure period spanning 3 days or less were included in the estimation of parameters involving exposure date, and a simple method for determining exposure date was adopted to ensure the error of estimates be small (< 0.3 day). Depending on specific parameters, three or four of normal, lognormal, Weibull, and gamma distributions were fitted to the datasets and the results from appropriate models were presented. FindingsIn total, 1155 cases from China, Japan, Singapore, South Korea, Vietnam, Germany and Malaysia were included for the final analysis. The mean and standard deviation were 7.44 days and 4.39 days for incubation period, 2.52 days and 3.95 days for the upper limit of latent period, 6.70 days and 5.20 days for serial interval, and -0.19 day (i.e., 0.19 day before infectors symptom onset) and 3.32 days for time point of exposure. R0 was estimated to be 1.70 and 1.78 based on two different formulas. For 39 (6.64%) cases, the incubation periods were longer than 14 days. In 102 (43.78%) infector-infectee pairs, transmission occurred before infectors symptom onsets. In 27 (3.92%) infector-infectee pairs, infectees symptom onsets occurred before those of infectors. Stratified analysis showed that incubation period and serial interval were consistently longer for those with less severe disease and for those whose primary cases had less severe disease. Asymptomatic transmission was also observed. InterpretationThis study obtained robust estimates of several key epidemiological parameters of COVID-19. The findings support current practice of 14-day quarantine of persons with potential exposure, but also suggest that longer monitoring periods might be needed for selected groups. The estimates of serial interval, time point of exposure and latent period provide consistent evidence on pre-symptomatic transmission. This together with asymptomatic transmission and the generally longer incubation and serial interval of less severe cases suggests a high risk of long-term epidemic in the absence of appropriate control measures. FundingThis work received no funding from any source.

Modelling the coronavirus disease (COVID-19) outbreak on the Diamond Princess ship using the public surveillance data from January 20 to February 20, 2020

The novel coronavirus disease 2019 (COVID-19) outbreak on the Diamond Princess ship has caused over 634 cases as of February 20, 2020. We model the transmission process on the ship with a stochastic model and estimate the basic reproduction number at 2.2 (95%CI: 2.1-2.4). We estimate a large dispersion parameter than other coronaviruses, which implies that the virus is difficult to go extinction. The epidemic doubling time is at 4.6 days (95%CI: 3.0-9.3), and thus timely actions were crucial. The lesson learnt on the ship is generally applicable in other settings.

Preliminary estimation of the basic reproduction number of novel coronavirus (2019-nCoV) in China, from 2019 to 2020: A data-driven analysis in the early phase of the outbreak

BackgroundsAn ongoing outbreak of a novel coronavirus (2019-nCoV) pneumonia hit a major city of China, Wuhan, December 2019 and subsequently reached other provinces/regions of China and countries. We present estimates of the basic reproduction number, R0, of 2019-nCoV in the early phase of the outbreak. MethodsAccounting for the impact of the variations in disease reporting rate, we modelled the epidemic curve of 2019-nCoV cases time series, in mainland China from January 10 to January 24, 2020, through the exponential growth. With the estimated intrinsic growth rate ({gamma}), we estimated R0 by using the serial intervals (SI) of two other well-known coronavirus diseases, MERS and SARS, as approximations for the true unknown SI. FindingsThe early outbreak data largely follows the exponential growth. We estimated that the mean R0 ranges from 2.24 (95%CI: 1.96-2.55) to 3.58 (95%CI: 2.89-4.39) associated with 8-fold to 2-fold increase in the reporting rate. We demonstrated that changes in reporting rate substantially affect estimates of R0. ConclusionThe mean estimate of R0 for the 2019-nCoV ranges from 2.24 to 3.58, and significantly larger than 1. Our findings indicate the potential of 2019-nCoV to cause outbreaks.