Name: production of high-titer infectious influenza pseudotyped particles with envelope glycoproteins from highly pathogenic h5n1 and avian h7n9 viruses
Uploaded: 2020-01-15T12:00:00
Description: Watch this Scientific Journal Video about Production of High-Titer Infectious Influenza Pseudotyped Particles with Envelope Glycoproteins from Highly Pathogenic H5N1 and Avian H7N9 Viruses at JoVE.com

This work was supported by grants from Zhejiang Provincial Medicine and Health Science and Technology Plan (Grant Numbers, 2017KY538), Hangzhou Municipal Medicine and Health Science and Technology Plan (Grant Numbers, OO20190070), Hangzhou Medical Science and Technology key Project (Grant Numbers, 2014Z11) and Hangzhou municipal autonomous application project of social development and scientific research (Grant Numbers, 20191203B134).

1. Day 1: Cell Culture and Seeding
<ol>
	<li>Cultivate human embryonic kidney (HEK) 293T/17 cells in 60 mm dishes with Dulbecco&#39;s modified essential medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 100 U/mL penicillin-streptomycin (DMEM Complete Medium, DCM) in a 37 &#176;C, 5% carbon dioxide (CO2) incubator until about 80% confluent. 
	NOTE: HEK 293T/17 low passage cells are recommended.</li>
	<li>Carefully wash the cells with 5 mL of phosphate buffered saline (PBS) 1x. 
	NOTE:...

