Immunity to Escherichia coli in pigs: IgG immunoglobulin in passive immunity to E. coli enteritis.

IgG immunoglobulin was isolated in large quantities from sows' colostrum. The sows were vaccinated intramammarily with a live, formalinized vaccine. A four-stage batch method with DEAE-A50 Sephadex was used in the isolation procedure. Antibacterial tests, heat labile enterotoxin neutralization tests and pig protection tests were employed to investigate the presence of any protective immunity in colostral IgG when compared with whole colostrum. In antibacterial tests, no bactericidal activity was found in colostral whey or colostral IgG from vaccinated or non-vaccinated sows. There was, however, a significant decrease in the rate of multiplication of organisms in tests containing colostral whey or IgG from vaccinated sows when compared with similar preparations from non-vaccinated sows. In enterotoxin neutralization tests using ligated intestinal segments of pigs, the neutralizing effects of colostral whey and IgG on the enterotoxin preparation were significant, whereas only colostral whey afforded significant protection against the vaccine strain of . In pig protection tests, the mean survival time of two groups of 5-day-old gnotobiotic pigs fed colostral whey or IgG was significantly greater than that of the untreated control group. There was no significant difference between the two treated groups.