Sindbis Virus: Propagation, Quantification, and Storage
1North Carolina State University, Raleigh, North Carolina
Abstract
The prototype of the Alphaviruses, Sindbis virus, has a broad host range. In nature, Sindbis virus shuttles from an insect vector to a vertebrate host and back to the insect vector in a complex transmission cycle. Sindbis virus must, therefore, be able to replicate in two biochemically and genetically divergent hosts, invertebrates and vertebrates. In the laboratory, Sindbis grows to high titers in a large variety of cultured cells of both vertebrate and invertebrate origin. Sindbis virus is easily titered for infectivity on several mammalian cell lines as well as certain mosquito cells. Full-length cDNA clones of several strains of Sindbis virus are available from which infectious RNA can be synthesized, making possible the genetic manipulation of the virus. Transfection of mammalian and insect cells by electroporation has facilitated expression of RNA mutants in the cell lines of choice. Curr. Protoc. Microbiol. 16:15B.1.1-15B.1.41. © 2010 by John Wiley & Sons, Inc.
Keywords: Sindbis virus; SVHR; plaque assay; focus assay; MTT titration; infection; transfection; insect cell culture; mammalian cell culture; Alphavirus
Table of Contents
- Introduction
- Basic Protocol 1: Infection of BHK or CEF Cells
- Basic Protocol 2: Sindbis Virus Purification
- Alternate Protocol 1: BHK Cell Transfection
- Basic Protocol 3: Assaying Virus by Plaque Formation on BHK Cells
- Alternate Protocol 2: Assaying Virus by Focus Formation on BHK or Mosquito Cells
- Alternate Protocol 3: Fluorescent Focus Assay on BHK or Mosquito Cells
- Support Protocol 1: Propagation of BHK Cells
- Support Protocol 2: Preparation of Primary Chick Embryo Fibroblast (CEF) Culture
- Basic Protocol 4: Vero Cell MTT Assay of Alphavirus Production
- Support Protocol 3: Propagation of Vero Cells
- Basic Protocol 5: Mosquito Cell Monolayer Infection
- Alternate Protocol 4: Mosquito Cell Infection in Suspension
- Alternate Protocol 5: Mosquito Cell Transfection
- Support Protocol 4: Propagation of Mosquito Cells
- Support Protocol 5: BHK and Mosquito Cell Storage
- Support Protocol 6: Transcription Reaction for the Production of Infectious Sindbis Virus RNA
- Basic Protocol 6: Assay of Virus by Plaque Formation on C7-10 Mosquito Cells
- Basic Protocol 7: Purification of Virus from Plaques
- Reagents and Solutions
- Commentary
- Literature Cited
- Figures
- Tables
- Topics
- Microbiology
- Cell Culture
- Cell Biology
- Other Versions
Materials
Basic Protocol 1: Infection of BHK or CEF Cells
- Baby hamster kidney (BHK) cells (ATCC #CCL10) or CEF cells, growing in culture (Support Protocol 1 or Support Protocol 2)
- 1× complete EMEM medium (see recipe)
- Sindbis virus (SVHR) stock (see note below), titered (see Basic Protocol 3)
- 1× PBS-D (see recipe for 10×) containing 3% FBS (heat-inactivated at 56°C; see appendix 2A)
- Glycerol, sterile
- Liquid nitrogen
- Platform rocker
- 25- or 75-cm
2 culture flasks (the authors have found that vented flasks are less susceptible to contamination with mold than the standard flasks) - 15- or 50-ml conical polypropylene centrifuge tubes, sterile
Basic Protocol 2: Sindbis Virus Purification
- Virus supernatant (see Basic Protocol 1, step 8)
- 15% and 35% (w/v) potassium tartrate in PBS-D (see recipe for PBS-D), 4°C
- 1× PBS-D (see recipe for 10×), 4°C
- Beckman UltraClear centrifuge tubes (25 × 89mm)
- Beckman ultracentrifuge with SW28 rotor and buckets (or equivalent), prechilled to 4°C
- Ring stands
- Small tube clamps
- Hand-held low-intensity (e.g., 20-W) lamp
- 30- to 100-ml gradient former (e.g., Bio-Rad model 385)
Alternate Protocol 1: BHK Cell Transfection
- Baby hamster kidney (BHK) cells (ATCC #CCL-10), growing in culture (see Support Protocol 1)
- 1× complete EMEM medium (see recipe) without gentamicin
- 1× PBS-D (see recipe for 10×; use RNase-free PBS-D as indicated in protocol)
- 0.25% trypsin (see recipe)
- Versene solution (see recipe)
- RNA transcript(s) from cDNA(s) of interest (see Support Protocol 6)
- 75- and 25-cm
2 tissue culture flasks - Siliconized, low-retention RNase-free microcentrifuge tubes (Fisher, cat. no. 02-681-331)
