ADVANCED CONTROL TECHNOLOGIES TO BIOCONTAIN AEROSOL TRANSMITTED SWINE DISEASES

<b>Project Methods</b><br> Objective # 1: Optimize the physical collection efficiency of a secondary ionization electrode ESP system. Our first objective is to design and optimize the performance of the ESP. Design will be carried out using a combination of SolidWorks and openFoam software. Following the design of 3 prototype models, using oleic acid droplets (from a nebulizer) and Arizona road dust (from a fluidized bed) as the test particles, the collection efficiency of 3 prototypes at 2800 L min-1 flow rate will be determined using differential mobility analysis with condensation particle counting as well as with aerodynamic particle spectrometry. Prototypes will differ in wire spacing and wire diameter, as well as with tuned operating voltages. Measurements will be carried out in a custom wind tunnel. The ion generation rate will be determined from measurements of the current to the porous plate for both the DC primary and AC secondary electrodes. Ozone production rates will additionally be monitored for all operating conditions. In both collection efficiency and ozone measurements, we will vary the temperature and relative humidity in the system. Toluene oxidation will further be monitored by introducing controlled concentrations of toluene vapor and using a photoionization detector to determine upstream and downstream toluene concentrations. Oxidation of VOCs, occurring due to ozone and hydroxyl radicals, is indicative of the potential for virus inactivation in the ESP, and by comparing toluene oxidation rates to inactivation (subsequently described), we will assess whether the efficacy of virus inactivation can be estimated from simpler, VOC oxidation tests.Objective # 2. Demonstrate a reduction in viable PRRSV and IAV by the ESP technology using experimentally generated aerosols In order to demonstrate reduction in viable virus concentration at the ESP outlet we will aerosolize a solution of PRRSV and influenza, again using our custom wind tunnel designed for control technology evaluation. Inactivation and physical collection, known from the objective #1 engineering studies, will be distinguished from one another by utilizing both quantitative PCR and virus titer measurements.The viruses will be propagated in cell culture media and quantified. A high concentration solution of the viruses will be aerosolized upstream from the ESP. Air samples to quantify the viruses will be collected upstream and dowstream from the ESP with two distinct air collection devices. In addition, the sizes and concentrations of all particles in the chamber will be measured during tests with an optical particle counter. Tests will be run in triplicate for each of the conditions tested, which will include ESP voltages off, ESP DC electrode voltage only, and ESP DC electrode voltage and AC electrode voltage applied. The voltages chosen will be determined by the results of ozone, toluene reduction, and collection efficiency measurements.After collection, samples will be processed, stored at -80°C and tested for molecular analysis of viral RNA and cell culture quantification to assess virus viability. We expect a reduction in the concentration of viable IAV and PRRSV recovered from the ESP treated air using experimentally generated aerosols.Objective # 3: Evaluate airborne transmission of PRRSV and IAV in ESP treated aerosols in pigs experimentally infected and housed under controlled conditions.In order to evaluate the impact of ESP treated aerosols on the transmission of IAV and PRRSV, we will use experimentally infected pigs housed in chambers specially designed to evaluate aerosol transmission of viruses between animals. Pigs in the downstream chamber will only be exposed to aerosols originating from the upstream chamber (no direct pig nose to nose pig contact). If the ESP is effective, negative viral status in the downstream pigs will indicate lack of airborne transmission and effectiveness of the ESP technology at inactivating airborne viruses and preventing airborne transmission.Briefly, two isolator chambers will be connected through a 12 inches long duct containing two partitions (grids) that allows unidirectional air flow from one chamber to the other but no direct nose to nose contact between animals of the two chambers. The chambers will be operated under negative pressure to allow air movement from the upstream chamber containing the virus challenged pigs to the downstream chamber containing sentinel pigs negative to the viruses in the study. Access to the animals during the study is through specially designed glove ports that allow handling of the animals without having to open the chambers.Each pair of chambers will have 4 pigs. Two pigs will be placed in the upstream chamber (inoculated pigs) and 2 pigs in the downstream chamber (sentinel pigs). We will have 3 pairs of chambers with experimentally infected animals with the ESP system ON in order to obtain data in triplicate. We will also have 1 pair of chambers with experimentally infected pigs but without the ESP unit ON to serve as positive control, and one pair without experimentally infected animals to serve as negative control.Eighteen day-old pigs will be purchased, tested on arrival at the isolation units and pigs in the upstream chamber will be inoculated with PRRSV or IAV 48 h after arrival at the isolation units in two different studies. After inoculation, pigs will only be handled through the specially designed glove ports to avoid any cross contamination. Pigs will be sampled prior to inoculation and after inoculation at selected intervals.Objective # 4: Develop an aerosol biosecurity course for undergraduate, graduate students, engineers and veterinarians. We will develop a two-week course focusing on aerosol science, control technology, and biosecurity to train a new generation of professionals towards understanding airborne disease transmission and methods to mitigate it. The course will include in class lectures and hands on experience at the aerosol laboratories. Some of the materials will also be delivered on-line.The course will be delivered in years 2 and 3 of the grant which will allow for course evaluation and incorporation of student feed-back for improving it. The course will be evaluated by asking the students to fill out a survey to evaluate relevance of course content, effectiveness of the instructors at delivering the content, and by asking open ended questions so that specific recommendations can be incorporated in the course. We expect to at least incorporate 2 recommendations made by the students in the delivery of the course during the last year.Objective # 5: Conduct workshops at swine industry conferences to advance awareness, technical understanding, and use of technologies to prevent the introduction and dissemination of airborne diseases in animal populations.Extension related to this project involves stakeholder involvement through engagement in problem identification and input on technology development strategies for testing and implementation of the technologies working with the industry partners at the Swine Disease Eradication Center (SDEC). Extension activities will also include continuing education of broader audiences with special focus to veterinarians, producers and engineers as part of extension workshops destined to the swine industry conducted during the annual meeting of the Allen D. Leman Swine Conference, in St. Paul, MN. A modified and abridged version of this workshop will be targeted to agricultural and environmental engineers, and offered in conjunction with the American Association for Aerosol Research Annual conference (in 2022).