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The objectives of this study were: a) to determine whether infectious PEDV could be detected in air samples under experimental conditions; and b) to evaluate whether the electrostatic particle ionization (EPI) system could reduce the quantity and viability of airborne PRRSV, influenza A virus (IAV) and PEDV in aerosols generated by acutely infected pigs.
The EPI system was installed at 1.3m height along the length of a 35 m3 unit. Ten out of 12 pigs were intra-nasally and intra-tracheally infected with an H1N1 IAV (4.4×106 TCID50/ml) and intra- nasally, and intra-muscularly with PRRSV strain 1-8-4 (1.13×105 TCID50/ml). At day 21 of the study, all pigs were intra-gastrically inoculated with 20 ml of PEDV- positive materia. Air samples were collected for 30 min with the EPI system ‘off ’ and ‘on’ during the 24 days of the study. Oral fluids, clinical signs, coughing and lethargy score were collected at each replicate. Samples were analyzed by quantitative IAV, PRRSV and PEDV RT-PCR for 9, 20 and 3 days respectively and virus viability tested on specific cell cultures or bioassay. Differences in the quantity of virus, removal efficiency and total particle counts by size were calculated during the study with the system ‘off ’ and ‘on.’
Pigs became positive to IAV, PRRSV and PEDV after challenge infection. Results from the air sampling dem- onstrated that PEDV was present in all air samples collected from the experimentally infected pigs. The estimated number of RNA copies/ m3 of air ranged from 1×106 to 1 × 109. Results from the bioassay demonstrated the presence of viable virus and inoculated pigs experienced moderate to severe diarrhea (Ct values ranged from 15 to 16) after 24h of inoculation. The EPI system was able to significantly reduce the quantity of IAV, PRRSV and PEDV from the air. Overall the removal efficiency was positive throughout all days of the study for all pathogens (with the exception of 1 replicate of PEDV) and ranged from 50-100% for IAV, 97-100% for PRRSV, and 26-99.8% for PEDV. Removal efficiency was calculated as the initial concentration of aerosolized virus with the EPI system ‘off ’ minus final concentration with the system ‘on’ divided by initial concentration.
Results from our study indicate for the first time, that PEDV can be found in the air and that suspended airborne particles can be infectious. Further studies are needed to investigate the role of infectious airborne transmission for PEDV under field conditions. In addition, the EPI system was effective at reducing the quantity of IA, PRRS and PED viruses found airborne. However the significance of this reduction needs to be further studied under field conditions.
Carmen Alonso, Peter Raynor, Robert Morrison, Peter R Davies, Montserrat Torremorell. Airborne transmission of PED virus and effect of the electrostatic particle ionization technology on decreasing airborne swine viruses. 2015 AASV Annual Meeting.