- Aerosol-barrier pipet tips
- Electroporator (Bio Rad Gene Pulser)
- Electroporation cuvettes, 2-cm gap width
- Additional reagents and equipment for counting cells using a hemacytometer (Strober, 1997) and harvesting of virus (see Basic Protocol 1)
Basic Protocol 3: Assaying Virus by Plaque Formation on BHK Cells
- Baby hamster kidney (BHK) cells (ATCC #CCL-10), growing in culture (see Support Protocol 1)
- 1× and 2× complete EMEM medium (see recipe)
- SVHR diluent (see recipe) or TM diluent for BHK cell assay (see recipe)
- Virus stock to be titered (e.g., Basic Protocol 1, Basic Protocol 2, or Alternate Protocol 1)
- 2% agarose (see recipe)
- 2× PBS-D (see recipe for 10×)
- 2% neutral red stock solution (see recipe)
- 20 mM HEPES, pH 7.2 to 7.4 (see recipe; for less stable virus)
- 25-cm
2 tissue culture flasks (the authors have found that vented flasks are less susceptible to contamination with mold than the standard flasks) - Dilution tubes: 13 × 100mm borosilicate glass test tubes
- Dilution tube rack
- Platform rocker
- Light box
Alternate Protocol 2: Assaying Virus by Focus Formation on BHK or Mosquito Cells
- Virus stock to be titered (e.g., Basic Protocol 1, Basic Protocol 2, or Alternate Protocol 1)
- 1× PBS-D (see recipe for 10×) containing 3% FBS (heat-inactivated at 56°C; see appendix 2A)
- Baby hamster kidney (BHK) cells (see Support Protocol 1) or mosquito cells (see Basic Protocol 5), growing in culture in 24-well plates (see protocol introduction)
- 2% carboxymethylcellulose (CMC; see recipe): dilute 1:1 in appropriate 2× medium for either BHK (Support Protocol 1) or mosquito (Support Protocol 4) cells
- 1× phosphate buffered saline (PBS; appendix 2A), pH 7.4, containing 0.05% (v/v) Tween 20
- 80% (v/v) methanol
- Antibody dilution buffer: 5% (w/v) powdered (Carnation) skim milk in 1× PBS, with and without 0.05% (v/v) Tween 20
- Primary antibody: antiSindbis virus antibody (usually rabbit; Cocalico Biologicals; http://www.cocalicobiologicals.com/)
- Goat anti-rabbit horseradish peroxidase (HRP)labeled antibody (Sigma, cat. no. A-8924)
- TrueBlue peroxidase substrate system (TrueBlue Peroxidase SubstrateKirkegaard & Perry Laboratories, cat. no. 50-78-02)
Alternate Protocol 3: Fluorescent Focus Assay on BHK or Mosquito Cells
- 100% methanol
- PBS-BSA: 1× PBS (appendix 2A) containing 0.2% bovine serum albumin (BSA)
- Fluorescently labeled secondary antibody: goat anti rabbit Alexa Fluor 488 labeled antibody (Invitrogen, cat. no. A-11017) for rabbit primary anti-Sindbis antibody
- Inverted fluorescent microscope
Support Protocol 1: Propagation of BHK Cells
- Baby hamster kidney (BHK) cells (ATCC #CCL-10), growing in culture
- 1× PBS-D (see recipe)
- 0.25% trypsin (see recipe)
- Versene solution (see recipe)
- 1× complete EMEM medium
- 25- or 75-cm
2 tissue culture flasks - Conical tubes
Support Protocol 2: Preparation of Primary Chick Embryo Fibroblast (CEF) Culture
- Fertile chicken eggs, 10 days old (Spafas; http://www.criver.com/)
- 70% ethanol
- 1× phosphate-buffered saline (PBS) with calcium and magnesium (see recipe)
- 0.25% trypsin
- Versene solution (see recipe)
- 1× complete EMEM (see recipe)
- Strong light source (75 to 100 W)
- Small sterile beaker
- Sharp scissors and forceps, sterile
- 50-ml conical tubes
- 37°C water bath
- 75-cm
2 tissue culture flasks
- Additional reagents and equipment for counting cells (Strober, 1997), subculturing BHK cells (see Support Protocol 1), and freezing cells (see Support Protocol 5)
Basic Protocol 4: Vero Cell MTT Assay of Alphavirus Production
- Vero cells (Support Protocol 3)
- 1× EMEM complete Vero media (see recipe)
- Virus stock (Basic Protocol 1, Basic Protocol 2, or Alternate Protocol 1)
- MTT labeling reagent (see recipe)
- MTT solubilizing reagent (see recipe)
- 96-well Corning Cellbind culture plates (Costar 3300)
- Plate reader with 500- to 700-nm excitation and emission capability
- Computer with Excel spreadsheet software
Basic Protocol 5: Mosquito Cell Monolayer Infection
- Mosquito cells (e.g., U4.4 cells; laboratory isolate; contact authors at raquel-hernandez@ncsu.edu), growing in tissue culture in 75-cm