<ol>
	<li>Knipe, D. M., Howley, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fields Virology (6th). , (2013).</li><li>White, J. M., Delos, S. E., Brecher, M., Schornberg, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structures+and+mechanisms+of+viral+membrane+fusion+proteins:+multiple+variations+on+a+common+theme.">Structures and mechanisms of viral membrane fusion proteins: multiple variations on a common theme.</a> Critical Reviews in Biochemistry and Molecular Biology. 43 (3), 189-219 (2008).</li><li>Bright, R. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cross-clade+protective+immune+responses+to+influenza+viruses+with+H5N1+HA+and+NA+elicited+by+an+influenza+virus-like+particle.">Cross-clade protective immune responses to influenza viruses with H5N1 HA and NA elicited by an influenza virus-like particle.</a> PLoS One. 3 (1), 1501 (2008).</li><li>Yang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliability+of+pseudotyped+influenza+viral+particles+in+neutralizing+antibody+detection.">Reliability of pseudotyped influenza viral particles in neutralizing antibody detection.</a> PLoS One. 9 (12), 113629 (2014).</li><li>Wyatt, R., Sodroski, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+HIV-1+envelope+glycoproteins:+fusogens,+antigens,+and+immunogens.">The HIV-1 envelope glycoproteins: fusogens, antigens, and immunogens.</a> Science. 280 (5371), 1884-1888 (1998).</li><li>Joe, A. K., Foo, H. H., Kleeman, L., Levine, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+transmembrane+domains+of+Sindbis+virus+envelope+glycoproteins+induce+cell+death.">The transmembrane domains of Sindbis virus envelope glycoproteins induce cell death.</a> Journal of Virology. 72 (5), 3935-3943 (1998).</li><li>Albecka, A., Laine, R. F., Janssen, A. F., Kaminski, C. F., Crump, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HSV-1+Glycoproteins+Are+Delivered+to+Virus+Assembly+Sites+Through+Dynamin-Dependent+Endocytosis.">HSV-1 Glycoproteins Are Delivered to Virus Assembly Sites Through Dynamin-Dependent Endocytosis.</a> Traffic. 17 (1), 21-39 (2016).</li><li>Huang, A. S., Palma, E. L., Hewlett, N., Roizman, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pseudotype+formation+between+enveloped+RNA+and+DNA+viruses.">Pseudotype formation between enveloped RNA and DNA viruses.</a> Nature. 252 (5485), 743-745 (1974).</li><li>Rubin, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+Control+of+Cellular+Susceptibility+to+Pseudotypes+of+Rous+Sarcoma+Virus.">Genetic Control of Cellular Susceptibility to Pseudotypes of Rous Sarcoma Virus.</a> Virology. 26, 270-276 (1965).</li><li>Steffen, I., Simmons, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pseudotyping+Viral+Vectors+With+Emerging+Virus+Envelope+Proteins.">Pseudotyping Viral Vectors With Emerging Virus Envelope Proteins.</a> Current Gene Therapy. 16 (1), 47-55 (2016).</li><li>Bartosch, B., Dubuisson, J., Cosset, F. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infectious+hepatitis+C+virus+pseudo-particles+containing+functional+E1-E2+envelope+protein+complexes.">Infectious hepatitis C virus pseudo-particles containing functional E1-E2 envelope protein complexes.</a> Journal of Experimental Medicine. 197 (5), 633-642 (2003).</li><li>Bian, T., Zhou, Y., Bi, S., Tan, W., Wang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HCV+envelope+protein+function+is+dependent+on+the+peptides+preceding+the+glycoproteins.">HCV envelope protein function is dependent on the peptides preceding the glycoproteins.</a> Biochemical and Biophysical Research Communications. 378 (1), 118-122 (2009).</li><li>Gudima, S., Meier, A., Dunbrack, R., Taylor, J., Bruss, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+potentially+important+elements+of+the+hepatitis+B+virus+large+envelope+protein+are+dispensable+for+the+infectivity+of+hepatitis+delta+virus.">Two potentially important elements of the hepatitis B virus large envelope protein are dispensable for the infectivity of hepatitis delta virus.</a> Journal of Virology. 81 (8), 4343-4347 (2007).</li><li>Yoshida, Y., Emi, N., Hamada, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=VSV-G-pseudotyped+retroviral+packaging+through+adenovirus-mediated+inducible+gene+expression.">VSV-G-pseudotyped retroviral packaging through adenovirus-mediated inducible gene expression.</a> Biochemical and Biophysical Research Communications. 232 (2), 379-382 (1997).</li><li>Burns, J. C., Friedmann, T., Driever, W., Burrascano, M., Yee, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vesicular+stomatitis+virus+G+glycoprotein+pseudotyped+retroviral+vectors:+concentration+to+very+high+titer+and+efficient+gene+transfer+into+mammalian+and+nonmammalian+cells.">Vesicular stomatitis virus G glycoprotein pseudotyped retroviral vectors: concentration to very high titer and efficient gene transfer into mammalian and nonmammalian cells.