Heat lability of five strains of infectious bursal disease virus

An extensive world trade environment has created a need for many nations to protect their food animal industries against the importation of pathogenic microorganisms. We initiated studies to determine how cooking conditions w ould affect the viability of different infectious bursal disease virus (IBD V) strains. Five different viral strains were tested. The strains included two serotype 1 variant viruses, Del-A and MD; two serotype 1 classic viruse s, STC and D78; and a serotype 2 virus, OH. A 100-mu L aliquot of each vira l stain in Dulbecco's Modified Eagle Medium with 2% fetal calf serum was he ated to 37, 65, 71, 74, 77, 82, or 100 C for 1 min. Following heat treatmen t, the virus titers were determined in a BGM-70 cell culture. Virus titers declined following each incubation,and there were no appreciable difference s among the five viral strains tested. The greatest decline in titer occurr ed at temperatures above 65 C. After 1 min at 65, 71, and 100 C, reduction of viable viruses were greater than or equal to 90, greater than or equal t o 99, and >99.9%, respectively, compared to nonheated controls. A viral red uction curve similar to the first heating trial was observed when viruses w ere heated at 71 or 74 C for 6 min. Drumsticks and boneless chicken patties were seeded with the virus at a mean value of 10(5.5) TCID50/25 mu L of TB DV and were cooked to internal temperatures of 71 and 74 C, respectively. A ll samples were quickly cooled after achieving target temperatures. Viable virus was recovered from both products following cooking.