Treponema pallidum membrane protein Tp47 induced autophagy and inhibited cell migration in HMC3 cells via the PI3K/AKT/FOXO1 pathway.

The migratory ability of microglia facilitates their rapid transport to a site of injury to kill and remove pathogens. However, the effect of Treponema pallidum membrane proteins on microglia migration remains unclear. The effect of Tp47 on the migration ability and autophagy and related mechanisms were investigated using the human microglial clone 3 cell line. Tp47 inhibited microglia migration, the expression of autophagy-associated protein P62 decreased, the expression of Beclin-1 and LC3-II/LC3-I increased, and the autophagic flux increased in this process. Furthermore, autophagy was significantly inhibited, and microglial cell migration was significantly increased after neutralisation with an anti-Tp47 antibody. In addition, Tp47 significantly inhibited the expression of p-PI3K, p-AKT, and p-mTOR proteins, and the sequential activation of steps in the PI3K/AKT/mTOR pathways effectively prevented Tp47-induced autophagy. Moreover, Tp47 significantly inhibited the expression of p-FOXO1 protein and promoted FOXO1 nuclear translocation. Inhibition of FOXO1 effectively suppressed Tp47-induced activation of autophagy and inhibition of migration. Treponema pallidum membrane protein Tp47-induced autophagy and inhibited cell migration in HMC3 Cells via the PI3K/AKT/FOXO1 pathway. These data will contribute to understanding the mechanism by which T. pallidum escapes immune killing and clearance after invasion into the central nervous system.

Serum Ubiquitin C-Terminal Hydrolase-L1, Glial Fibrillary Acidic Protein, and Neurofilament Light Chain Are Good Entry Points and Biomarker Candidates for Neurosyphilis Diagnosis Among Patients Without Human Immunodeficiency Virus to Avoid Lumbar Puncture.

BACKGROUND: Laboratory tests to diagnose neurosyphilis using cerebrospinal fluid (CSF) are currently disadvantageous as a lumbar puncture is required, which may result in patients with neurosyphilis missing an opportunity for early diagnosis. Thus, blood biomarker candidates that are more convenient and minimally invasive to collect for diagnosing neurosyphilis is urgently needed. METHODS: This observational study aimed to analyze serum ubiquitin C-terminal hydrolase-L1 (UCH-L1), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NF-L) levels in 153 patients without human immunodeficiency virus (HIV) and to evaluate their diagnostic performance in neurosyphilis compared with CSF. RESULTS: Serum UCH-L1, GFAP, and NF-L levels were significantly higher in patients with neurosyphilis compared with patients with uncomplicated syphilis or non-syphilis. For the diagnosis of neurosyphilis, serum UCH-L1, GFAP, and NF-L revealed sensitivities of 90.20%, 80.40%, and 88.24%, and specificities of 92.16%, 78.43%, and 80.39%, respectively, at cutoff levels of 814.50 pg/mL, 442.70 pg/mL, and 45.19 pg/mL, respectively. In patients with syphilis, serum UCH-L1, GFAP, and NF-L levels correlated strongly or moderately with those in the CSF, with similar or better diagnostic performance than those in the CSF. The testing algorithms' sensitivity and specificity increased to 98.04% and 96.08%, respectively, when subjected to parallel and combination testing, respectively. CONCLUSIONS: To avoid lumbar puncture, each serum UCH-L1, GFAP, and NF-L is a good entry point and biomarker candidate for the diagnosis of neurosyphilis among patients without HIV. These proteins used in concerto can further improve the diagnostic sensitivity and specificity.

Recombinant Treponema pallidum protein Tp47 promotes the migration and adherence of THP-1 cells to human dermal vascular smooth muscle cells by inducing MCP-1 and ICAM-1 expression.

