Two variant strains of infectious bursal disease virus, IN and E, were adapted and passaged in an established cell line (BGM-70) 30 times and 40 times, respectively. Passage in cell culture resulted in loss of pathogenicity. However, both viruses maintained their antigenicity and immunogenicity, as demonstrated by the immunofluorescence and virus-neutralization tests and by the satisfactory protection induced by vaccinating specific-pathogen-free (SPF) chickens with inactivated preparations of both passaged viruses. No protection was induced when the passaged viruses were given to SPF chickens as live vaccines. It is speculated that the passaged viruses might have lost some ability to replicate in their natural host, resulting in lack of protection.

Seven hundred eighty male and female turkeys representing four genetic lines were challenged in four experiments with the Texas GB strain of Newcastle disease virus (NDV). The lines of turkeys included two randombred control lines (RBC1 and RBC2), a subline (E) of RBC1 selected for increased egg production, and a subline (F) of RBC2 selected for increased 16-week body weight. Mortality in turkeys of subline F (32.5%) was significantly higher than that in turkeys of line RBC2 (15.8%), subline E (17.5%), and line RBC1 (18.4%). At the end of each experiment, surviving birds were tested for antibody to NDV using the enzyme-linked immunosorbent assay (ELISA) and hemagglutination-inhibition (HI) test. Turkeys of subline E and line RBC1 had significantly lower ELISA antibody titers than those of subline F and line RBC2. Subline F had the highest HI antibody titers, followed in decreasing order by lines RBC2 and RBC1 and subline E. No apparent correlation was found between antibody response and mortality after NDV challenge.

Treatment of cytochronne c with iodoacetate a t pH = 3.0 Ieads to loss of activity in the succi~iate oxidase system, alteration of spectra, and loss of the specific hemochronne properties characteristic of the native protein. The change in properties is paralieled by the incorporation of carboxymethyl groups (up to a maximum of two) and the destruction of methiotnine. The chymotryptic peptide maps also suggest that the loci of modification are the naethionine residues a t positions 65 and 80. Both residues are equally amenable to attack a t about the same rate as free methionine, suggesting that they are located on the surface of the molecule. Certain features of the kinetics of carboxyrnethyIation suggest the E ossible existence of a monocarboxymethyl derivative with unmodified properties, tst modification of both methionines clearly leads to marked loss of function.

Primary and secondary antibody responses of 671 turkeys of two genetic lines to Newcastle disease virus (NDV) and Pasteurella multocida vaccines were examined. The randombred control line (RBC2) and a subline (F) of RBC2 had been selected for increased 16-week body weight. Poults were vaccinated at 6 and 12 weeks of age, and serum samples were collected 3 weeks after each vaccination. Antibody titers were determined using an enzyme-linked immunosorbent assay. Line F turkeys had significantly higher 9-week and 15-week serum antibody titers to NDV than line RBC2. However, line RBC2 had significantly higher serum antibody titers to P. multocida at 15 weeks of age than line F. The 9-week and 15-week serum antibody titers to NDV were significantly higher in females than males, but males had significantly higher 15-week serum antibody titers to P. multocida than females. Sex of poults did not contribute significantly to variation in serum antibody response to P. multocida at 9 weeks of age.

An avidin-biotin-enhanced enzyme-linked immunosorbent assay (AB-ELISA) and an avidin-biotin-enhanced dot-immunobinding (AB-DIB) assay for detecting antibody to Bordetella avium in turkey sera were developed and compared with the microagglutination (MA) test. Whole-cell antigen, biotin-labeled goat anti-turkey IgG conjugate, and horseradish-peroxidase-labeled streptavidin were used in the AB-ELISA and AB-DIB assay. The AB-ELISA and AB-DIB assay were sensitive, specific, and reproducible. These assays were superior to the MA test for measuring acquired and maternal antibodies against B. avium. All MA-positive sera were positive by two assays, but some sera negative by MA test had titers in the AB-ELISA and AB-DIB assay. AB-ELISA and AB-DIB titers showed a positive correlation (r = 0.866), and AB-ELISA was more sensitive than the AB-DIB assay.