1638
Immuno - cytochemistry , using antisera against Campylobacter jejuni , showed that the positive staining in altered epithelial cells were restricted to intracellular organisms having a structure resembling Campylobacter spp .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
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