Molecular Subtyping and Source Attribution of Campylobacter Isolated from Food Animals.

Campylobacter spp. commonly cause gastrointestinal illness in humans. Poultry meats have long been considered the predominant source of these infections, but few in-depth Campylobacter source attribution studies have been completed. We analyzed more than 1,300 Campylobacter isolates recovered from a number of animal and food sources, including dairy and beef cattle, pigs, poultry, and retail poultry meat, and compared them with Campylobacter isolates recovered from human clinical samples. Each isolate was subtyped using pulsed-field gel electrophoresis (PFGE) with SmaI and queried against the Centers for Disease Control and Prevention PulseNet database to identify human isolates with indistinguishable patterns. Half (49.5%) of the PFGE patterns from poultry animal and retail meat isolates were indistinguishable from patterns of at least one human isolate. Among the isolates from beef and dairy cows, 56.6 and 65.0%, respectively, of their PFGE patterns were indistinguishable from those of human isolates. Only a small portion of the PFGE patterns of Campylobacter isolated from pigs (9.5%) were found to have PFGE patterns in common with human isolates. These data imply that cattle may be larger contributors to Campylobacter infections than previously recognized and help further our understanding of potential sources of human campylobacteriosis.

Host differences in serum antibody response during infection of goats by caprine arthritis-encephalitis virus.

The response of goats infected with caprine arthritis encephalitis virus was evaluated by estimating the binding antibodies in serum. The immunoreactive proteins of the CAEV, strain 63, were determined by immunobloting the lysate against the serum of the infected goat. The major proteins identified were of the molecular weights of 135, 120, 56, 44, 38, 28, 20 and 13 kDa. Proteins with less prominence were of the molecular weights of 96, 32 and 30 kDa. The responses to the viral proteins at several stages of the infection were examined. Antibodies to viral proteins of 135, 121 and 90 kDa were the first to appear in the goat kids that were apparently infected through breast-feeding by infected dam. The time of appearance of these antibodies in the serum varied widely between the goats from one to six months, and preceded the appearence of antibodies to other proteins by two to four weeks. Salient variations revealed in the immunoblot patterns reflect the differences in the immunological responses by the goats to the viral proteins. Littermate goat kids infected through the same dam showed slightly different responses. In the same manner, dissimilarities were observed in the patterns produced by the serums of the damand the corresponding offsprings, when run against the same virus lysate. This study indicates that some differences occur in the immunoblot pattern when this assay is used for diagnosis, although such discrepancies should not affect the interpretation of the diagnostic assay. The host differences in the response to the viral proteins also suggest the potential problems that can be encountered developing an effective vaccine for CAEV, if the binding antibody production reflects that of the neutralizing antibodies in the goats. For effective vaccine coverage, there should be little variability in the immunogenicity of candidate vaccine antigens among the hosts.