</a> Proceedings of the National Academy of Sciences of the United States of America. 90 (17), 8033-8037 (1993).</li><li>Zhang, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+pseudoparticles+paired+with+hemagglutinin+and+neuraminidase+from+highly+pathogenic+H5N1+influenza+and+avian+influenza+A+(H7N9)+viruses.">Characterization of pseudoparticles paired with hemagglutinin and neuraminidase from highly pathogenic H5N1 influenza and avian influenza A (H7N9) viruses.</a> Virus Research. 253, 20-27 (2018).</li><li>Zhang, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infectivity+of+Pseudotyped+Particles+Pairing+Hemagglutinin+of+Highly+Pathogenic+Avian+Influenza+a+H5N1+Virus+with+Neuraminidases+of+The+2009+Pandemic+H1N1+and+a+Seasonal+H3N2.">Infectivity of Pseudotyped Particles Pairing Hemagglutinin of Highly Pathogenic Avian Influenza a H5N1 Virus with Neuraminidases of The 2009 Pandemic H1N1 and a Seasonal H3N2.</a> Journal of Bioterrorism &amp; Biodefense. 2, 104 (2011).</li><li>Wu, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+neuraminidases+from+the+highly+pathogenic+avian+H5N1+and+2009+pandemic+H1N1+influenza+A+viruses.">Characterization of neuraminidases from the highly pathogenic avian H5N1 and 2009 pandemic H1N1 influenza A viruses.</a> PLoS One. 5 (12), 15825 (2010).</li><li>Nefkens, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemagglutinin+pseudotyped+lentiviral+particles:+characterization+of+a+new+method+for+avian+H5N1+influenza+sero-diagnosis.">Hemagglutinin pseudotyped lentiviral particles: characterization of a new method for avian H5N1 influenza sero-diagnosis.</a> Journal of Clinical Virology. 39 (1), 27-33 (2007).</li><li>Zhang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemagglutinin+and+neuraminidase+matching+patterns+of+two+influenza+A+virus+strains+related+to+the+1918+and+2009+global+pandemics.">Hemagglutinin and neuraminidase matching patterns of two influenza A virus strains related to the 1918 and 2009 global pandemics.</a> Biochemical and Biophysical Research Communications. 387 (2), 405-408 (2009).</li><li>Lin, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oseltamivir+boosts+2009+H1N1+virus+infectivity+in+vitro.">Oseltamivir boosts 2009 H1N1 virus infectivity in vitro.</a> Biochemical and Biophysical Research Communications. 390 (4), 1305-1308 (2009).</li><li>McKay, T., Patel, M., Pickles, R. J., Johnson, L. G., Olsen, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influenza+M2+envelope+protein+augments+avian+influenza+hemagglutinin+pseudotyping+of+lentiviral+vectors.">Influenza M2 envelope protein augments avian influenza hemagglutinin pseudotyping of lentiviral vectors.</a> Gene Therapy. 13 (8), 715-724 (2006).</li><li>Pan, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autophagy+mediates+avian+influenza+H5N1+pseudotyped+particle-induced+lung+inflammation+through+NF-kappaB+and+p38+MAPK+signaling+pathways.">Autophagy mediates avian influenza H5N1 pseudotyped particle-induced lung inflammation through NF-kappaB and p38 MAPK signaling pathways.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 306 (2), 183-195 (2014).</li><li>Szecsi, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+neutralising+antibodies+by+virus-like+particles+harbouring+surface+proteins+from+highly+pathogenic+H5N1+and+H7N1+influenza+viruses.">Induction of neutralising antibodies by virus-like particles harbouring surface proteins from highly pathogenic H5N1 and H7N1 influenza viruses.</a> Virology Journal. 3, 70 (2006).</li><li>Garcia, J. M., Lagarde, N., Ma, E. S., de Jong, M. D., Peiris, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+and+evaluation+of+an+influenza+A+(H5)+pseudotyped+lentiviral+particle-based+serological+assay.">Optimization and evaluation of an influenza A (H5) pseudotyped lentiviral particle-based serological assay.</a> Journal of Clinical Virology. 47 (1), 29-33 (2010).</li><li>Garcia, J. M., Lai, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+influenza+pseudotyped+lentiviral+particles+and+their+use+in+influenza+research+and+diagnosis:+an+update.">Production of influenza pseudotyped lentiviral particles and their use in influenza research and diagnosis: an update.</a> Expert Review of Anti-infective Therapy. 9 (4), 443-455 (2011).</li><li>Haynes, J. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influenza-pseudotyped+Gag+virus-like+particle+vaccines+provide+broad+protection+against+highly+pathogenic+avian+influenza+challenge.">Influenza-pseudotyped Gag virus-like particle vaccines provide broad protection against highly pathogenic avian influenza challenge.