Summary

Geração de recombinante do vírus Influenza de DNA plasmidial

Published: August 03, 2010
doi:

Summary

Resgate de vírus influenza A partir de DNA plasmídeo é uma técnica básica e essencial experimental que permite aos pesquisadores a gripe para gerar vírus recombinante para estudar os múltiplos aspectos da biologia do vírus da gripe, e para ser usado como vetores potenciais ou vacinas.

Abstract

Esforços por um número de grupos de pesquisa da gripe têm sido fundamental no desenvolvimento e melhoria da influenza A genética reversa do vírus. Originalmente estabelecida em 1999<sup> 1,2</sup> Plasmídeo baseado em técnicas de genética reversa para gerar vírus recombinante revolucionaram o campo de pesquisa da gripe, porque determinadas questões foram respondidas por engenharia genética, infecciosa, vírus da influenza recombinante. Esses estudos incluem a replicação do vírus, a função de proteínas virais, a contribuição de mutações específicas em proteínas virais na replicação viral e / ou patogênese e, também, vetores virais usando vírus influenza recombinantes expressando proteínas estranhas<sup> 3</sup>.

Protocol

1. Influenza transfecção de resgate de vírus Vírus influenza A pertence à família Orthomyxoviridae de vírus de RNA de fita negativa envolvido. A influenza A genoma do vírus é composto por oito genes diferentes de RNA de polaridade negativa que codificam, pelo menos, 11 proteínas virais (Figura 1) 4. Vamos nos concentrar, neste relatório, sobre o resgate de um dos cepa de laboratório mais comum, a influenza A/PR/8/34, 5 usando plasmídeos ambisense (PD…

Discussion

Resgate de vírus influenza recombinante de DNA plasmídeo é um processo simples e direta uma vez que o protocolo é realizada rotineiramente no laboratório, mas no início, várias coisas podem dar errado. É imperativo ter boa preparação plasmídeo para gerar o vírus. Manutenção adequada das linhas celulares (293T e MDCK) é crucial para um resgate bem sucedido viral. Tradicionalmente, uma marca genética é inserido em um gene que codifica a gripe-plasmídeo, por mutagênese em silêncio. Introdução desta mu…

Offenlegungen

The authors have nothing to disclose.

Acknowledgements

Os autores querem agradecer aos membros do passado e presente na Adolfo García-Sastre e Peter Palese laboratórios para o desenvolvimento de técnicas de genética e reverter influenza plasmídeos. Pesquisa em laboratórios AG-S é parcialmente financiado pelo CRIP, um Centro de NIAID-financiado de Excelência para Pesquisa e Vigilância da Influenza (HHSN266200700010C) e por doações NIAD R01AI046954, U01AI070469 e P01AI058113. Pesquisa em LM-S laboratório é parcialmente financiado pelo NIAID conceder RO1AI077719.

Materials

Material Name Typ Company Catalogue Number Comment
DMEM   Invitrogen 11995-065 Store at 4°C
OptiMEM   Invitrogen 51985-034 Store at 4°C
Lipofectamine 2000 (LPF2000)   Invitrogen 11668-019 Store at 4°C
TPCK-trypsin   Sigma T-8802 Store at -20°C
Bovine Albumin (BA)   Sigma A7979 Store at 4°C
Trypsin-EDTA   Invitrogen 25300-054 Store at -20°C
Penicillin/Streptomycin (PS) 100X   Invitrogen 15140-122 Store at -20°C
Fetal Bovine Serum (FBS)   Hyclone SH30070.03 Store at -20°C
V-bottom 96-weel plates   Nunc 249570  

Cell lines

293T (catalogue number CRL-11268) and MDCK (catalogue number CCL-34) cell lines are maintained in a 37°C incubator with 5% CO2 in DMEM 10% FBS, 1% PS. Cells are available form the American Type Culture Collection (ATCC, 10801 University Boulevard, Manassas, VA. 20110-2209 USA).

Embryonated chicken eggs

Embryonated 10-day-old chicken eggs can be obtained from Charles River Laboratories, Specific Pathogen Fee Avian Supply (SPAFAS) Avian Products and Services. Franklin Commons, 106 Route 32, North Franklin, CT 06254 USA. Eggs are incubated at 37°C preceding and after viral infection. Before and after viral infection, eggs are candled to determine viability of the embryos. It is very important to look for dead eggs before and after viral infection. Before infection a dead egg can be easily spotted by the absence of blood vessels as well as the absence of embryo mobility. When candled, live embryos move. After viral infection a dead egg (probably related to influenza virus infection) will be easily spotted by the bad appearance of the egg as seen by the smaller and bloody volume of allantoic fluid. Infected-eggs are discarded in double autoclavable bags and autoclaved following standard procedures.