Vascular inflammation is a complex and multifactorial pathophysiological process that plays a crucial role in all stages of syphilis and is responsible for tissue damage. Little is known about the interactions of infiltrating immunocytes with human dermal vascular smooth muscle cells (HDVSMCs) in arterioles during the immunopathogenesis of syphilis. The Treponema pallidum subsp. pallidum membrane protein Tp47 is considered a major inducer of inflammation initiation and development. In this study, we demonstrated that Tp47 promoted the migration and adhesion of THP-1 cells to HDVSMCs. Furthermore, Tp47 increased monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1 (ICAM-1) mRNA and protein expression levels in a dose- and time-dependent manner. The migration and adhesion of THP-1 cells to HDVSMCs were significantly suppressed by anti-MCP-1 and anti-ICAM-1 neutralizing antibodies, respectively. Further studies revealed that treatment of HDVSMCs with Tp47 activated the PI3K/Akt, p38 MAPK and NF-κB signalling pathways. Inhibition of PI3K/Akt, p38 MAPK and NF-κB suppressed the MCP-1 and ICAM-1 expression induced by Tp47. In addition, the migration and adhesion of THP-1 cells to Tp47-treated HDVSMCs were significantly decreased by pretreatment with PI3K/Akt, p38 MAPK and NF-κB inhibitors. These findings demonstrate that Tp47 promotes the migration and adherence of THP-1 cells to HDVSMCs by inducing MCP-1 and ICAM-1 expression, which is mediated by activation of the PI3K/Akt, p38 MAPK and NF-κB pathways. This study provides a novel potential therapeutic strategy for controlling the vascular inflammatory response in syphilis patients.

Metabolic Disorders in Patients with Central Nervous System Infections: Associations with Neurosyphilis.

INTRODUCTION: Recently, neurosyphilis was found to be associated with diabetes mellitus (DM). Whether the association was specific to neurosyphilis among central nervous system (CNS) infections, and whether neurosyphilis is associated with other prevalent metabolic disorders deserves further study. METHODS: An in-depth cross-sectional study was conducted with 74 neurosyphilis patients and 74 sex- and age-matched patients with other CNS infections. DM-, hypertension-, and dyslipidemia-related factors were compared between patients with neurosyphilis and those with other CNS infections. RESULTS: The prevalence rates of hypertension and hyperlipidemia in neurosyphilis patients were 45.9 and 21.4%, respectively, which were higher than those in patients with other CNS infections (45.9 vs. 28.4%, p = 0.027; 21.4 vs. 8.3%, p = 0.028). In addition, neurosyphilis patients had significantly higher systolic blood pressure (BP; median 139 mm Hg; interquartile range [IQR] 121-151 mm Hg), -diastolic BP (median 83 mm Hg; IQR 76-89 mm Hg), total cholesterol (median 4.86 mmol/L; IQR 3.80-5.51 mmol/L), low-density lipoprotein (median 3.39 mmol/L; IQR 2.52-3.95 mmol/L), and apolipoprotein A1 (apoA1; median 1.31 g/L; IQR 1.06-1.52 g/L) levels and lower apoB/A1 ratios (median 0.67; IQR 0.49-0.99) than patients with other CNS infections (p< 0.05). There were no differences in the DM-related factors between patients with neurosyphilis and those with other CNS infections (p> 0.05). CONCLUSION: Potential association between neurosyphilis and metabolic disorders was found among CNS infections. The results could have important implications for clinical practice, alerting more clinicians to this issue.

Origin of Nontreponemal Antibodies During Treponema pallidum Infection: Evidence From a Rabbit Model.

The origin of nontreponemal antibodies during syphilis infection is hotly debated. Here, we analyzed the immune response in rabbits immunized with various antigens. Inactivated treponemes elicited the production of low-titer nontreponemal antibodies in some rabbits. Cardiolipin combined with bovine serum albumin also induced anticardiolipin antibody production. These findings indicate that Treponema pallidum contained a cardiolipin antigen with weak immunogenicity. However, active T. pallidum induced higher nontreponemal antibody production with strong immunogenicity at an earlier time point, and the antibody titer was consecutive, suggesting the high nontreponemal antibody titer resulted from the combined effects of both the T. pallidum cardiolipin antigen and the damaged host-cell cardiolipin antigen during syphilis infection, the latter of which plays a major role in the induction of nontreponemal antibody production. Our study provides direct animal evidence of the origin of nontreponemal antibodies during T. pallidum infection.

