The COVID-19 epidemic that occurred at the end of 2019 spreads rapidly to all parts of the world, putting the global public health system to a severe test. With the continuation of the epidemic, SARS-CoV-2 variants are constantly emerging. In particular, the mutation of the spike protein can cause changes in the infectivity and antigenicity of the virus, resulting in an increase in the infectivity and a decline in the protective efficacy of existing vaccines, and even the replacement of epidemic strains. This is also one of the reasons why the epidemic has not been effectively controlled so far. Nowadays, the main circulating variants have changed their characteristics to a certain extent, and the neutralization sensitivity of some variants to neutralizing monoclonal antibodies, immune sera and convalescent sera has decreased to a certain extent compared with the original strains. The emergence of variants is not only related to the characteristics of the virus itself, but also to the changes of transmission host and the chronic infection in people with deficient immunity. The emerging variants should be closely monitored, and their functional characteristics should be systematically studied so as to provide data for vaccine research and development and the designation of immunization strategies.

Objective:To analyze the neutralization properties of different genotypes and mutants of severe fever with thrombocytopenia syndrome virus (SFTSV).Methods:Pseudoviruses of SFTSV of different genotypes and mutants were constructed using VSVΔG-Fluc*G backbone. Neutralization assays were established based on the pseudoviruses. DNA vaccines for different SFTSV genotypes were prepared. Serum samples were collected from guinea pigs immunized with the DNA vaccines. Neutralizing antibodies in serum samples from immunized guinea pigs and naturally infected patients were detected using neutralization assays and analyzed.Results:The pseudoviruses of five genotypes and 43 mutants were successfully constructed and the neutralization assays based the pseudoviruses were successfully established after optimizing the reaction parameters. The dilution multiple corresponding to the inhibition rate of neutralizing antibody to half of the pseudovirus infection was taken as the titer of neutralizing antibody by the reduction in pseudovirus reporter gene. The neutralization antibody titers in naturally infected patients and immunized guinea pigs were respectively in the ranges of 1∶100-1∶43 000 and 1∶100-1∶2 500 when detected with the reference HB29 pseudovirus. The neutralization antibody titers ranged from 1∶100-1∶2 500 after immunization with different genotypes of DNA vaccines. No significant statistical difference in neutralization antibody titer was observed among different genotypes or mutant strains.Conclusions:The neutralization properties of different genotypes and mutants showed no significant change, which would be very useful for developing vaccines.

Twenty-six novel tricyclic sophoridinic and matrinic derivatives containing a common chlorinated benzene fragment were designed, synthesized and evaluated for their anti-ebolavirus (EBOV) activities. Structure-activity relationship analysis indicated: (i) 12-dichlorobenzyl motif was beneficial for the activity; (ii) the chiral configuration at C5 atom might not affect the activity much. Among the target compounds, compound exhibited the most potent potency against EBOV with an IC value of 5.29 μmol/L and an SI value of over 37.8. Further anti-EBOV assay of identified its high effectiveness, and anti-MARV assay of suggested its inspiring broad-spectrum anti-filovirus activity. The results provided powerful information on further strategic optimization and development of this kind of compounds against filoviruses.

Marburg virus (MARV) is a lethal virus that causes fatal hemorrhagic fever.It belongs to the Filoviridae family which also includes Ebola virus.MARV is similar to Ebola virus in structure and infection mechanism.Moreover,the diseases caused by them have similar clinical symptoms.However,researches on MARV are less than those on Ebola virus.In this review,we focus on the viral structure,especially the structure of MARV glycoprotein (GP) which determines its infectivity,functions of MARV GP as well as protective antibodies and vaccines against this protein.

Objective To study the in vivo expression and biodistribution of Ad5-Fluc (Adenovirus carrying firefly luciferase genes) in mice.Methods The recombinant Ad5-Fluc virus was constructed and infected to BALB/c or nude mice through three different routes.The protein expression level,tissue distribution and the characteristics of infection were analyzed by in vivo bioluminescence imaging technology.Results Compared to other two routes,the BALB/c mice infected through muscular route had the longest expression cycle (over 60 days) and the highest expression level,while the virus was transferred into the liver and spleen after infection.The nude mice had a significantly extended expression cycle than BALB/c mice.Moreover,the characteristic of liver tropism was eliminated after Ad5 F35 infection in mice,while maintained similar expression efficiency.Conclusion Due to the highest expression efficiency,the muscular route would be the optimal route for Ad5 vector based vaccination.In addition,Ad5F35 virus could become an ideal alternative vaccine vector for eliminating the liver tropism.

