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 research is directly related to inhouse objective 1- Characterize variant and emerging avian influenza viruses in live poultry markets and commercial production systems. For FY2013, survival curves following thermal treatment were generated for 4 Infectious Bursal Disease Viruses (IBDV): STC, OH, VarE and vv/CA strains. The data for chicken and turkey meat were merged and probability plots were generated. Inactivating of greater than 2 log10 IBDV TDIC50/g for IBDV-OH, STC, VarE and vv/CA would require cooking at 70 ºC for 105, 112, 100 and 133 min, respectively, at 75 ºC for 103, 98, 104 and 100 min, respectively, at 100 ºC were 11, 8, 38 and 13 min, respectively. This indicates IBDV is moderately resistant to heat inactivation and the quantity of virus in the tissue will determine the required time and temperature for cooking to inactivate the virus.