Treponema pallidum promotes macrophage polarization and activates the NLRP3 inflammasome pathway to induce interleukin-1ß production.

BACKGROUND: The involvement of inflammasome activation and macrophage polarization during the process of syphilis infection remains unknown. In this study, A series of experiments were performed using human macrophages to research the role of NLRP3 inflammasome regulation in interleukin (IL)-1ß production and its influence on macrophage polarization triggered by T. pallidum. RESULTS: The results showed that in M0 macrophages treated with T. pallidum, the M1-associated markers inducible nitric oxide synthase (iNOS), IL-1ß and TNF-α were upregulated, and the M2-associated markers CD206 and IL-10 were downregulated. In addition, we observed NLRP3 inflammasome activation and IL-1ß secretion in T. pallidum-treated macrophages, and the observed production of IL-1ß occurred in a dose- and time-dependent manner. Moreover, the secretion of IL-1ß by macrophages after T. pallidum treatment was notably reduced by anti-NLRP3 siRNA and caspase-1 inhibitor treatment. NAC, KCl, and CA074-ME treatment also suppressed IL-1ß release from T. pallidum-treated macrophages. CONCLUSIONS: These findings showed that T. pallidum induces M0 macrophages to undergo M1 macrophage polarization and elevate IL-1ß secretion through NLRP3. Moreover, the process of NLRP3 inflammasome activation and IL-1ß production in macrophages in response to T. pallidum infection involves K+ efflux, mitochondrial ROS production and cathepsin release. This study provides a new insight into the innate immune response to T. pallidum infection.

Assessing effects of different processing procedures on the yield of Treponema pallidum DNA from blood.

In this work, we employed real-time PCR analysis targeting tp0574 to investigate the effects of different processing procedures on the yield of T. pallidum DNA from blood to improve assay sensitivity. The T. pallidum DNA yields following red blood cell lysis pretreatment were 40.4 times greater from whole blood and 32.4 times greater from residual hematocytes than yields without pretreatment. For the simulated whole-blood experiments, the T. pallidum DNA yields from the lower layer were 2.8, 4.6, 7.3, 12.6, 15.24, 16.7, 65.1 and 73.1 times those from the upper layer following centrifugation at 500×, 1000×, 2000×, 4000×, 5000×, 7000×, 10,000× and 20,000 × g, respectively. However, the T. pallidum DNA yields from blood clots were only 1.0% at different centrifugal forces. The experiment with infected rabbit blood showed results similar to those mentioned above. In addition, sample processing time (within 48 h) and storage temperature (4 °C and 25 °C) did not affect T. pallidum DNA extraction efficiency. The T. pallidum DNA yield can be significantly improved by red blood cell lysis pretreatment and appropriate centrifugation. Furthermore, the T. pallidum DNA extraction yield is greater from whole blood or residual hematocytes from anti-coagulated blood than from plasma, serum or blood clots.

Correlation between polymorphisms in toll-like receptor genes and the activity of hepatitis B virus among treatment-naïve patients: a case-control study in a Han Chinese population.

BACKGROUND: Because of the high prevalence and absence of cure for infection, chronic hepatitis B virus (HBV) infection has been acknowledged as a pressing public health issue. Toll-like receptors (TLRs) activate the human innate immune system and the polymorphisms in TLRs may alter their function. The present study aimed to investigate the association between TLR polymorphisms and disease progression of chronic HBV infection. METHODS: During the study period, 211 treatment-naïve patients with chronic HBV infection were recruited, and blood samples were collected from each individual. Matrix-assisted laser desorption/ionization time of flight mass spectrometry was employed to genotype the selected TLR polymorphisms after human genome extraction. In addition, HbsAg, TNF-α, and IL-6 levels were quantified using enzyme linked immunosorbent assay (ELISA). Statistical analyses were conducted to investigate the association between TLR polymorphisms and hepatitis activity, liver function parameters, HbsAg level, and cytokine level. RESULTS: We did not observe any mutations in rs4986790, rs4986791, and rs5743708 among all study subjects. A logistic regression revealed that mutations in rs3804099 and rs4696480 were associated with milder hepatitis activity. Consistent with the logistic regression, improved liver function parameters and reduced level of both HbsAg and cytokines were also correlated with the mutant carriers of rs3804099 and rs4696480. CONCLUSIONS: TLR mutations were significantly associated with milder hepatitis activity among patients with chronic HBV infection. Therefore, we conclude that the activation of TLR pathways may further intensify the inflammation of hepatocytes, and leads to progression of disease.

