Evaluating the Virucidal Efficiency of Xpert® Hemorrhagic Fever Test Sample Reagent

The objective of this study is to determine the efficiency of the Xpert® Hemorrhagic Fever

Sample Reagent (HFSR) to inactivate Ebola, Crimean-Congo Hemorrhagic Fever, Marburg and Lassa viruses. The live EBOV, CCHF, MARV or LASV virus stocks concentration was previously determined by the plaque forming assay performed by the Galveston National Laboratory and virus titers should be as high as possible in the laboratory condition.

 

To evaluate inactivation capacity with the highest virus concentration as possible, the stock virus culture will not be diluted in a whole blood matrix but will be added directly to the HFSR. The 100 µL of virus stock is added to 1 mL of HFSR and the samples will be inverted 15 times to mix virus and HFSR and incubated at ambient/room temperature (RT) for 10 minutes.

 

After incubation, the mixture will be diluted in 1/100 to reduce potential artefacts from the HFSR on tissue culture cells. The virucidal efficiency of the HFSR is assessed by carrying out 3 serial passages of the diluted virus/HFSR mixture in Vero E6 or SW-13 cells (1 week for each passage) with each passage monitored for cytopathic effect (CPE) and followed by PCR analysis (RUO, CE-IVD, or well-validated PCR method) to show there is no detectable level of virus present.

 

As PCR methods detect the presence of viral RNA rather than viable and infectious virus, it will be considered as no viable virus detected if Ct values of PCR analysis do not significantly decrease over 3 passages. If any CPE is observed or earlier Ct is observed over 3 passages, plaque forming assay will be performed to verify and quantify any remaining live virus in media.

 

Proposed inactivation testing will be conducted by Dr. Dennis Bente’s laboratory at the Galveston National Laboratory under BSL-4 biological security confinement and shall be in strict compliance with Federal & State biosafety regulations