Mechanisms involved in protection provided by immunization against core lipopolysaccharides of Escherichia coli J5 from lethal Haemophilus pleuropneumoniae infections in swine

Abstract

In an investigation of the potential protective effects of immunity against common lipopolysaccharide core antigens of gram-negative bacteria during a severe gram-negative infection in the natural host, we induced Haemophilus pleuropneumoniae infections in weanling pigs immunized with a vaccine of an Rc mutant of Escherichia coli (strain J5). To help define the mechanism involved in J5-mediated protection, we compared the clinical, hematologic, bacteriologic, and serologic responses following an H. pleuropneumoniae infection in J5-immunized pigs with those following an H. pleuropneumoniae infection in nonimmunized control animals. As a result of an intranasal inoculation, all of the control animals and the J5-immunized animals were infected with H. pleuropneumoniae. However, while 80% (4 of 5) of the nonimmunized pigs died within 24 h as a result of the infection, no deaths occurred in the J5-immunized animals. In the immunized group, J5 titers dropped during the acute stages of the infection and rebounded to well above the prechallenge levels during convalescence. The J5 titer also increased in the single surviving control animal. These findings suggest that antibodies against common subsurface components of gram-negative bacterial cell walls correlate with protection from an otherwise lethal challenge of H. pleuropneumoniae but do not prevent infection. Important growth-phase-dependent antigenic changes have been recognized to occur during the growth of H. pleuropneumoniae in cultures (R. Nielson, Nord. Veterinaermed. 28:337-348, 1976). In a study of these changes and during an inquiry into the mechanism of J5 antibody-mediated protection, measured quantities of H. pleuropneumoniae were removed from a broth culture at hourly intervals and used to absorb hyperimmune equine J5 antiserum. Significantly greater amounts of J5-specific antibodies were absorbed during the log phase of bacterial growth than during the early or late phase. The availability of epitopes recognized by J5 antibodies appears to be closely related to the rate of bacterial multiplication. The results of these experiments suggest a mechanism of protection provided by increased immunity to E. coli J5 during gram-negative infections.

Virulence properties and protective efficacy of the capsular polymer of Haemophilus (Actinobacillus) pleuropneumoniae serotype 5

“…Twenty hours later the animals were challenged intratracheally with 5 x 107 CFU of strain J45 (Table 3). Strain J45 was used for challenge studies because this strain is a relatively fresh porcine isolate that has been used in other pathogenesis studies (6). Antiserum to strain K17 was used for passive 0/3 3/3 Monospecific to capsule 80-160 <10 3/3 3/3 Swine antiserum to live 80-160c 40c 2/3 1/3 K17 a Pigs were challenged intratracheally with 5 x 10' CFU of serotype 5 strain J45 20 h after passive transfer of 20 ml of immune or normal swine serum.…”

Effect of Passive Transfer Status and Vaccination with Escherichia coli (J5) on Mortality in Comingled Dairy Calves

“…4,5 The basis of R mutant immunization is the hypothesis that vaccination with homologous core antigens may provide protection against disease caused by unrelated gram-negative bacteria. Examples of diseases for which heterologous protection using E. coli J5 as a vaccine antigen has been demonstrated include Actinobacillus pleuropneumoniae infections of pigs, 6,7 gram-negative mastitis of dairy cows, [8][9][10] and Edwardsiella ictaluri septicemia in channel catfish. 11 Although Cullor et al 12 demonstrated that calves vaccinated with an experimental bacterin containing E. coli J5 were protected against virulent challenge with Salmonella dublin, field trials with similar vaccines have had mixed results.…”

Efficacy of a cell extract from Actinobacillus (Haemophilus) pleuropneumoniae serotype 1 against disease in swine

“…The capsule may not play a major role in protection, since capsule alone is a poor immunogen (18) and acapsular mutants appear to be as virulent as the parent strain (17). This theory may also be extended to include endotoxin, on the basis of previous work by Fenwick and co-workers (10)(11)(12). However, capsule, endotoxin, and OMPs may be collectively involved in protection.…”

“…Capsular polysaccharides are serotype specific and poorly immunogenic (18). Protection with partially purified outer membrane proteins (OMPs) and lipopolysaccharides was comparable with that of current commercial products (10)(11)(12)33), and partial protection was reported for a capsular polymer (17).…”