Novel predictors of neurosyphilis among HIV-negative syphilis patients with neurological symptoms: an observational study.

BACKGROUND: Known predictors of neurosyphilis were mainly drawn from human immunodeficiency virus (HIV)-infected syphilis patients, which may not be applicable to HIV-negative populations as they have different characteristics, particularly those with neurological symptoms. This study aimed to identify novel predictors of HIV-negative symptomatic neurosyphilis (S-NS). METHODS: From June 2005 to June 2015, 370 HIV-negative syphilis patients with neurological symptoms were recruited, consisting of 191 S-NS patients (including 123 confirmed neurosyphilis and 68 probable neurosyphilis patients) and 179 syphilis/non-neurosyphilis (N-NS) patients. Clinical and laboratory characteristics of S-NS were compared with N-NS to identify factors predictive of S-NS. Serum rapid plasma reagin (RPR), Treponema pallidum particle agglutination (TPPA), and their parallel testing format for screening S-NS were evaluated. RESULTS: The likelihood of S-NS was positively associated with the serum RPR and TPPA titers. The serum TPPA titers performed better than the serum RPR titers in screening S-NS. The optimal cut-off points to recognize S-NS were serum RPR titer ≥1:4 and serum TPPA titer ≥1:2560 respectively. A parallel testing format of a serum RPR titer ≥1:2 and serum TPPA titer ≥1:1280 screened out 95.8% of S-NS and all confirmed cases of neurosyphilis. S-NS was independently associated with male sex, serum RPR titer ≥1:4, serum TPPA titer ≥1:2560, and elevated serum creatine kinase. Concurrence of these factors increased the likelihood of S-NS. CONCLUSIONS: Quantitation of serum TPPA is worthwhile and performs better than serum RPR in screening S-NS. Serum RPR, serum TPPA, male sex, and serum creatine kinase can predict S-NS. Moreover, patients with both a serum RPR titer <1:2 and a serum TPPA titer <1:1280 have a low probability of S-NS, suggesting that it is reasonable to reduce lumbar punctures in such individuals.

Evaluation of the boson chemiluminescence immunoassay as a first-line screening test in the ECDC algorithm for syphilis serodiagnosis in a population with a high prevalence of syphilis.

We developed a new Boson chemiluminescence immunoassay (CIA) and evaluated its application with cross-sectional analyses. Our results indicated that the Boson CIA demonstrated strong discriminatory power in diagnosing syphilis and that it can be used as a first-line screening test for syphilis serodiagnosis using the European Centre for Disease Prevention and Control algorithm or as a confirmatory test when combined with a patient's clinical history.

A survey of five broad-host-range plasmids in gram-negative bacilli isolated from patients.

