China 
Africa 
Explore chapters and articles related to this topic
Quantitative Cell Culture Techniques
Published in Jay L. Nadeau, Introduction to Experimental Biophysics, 2017
With viruses, even more so than bacteria and mammalian cells, it is important to measure the number of functional particles per unit volume. Thus, methods like electron microscopy, which allow for direct counting of particles, are of minimal use. In most viral preparations, a large fraction of the particles are noninfectious, either because they are incomplete or because they have been inactivated by purification methods such as ultracentrifugation. It is thus the infectivity of the solution to a target cell line that is quantified. This unit is referred to as infectious units (i.u.) or transducing units (TUs) per unit volume. Another unit often used in virology is the multiplicity of infection (MOI or m), which refers to the average number of (functional) viral particles per target cell assuming that the distribution of particles within cells follows a Poisson distribution. That is, if m particles/cell are added, the probability P(n) of a cell containing n particles is given by
Sampling and recovery of infectious SARS-CoV-2 from high-touch surfaces by sponge stick and macrofoam swab
Published in Journal of Occupational and Environmental Hygiene, 2023
Rachael L. Hardison, Sang Don Lee, Rebecca Limmer, Joel Marx, Brian M. Taylor, Daniela Barriga, Sarah W. Nelson, Nino Feliciano-Ruiz, Michael J. Stewart, M. Worth Calfee, Ryan R. James, Shawn P. Ryan, Megan W. Howard
Murine hepatitis virus strain A59 (MHV-A59) and L2 cells were kindly provided by Dr. Julian Leibowitz (Texas A&M College of Medicine, College Station, TX) and 17 Clone 1 (17CL-1) cells were provided by Dr. Susan Baker (Loyola University, Chicago, IL). MHV-A59 was titrated on L2 cells and propagated in 17CL-1 cells as described previously (Hardison, Nelson, et al. 2022). Briefly, cells were maintained and propagated in CGM supplemented with Glutamax at 37 °C, 5% CO2. MHV-A59 was propagated in 17CL-1 cells at a multiplicity of infection of 0.3 in low-FBS media (DMEM with Glutamax, 2% FBS, 1% penicillin-streptomycin). Post-inoculation, virus was adsorbed at room temperature for 1 hr; post-adsorption, low-FBS media was added to each flask and incubated at 37 °C, 5% CO2 until the flask reached 80% to 90% cytopathic effect. Infected flasks were directly frozen (−80 °C), thawed at room temperature, and contents were clarified (2,000 × g, 4 °C, 20 min). Clarified viral lysate was aliquoted and stored at −80 °C in single-use (1 mL) vials.
Virucidal Efficacy of Gaseous Ozone Against Type 1 Herpes Simplex Virus (HSV-1)
Published in Ozone: Science & Engineering, 2023
Evans Ahortor, Les Baillie, David Lloyd, James Blaxland
Vero cells were propagated in complete culture medium consisting of DMEM supplemented with 10% fetal bovine serum (FBS, Gibco), 1% Penicillin-Streptomycin (Gibco) and 1% L-Glutamine (Gibco) in a T75 flask at 37°C in 5% CO2. Cells were grown to 90% confluency and harvested for cytotoxicity testing. To propagate HSV-1, Vero cells were cultured to about 90% confluency in complete culture medium as described above washed with 1× PBS and replaced with serum-free DMEM containing HSV-1 suspension. Cells were infected at a multiplicity of infection (MOI) of 0.01 at 37°C for 1 h to allow the virus to attach to cells. After 1 h, the medium was replaced with complete culture media and incubated at 37°C in 5% CO2 for 3–4 days until cytopathic effect (CPEs) was observed. Viruses were harvested and the titer was determined at 2.37 × 107 (TCID 50/mL) using the Spearman–Karber’s method (Lei et al. 2021; Ramakrishnan 2016).
Evaluation of surface disinfection methods to inactivate the beta coronavirus Murine Hepatitis Virus
Published in Journal of Occupational and Environmental Hygiene, 2022
R. L. Hardison, S. W. Nelson, D. Barriga, N. Feliciano Ruiz, J. M. Ghere, G. A. Fenton, D. J. Lindstrom, R. R. James, M. J. Stewart, S. D. Lee, M. W. Calfee, S. P. Ryan, M. W. Howard
Virus and cells [Murine Hepatitis Virus strain A59 (MHV-A59), L2 cells and 17 Clone 1 cells (17CL-1)] were kindly provided by Dr. Julian Leibowitz (MHV-A59 and L2 cells, Texas A&M College of Medicine, College Station TX) and by Dr. Susan Baker (17-CL-1 cells, Loyola University, Chicago, IL). MHV-A59 was titered on L2 cells and propagated in 17 Clone 1 cells (17CL-1) (Sturman and Takemoto 1972). Cells were maintained and propagated in Dulbecco’s Modified Eagle’s Medium with Glutamax (DMEM, Gibco, ThermoFisher Scientific, Allentown, PA), supplemented with 10% Fetal Bovine Serum (FBS, Omega Scientific) and 1% Penicillin-Streptomycin (P/S; ThermoFisher Scientific) at 37 °C, 5% CO2 in tissue-culture treated flasks (CellTreat, Pepperell, MA). MHV-A59 was propagated in 17-Cl-1 cells, at a multiplicity of infection (MOI) of 0.3 in low-FBS media (DMEM with Glutamax, 2% FBS, 1% P/S) using methods previously described (Leibowitz et al. 2011). Post-inoculation, virus was adsorbed at room temperature for 1-hr; post-adsorption, low-FBS media was added to each flask (final volume 12 mL per T-75 flask) and incubated at 37 °C, 5% CO2. Virus was harvested at 80–90% cytopathic effect (CPE); flasks were frozen (-80 °C), thawed at room temperature protected from light and clarified (2000 × g, 4 °C, 20 min). Clarified viral lysate was aliquoted and stored at −80 °C in single-use (1 mL) vials for testing.