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COVID-19 is caused by a novel coronavirus-severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), which has being spreading around the world, posing a serious threat to human health and lives. Neutralizing antibodies and small molecule inhibitors for virus replication cycle are the main antiviral treatment for novel coronavirus recommended in China. To further promote the rational use of antiviral therapy in clinical practice, the National Center for Infectious Diseases (Beijing Ditan Hospital Capital Medical University and the First Affiliated Hospital, Zhejiang University School of Medicine) invited experts in fields of infectious diseases, respiratory and intensive care to develop an Expert Consensus on Antiviral Therapy of COVID-19 based on the Diagnosis and Treatment Guideline for COVID-19 ( trial version 10) and experiences in the diagnosis and treatment of COVID-19 in China. The consensus is concise, practical and highly operable, hopefully it would improve the understanding of antiviral therapy for clinicians and provide suggestions for standardized medication in treatment of COVID-19.
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Objective:To investigate the expression levels of interferon-α receptor (IFNAR), interferon-stimulated gene factor 3(ISGF3), double-stranded RNA-activated protein kinase(PKR) and ribonuclease L (RNase L) in patients with chronic hepatitis B (CHB) treated with interferon.Methods:From July 2014 to June 2017, 41 treatment naive CHB patients were enrolled in the Department of Infectious Diseases, First Affiliated Hospital of Nanchang University. Eighteen patients were treated with polyethylene glycol interferon α-2b, and 23 patients were treated with conventional interferon. The mRNA and protein expression levels of IFNAR1, IFNAR2, ISGF3, PKR and RNase L in peripheral blood mononuclear cells (PBMC) were detected by reverse transcription polymerase chain reaction and Western blot, respectively. The differences of these molecular expression levels in PBMC between the effective and ineffective groups were compared. The data were analyzed by t test. Results:After 24 weeks of treatment, 25 cases were effective, while 16 cases were ineffective. At four weeks of treatment, the mRNA expression levels of IFNAR1, IFNAR2 and PKR in PBMC of the effective group were 0.748±0.129, 1.169±0.125 and 1.047±0.091, respectively, which were all higher than those in the ineffective group (0.591±0.021, 0.689±0.059 and 0.791±0.033, respectively). The differences were statistically significant ( t=-4.304, 16.482 and -5.346, respectively, all P<0.01). The mRNA expressions of ISGF3 and RNase L in PBMC of the effective group were 0.739±0.159 and 0.780±0.140, respectively, while those in the ineffective group were 0.690±0.035 and 0.733±0.122, respectively, which were not significantly different ( t=-0.160 and -1.443, respectively, both P>0.05). The mRNA expression levels of IFNAR1, IFNAR2, ISGF3, PKR and RNase L at baseline, week eight, 12 and 24 of treatment in the effective group were all higher than those in the ineffective group (all P<0.01). The protein expression levels of IFNAR1, IFNAR2, ISGF3, PKR and RNase L in the effective group were all higher than those in the ineffective group (all P<0.01). Conclusion:After interferon treatment, the mRNA and protein expression levels of IFNAR1, IFNAR2, ISGF3, PKR and RNase L in PBMC of CHB patients are all increased, especially IFNAR2 and PKR levels increase in the early stage of treatment (four weeks).
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Objective To investigate the antimicrobial resistant mechanisms of high level carbapenem resistant Klebsiella pneumoniae infection of burn patients .Methods A retrospective study was conducted on totally 18 non-repetitive high level CR-KP which were isolated from burn patients hospitalized between July 2014 and June 2015.MIC of antibiotics were determined by using the GN 13 cards and agar dilution method.The specific PCR and DNA sequence analysis were performed to confirm the β-lactamase type.Plasmid conjugation transfer experiments and southem hybridization were applied to study the mode of carbapenem resistance transmission .Outer membrane proteins ( Omps) were isolated and examined by PCR and ( sodium dodecyl sulfate polyacrylamide gel electrophores ) SDS-PAGE.Pulsed-field gel electrophoresis( PFGE ) and Multilocus sequence typing ( MLST ) was used to determine the genotypes . Results Susceptibility of antimicrobial agents indicated that all these strains with multiple drug resistance . The resistance rate to piperacillin/tazobactam, ceftriaxone, levofloxacin, ciprofloxacin, gentamicin, tobramycin, cefotetan, ceftazidime, cefepime, aztreonam, imipenem, and meropenem was 100％ (18/18).Moreover, the resistance rate of CR-KP isolates to amikacin was 72.2％ ( 13/18 ) , compound sulfamethoxazole was 61.1％(11/18), tigecycline was 0％(0/18).Conjugation study with Escherictda coli J53 resulted in the transfer of significant reduced carbapenem susceptibility from donors (MICs increased at least 8-fold).By PCR, eighteen strains of Klebsiella pneumoniae carried NDM-1 gene, 5 strains carried KPC-2 gene.The blaNDM-1 was transferable by plasmids.Southern blot hybridization indicated that the blaNDM-1 gene was located on plasmid in size of 46 kb.The plasmid belonged to incompatibility group IncX 3.Seven types of CR-KP were detected by PFGE.In addition, MLST assigned them to sequence type ( ST)11, ST395, ST17, ST37, ST263, ST14 and ST76 types.SDS-PAGE and ompK35/36 genes sequence analysis of Omp indicated that there was absence of outer membrane proteins OmpK 36 in ST11, ST395, ST37 strains.However, the other STs strains expressed lower quantities of OmpK 36.Conclusions High level carbapenem resistance in K.pneumoniae causing infection in burn patients is attributable to production of plasmid-mediated metallo· β-laetamase NDM-1 combined with porin OmpK36 deficiency or low expression .The K.pneumoniae with NDM-1 and KPC-2 carbapenemase were detected .