OBJECTIVES: To learn the prevalence of the primary classical broad-host-range (BHR) IncA/C, IncN, IncP, IncQ, and IncW plasmids in dominant gram-negative bacilli from inpatients in a teaching hospital in southern China. METHODS: A multiplex polymerase chain reaction based on the replicons of BHR IncA/C, IncN, IncP, IncQ, and IncW plasmids was developed and used to determine these BHR plasmids. The difference in prevalence rates among the different species from three specimens was evaluated by a binary logistic regression model and the differences between multidrug-resistant organisms (MDRO) and non-MDRO were assessed using a chi-square test. RESULTS: The average positive detection percentages of the replicons were 4.3%, 3.7%, 3.0%, 2.6%, and 1.9%, respectively, for IncN, IncP, IncQ, IncW, and IncA/C in descending order. The distribution of all five BHR plasmids did not differ significantly between specimens collected from wounds and urine, although both were significantly higher than those of sputum. The prevalence rates of all five BHR plasmids in MDROs were significantly higher than those in non-MDRO for Enterobacteriaceae; however, no significant difference was seen in non-fermenting gram-negative bacilli (NFGNB). CONCLUSIONS: BHR IncA/C, IncN, IncP, IncQ, and IncW plasmids, which occur more often in bacilli from wound and urine specimens than those of sputum, are widespread in Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter cloacae, Pseudomonas aeruginosa, and Acinetobacter baumannii strains isolated from inpatients. The prevalence rates in MDRO are higher than those in non-MDRO for Enterobacteriaceae but not significantly different for NFGNB.

Red Blood Cell Lysis Pretreatment Can Significantly Improve the Yield of Treponema pallidum DNA from Blood.

PCR can be a supplement to Treponema serological testing. However, its sensitivity is not satisfactory for blood sample testing. The aim of this study was to investigate whether pretreatment with red blood cell (RBC) lysis could enhance the yield of Treponema pallidum subsp. pallidum DNA extraction from blood. We developed and verified the efficacy of a quantitative PCR (qPCR) assay that utilizes TaqMan technology to specifically detect T. pallidum DNA by targeting the polA gene. Simulation media with 106 to 100 treponemes/mL were prepared in normal saline (NS), whole blood, plasma, and serum, and RBC lysis pretreatment was performed on a portion of whole blood. Then, blood samples drawn from 50 syphilitic rabbits were divided in parallel into five groups, labeled whole blood, whole blood/lysed RBCs, plasma, serum, and blood cells/lysed RBCs. DNA extraction and qPCR detection were performed. The detection rate and copy number were compared among different groups. The polA assay showed good linearity and an excellent amplification efficiency of 102%. In the simulated blood samples, the detection limit of the polA assay reached 1 × 102 treponemes/mL in whole blood/lysed RBCs, plasma, and serum. However, the detection limit was only 1 × 104 treponemes/mL in NS and whole blood. Among the blood samples from syphilitic rabbits, whole blood/lysed RBCs showed the best detection rate (82.0%), while the detection rate for whole blood was only 6%. The copy number of whole blood/lysed RBCs was higher than that of whole blood. RBC lysis pretreatment can significantly improve the yield of T. pallidum DNA from whole blood, and the yield is better than that from whole blood, plasma, serum, and blood cells/lysed RBCs. IMPORTANCE Syphilis is a sexually transmitted disease caused by T. pallidum that can spread into the blood. T. pallidum DNA can be detected in blood by PCR but with low sensitivity. Few studies have applied RBC lysis pretreatment to blood T. pallidum DNA extraction. This study shows that the detection limit, detection rate, and copy number of whole blood/lysed RBCs were better than those of whole blood, plasma, and serum. After RBC lysis pretreatment, the yield of low concentrations of T. pallidum DNA was improved, and the low sensitivity of blood-based T. pallidum PCR was improved. Therefore, whole blood/lysed RBCs are the ideal sample for acquiring blood T. pallidum DNA.

Membrane location of cardiolipin antigen in Treponema pallidum: further study on the origin of nontreponemal antibodies.

Aim: The present study examined the membrane location of cardiolipin antigen in treponemes. Materials & methods: The authors used different methods to disrupt the outer membrane of treponemes, detected the location of the cardiolipin antigen and analyzed the immune response in rabbits immunized with various antigens. Results: All organisms were labeled with nontreponemal antibodies on immunoelectron and fluorescence microscopy, except the citrate buffer-treated group, which is a method leading to relatively complete removal. Except for citrate buffer-treated spirochetes, all treponemes produced low-titer, nontreponemal antibodies in immunized rabbits. Conclusion: These findings indicated that the cardiolipin antigen was localized in the outer membrane of spirochetes. This study provided further evidence of the origin of nontreponemal antibodies during Treponema pallidum infection.