</a> Vaccine. 27 (4), 530-541 (2009).</li><li>Schmeisser, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+and+characterization+of+mammalian+virus-like+particles+from+modified+vaccinia+virus+Ankara+vectors+expressing+influenza+H5N1+hemagglutinin+and+neuraminidase.">Production and characterization of mammalian virus-like particles from modified vaccinia virus Ankara vectors expressing influenza H5N1 hemagglutinin and neuraminidase.</a> Vaccine. 30 (23), 3413-3422 (2012).</li><li>Liu, Y. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chimeric+severe+acute+respiratory+syndrome+coronavirus+(SARS-CoV)+S+glycoprotein+and+influenza+matrix+1+efficiently+form+virus-like+particles+(VLPs)+that+protect+mice+against+challenge+with+SARS-CoV.">Chimeric severe acute respiratory syndrome coronavirus (SARS-CoV) S glycoprotein and influenza matrix 1 efficiently form virus-like particles (VLPs) that protect mice against challenge with SARS-CoV.</a> Vaccine. 29 (38), 6606-6613 (2011).</li><li>Moeschler, S., Locher, S., Conzelmann, K. K., Kramer, B., Zimmer, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+Lyssavirus-Neutralizing+Antibodies+Using+Vesicular+Stomatitis+Virus+Pseudotype+Particles.">Quantification of Lyssavirus-Neutralizing Antibodies Using Vesicular Stomatitis Virus Pseudotype Particles.</a> Viruses. 8 (9), 254 (2016).</li><li>Lai, A. L., Millet, J. K., Daniel, S., Freed, J. H., Whittaker, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+SARS-CoV+Fusion+Peptide+Forms+an+Extended+Bipartite+Fusion+Platform+that+Perturbs+Membrane+Order+in+a+Calcium-Dependent+Manner.">The SARS-CoV Fusion Peptide Forms an Extended Bipartite Fusion Platform that Perturbs Membrane Order in a Calcium-Dependent Manner.</a> Journal of Molecular Biology. 429 (24), 3875-3892 (2017).</li><li>Millet, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Middle+East+respiratory+syndrome+coronavirus+infection+is+inhibited+by+griffithsin.">Middle East respiratory syndrome coronavirus infection is inhibited by griffithsin.</a> Antiviral Research. 133, 1-8 (2016).</li><li>Millet, J. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+Pseudotyped+Particles+to+Study+Highly+Pathogenic+Coronaviruses+in+a+Biosafety+Level+2+Setting.">Production of Pseudotyped Particles to Study Highly Pathogenic Coronaviruses in a Biosafety Level 2 Setting.</a> Journal of Visualized Experiments. (145), e59010 (2019).</li><li>Ma, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+leukemia+virus+pseudotypes+of+La+Crosse+and+Hantaan+Bunyaviruses:+a+system+for+analysis+of+cell+tropism.">Murine leukemia virus pseudotypes of La Crosse and Hantaan Bunyaviruses: a system for analysis of cell tropism.</a> Virus Research. 64 (1), 23-32 (1999).</li><li>Wool-Lewis, R. J., Bates, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+Ebola+virus+entry+by+using+pseudotyped+viruses:+identification+of+receptor-deficient+cell+lines.">Characterization of Ebola virus entry by using pseudotyped viruses: identification of receptor-deficient cell lines.</a> Journal of Virology. 72 (4), 3155-3160 (1998).</li><li>Chen, C. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+and+design+of+more+effective+avian+replication-incompetent+retroviral+vectors.">Production and design of more effective avian replication-incompetent retroviral vectors.</a> Developmental Biology. 214 (2), 370-384 (1999).</li><li>Kaku, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Second+generation+of+pseudotype-based+serum+neutralization+assay+for+Nipah+virus+antibodies:+sensitive+and+high-throughput+analysis+utilizing+secreted+alkaline+phosphatase.">Second generation of pseudotype-based serum neutralization assay for Nipah virus antibodies: sensitive and high-throughput analysis utilizing secreted alkaline phosphatase.</a> Journal of Virological Methods. 179 (1), 226-232 (2012).</li><li>Rudiger, D., Kupke, S. Y., Laske, T., Zmora, P., Reichl, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiscale+modeling+of+influenza+A+virus+replication+in+cell+cultures+predicts+infection+dynamics+for+highly+different+infection+conditions.">Multiscale modeling of influenza A virus replication in cell cultures predicts infection dynamics for highly different infection conditions.</a> PLOS Computational Biology. 15 (2), 1006819 (2019).</li><li>Petiot, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influenza+viruses+production:+Evaluation+of+a+novel+avian+cell+line+DuckCelt(R)-T17.">Influenza viruses production: Evaluation of a novel avian cell line DuckCelt(R)-T17.</a> Vaccine. 36 (22), 3101-3111 (2018).</li></ol>

