Effects of HPV Pseudotype Virus in Cutting E6 Gene Selectively in SiHa Cells

The objectives of this study were to investigate the effects of the CRISPR/Cas9 system mediated by the HPV pseudotype virus on SiHa cytobiology behavior by cutting the HPV16 E6 gene selectively and to explore the role of this system in the treatment of cervical cancer. After designing specific gRNA sequences targeting HPV 16 E6, generating hCas9-EGFP and E6-gRNA-RFP plasmids, and preparing the pseudovirus of HPV16 carrying E6-gRNA and Cas9 plasmids, we determined the titer of the pseudotype virus using the TCID50 method. We obtained the pseudotype virus of HPV16 carrying E6-gRNA and Cas9 plasmids to transfect cervical cancer SiHa cells. Experimental subjects were divided into control group, empty virus group, E6-gRNA transfected group, Cas9 transfected group and Cas9＋E6-gRNA transfected group. The molecular size of the cutting sequence was detected using the T7E1 enzyme digestion method and agarose gel electrophoresis, and the cleavage function of CRISPR/Cas9 on the E6 gene was determined at the same time. RT-PCR and Western blotting were performed to detect the mRNA and protein expression levels of E6 in all the groups; the Transwell cell migration assay was performed to detect the cell migration ability and metastasis in all groups. Heterotopic transplantation tumors were incorporated into mice and were used to investigate the effects of the CRISPR/Cas9 system mediated by the HPV pseudovirus on the tumorigenic ability of SiHa cells by selectively cutting HPV16 E6. The HPV16 pseudotype virus carrying E6-gRNA and Cas9 plasmids could successfully infect SiHa cells, and there were two cutting zones in the Cas9＋E6- gRNA transfected group. However, the empty virus group, E6-gRNA transfected group and Cas9 transfected group had no corresponding zone. Compared with those in the control group, the empty virus group, E6-gRNA transfected group and Cas9 transfected group, the mRNA and protein expression levels of E6 in SiHa cells were downregulated in the Cas9＋E6-gRNA transfected group （P〈0.01）. In addition, the proliferation and migration abilities of SiHa cells were significantly inhibited （P〈0.01）. There were no significant differences among the other groups. In contrast to the control group, the HPV pseudotype virus carrying E6-gRNA and Cas9 plasmids could significantly delay the growth of tumor cells of the ectopic tumor transplantation model （P〈0.01）. The CRISPR/Cas9 system mediated by the HPV pseudotype virus to knockout E6 gene expression exhibited a clear inhibitory effect on the biological function of SiHa cells, which indicated that knocking out the E6 gene using the CRISPR/Cas9 system mediated by the HPV pseudotype virus had a potential effect of eliminating HPV infection and inhibiting the growth of HPV-related tumors. Taken together, these findings provide insight into a new treatment strategy for the prevention and treatment of hr-HPV infected disease, particularly in HPV-related tumors.

Enhanced Protective Efficacy of H5 Subtype Influenza Vaccine with Modification of the Multibasic Cleavage Site of Hemagglutinin in Retroviral Pseudotypes

Traditionally, the multibasic cleavage site （MBCS） of surface protein H5-hemagglutinin （HA） is converted to a monobasic one so as to weaken the virulence of recombinant H5N1 influenza viruses and to produce inactivated and live attenuated vaccines. Whether such modification benefits new candidate vaccines has not been adequately investigated. We previously used retroviral vectors to generate wtH5N1 pseudotypes containing the wild-type HA （wtH5） from A/swine/Anhui/ca/2004 （H5N1） virus. Here, we generated mtH5N1 pseudotypes, which contained a mutant-type HA （mtH5） with a modified monobasic cleavage site. Groups of mice were subcutaneously injected with the two types of influenza pseudotypes. Compared to the group immunized with wtH5N1 pseudotypes, the inoculation of mtH5N1 pseudotypes induced significantly higher levels of HA specific IgG and IFN-y in immunized mice, and enhanced protection against the challenge of mouse-adapted avian influenza virus A/Chicken/Henardl2/2004 （H5N1）. This study suggests modification of the H5-hemagglutinin MBCS in retroviral pseudotypes enhances protection efficacy in mice and this information may be helpful for development of vaccines from mammalian cells to fight against H5N 1 influenza viruses.

