Cross-reactive antibody in immunity to colisepticemia in calves

Review: Evidence against the hypothesis that antibodies to the inner core of lipopolysaccharides in antisera raised by immunization with enterobacterial deep-rough mutants confer broad-spectrum protection during Gram-negative bacterial sepsis

Antisera to rough enterobacterial mutants of chemotypes Ra, Rc, and Re have been reported to confer broad-spectrum protection against wild-type smooth strains. It has been hypothesized that binding and neutralization of lipopolysaccharides (LPS) by antibodies to common core epitopes underlies such protection. This review summarizes experiments by our laboratory and others that do not confirm this concept and proposes reasons for the divergent results. Studies indicating broad-spectrum protection by rough-mutant antisera often had defects in experimental design or methodology. These include the failure: (i) to use matched pre- and postimmune sera from the same donors to control for variable protective activity of normal sera; (ii) to exclude the role of natural and polyclonally stimulated antibodies with proven protective activity against the infecting bacterial strain (e.g. O-specific, capsular, Pseudomonas exotoxin A); (iii) to exclude protective effects of acute-phase serum factors; (iv) to exclude protective effects of endotoxin contamination after adsorption or fractionation of antibody preparations; (v) to use non-boiled bacteria and LPS not subjected to acid-hydrolysis or gel-fractionation, and to exclude nonspecific adsorption, to demonstrate physiologically meaningful binding of rough-mutant antibodies to smooth enterobacteria and their LPS.

Efficacy of a single dose of oral antibiotic given within two hours of birth in preventing watery mouth disease and illthrift in colostrum-deficient lambs

An antibiotic with a product licence limited to the treatment and control of infectious bacterial enteritis associated with Escherichia coli in piglets was tested for its ability to control watery mouth disease in neonatal lambs. Three groups of lambs were kept in conditions commonly encountered in intensive lambing systems, where high levels of environmental bacterial contamination may be expected. They were allocated at birth to: a control group (group 1) consisting of 18 colostrum-deprived lambs; group 2, consisting of 17 lambs given one feed of colostrum when they were two hours old; and group 3, consisting of 18 colostrum-deprived lambs given spectinomycin orally when they were two hours old. Nine group 1 lambs became diseased and were killed for humane reasons. Blood biochemical changes included hyperglycaemia followed by hypoglycaemia, lactacidaemia, hypoproteinaemia and metabolic acidosis, and postmortem examination of the diseased lambs showed signs consistent with endotoxaemia and a clinical diagnosis of watery mouth disease. Coliforms were isolated from the blood of all group 1 lambs and from half the lambs in groups 2 and 3, but endotoxaemia and watery mouth disease occurred only in group 1 lambs. The results for groups 2 and 3 showed that neither colostrum nor antibiotic at the rates and frequency used prevented bacteraemia, although consecutive samples were positive only on three occasions. Group 3 lambs consistently grew more rapidly than the surviving group 1 lambs and as rapidly as group 2 lambs. There was no evidence that male lambs were more prone to watery mouth disease than female lambs. The results indicated that the antibiotic spectinomycin did not induce endotoxaemia during low-grade bacteraemia and that a single oral dose given within two hours of birth protected colostrum-deprived lambs delivered into a contaminated indoor environment against watery mouth disease.

Bacteraemia in man and animals: an overview

Bacteraemia signifies invasion of the bloodstream by bacteria. In most systemic infections in man and animals, bacteria enter the blood at some stage during the infection and are rapidly distributed throughout the body. A wide variety of organisms have been associated with bacteraemia. Prompt detection of the aetiological agents of bacteraemia is of prime importance in clinical microbiology. There are no defined recommendations for blood cultures in animals but both conventional and improved methods are available for detection of bacteraemia in man. The consequences of bacteraemia are as diverse as the potential aetiological agents. Monoclonal antibodies to the core glycolipid (lipid A) seems very promising for the treatment of bacteraemia and septic shock caused by Gram-negative bacteria in man and animals.

Immunity targeting common core antigens of gram-negative bacteria

Antibodies against common gram-negative core antigens can provide protection against environmental, commensual, and contagious bacteria that cause life-threatening gram-negative sepsis/endotoxemia. Cross-protective immunity may be effective against many common livestock diseases, including neonatal coliform septicemia, coliform mastitis, septic metritis, and severe enteritis. The greatest potential benefit of cross-protective immunity may be realized in the reduction of ill-thrift and mortality of neonates. The use of active and passive immunization against core antigens common to gram-negative bacteria has been successful in human beings, laboratory animals, and livestock. Protection has been observed following challenge with either heterologous endotoxin or unrelated, live, virulent gram-negative bacteria.

CS31A, a new K88-related fimbrial antigen on bovine enterotoxigenic and septicemic Escherichia coli strains

The nature of the common surface antigen of six hemagglutinating and adhesive piliated Escherichia coli strains isolated from diarrheic or septicemic calves was studied. By electron microscopy studies, the E. coli surface antigen designated CS31A was found on bacterial cells and in purified form to consist of thin (2-nm) "fibrillar" fimbriae. E. coli 31A, which was cured of a 105-megadalton plasmid, failed to express CS31A fimbriae, but retained the ability to hemagglutinate and to adhere in vitro on intestinal cells. Conversely, E. coli K-12, harboring the 105-megadalton plasmid originating from strain 31A, produced CS31A fimbriae but was not able to hemagglutinate or adhere on intestinal cells. A single fimbrial subunit of 29 kilodaltons was observed when purified fimbriae from the 105-megadalton plasmid-containing E. coli K-12 strain was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis or eluted by gel filtration after dissociation by 8.5 M guanidium hydrochloride from an S300 Sephacryl column. Western immunoblot analysis and the N-terminal sequence and amino acid composition of CS31A indicate structural and immunological relatedness between CS31A and K88 protein subunits.