In this protocol, we describe a method to produce influenza virus pseudotyped particles (pp) in a BSL-2 setting. The reporter plasmid pcDNA-GFP is incorporated into the pps and can be used to quantify pps by FACS in an infectivity assay. We chose two types of susceptible cell lines because they are widely used in influenza research. MDCK cells would provide a good control to the variable immortalized human cells used in these studies.
This protocol is based on the retrovirus MLV, which can inc...

The mission of a viral particle is to transport its genome from an infected host cell to a non-infected host cell and to deliver it into the cytoplasm or the nucleus in a replication-competent form1. This process is initially triggered by binding to host cell receptors, followed by fusion of virion and cellular membranes. For enveloped viruses, like influenza viruses, the spike glycoproteins are responsible for receptor binding and fusion1,2. Viral envelope glycoproteins (e.g., pyrogens, antigens), are involved in many important properties and events, such as virus lifecycle initiation (binding and fusion), viral pathogenesis, immunogenicity, host cell apoptosis and cellular tropism, the cellular endocytic pathway, as well as interspecies transmission and reassortment1,3,4,5,6,7. Research on viral envelope glycoproteins will help us understand many aspects of the viral infection process. Pseudotyped viral particles (pp), also termed pseudovirions or pseudoparticles, can be generated through a pseudotyping technique8,9,10. This technology has been used to develop pseudotyped particles of many viruses, including hepatitis C11,12, hepatitis B13, vesicular stomatitis virus (VSV)14,15, and influenza virus16,17,18,19. This technology is based on the Gag-Pol protein of lentiviruses or other retroviruses.
Pseudotyped viral particles can be obtained using a three-plasmid system by cotransfecting a viral envelope glycoprotein expression plasmid, a retroviral packaging plasmid missing the envelope env gene, and a separate reporter plasmid into pp producer cells. The retrovirus is assembled by its Gag protein, and it buds from an infected cell membrane that expresses the virus envelope protein1. Therefore, it is possible to obtain high titer influenza pps using the retrovirus Gag protein to produce buds on a cellular membrane expressing influenza HA and NA. In our previous studies, HAs/NAs in all combinations were functional and able to perform their corresponding functions in the viral life cycle16,17,18,20,21. These pps are used to investigate influenza biological characteristics, including hemagglutination, neuraminidase activity, HA-receptor binding tropism, and infectivity. Because HA and NA are both important surface functional proteins in the viral life cycle, mismatched HAs and NAs derived from different strains of influenza can partly demonstrate reassortment between them. Here, we generate eight types of influenza pps by combining two HAs and two NAs (derived from the HPAI H5N1 strain and the H7N9 stain), using a three-plasmid pseudotyping system. These eight types of pps include two native pps, H5N1pp, H7N9pp; two mismatched pps, (H5+N9)pp, (H7+N1)pp; and four pps only harboring a single glycoprotein (HA or NA), H5pp, N1pp, H7pp, N9pp. Studies on the influenza virus, such as H5N1 and H7N9, are limited by biosafety requirements. All studies of the wild influenza virus strains should be performed in a biosafety level 3 (BSL-3) laboratory. Pseudotyped viral particle technology can be used to package an artificial virion in a biosafety level 2 (BSL-2) setting. Therefore, pps represent a safer and useful tool to study the influenza virus processes depending on its two major glycoproteins: hemagglutinin (HA) and neuraminidase (NA).
This protocol describes the generation of these pps with a three-plasmid cotransfection strategy (overviewed in Figure 1), how to quantify pps, and infectivity detection. The pp production involves three kinds of plasmids (Figure 1). The gag-pol gene, which encodes the retrovirus Gag-Pol protein, was cloned from a retrovirus packaging kit and inserted into the pcDNA 3.1 plasmid and named pcDNA-Gag-Pol. The enhanced green fluorescent protein (eGFP) gene, which encodes Green Fluorescent Protein, was cloned from pTRE-EGFP vector, inserted into the pcDNA 3.1 plasmid, and called pcDNA-GFP. During cloning, a packaging signal (&#968;) sequence was added via a primer. The HA and NA genes were cloned into a pVRC plasmid, named pVRC-HA and pVRC-NA, respectively. The last plasmid encodes the fusion protein and can be replaced with any other fusion protein of interest. Our pseudotyping platform includes two glycoprotein expression plasmids: pVRC-HA and pVRC-NA. This can simplify the research on reassortment between different virus strains in a BSL-2 setting.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Benzonase Nuclease</td>
			<td>Millipore</td>
			<td>70664</td>
			<td>Effective viscosity reduction and removal of nucleic acids from protein solutions</td>
		</tr>
		<tr>
			<td>Clear Flat Bottom Polystyrene TC-treated Microplates (96-well)</td>
			<td>Corning</td>
			<td>3599</td>
			<td>Treated for optimal cell attachment 
			Sterilized by gamma radiation and certified nonpyrogenic 
			Individual alphanumeric codes for well identification</td>
		</tr>
		<tr>
			<td>Clear TC-treated Multiple Well Plates (6-wells)</td>
			<td>Costar</td>
			<td>3516</td>
			<td>Individual alphanumerical codes for well identification 
			Treated for optimal cell attachment 
			Sterilized by gamma irradiation</td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s modified essential medium (DMEM)</td>
			<td>Gibco</td>
			<td>11965092</td>
			<td>A widely used basal medium for supporting the growth of many different mammalian cells</td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>Excell</td>
			<td>FND500</td>
			<td>fetal bovine sera that can offer excellent value for basic cell culture, specialty research, and specific assays</td>
		</tr>
		<tr>
			<td>Fluorescence Activated Cell Sorting (FACS)</td>
			<td>Beckman coulter</td>
			<td>cytoflex</td>
			<td></td>
		</tr>
		<tr>
			<td>Human alveolar adenocarcinoma A549 cells</td>
			<td>ATCC</td>
			<td>CRM-CCL-185</td>
			<td></td>
		</tr>
		<tr>
			<td>Human embryonic kidney (HEK) HEK-293T/17 cells</td>
			<td>ATCC</td>
			<td>CRL-11268</td>
			<td>A versatile transfection reagent that has been shown to effectively transfect the widest variety of adherent and suspension cell lines</td>
		</tr>
		<tr>
			<td>Inverted fluorescent biological microscope</td>
			<td>Olympus</td>
			<td>BX51-32P01-FLB3</td>
			<td></td>
		</tr>
		<tr>
			<td>Inverted light microscope</td>
			<td>Olympus</td>
			<td>CKX31-12PHP</td>
			<td></td>
		</tr>
		<tr>
			<td>Lipofectamine 2000 Transfection Reagent</td>
			<td>Invitrogen</td>
			<td>11668019</td>
			<td>Rapid, sensitive and precise probe-based qPCR detection and quantitation of target RNA targets.</td>
		</tr>
		<tr>
			<td>Luna Universal Probe One-Step RT-qPCR Kit</td>
			<td>NEB</td>
			<td>E3006L</td>
			<td>Will withstand up to 14,000 RCF 
			RNase-/DNase-free Nonpyrogenic</td>
		</tr>
		<tr>
			<td>Madin-Darby Canine Kidney (MDCK) cells</td>
			<td>ATCC</td>
			<td>CCL-34</td>
			<td></td>
		</tr>
		<tr>
			<td>MaxyClear Snaplock Microcentrifuge Tube (1.5 mL)</td>
			<td>Axygen</td>
			<td>MCT-150-C</td>
			<td>33 mm, gamma sterilized</td>
		</tr>
		<tr>
			<td>Millex-HV Syringe Filter Unit, 0.45 &#181;m, PVDF</td>
			<td>Millipore</td>
			<td>SLHV033RS</td>
			<td>an improved Minimal Essential Medium (MEM) that allows for a reduction of Fetal Bovine Serum supplementation by at least 50% with no change in cell growth rate or morphology. Opti-MEM I medium is also recommended for use with cationic lipid transfection reagents, such as Lipofectamine reagent.</td>
		</tr>
		<tr>
			<td>Opti-MEM I Reduced Serum Medium</td>
			<td>Gibco</td>
			<td>11058021</td>
			<td>The antibiotics penicillin and streptomycin are used to prevent bacterial contamination of cell cultures due to their effective combined action against gram-positive and gram-negative bacteria.</td>
		</tr>
		<tr>
			<td>penicillin-streptomycin</td>
			<td>Gibco</td>
			<td>15140122</td>
			<td>Maximum RCF is 12,500 xg 
			Temperature range from -80 &#176;C to 120 &#176;C 
			RNase-/DNase-free 
			Sterile</td>
		</tr>
		<tr>
			<td>PP Centrifuge Tubes (15 mL)</td>
			<td>Corning</td>
			<td>430791</td>
			<td>a stable and highly reactive serine protease</td>
		</tr>
		<tr>
			<td>Proteinase K</td>
			<td>Beyotime</td>
			<td>ST532</td>
			<td>Treated for optimal cell attachment 
			Sterilized by gamma radiation and certified nonpyrogenic</td>
		</tr>
		<tr>
			<td>TC-treated Culture Dish (60mm)</td>
			<td>Corning</td>
			<td>430166</td>
			<td>Trypsin from bovine pancreas 
			TPCK Treated, essentially salt-free, lyophilized powder, &#8805;10,000 BAEE units/mg protein</td>
		</tr>
		<tr>
			<td>TPCK-trypsin</td>
			<td>Sigma</td>
			<td>T1426</td>
			<td>This liquid formulation of trypsin contains EDTA and phenol red. Gibco Trypsin-EDTA is made from trypsin powder, an irradiated mixture of proteases derived from porcine pancreas. Due to its digestive strength, trypsin is widely used for cell dissociation, routine cell culture passaging, and primary tissue dissociation. The trypsin concentration required for dissociation varies with cell type and experimental requirements.</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.25%), phenol red</td>
			<td>Gibco</td>
			<td>25200056</td>
			<td></td>
		</tr>
	</tbody>
</table>