Pseudotyped lentiviral vectors:Ready for translation into targeted cancer gene therapy?

Gene therapy holds great promise for curing cancer by editing the deleterious genes of tumor cells,but the lack of vector systems for efficient delivery of genetic material into specific tumor sites in vivo has limited its full therapeutic potential in cancer gene therapy.Over the past two decades,increasing studies have shown that lentiviral vectors(LVs)modified with different glycoproteins from a donating virus,a process referred to as pseudotyping,have altered tropism and display cell-type specificity in transduction,leading to selective tumor cell killing.This feature of LVs together with their ability to enable high efficient gene delivery in dividing and non-dividing mammalian cells in vivo make them to be attractive tools in future cancer gene therapy.This review is intended to summarize the status quo of some typical pseudotypings of LVs and their applications in basic anti-cancer studies across many malignancies.The opportunities of translating pseudotyped LVs into clinic use in cancer therapy have also been discussed.

Efficient transfer and expression of human clotting factor IX cDNA in neonatal hemophilia B mice mediated by VSV-G pseudotyped retrovi-rus

The feasibility of in vivo gene therapy for hemophilia B by VSV-G pseudotyped retroviral vector was introduced. The novel packaging cell line 293GPG was used to produce VSV-G/G1NaBAIX pseudotyped virus with the highest liters up to 8.5×108cfu .mL-1. In contrast to the conventional retrovirus, VSV-G pseudotyped virus was more resistant to inactivation by serum complements (P【0.001). Our results also demonstrated that VSV-G pseudotyped virus was more stable in neonatal mice serum than in adult mice serum (P【0.01). After intraperitoneal injection of different doses of virus, hFIX antigen was detected and lasted for more than 120 d, the highest level reached (72.5+6.1) ng- mL11. Moreover, the functional activity was improved to some extent in all hFIX-treated mice, the most remarkable improvement was observed in the mice treated with higher dose of virus whose clotting activity increased to (3.4±1.5)% and APTT (activated partial thromboplastin time) reduced to (43.2±7.2) s. The anti-hFIX antibody was

Development and effectiveness of pseudotyped SARS-CoV-2 system as determined by neutralizing efficiency and entry inhibition test in vitro

With the development of the COVID-19 epidemic,there is an urgent need to establish a system for determining the effectiveness and neutralizing activity of vaccine candidates in biosafety level 2(BSL-2)facilities.Previously,researchers had developed a pseudotyped virus systemfor SARS-CoV andMERS-CoV,based onHIV-1 core,bearing virus spike protein.During the development of a pseudotyped SARS-CoV-2 system,a eukaryotic expression plasmid expressing SARSCoV-2 spike(S)protein was constructed and then co-transfectedwith HIV-1 based plasmid which containing the firefly luciferase reporter gene,into HEK293T cells to prepare the pseudotyped SARS-CoV-2 virus(ppSARS-2).We have successfully established the pseudotyped SARS-CoV-2 system for neutralization and entry inhibition assays.Huh7.5 cell line was found to be the most susceptible to our pseudotyped virus model.Different levels of neutralizing antibodies were detected in convalescent serum samples of COVID-19 patients using ppSARS-2.The recombinant,soluble,angiotensin-converting enzyme 2 protein was found to inhibit the entry of ppSARS-2 in Huh7.5 cells effectively.Furthermore,the neutralization results for ppSARS-2 were consistent with those of live SARS-CoV-2 and determined using the serum samples fromconvalescent patients.In conclusion,we have developed an easily accessible and reliable tool for studying the neutralizing efficiency of antibodies against SARS-CoV-2 and the entry process of the virus in a BSL-2 laboratory.

