Thursday, October 16, 2014

Aerosolization tests of Ebola in Animals at USAMRIID confirms disease can spread via air

Because there is so much confusion about the issue of airborne spread of Ebola, this article should clarify the fact that our premier biodefense lab clearly shows that transmission through air may cause infection.  The article is titled, "Development of a Murine (mouse) Model for Aerosolized Ebolavirus Infection Using a Panel of Recombinant Inbred Mice." The URL below will give you the full text article, for free.

Elizabeth E. Zumbrun, Nourtan F. Abdeltawab, [...], and Aysegul Nalca
Countering aerosolized filovirus infection is a major priority of biodefense research. Aerosol models of filovirus infection have been developed in knock-out mice, guinea pigs and non-human primates; however, filovirus infection of immunocompetent mice by the aerosol route has not been reported. A murine model of aerosolized filovirus infection in mice should be useful for screening vaccine candidates and therapies. In this study, various strains of wild-type and immunocompromised mice were exposed to aerosolized wild-type (WT) or mouse-adapted (MA) Ebola virus (EBOV). Upon exposure to aerosolized WT-EBOV, BALB/c, C57BL/6 (B6), and DBA/2 (D2) mice were unaffected, but 100% of severe combined immunodeficiency (SCID) and 90% of signal transducers and activators of transcription (Stat1) knock-out (KO) mice became moribund between 7–9 days post-exposure (dpe). Exposure to MA-EBOV caused 15% body weight loss in BALB/c, but all mice recovered. In contrast, 10–30% lethality was observed in B6 and D2 mice exposed to aerosolized MA-EBOV, and 100% of SCID, Stat1 KO, interferon (IFN)-γ KO and Perforin KO mice became moribund between 7–14 dpe. In order to identify wild-type, inbred, mouse strains in which exposure to aerosolized MA-EBOV is uniformly lethal, 60 BXD (C57BL/6 crossed with DBA/2) recombinant inbred (RI) and advanced RI (ARI) mouse strains were exposed to aerosolized MA-EBOV, and monitored for disease severity. A complete spectrum of disease severity was observed. All BXD strains lost weight but many recovered. However, infection was uniformly lethal within 7 to 12 days post-exposure in five BXD strains. Aerosol exposure of these five BXD strains to 10-fold less MA-EBOV resulted in lethality ranging from 0% in two strains to 90–100% lethality in two strains. Analysis of post-mortem tissue from BXD strains that became moribund and were euthanized at the lower dose of MA-EBOV, showed liver damage in all mice as well as lung lesions in two of the three strains. The two BXD strains that exhibited 90–100% mortality, even at a low dose of airborne MA-EBOV will be useful mouse models for testing vaccines and therapies. Additionally, since disease susceptibility is affected by complex genetic traits, a systems genetics approach was used to identify preliminary gene loci modulating disease severity among the panel BXD strains. Preliminary quantitative trait loci (QTLs) were identified that are likely to harbor genes involved in modulating differential susceptibility to Ebola infection.e article] [PubMed]


Anonymous said...

That is not what this article states. This article is testing the best model mouse for use in studying aerosolized ebola...they used a modified virus for this study. None of the mice models were killed using the aerosolized wild-type virus.

Meryl Nass, M.D. said...

Technically, you are correct that the current wild-type Ebola strain was not used, and another adapted strain was used to infect mice. Mice tend to not be very susceptible to Ebola, unlike humans.

What the study confirmed is that genetic variants of Ebola did infect mice via aerosols.

We know Ebola can survive an hour or more in droplet nuclei. We know Ebola is naturally passaging through many humans and naturally mutating at a high rate. There is no reason to believe that current versions would not also persist in droplets and remain infectious via the aerosol route.

If USAMRIID, which performed these experiments, has shown that Ebola Zaire cannot infect susceptible monkeys or other species via aerosols, I would be delighted to post the data from experiments of this nature..