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@#Objective To culture human sapovirus(HuSaV) GⅠ.1 in vitro and prepare polyclonal antibody against the capsid protein VP1.Methods HuSaV GⅠ.1 positive stool specimens preserved in diarrhea department of National Institute for Viral Disease Control and Prevention were inoculated with HuTu-80 cells supplemented with different bile acid salts[glycine chenodeoxycholic acid(GCDCA) and glycine cholic acid(GCA)],and the infection,proliferation and passage of the virus were determined by PCR and RT-qPCR.The VP1 gene was amplified by PCR and cloned into prokaryotic expression vector pGEX-6P-1.The constructed recombinant expression plasmid pGEX-6P-1-VP1 was transformed into E.coli BL21(DE3) and induced by IPTG.Two female New Zealand white rabbits were immunized with the purified recombinant VP1 protein for 4 times.The blood samples were collected 18,28,38 and 48 d after immunization,and the serum titers were detected by ELISA.Results HuTu-80 cells were effectively infected by HuSaV GⅠ.1 in the presence of bile acid salt GCA,and the proliferated virus were stably and continuously transmitted for three generations in HuTu-80 cells.The expressed recom-binant GST-VP1 protein showed a relative molecular mass of about 86 000,and about 60 000 after purification(GST tag excision).The titer of polyclonal antibody against HuSaV VP1 protein was over 1:12 800.Conclusion HuSaV was successfully isolated and cultured in vitro using HuTu-80 cells supplemented with bile acid salt,and polyclonal antibody with high titer against HuSaV VP1 protein was prepared,which laid a foundation of in-depth research of HuSaV identification,infection and pathogenesis.
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Human enterovirus 71 (EV71) is one of the major causative agent of hand,foot and mouth disease (HFMD) in infant.Clinical studies find that EV71 infection can cause a variety of clinical manifestations,from mild HFMD to fatal neurogenic pulmonary edema and even death,but the reasons remain unclear.The capsid protein VP1 of EV71 plays a key role in the processes of viral recognizing,binding and entering into the targeted cells and viral particles assembling.VP1 variation is a major determinant to EV71 fitness and immunogenicity.This study reviews the research progress of the structure,functions and associated antiviral vaccines and drugs of VP1,which further provides a theoretical basis for developing new and more effective antiviral vaccine and drugs.
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Objective To establish an enterovirus 71(EV71) infection model of tree shrew primary renal cells.Methods Tree shrew primary renal cells were obtained by trypsin digestion.After subculture and purification,EV71 virus was used to infect these primary cells.The culture supernatant of these EV71-infected cells was collected for virus titer detection at 1,2,4,6 and 8 days post-infection.The cells were collected for detection of EV71 VP1 protein by Western blot assay.Furthermore,the expression and location of VP1 protein in the infected cells were detected by indirect immunofluorescence assay.Vero cells were taken as positive control to evaluate the infectivity of EV71 virus to tree shrew primary renal cells.Results Morphologically,the cultured cells were proved to be majorly consisted of the primary renal cells after subculture and purification.The obtained primary cells were infected by EV71 virus.The virus titer was up to 1.3×106 TCID 50/mL during 48-96 h post-infection,proving that EV71 virus infected and proliferated in the tree shrew primary renal cells.Western blot showed that the viral VP1 protein was detected from infected primary cells at 2 to 8 d post infection.VP1 protein was also observed in the cytoplasm at 2 to 6 d post infection by indirect immunofluorescence.Compared with Vero cells,the infectivity of EV71 virus to tree shrew primary renal cells and its proliferation were confirmed.Conclusions Based on the successful establishment of cell culture of tree shrew primary renal cells,the infectivity to the obtained cells and proliferation of EV71 virus in the cells are confirmed.The model of EV71 virus-infected tree shrew primary renal cells is initially established.
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Objective To evaluate inhibitory effects of the Chlamydiaphage phiCPG1 capsid protein Vp1 on Chlamydia psittaci strain guinea pig inclusion conjunctivitis (GPIC) and Chlamydia trachomatis (Ct) serovar E,and to provide new ideas for the treatment of Ct infection.Methods The Chlamydiaphage phiCPG1 capsid protein Vp1 was expressed in Escherichia coli BL21 transfected with the recombinant plasmid Vp1-pET30a (+),identified by Western blot analysis and purified by using dialysis bags.Bicinchonininc acid (BCA) assay was performed to determine the concentration of Vp1 protein.GPIC and Ct serovar E strains were both classified into 4 groups to be firstly incubated with Vp1 protein (Vp1 group),Tris-glycine solution (Tris group),S protein (S group) or Dulbecco's Modified Eagle Medium (DMEM,DMEM group) at room temperature for 3 hours,then were used to infect Hela cells followed by 72-hour (GPIC) or 48-hour (Ct serovar E) culture with the presence of Vp 1 protein (Vp 1 group),Tris-glycine solution (Tris group),S protein (S group) or DMEM (DMEM group).Subsequently,immunofluorescence staining was conducted to observe and count chlamydial inclusions.Results The number of GPIC inclusions was significantly different between the 4 groups after 72-hour culture (F=476.632,P＜ 0.05),and lower in the Vp1 group (5.0 ± 1.5) than in the Tris group (24 ± 1.2,P＜ 0.05),S group (25 ± 1.7,P＜ 0.05) and DMEM group (25 ± 1.5,P＜ 0.05),but insignificantly different between the latter 3 groups (P ＞ 0.05).Compared with the DMEM group,the Vp1 group showed a significant decrease of 80.2％ ± 3.99％ and 77.2％ ± 1.79％ in the number of GPIC and Ct serovar E inclusions respectively,with no significant difference in the inhibitory effect of Vp1 on GPIC versus Ct serovar E (t =2.057,P ＞ 0.05).Conclusion The phiCPG1 capsid protein Vp1 can obviously inhibit GPIC and Ct serovar E infections to a similar degree.