Aims: To develop infectious (live/dead) enveloped virus test indicators and response surface methodology (RSM) models that evaluate survival of an enveloped ribonucleic acid (RNA) virus on contaminated aircraft materials after exposure to hot, humid air (HHA). Methods and Results: Enveloped RNA bacteriophage Phi6 (6) was dried on wiring insulation, aircraft performance coating (APC), polypropylene, and nylon at ≥ 8 log 10 plaque-forming units (PFU) test coupon −1. Only 2.4 log 10 inactivation was measured on APC at 70 • Celsius (• C), 5% relative humidity (RH) after 24 h. In contrast, HHA RSM models showed a 90% probability of a 7 log 10 inactivation at ≥63 • C, 90% RH after 1 h, and decontamination kinetics were similar across different materials. HHA decontamination of C-130 and C-17 aircraft showed >7 log 10 and ≥5.9 log 10 inactivation of enveloped virus on 100 and 110 test indicators, respectively, with a 1-h treatment, excluding ramp-up and ramp-down times. Conclusions: Enveloped RNA virus test indicators were successfully developed, lab tested for HHA decontamination, analyzed for RSM, and field-tested in aircraft demonstrations. Significance and Impact of the Study: The utility of HHA decontamination was demonstrated after inactivating enveloped RNA virus on aircraft with a 1-h HHA treatment within aircraft temperature and RH limits.

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Aims: To develop infectious (live/dead) enveloped virus test indicators and Response Surface Methodology (RSM) models that evaluate survival of an enveloped ribonucleic acid (RNA) virus on contaminated aircraft materials after exposure to hot, humid air (HHA). Methods and Results: Enveloped RNA bacteriophage Phi6 (φ6) was dried on wiring insulation, aircraft performance coating (APC), polypropylene, and nylon at ≥8 log10 plaque-forming units (PFU) test coupon-1. Only 2.4 log10 inactivation was measured on APC at 70°Celsius (°C), 5% relative humidity (RH) after 24 h. In contrast, HHA RSM models showed a 90% probability of a 7-log10 inactivation at ≥63°C, 90% RH after 1 h, and decontamination kinetics were similar across different materials. HHA decontamination of C-130 and C-17 aircraft showed >7 log10 and ≥5.9 log10 inactivation of enveloped virus on 100 and 110 test indicators, respectively, with a 1-h treatment, excluding ramp-up and ramp-down times. Conclusions: Enveloped RNA virus test indicators were successfully developed, lab tested for HHA decontamination, analyzed for RSM, and field-tested in aircraft demonstrations. Significance and Impact of the Study: The utility of HHA decontamination was demonstrated after inactivating enveloped RNA virus on aircraft with a 1-h HHA treatment within aircraft temperature and RH limits.

Aims: To add a spore germination step in order to reduce decontamination temperature and time requirements compared to the current hot, humid air decontamination parameters, which are 75-80°C, ≥72 h, 70-90% RH, down to ≤60°C and ≤24 h total decontamination time. Methods and Results: Bacillus anthracis spore germination with L-alanine+inosine+calcium dipicolinate (CaDPA) was quantified at 0-40°C, several time points and spore concentrations of 5-9 log 10 per ml. Germination efficiency at 0-40°C was >99% at <8 log 10 spores per ml. The temperature optimum was 20°C. Germination efficiency was significantly higher but slower at 0°C compared to ≥30°C at ≥8 log 10 spores per ml. A single germinant application followed by 60°C, 1-h treatment consistently inactivated >2 log 10 (>99%) of spores. However, a repeat application of germinant was needed to achieve the objective of ≥6 log 10 spore inactivation out of a 7 log 10 challenge (≥99Á9999%) for ≤24 h total decontamination time for nylon and aircraft performance coating. Conclusions: L-alanine+inosine+CaDPA stimulated germination across wide temperature and spore concentration ranges. Significance and Impact of the Study: Germination expands the scope of spore decontamination to include materials from any industry sector that can be sprayed with an aqueous germinant solution.

Aims:  The aims of this work were to investigate the effects of sera on B. anthracis Sterne germination and growth. Sera examined included human, monkey and rabbit sera, as well as sera from eight other species. Methods and Results:  Standard dilution plate assay (with and without heat kill) was used as a measure of germination, and spectroscopy was used to measure growth. In addition, a Coulter Counter particle counter was used to monitor germination and growth based on bacterial size. Spores germinated best in foetal bovine and monkey sera, moderately with human sera and showed limited germination in the presence of rabbit or rat sera. Vegetative bacteria grew best in foetal bovine sera and moderately in rabbit sera. Human and monkey sera supported little growth of vegetative bacteria. Conclusion:  The data suggested sera can have a significant impact on germination and growth of Sterne bacteria. Significance and Impact of the Study:  These data should be considered when conducting in vitro cell culture studies and may aid in interpreting in vivo infection studies.