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Objective To investigate the capsular polysaccharide (CPS) serotypes and molecular characteristics of carbapenem resistant hypermucoviscous Klebsiella pneumoniae (CR-HMKP) and study the possible mechanism of carbapenem resistance. Methods A retrospective study was conducted on 18 nonduplicate CR-HMKP strains which were collected from the First Affiliated Hospital of Nanchang University from 2012 to 2016. The clinical data were retrieved from medical records. The capsular serotypes, resistance genes and virulence factors were detected by polymerase chain reaction and DNA sequencing. Antimicrobial susceptibility testing was determined on VITEK 2 compact system. The CR-HMKP strains were characterized molecularly by using PCR, multilocus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE). Modified carbapenem inactivation method was used to screen carbapenemase-producing strains. Plasmid conjugation transfer experiments were carried out to study transmission of carbapenem resistance. Results Eighteen (2.7％) CR-HMKP isolates were identified, which belonged to 4 serotypes, including wzi128-K1 (n=1), wzi206-K57 (n=1), wzi2-K2 (n=2), and wzi64-K14.64 (n=14). PCR and sequencing analysis identified blaNDM-1 gene in 2 CR-HMKP strains, blaKPC-2 gene in 17 strains, qnrS1 gene in 18 strains, blaCTX-M-3 gene in 3 strains, blaCTX-M-14 gene in 18 strains, blaTEM-1 gene in 16 strains, blaSHV-12 gene in 17 strains, and rmtB in 5 strains. All the 18 CR-HMKP strains carried virulence-associated genes, including rmpA (88.9％, 16/18), magA (5.6％, 1/18), iroN (83.3％, 15/18), aerobactin (27.8％, 5/18), rmpA2 (66.7％, 12/18) and mrkD (100％, 18/18). Three sequence types (STs) were identified by MLST, including ST11 (15 strains), ST86 (2 strains), and ST412 (1 strain). PFGE resulted in three major PFGE clusters, of which cluster A corresponds to ST1 isolates, and cluster B corresponds to ST86 isolates, and cluster C corresponds to ST412 isolates. All the blaKPC-2- positive strains belonged to ST11. Plasmid conjugation was successful in 5 (27.8％) of the 18 CR-HMKP isolates. Conclusions wzi64-K14.64 is the predominant capsule serotype of the CR-HMKP strains in this hospital. KPC-2 gene conjugationmay contribute to the emergence of CR-HMKP isolates. In addition, CRHMKP strain may be the highly prevalent ST11, and highly virulent CPS serotypes harboring K1/K2.
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Objective To obtain the antigen and antibody of JC virus(JCV)VP2.Methods The JCV VP2 gene were amplified from a cerebrospinal fluid sample by polymerase chain reaction (PCR)and confirmed by sequencing.Then,the gene was cloned into plasmid pET32a(+)to construct recombinant prokaryotic expression vector pET-32a(+)-VP2.The recombinant plasmid was transformed into the competent E.coli BL21.Induced with isopropyl-β-D-1-1 thiogalactopyranoside (IPTG),E.coli BL21 were subsequently crushed by ultrasound.The gene expression in the supernatant was analyzed by Western blot.Thereafter,the expressed protein was purified by isoeleetric point method.The polyclonal antibody against JCV VP2 protein was obtained from the BALB/c mouse immunized with the purified protein.Results The VP2 fusion protein was expressed in the E.coli BL21.The recombinant fusion protein was expressed by IPTG induetion with relative molecular mass of 58.5×10~3.Sodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDSPAGE)analysis showed that the expression level was highter after 6-10 h of IPTG induction.The recombinant protein had good antigenicity which was confirmed by BALB/c mice immunized with the protein.Conclusions The successful expression and purification of VP2 fusion protein and the antibody will be valuable for the study on the biological function of VP2 and JCV epidemiologieal investigation.