ObjectiveTo investigate the context-sensitive half-times of etomidate. Methods Twenty patients ( ASA Ⅰ - Ⅱ ) underwent selective thoracic operation were divided into 2 groups by random digits table with 10 cases each,the patients were allocated to receive either continuous infusion etomidate 10μg/(kg·min) for 1 h(Gl group) or continuous infusion etomidate 10 μg/(kg·min) for 2 h(G2 group) of maintenance anesthesia. The samples were collected at the following time points: 1 min before stop infusion,2,5, 10,15,20,30,40,50 and 60 min after stop infusion. The plasma concentrations of etomidate were measured by high-performance liquid chromatography and the changes of the context-sensitive half-times of etomidate were calculated. ResultsThe context-sensitive half-times of etomidate was ( 17.1 ± 13.1 )min in G1 group and (21.7 ± 15.1 ) min in G2 group. There was no significant difference between two groups (P＞0.05). ConclusionThe context-sensitive half-times of etomidate is short and its pharmacokinetic profile is suitable for continuous infusion.

Objective To evaluate the quality of four domestic and three imported fourth-generation HIV diagnostic reagents.Methods The specificity and sensitivity of these assays were analyzed when testing HIV negative samples and HIV-1 RNA positive samples.The relative seroconversion sensitivity index was analyzed when testing BBI seroconversion panels.Results The sensitivity of seven 4th-generation assays were 100％ (95％ CI:99.86％-100％ ),and one sample at the window period of HIV-1 infection were detected as positive.Of the seven assays,one imported assay exhibited the relative largeδ + value (1.0892),and the small δ+ value were found on the remaining six assays (0.0836-0.3003 ).For the samples negative for HIV antibody,varying degrees of false positives were observed on the seven assays ( specificity:97.80％ -99.60％,δ- value:-1.3803 to -0.4778).When testing the BBI seroconversion panels,the relative seroconversion sensitivity index of domestic assays were -0.500-0,however,which of imported assays were -0.600 and -0.700.Conclusion The seven reagents exhibited high sensitivity and specificity.The 4th generation HIV assays can be used as blood screening reagents to find the samples at window period of HIV-1 infection,thus indicating the certain meaning in reducing the transmission risk of HIV-1 for fourth-generation HIV diagnostic reagents.However,the better efficiency to detect HIV-1 early infection was observed on the imported assays than on the domestic assays.

Objective To pan and characterize anti-HIV-1 Fab by the phage antibody library technology. Methods Total RNA were extracted from lymphocytes which were isolated from peripheral blood collected from asymptomatic HIV-1 infected donors with high titer antibody against HIV-1. The genes of heavy chains Fd fragment and light chains of antibody were amplified by RT-PCR. The phagmids pComb3X cloned Fd and light chain genes were transformed into E. coli XL1-Blue by electroporation to construct phage Fab library. By three runs of "absorption-elution-neutralization-enrichment", the clones were induced by IPTG and characterized by ELISA. The positive clones were sequenced and analyzed the sequences. Subsequently, Fab antibodies of these positive clones were induced to expressed and purified, then the recombinant virus neutralization assay was performed. Results A phage Fab library was constructed with 8×106 members, and 11 positive clones were obtained by detecting IPTG-induced-expressing Fabs with ELISA. By analysis of the sequences, 10 light chain genes and 8 Fd genes were ensured to be obtained. Compared with the genes of anti-HIV-1 antibodies in HIV sequence database, the gene sequences we obtained were highly homologous to some patent genes of anti-HIV-1 gp120 antibodies in HIV sequence database( light chains with 60%-90% identity, Fd with 71%-85% identity); The CDRs of these positive clones were determined by comparing the positive clone genes with antibodies' genes in V base database, furthermore, CDRH3 of these positive clones has the length of 12-22 aa. Strand shift had little effect to improving affinity of our Fab clones. Fab antibodies were induced to express at the concentration of ＞ 10 mg/L. Three Fab antibodies neutralize HIV-1 virus to some extent. Conclusion The studies will provide the basis on further study on the anti-HIV-1 Fabs obtained successfully.

Objective To detect the protection induced by HPV-58 L2 11-200 AA in animal, and analyze the relationship between antibody or neutralizing antibody titers and the protection generated by the immunizmg agent. Methods The peptide of HPV-58 L2 11-200 AA was expressed in E. coli and the mice were immunized with the peptide after purification and adsorption with aluminum adjuvant. The protection provided by different immunizing doses was detected in the mouse model against the challenge of the pseud-ovirions of human papiilomavirus types 58. The total antibodies and neutralizing antibody titers of serum were tested with ELISA and neutralization assay against HPV-58 pseudovirus, respectively. The total antibodies or neutralizing antibody titers that can protect the mouse from infection were analyzed. Results The mice can be protected from the challenge with HPV pseudovirus when the immunizing dose was 8 μg. The neutralizing antibody can not be detected in the immune serum by neutralization assay against pseudovirus. The total anti-body level has a corresponding relationship with the protection showed in mouse model. The results of total antibodies detected by ELISA showed that when the titer of total antibodies was ≥25 000, luminescent signal can not be detected and the mice can be protected from pseudovirus infection. Conclusion HPV-58 L2 11-200 AA peptide can protect mice from pseudovirus infection. L2 peptide has a promising perspective to be a candidate vaccine and the level of total antibodies in the immune serum can be used as a surrogate for the evaluation of protection against HPV infection.