2 flasks (also see Support Protocol 4) - 1× PBS-D (see recipe)
- Serum-free M&M or EMEM medium (e.g., Invitrogen; also see recipes)
- Sindbis virus (SVHR) stock, titered (see Basic Protocol 3 or 6)
- Fresh 1× complete Mitsuhashi and Maramorosch (M&M) medium (see recipe) or 1× complete EMEM medium (see recipe)
- Glycerol
- Neutral-pH buffer (PBS-D or culture medium buffered to pH 7.2 to 7.4 using 10 to 20 mM HEPES)
- 28°C humidified 5% CO
2 incubator (CO2 required only for use with EMEM) - 75-cm
2 tissue culture flask
- Additional reagents and equipment for counting cells (Strober, 1997) and infecting cell cultures with Sindbis virus and harvesting and storing the virus (see Basic Protocol 1)
Alternate Protocol 4: Mosquito Cell Infection in Suspension
- Mosquito cells (e.g., U4.4 cells; laboratory isolate; contact authors at raquel-hernandez@ncsu.edu), growing in tissue culture in 75-cm
2 flasks at ~6 × 107 cells/flask (also see Support Protocol 4) - Fresh 1× complete Mitsuhashi and Maramorosch (M&M) medium (see recipe) or 1× complete EMEM medium (see recipe)
- Sindbis virus (SVHR) stock, titered (see Basic Protocol 3)
- Liquid nitrogen
- 75- and 25-cm
2 tissue culture flasks - Humidified 28°C, 5% CO
2 incubator (CO2 required only for use with EMEM)
- Additional reagents and equipment for counting cells (Strober, 1997)
Alternate Protocol 5: Mosquito Cell Transfection
- Mosquito cells (e.g., U4.4 cells; laboratory isolate; contact authors at raquel-hernandez@ncsu.edu), growing in tissue culture in 75-cm
2 flasks (also see Support Protocol 4) - 1× PBS-D (see recipe for 10×)
- HBS buffer (see recipe), RNase-free, ice-cold
- RNA transcript(s) from cDNA(s) of interest (see Support Protocol 6)
- 1× complete Mitsuhashi and Maramorosch (M&M) medium (see recipe)
- 1 M MOPS buffer (see recipe; for use with mosquito cell cultures and mutant viruses requiring additional buffering)
- 50-ml conical polypropylene centrifuge tubes
- Aerosol-barrier pipet tips, RNase free
- RNase-free microcentrifuge tubes
- Electroporation cuvettes 2-cm gap width
- Electroporator (e.g., BioRad Gene Pulser)
- Additional reagents and equipment for counting cells (Strober, 1997) and harvesting virus (see Basic Protocol 1)
Support Protocol 4: Propagation of Mosquito Cells
- Mosquito cellsU4.4 and C7-10 (contact authors at raquel-hernandez@ncsu.edu) and C6/36 cells (ATCC #CRL-1660)growing in semisuspension
- Medium: 1× complete Mitsuhashi and Maramorosch (M&M) medium (see recipe) or 1× complete EMEM medium (see recipe)
- Tissue culture flasks
- Humidified 28°C, 5% CO
2 incubator (CO2 required only for use with EMEM)
Support Protocol 5: BHK and Mosquito Cell Storage
- BHK cells (ATCC #CCL-10)
- 0.25% trypsin (see recipe)
- Versene solution (see recipe)
- 1× complete EMEM medium
- Freezing medium (see recipe) made with EMEM for BHK cells or with either M&M or EMEM for mosquito cells, depending on optimal growth medium
- Mosquito cells: U4.4 and C7-10 (contact authors at raquel-hernandez@ncsu.edu) and C6/36 cells (ATCC #CRL-1660)
- Cryotubes
- Nalgene Cryo 1°C freezing container
- Liquid nitrogen freezer
Support Protocol 6: Transcription Reaction for the Production of Infectious Sindbis Virus RNA
- RNase-free H
2 O (Gilman, 2002; also see appendix 2A) - Linearized cDNA of interest: do not treat with RNase
- 10× transcription buffer (see recipe)
- dNTPs: ATP, UTP, GTP, and CTP (appendix 2A)
- m
7 GpppG (New England Biolabs) - RNase inhibitor (Ambion)
- SP6 RNA polymerase (New England Biolabs)
- Ethidium bromide staining solution (appendix 2A)
- RNase-free DNase
- RNase-free tubes and pipets
- 40°C water bath
Basic Protocol 6: Assay of Virus by Plaque Formation on C7-10 Mosquito Cells
- C7-10 mosquito cells (laboratory isolate; contact authors at raquel_hernandez@.ncsu.edu) growing in 75-cm
2 tissue culture flasks - 1× and 2× serum-free EMEM medium (see recipe)
- TM diluent for C7-10 plaque assay (see recipe)
- SVHR sample to be titered (any cell source)
- 2× complete EMEM (see recipe)
- 2% agarose (see recipe)
- 1× PBS-D (see recipe) containing 20 mM MOPS (prepare using 1 M MOPS buffer; see recipe)
- 2% neutral red stock solution (see recipe)