Evaluation of the efficacy of four anti-SARS-CoV-2 antibodies after vaccination using kits from two manufacturers: A prospective, longitudinal, cohort study at 11 serial time points within 160 days.

PURPOSE: The accuracy of level of anti- severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies is a great concern. We aimed to compare the efficacy of anti-SARS-CoV-2 antibody detection kits from two manufacturers in evaluating the efficacy of SARS-CoV-2 vaccines. METHODS: The immune responses and consistency of four anti-SARS-CoV-2 antibodies were evaluated using two manufacturers' antibody kits (A and B) in 61 subjects within 160 days after vaccination with the CoronaVac vaccine. RESULTS: The total seropositivity rates of neutralizing antibodies and IgM antibodies detected by kit A were higher than those detected by kit B (P = 0.003 and P < 0.001, respectively). Conversely, the total seropositivity rates of total antibodies and IgG antibodies were higher in kit B than kit A (P < 0.001 and P < 0.001, respectively). The consistency rates showed less than 90% agreement between the kits for the detection of the four antibodies, and the κ score showed moderate or substantial consistency. The half-lives of neutralizing antibodies, total antibodies, and IgG antibodies within 160 days after vaccination, detected by kit A were 63.88 days, 80.50 days, and 63.70 days, respectively and by kit B were 97.06 days, 65.41 days, and 77.99 days, respectively. CONCLUSION: The efficacy of antibody detection differed between the two commercial anti-SARS-CoV-2 antibody kits, although there was moderate consistency, which may affect the clinical application and formulation of the vaccine strategy.

Treponema pallidum protein Tp0136 promoting MMPs/TIMPs imbalance via PI3K, MAPK and NF-κB signalling pathways in HDVSMCs.

The invasive capability of Treponema. pallidum is central to its infection process. Matrix metalloproteinases (MMPs), which are specifically inhibited by the tissue inhibitors of metalloproteinases (TIMPs), play a pivotal role in promoting pathogenic invasion by destroying tissue barriers within the body. This study aimed to explore the effect of T. pallidum protein Tp0136 on the balance of MMPs/TIMPs in human dermal vascular smooth muscle cells (HDVSMCs) and the related underlying mechanisms. A number of in vitro studies were conducted to access the impact of recombinant Tp0136 protein on the balance of MMPs/TIMPs in HDVSMCs. The involvement of the PI3K, MAPK, and NF-κB signaling pathways in this process was also investigated. Tp0136 induced the mRNA and protein expressions of MMP1 in HDVSMCs in a concentration-dependent way. In addition, MMP1/TIMP1 and MMP1/TIMP2 ratios were also increased. Furthermore, the study demonstrated that treatment of HDVSMCs with Tp0136 activated the PI3K, MAPK, and NF-κB signaling pathways. Inhibition of PI3K, JNK, P38, and NF-κB, suppressed MMP1 expression and reduced the induction of MMP1/TIMP1 and MMP1/TIMP2 ratios by Tp0136. These findings demonstrate that Tp0136 enhanced the expression of MMP1 involving the PI3K, MAPK, and NF-κB signaling pathways in HDVSMCs, and thus generated the unbalance of MMPs/TIMP, which could contribute to the early spread of T. pallidum and pathogenesis of syphilis.

A 14+7 day quarantine period and a dual nucleic acid testing reagent strategy detect potentially indiscoverable Coronavirus disease 2019 infections in Xiamen, China.