production of high-titer infectious influenza pseudotyped particles with envelope glycoproteins from highly pathogenic h5n1 and avian h7n9 viruses

The occasional direct transmission of the highly pathogenic avian influenza A virus H5N1 (HPAI H5N1) and H7N9 to humans and their lethality are serious public health issues and suggest the possibility of an epidemic. However, our molecular understanding of the virus is rudimentary, and it is necessary to study the biological properties of its envelope proteins as therapeutic targets and to develop strategies to control infection. We developed a solid viral pseudotyped particle (pp) platform to study avian influenza virus, including the functional analysis of its hemagglutinin (HA) and neuraminidase (NA) envelope glycoproteins, the reassortment characteristics of the HAs and NAs, receptors, tropisms, neutralizing antibodies, diagnosis, infectivity, for the purposes of drug development and vaccine design. Here, we describe an experimental procedure to establish pps with the envelope glycoproteins (HA, NA) from two influenza A strains (HAPI H5N1 and 2013 avian H7N9). Their generation is based on the capacity of some viruses, such as murine leukemia virus (MLV), to incorporate envelope glycoproteins into a pp. In addition, we also detail how these pps are quantified with RT-qPCR, and the infectivity detection of native and mismatched virus pps depending on the origin of the HAs and NAs. This system is highly flexible and adaptable and can be used to establish viral pps with envelope glycoproteins that can be incorporated in any other type of enveloped virus. Thus, this viral particle platform can be used to study wild viruses in many research investigations.

