1a. Objectives (from AD-416):
1. Develop a protocol for the recovery and determination of virus titer for four Infectious Bursal Disease Viruses artificially-inoculated chicken and turkey meat. 2. Develop thermal inactivation curves for infectious bursal disease virus in artificially-inoculated chicken and turkey meat. 3. Determine infectious bursal disease virus titers in breast and thigh meat, thymus and cloacal bursal of chickens inoculated with one of four viruses. 4. Determine thermal inactivation times and temperatures for naturally infected chicken meat and cloacal bursal tissue.
1b. Approach (from AD-416):
1. Artificially infected meat (breast and thigh meat) will be prepared by injecting 1 µl of allantoic fluid containing the virus into the center of packed meat or tissue samples (0.05g). Sample will be maintained at 4C. The concentration of virus in chicken meat and tissue will be determined following the artificial inoculation. Thermal inactivation curves will be generated from which decimal reduction times (D value) and change in thermal resistance (zD values) will be calculated. D-values for 4 infectious bursal disease viruses in artificially inoculated chicken meat will be calculated following thermal treatment at 74C, 75C, 78C, and 80C for 0, 5, 10, 20, 30, 45, 60 and 100 min. 2. Groups of fifteen 4 -week-old chickens will be orally infected with one of four infectious bursal disease viruses to simulate a natural route of infection. At 2, 4, 7, 14 and 21 days after inoculation chickens will be sampled with collection of breast and thigh meat, thymus and cloacal bursa. Samples will be frozen at -70C until used. Tissue samples from naturally-infected chickens (0.05g) will be dispensed into thin walled PCR tubes and centrifuged to pack the meat into the bottom of the tube. Samples will be taken from 3 chickens on 2, 4, 7, 14 and 21 days after inoculation for testing via virus quantification methods. 3. Thermal inactivation curves will be generated from which decimal reduction times (D value) and change in thermal resistance (zD values) will be calculated. D-values for 4 IBDV viruses in natural infected chicken meat and cloacal bursa tissue will be calculated following thermal treatment at 74C, 75C, 78C, and 80C for 0, 5, 10, 20, 30, 45, 60 and 100 min.
3. Progress Report:
This project is related to objective 3 of this in-house project: Identify genetic and biological determinants of avian influenza virus susceptibility and resistance in avian species. For FY2012, thermal inactivation data was generated for infectious bursal disease virus (IBDV) STC and OH strains artificially added to chicken and turkey meat. The thermal death rate for IBDV-STC strain ranged from 38.5 min for D70 to 2.5 min for D100 in chicken meat, and 35.6 min for D70 to 2.3 min for D100 in turkey meat, with z values of 25.4 C and 25.1 C, respectively. Thermal inactivation data generated for IBDV-OH in chicken meat ranged from 33.1min for D70 to 5.3 min for D100, and in turkey meat ranged from 32.4 min at D70 to 2.1 min at D100. The z value was 37.2 C in chicken meat and 23.1 C in turkey meat. The thermal resistance of IBDV2-OH in turkey (23.1 ºC) was lowest compared to the thermal resistance of IBDV-STC in both chicken and turkey, and IBDV2-OH in chicken.