Table 1. Disinfection study parameters for evaluation of 6 disinfectants for reducing Ebola virus titers in dry blood or cell culture medium*.
| Parameter | NBACC | DSTL |
|---|---|---|
| Virus (dilution in blood) |
Ebola virus/Makona-C05 (1:10) |
Ebola virus/Makona-C07 (1:10) |
| Cells |
Vero C1008, Vero 76, clone E6, Vero E6
(ATCC CRL-1586) |
Vero C1008, ECACC #85020206 |
| Blood source |
Human whole blood in EDTA
(Bioreclamation IVT, Westbury, NY, USA) |
Fresh whole blood in EDTA from male Porton rats |
| Blood droplet size (µL) and state |
10, wet or dried |
20, dried |
| Surface coupons |
304 stainless steel (Diamond Perforated Metals, Visalia, CA, USA); 6061 Aluminum (Speedy Metals, New Berlin, WI, USA) used for experiments with dry medium (peracetic acid and acidified bleach) and wet blood (peracetic acid) only |
3014 stainless steel |
| Disinfectant | ||
| Sodium hypochlorite | ||
| Supplier | Clorox (Oakland, CA, USA) | Sychem (Leigh On Sea, UK) |
| Concentration tested, vol/vol | 0.5%, 10% hypochlorite | 1% hypochlorite |
| Volume tested, µL | 30 or 100 | 100 |
| Contact time, min | 15 | 15 |
| Peracetic acid | ||
| Supplier | Sigma-Aldrich (St. Louis, MO, USA) | Sigma-Aldrich |
| Concentration tested, vol/vol | 5% | 0.2% |
| Volume tested, µL | 100 | 100 |
| Contact time, min | 5 | 10 |
| Micro-Chem Plus | ||
| Supplier | National Chemical Laboratories, Inc. (Winona, MN, USA) | ND |
| Concentration tested, vol/vol | 1.5% | |
| Volume tested, µL | 30 or 100 | |
| Contact time, min | 10 | |
| Purell Advanced | ||
| Supplier | GOJO Industries (Akron, OH, USA) | ND |
| Concentration tested, vol/vol | 70% ethanol | |
| Volume tested, µL | 30 | |
| Contact time, min | 2 | |
| Steriplex SD | ||
| Supplier | sBioMed LLC (Orem, UT, USA) | ND |
| Concentration tested | 0.015% silver, 10.000% ethanol, 0.020% H2O2, 0.150% peroxyacetic acid, 0.150% acetic acid, 0.075% inert food grade ingredients proprietary, 89.590% water | |
| Volume tested, µL | 100 | |
| Contact time, min | 5 | |
| Acidified bleach | ||
| Supplier | Clorox | ND |
| Concentration tested, vol/vol | 10% bleach (0.5% sodium hypochlorite) + 1% acetic acid | |
| Volume tested, µL | 100 | |
| Contact time, min |
15 |
|
| Method | ||
| Neutralization | 5 mL cell culture medium (10% FBS) or direct recovery using washing/filtration | 2 mL cell culture medium (2% FBS) |
| Recovery method | 30 μL bleach: none (5 mL medium only); 100 µL bleach; Steriplex SD: acidified bleach or peracetic acid; after neutralization in 5 mL medium, 2 mL was ultrafiltered in an Amicon (Bedford, MA, USA) 100-kDa NMWL unit, washed 3 times with 2 mL PBS after centrifugation at 5,000 × g for 10 min, and resuspended in 2 mL medium; Purell Advanced: diluted to 130 μL with PBS and recovered using a PD MultiTrap G-25 96-well microplate column array. Dilute supernatant to 5 mL with medium; Micro-Chem Plus: samples directly added to Amicon Ultra-0.5 (30- or 100-kDa NMWL) ultrafiltration unit, washed 3 times with 0.5 mL PBS by centrifugation at 5,000 × g for 10 min, and resuspended in 5 mL medium | Washed by centrifugation 8,000 rpm for 5 min and resuspended in 1 mL medium |
*Titers were assessed by using the 50% tissue culture infectious dose assay. ATCC, American Type Culture Collection; DSTL, Defence Science and Technology Laboratory; ECACC, European Collection of Authenticated Cell Cultures; FBS, fetal bovine serum; NBACC, National Biodefense Analysis and Countermeasures Center; ND, no data; NMWL, nominal molecular weight limit; PBS, phosphate-buffered saline.