1a.Objectives (from AD-416):
1. Investigate modified simple slaughter methods to reduce aerosol generation during home slaughter process and determine the impact of such improvements on reducing virus transmission.
2. Improved methods of evaluating vaccine efficacy in poultry AI vaccines.
3. Determining infectivity, transmissibility, and pathogenicity of 5 isolates of H5N1 highly pathogenic avian influenza virus (HPAIV) for pigs.
1b.Approach (from AD-416):
Aerosol generation and virus levels will be measured in rooms conducting simulated home processing of asymptomatic H5N1 HPAI virus infected chickens. A simple, plastic-bag method for processing will be evaluated for reducing aerosol and virus generation and reducing transmission to chicken and ferret models. Develop attenuated H5 AI viruses that will be used to produce reference antibodies from chickens for testing cross neutralization of H5 HPAI viruses in a chicken egg neutralizing test as a means to assess vaccines seed strain efficacy against drift variant field viruses. Five H5N1 HPAI viruses will be intrabronchally inoculated into pigs and examined for contact transmission. Pigs will be examined for infection by serology, virus isolation, and RRT-PCR assays.
This project is related to objective of this in-house project: Identify genetic and biological determinants of avian influenza virus susceptibility and resistance in avian species.
During FY 2012, multiple experiments were performed. For transmission studies, the high efficiency particle air (HEPA) filtered flexible film isolation unit was validated for conducting and containing high pathogenicity avian influenza (HPAI) virus when used for infected chicken processing studies. Studies indicated that negative-ionizing air samplers were more efficient at recovering HPAI virus in air when using a dry sample collector than a liquid filled sample collector. In looking at the initial step in chicken processing, using a standard open barrel method for slaughter produced high concentrations of HPAI virus in the air while reduced quantities of airborne virus were produced when using a Hala pot with a sliding lid for initial kill step. A cyclone sampler was validated to replace the negative-ionizing air sampler as a more efficient instrument to detect airborne virus. The cyclone sampler determined that the majority of the airborne virus was contained in large respiratory droplets, but some was present in aerosolized particles. In examining slaughter methods, the standard open-barrel method produced the most airborne virus, with increased reductions in airborne virus using a cook pot with lifting lid, a cook pot with sliding lid and modified plastic bucket. These data indicate that alternative methods can be used in developing countries for household slaughter to decrease human risk for HPAI virus infections.