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McOrist, S.

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McOrist, S

OpenGrey Repository

The aetiology of the proliferative enteropathies

The entezopathogenicity and antigens of Campylobacter-like organisms and
Campylobacter app associated with the proliferative enteropathies were investigated.

Two gnotobiotic pigs exposed orally to a filtered suspension of intestinal mucosa
designated 284/86 from a naturally infected pig subsequently developed lesions of
proliferative enteritis. Culture of the successful mucosal inoculum only revealed a
moderate number of C. coli, however an apparently greater number of Campylobacter-like
organisms was evident in smears of this inoculum. The pathogenesis of porcine
proliferative enteritis was clearer from the results of this study. Ten days after
infection, curved bacilli had colonised the ileal and large intestinal crypts. Attachment and 
entry of Campylobacter-like organisms into crypt enterocytes was also
evident, with some proliferation of both bacteria within cells and of the enterocytes
themselves. Twenty days after infection there was similar intracellular colonisation
of bacteria and proliferative activity, although no luminal bacteria were evident. A 
moderate sub-acute inflammatory reaction was evident throughout.

Conventional hamsters dosed with C. jejuni developed varying degrees of localised
acute intestinal inflammation. Hamsters dosed with C. hyointestinalis or C. cola
did not develop any lesions. Lesions of proliferative enteritis were detected in
hamsters dosed with porcine tissue 284/86. Numerous intra-cytoplasmic Campylobacter-like
organisms were detected within enterocytes in affected portions of intestine. Weanling
hamsters this proved to be susceptible to the agent of porcine proliferative enteritis by
cross-species transmission.

Whole cell antigen preparations were made of various Camoylobacter sp. Indirect
immunofluorescence assays incorporating rabbit antisera to each Campylobacter sp gave
specific endpoints for each antiserum of 1: 160 to 1: 320. Rabbit antisera prepared to
Campylobacter-like organisms partly purified from proliferative enteritis mucosa, by
a homogenisation and filtration technique, also gave specific reactions in this assay,
up to 1: 610. Intracellular Campylobacter-like organisms were also compared in gel
electrophoresis protein profiles and immunoblotting reactions to Campylobacter spp.
The intracellular organisms tested had a distinctive protein profile dissimilar to the
profiles of the known Campylobacter spp. In immunoblotting reactions, each of the
Camoylobacter sp antisera reacted strongly with homologous antigens, but none reacted
with Camcylobacter-like organisms prepared from lesions, except for a minor reaction
seen with one serum. Similarly antisera to Campylobacter-like organisms showed a
strong reaction to 25K to 27K components of homologous antigens, with only minor
reactions to various other components of the cultivated Campylobacter app. Therefore it
is likely that the intracellular Campylobacter-like organisms have a distinctive antigenic
profile and that the 25 and 27K components are major antigenic components.

Mouse monoclonal antibodies were produced that were apparently specific to the
intracellular Camoylobacter-like organisms. Immunoblotting results showed that these
antibodies only bound to a 251 to 27K outer membrane component present in the intracellular
organisms. Reactions with this component could not be detected in assays with normal pig
intestine, or Camoylobacter sp antigen.

Restriction endonuclease digestion of Camoylobacter sp with Bgl II gave suitably
resolved DNA fragments of between 2kb and 25kb. Patterns obtained with Bgl II digestion
of Camoylobacter sp were dissimilar to those of Camoylobacter-like organisms, and each
Camoylobacter sp had a characteristic distinct pattern. Digestion of DNA from porcine
tissue samples with Bgl II produced a diffuse smear of fragmented DNA bands between
0.5 and19kb, with no recognizable "ladder" effect. The genome of the Carylobacter-like
organisms within enterocytes in proliferative enteritis therefore is different to that of
known Camoylobacter spp associated with the disease. This suggests that the differences
in antigenic structures between these bacteria axe due to genetic differences. Only a
limited number of strains were examined.

Looking at the evidence provided by this study, the overall tenor of the results
suggests that the intracellular organisms could be a separate, new species of
Campylobacter. If indeed the intracellular organisms are a single, new Cammylobacter
species, then a new name may be proposed, such as "C. intracellulare". Verificationth of 
the validity of such a proposal would require further DNA studies

McOrist, Steven

Edinburgh Research Archive

The aetiology of the proliferative enteropathies.

https://era.ed.ac.uk/bitstream/1842/6938/1/383022.pdf

The aetiology of the proliferative enteropathies.

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