Depending on the general procedure described above, we have generated 10 types of pps combining two group HAs/NAs or VSV-G glycoprotein or no-envelope glycoproteins (shown in Table 1). Seven of them are infectious. The pps that harbor no-envelope glycoprotein or only harbor NA did not show any infectivity here. The influenza pp production procedure is overviewed in Figure 1. Transmission electron micrographs of pps (e.g., H5N1pp) are shown in Figure 3</s...

Watch this Scientific Journal Video about Production of High-Titer Infectious Influenza Pseudotyped Particles with Envelope Glycoproteins from Highly Pathogenic H5N1 and Avian H7N9 Viruses at JoVE.com

Production of High-Titer Infectious Influenza Pseudotyped Particles with Envelope Glycoproteins from Highly Pathogenic H5N1 and Avian H7N9 Viruses

This protocol describes an experimental process to produce high-titer infectious viral pseudotyped particles (pp) with envelope glycoproteins from two influenza A strains and how to determine their infectivity. This protocol is highly adaptable to develop pps of any other type of enveloped viruses with different envelope glycoproteins.

The occasional direct transmission of the highly pathogenic avian influenza A virus H5N1 (HPAI H5N1) and H7N9 to humans and their lethality are serious ...

Research

JoVE Journal

Immunology and Infection

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Conformational Evaluation of HIV-1 Trimeric Envelope Glycoproteins Using a Cell-based ELISA Assay

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Intranasal Administration of Recombinant Influenza Vaccines in Chimeric Mouse Models to Study Mucosal Immunity

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Rapid Molecular Detection and Differentiation of Influenza Viruses A and B

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Fluorescence-based Neuraminidase Inhibition Assay to Assess the Susceptibility of Influenza Viruses to The Neuraminidase Inhibitor Class of Antivirals

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