Chicken red blood cells (RBC)

Chicken RBC can be purchased from Truslow Farms, 201 Valley Road, Chestertown, Md 21620. Store at 4°C. For HA assays, wash 5 ml of the chicken RBC with 45 ml of PBS 1X in a 50 ml centrifuge tube. Centrifuge for 5 minutes at 1000 rpms, RT. Discard carefully the supernatant and use a 1:1000 dilution of the pelleted RBC in PBS 1X (final concentration of 0.5-1.0% RBC).

Tissue culture supernatants and allantoic fluids

Both, tissue culture supernatants and allantoic fluids can be stored at 4°C for a short period of time. After confirming virus rescue, viruses from cell supernatants or allantoic fluid are stored at -80°C.

Plasmids

All plasmids are prepared using a plasmid maxi kit following manufacturer’s recommendations. All plasmids are aliquot at concentrations of 1 μg/ml in ddH2O and stored at -20°C. For short-term storage, the plasmid can be keep at 4°C. The concentration of the purified DNA plasmid is determined by spectrophotometry at 260 nm, with purity being estimated using the 260:280 nm ratio. Preparations with 1.8-2.0 260:280 nm ratios are considered appropriated for virus rescue purposes. Additionally, plasmid concentration and purity should be confirmed with agarose gel chromatography. Ambisense pDZ plasmids (6) containing the eight influenza A/PR/8/34 viral genes (7) are illustrated in Figure 2.

Viruses

The described protocol for rescuing influenza A/PR/8/34 can be performed under biosafety level (BSL) 2 conditions. Contaminated material, including tissue culture supernatants and embryonated eggs, should be sterilized before disposal. Rescue of other influenza virus may require higher BSL conditions and, therefore, special conditions/security measurements will need to be followed.

Tissue culture media and solutions

DMEM 10%FBS 1%PS: 445 ml Dulbecco’s modified Eagle’s medium (DMEM), 50 ml of Fetal Bovine Serum (FBS), and 5 ml of 100X Penicillin/Streptomycin (PS). Store at 4°C. This media will be used to maintain 293T and MDCK cells as well as for the transfections. DMEM 0.3%BA 1%PS: 495.7 ml of DMEM, 4.3 ml of 35% Bovine Albumin (BA). Store at 4°C. Just before use, add TPCK treated trypsin to a final concentration of 1 μg/ml. Infectious media.

10X Phosphate buffered saline (PBS): 80 g of NaCl, 2 g of KCl, 11.5 g of Na2HPO4.7H2O, 2 g of KH2PO4. Add ddH2O up to 1 liter. Adjust pH to 7.3. Sterilize by autoclave. Store at room temperature.

1X PBS: Dilute 10X PBS 1:10 with ddH2O. Sterilize by autoclave and store at room temperature.

Referenzen

  1. Neumann, G., Watanabe, T., Ito, H., Watanabe, S., Goto, H., Gao, P., Hughes, M., Perez, D. R., Donis, R., Hoffmann, E., Hobom, G., Kawaoka, Y. Generation of influenza A viruses entirely from cloned cDNAs. Proc Natl Acad Sci U S A. 96, 9345-9350 (1999).
  2. Fodor, E., Devenish, L., Engelhardt, O. G., Palese, P., Brownlee, G. G., Garcia-Sastre, A. Rescue of influenza A virus from recombinant DNA. J Virol. 73, 9679-9682 (1999).
  3. Martinez-Sobrido, L., Garcia-Sastre, A. Recombinant influenza virus vectors. Future Virology. 2, 401-416 (2007).
  4. Palese, P., Shaw, M. L., Knipe, D. M., Howley, P. H. Orthomyxoviridae. The viruses and their replication. Fields Virology. , 1647-1689 (2006).
  5. Schickli, J. H., Flandorfer, A., Nakaya, T., Martinez-Sobrido, L., Garcia-Sastre, A., Palese, P. Plasmid-only rescue of influenza A virus vaccine candidates. Philos Trans R Soc Lond B Biol Sci. 356, 1965-1973 (2001).
  6. Quinlivan, M., Zamarin, D., Garcia-Sastre, A., Cullinane, A., Chambers, T., Palese, P. Attenuation of equine influenza viruses through truncations of the NS1 protein. J Virol. 79, 8431-8439 (2005).
  7. Niwa, H., Yamamura, K., Miyazaki, J. Efficient selection for high-expression transfectants with a novel eukaryotic vector. Gene. 108, 193-199 (1991).

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Martínez-Sobrido, L., García-Sastre, A. Generation of Recombinant Influenza Virus from Plasmid DNA. J. Vis. Exp. (42), e2057, doi:10.3791/2057 (2010).

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