- 25-cm
2 tissue culture flasks - Humidified 28°C 5% CO
2 incubator (CO2 required only for use with EMEM) - Dilution tubes: 13 × 100mm borosilicate glass test tubes
- Dilution tube rack
- Platform rocker
- Additional materials for counting cells (Strober, 1997)
Basic Protocol 7: Purification of Virus from Plaques
- Virus stock to be purified (see above protocols)
- Virus diluent: 1× PBS-D (for wild-type SVHR; see recipe) or TM diluent for BHK or C7-10 plaque assay as appropriate (for mutants; see recipes)
- Soldering iron
- Sterile Pasteur pipets and tubes
- Additional reagents and equipment for plaque assay (see Basic Protocol 3 for BHK cells or Basic Protocol 6 for mosquito cells)
Figures
-
Figure 15B.1.1Schematic of the step gradient used for virus purification. The 35% potassium tartrate step is shown at the bottom of the tube. 15% potassium tartrate is overlaid onto this step to form the second layer. The culture supernatant containing the virus forms the final layer on the gradient. After the centrifugation, a virus band (shown as light gray) will be visible at the interface between the 15% and 35% steps.
-
Figure 15B.1.2Schematic of a linear gradient. A linear gradient is used as the second purification step. As with the step gradient, 35% potassium tartrate will be at the bottom of the tube and in the first chamber of the gradient former. The gradient former will mix the 35% and 15% solutions together to form a linear gradient. The diluted virus band from the first step gradient (Fig. 15B.1.1) is pipetted onto the top of the linear gradient.
-
Figure 15B.1.3Plaque assay flasks. Note the appearance of SVHR plaques at 10
7 (flask 3), 108 (flask 2), and 109 dilutions (flask 1). Most plaques are large; however, medium-sized plaques are also visible. Sindbis virus forms symmetrical plaques. At the lower dilutions, (107 ), plaques are seen overlapping. Some monolayers, such as flask 2, may have monolayers that display faint less well defined plaques. -
Figure 15B.1.4Titration of Sindbis virus mutants by fluorescent TCID
50 assay. -
Figure 15B.1.5Sample MTT data plots. (A) A plot of all dilutions calculated as in step 8. This plot gives a sigmoidal curve. (B) A graph of the linear portion of the graph in (A). In this example, these are samples 5 to 9. The x intercept is calculated as in step 11.
-
Figure 15B.1.61% agarose gel of transcripts from the transcription reaction. Lane 1, mass ladder; ~200 ng are present in the upper band. Lane 2, kb ladder; Sindbis virus cDNA (top bands in lanes 3 to 6) runs just slightly above the uppermost 10 kb band. Lanes 3 to 6, transcription reactions run prior to DNase digestion. Note the nice tight bands of RNA above a smear of product. This quality and quantity, ~500 µg per 20-µl reaction of RNA, will produce a good transfection. The smaller transcript in lane 4 is used as a positive control for the transcription reaction. The resulting RNA is noninfectious and serves as a negative control for the cell transfection (see Alternate Protocols 1 and 5).
Literature Cited
| Literature Cited | |
| Brown, D.T., Smith, J.F., Gliedman, J.B., Riedel, B., Filtzer, D., and Renz, D. 1976. "Morphogenesis of Sindbis virus in cultured mosquito cells". In Invertebrate Tissue Culture, Applications in Medicine, Biology, and Agriculture (E. Kurstak and K. Maramorosch, eds.) pp. 35-48. Academic Press, New York. | |
| Gilman, M. 2002. Preparation of cytoplasmic RNA from tissue culture cells. Curr. Protoc. Mol. Biol. 58:4.1.1-4.1.5. | |
| Heldt, C.L., Hernandez, R., Mudiganti, U., Gurgel, P.V., Brown, D.T., and Carbonell, R.G. 2006. A colorimetric assay for viral agents that produce cytopathic effects. J. Virol. Methods 135:56-65. | |
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Author Notes
Updates to this chapter are in progress and will include MTT assay titration of Sindbis virus on Vero cell, a colorometric immunostain focus assay and a fluorescence based immunostain assay. These assays have been developed to deal with titration of mutants which do not form good plaques on BHK or mosquito cells, and to screen for structural mutants.
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