BACKGROUND: Determining what quarantine period and detection strategy are more effective and sustainable remains a challenge for further prevention and social stability. METHODS: From October 2020 to December 2021, 290,547 inbound overseas travelers were subject to government quarantine in Xiamen, China. The detection rate of COVID-19 during different quarantine periods using dual or single nucleic acid testing reagents. RESULTS: The COVID-19 positive rate was 1.79% (519/290,547). The detection rates during the 7-day, 14-day and 14+7-day quarantine periods using the dual reagents were 78.4%, 91.7%, and 100%, respectively. The detection rate of the 7-day, 14-day and 14+7-day quarantine periods were 73.99%, 86.51%, and 94.22%, respectively, using the Liferiver reagent and 72.25%, 84.59%, and 91.91%, respectively, using the Daan reagent. Based on the 14+7 day strategy, dual nucleic acid testing reagent strategy detected all imported cases, but 30 cases (5.78%) were not detected via Liferiver reagent and 42 (8.09%) cases not detected via Daan reagent. CONCLUSION: A 14+7-day quarantine period and dual nucleic acid testing reagent strategy are effective screening methods for COVID-19 among inbound overseas travelers. The superior detection rate of these strategies reduce the risk of secondary transmission of the SARS-CoV-2 virus.

Anti-Receptor-Binding Domain Immunoglobulin G Antibody as a Predictor of Seropositivity for Anti-SARS-CoV-2 Neutralizing Antibody.

CONTEXT.­: Neutralizing antibody detection can assess the incidence of COVID-19 and the effectiveness of vaccines. However, commercial reagents for neutralizing antibodies were developed after the anti-SARS-CoV-2 immunoglobulin (Ig) G and IgM antibodies. Therefore, some laboratories did not perform neutralizing antibody testing services because of multiple factors. OBJECTIVE.­: To find a fast, accurate, and economic alternative for the detection of neutralizing antibodies for the development of COVID-19 screening programs. DESIGN.­: The response and correlation of 3 antibodies (anti-spike protein neutralizing antibody, total anti-receptor-binding domain [RBD] antibody, and anti-RBD IgG) were determined by observing the dynamics in 61 participants for 160 days after vaccination. RESULTS.­: The levels of neutralizing and anti-RBD IgG antibodies reached their peak values on day 42 after vaccination (120.75 IU/mL and 14.38 signal-to-cutoff ratio [S/CO], respectively). The total antibody levels peaked at 138.47 S/CO on day 35 after vaccination. The strongest correlation was found between neutralizing and anti-RBD IgG antibody levels (r = 0.894, P < .001). The area under the receiver operating characteristic curve for total antibody levels for the prediction of seropositivity for neutralizing antibodies was 0.881 (P < .001), and that for anti-RBD IgG antibody levels was 0.937 (P < .001). CONCLUSIONS.­: Neutralizing and anti-RBD IgG antibody levels were strongly correlated, and thus anti-RBD IgG antibody levels can be used for the accurate assessment of immunity following SARS-CoV-2 infection or vaccination.

[Analyzing the mutations of rpoB gene in Mycobacterium tuberculosis clinical isolates by probe melting analysis assay].

OBJECTIVE: To evaluate the clinical performance of a probe melting analysis (PMA)-based real-time PCR detection kit in rapid detection of rifampin-resistant mutations in Mycobacterium tuberculosis (MTB). METHODS: The specificity of the assay was evaluated by detecting 37 non-tuberculous mycobacteria (NTM), and the detection limit of the method was evaluated by genomic DNA of a standard strain H37Rv. Finally, 962 clinical isolates were analyzed with the PMA assay by detecting mutations in rifampin resistance-determining region (RRDR) of rpoB gene, and results were verified with DNA sequencing. RESULTS: Among 37 NTM strains, three strains showed drug resistant mutation signals. The PMA method could detect down to 30 bacteria per reaction. Sample analysis showed that 186 of 962 isolates were mutants, 751 isolates were wild type and 25 isolates failed to give amplification signals. Among the mutant samples detected, 112 samples from November 2009 to April 2010 were further analyzed by sequencing, as well as 200 wild-type samples. The results showed a complete agreement with the PMA assay except for 5 samples failed in sequence analysis. CONCLUSION: The PMA assay is rapid, accurate and easy-to-use, and thus can be used for detection of rifampin-resistant in clinical isolate samples.