HearNPV Pseudotyped with PIF1,2,and 3 from MabrNPV：Infectivity and Complex Stability

Effective oral infection is set off by interaction of a group of conserved per os infectivity factors(PIFs) with larval midgut columnar epithelial cells. We constructed pseudotyped viruses by substituting pif1, pif2 or pif3 genes of Helicoverpa armigera nucleopolyhedrovirus(Hear NPV) with their homologs from Mamestra bracissae multiple nucleopolyhedrovirus and tested their infectivity to tissue culture cells and to larvae. Transfection and infection assays revealed that all recombinant viruses generated infectious budded virus in both cell culture and in larvae. Electron microscopy showed synthesized occlusion body and occlusion derived virus(ODV) were morphologically indistinguishable from those of the parental virus. By contrast, feeding assays revealed that pseudotyped viruses could not rescue oral infectivity except for pif3 pseudotyped virus that only partially rescued oral infectivity but at a mortality rate much lower than that of the parental Hear NPV. Consistent with the bioassay result, PIF complex was detected in ODVs of pif3 pseudotyped virus only but not in pif1 or pif2 pseudotyped viruses. Our results suggest that PIF complex is essential for oral infectivity, and in the formation of the PIF complex, PIF1, 2 are virus-specific while PIF3 does not appear to be as specific and can function in heterologous environment, albeit to a much more limited extent.

Comparison of lentiviruses pseudotyped with S proteins from coronaviruses and cell tropisms of porcine coronaviruses

The surface glycoproteins of coronaviruses play an important role in receptor binding and cell entry. Different coronaviruses interact with their specific receptors to enter host cells. Lentiviruses pseudotyped with their spike proteins(S) were compared to analyze the entry efficiency of various coronaviruses. Our results indicated that S proteins from different coronaviruses displayed varied abilities to mediate pseudotyped virus infection. Furthermore, the cell tropisms of porcine epidemic diarrhea virus(PEDV) and transmissible gastroenteritis virus(TGEV) have been characterized by live and pseudotyped viruses. Both live and pseudoviruses could infected VeroCCL-81(monkey kidney), Huh-7(human liver), and PK-15(pig kidney) cells efficiently. CCL94(cat kidney) cells could be infected efficiently by TGEV but not PEDV. Overall, our study provides new insights into the mechanisms of viral entry and forms a basis for antiviral drug screening.

Construction of pseudotyped human coronaviruses and detection of pre-existing antibodies in the human population

In order to clarify the pre-exist immunity background of different human coronaviruses(HCoV),this study investigated the positive rate of spike(S)protein antibodies of HCoV,including HCoV-severe acute respiratory syndrome(SARS)-associated coronavirus(SARS-CoV-1),severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),Middle East respiratory syndrome coronavirus(MERS-CoV),HCoV-229E,HCoV-NL63,HCoV-HKU1 and HCoV-OC43,before and after the Coronavirus Disease 2019(COVID-19)outbreak.We utilized pseu-dotyped virus-based neutralization assays(PBNA)or enzyme-linked immunosorbent assays(ELISA)to detect antibody levels against HCoV in serum samples collected in 2009-2010 and 2023.The PBNA results showed that neutralizing antibodies against SARS-CoV-1 and the MERS-CoV were negative.In the serum samples from 2009 to 2010,neutralizing antibodies against SARS-CoV-2(D614G)were negative,whereas in the serum sam-ples from 2023,73 samples(73%)showed neutralizing reactions with the SARS-CoV-2 D614G strain,96 sam-ples(96%)with the BA.5 strain,and 91 samples(91%)with the BF.7 strain.Among pre-COVID-19 samples,33%(33/100)showed neutralizing reactions with HCoV-229E and 63%(63/100)with HCoV-NL63.Among post-COVID-19 samples,50%(50/100)showed neutralizing reactions with HCoV-229E and 49%(49/100)with HCoV-NL63.Due to the different receptors of alpha coronavirus genus compared to other beta coron-avirus genus,neutralizing antibodies against HCoV-OC43 and HCoV-HKU1 virus cannot be detected by con-structing corresponding pseudotyped virus.Binding antibodies against HCoV-OC43 and HCoV-HKU1 virus were detected using ELISA.The results revealed that among pre-COVID-19 samples,83%(83/100)and 45%(45/100)had binding activity with HCoV-OC43 and HCoV-HKU1,respectively.Among post-COVID-19 samples,100%(100/100)and 81%(81/100)had binding activity with HCoV-0C43 and HCoV-HKU1,respectively.