POLYMERASE CHAIN-REACTION ANALYSIS OF TNF-ALPHA AND IL-6 MESSENGER-RNA LEVELS IN WHOLE-BLOOD FROM CATTLE NATURALLY OR EXPERIMENTALLY INFECTED WITH MYCOBACTERIUM-PARATUBERCULOSIS

Johne's disease is characterized by a chronic enteritis that results i n granulomatous inflammation, cachexia, and eventual death of cattle i nfected with Mycobacterium paratuberculosis. The cytokines tumor necro sis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) have been associ ated with granuloma formation and wasting in other disease syndromes, The potential role of these cytokines in the development and progressi on of Johne's disease has not been investigated, Using the polymerase chain reaction (PCR) and specific bovine oligonucleotide cytokine prim ers and probes, we examined the expression of messenger RNA for these cytokines in whole blood from M. paratuberculosis infected and uninfec ted cattle, Cytokine mRNA levels were examined before and after in vit ro incubation with E. coli lipopolysaccharide (LPS) and lipoarabinoman nan (LAM) purified from M. paratuberculosis, Uninfected calves, experi mentally infected calves, and naturally infected cattle all displayed similar cytokine mRNA expression patterns. However, individual animals demonstrated variability in the levels of IL-6 and TNF-alpha mRNA exp ression as determined by a semiquantitative PCR method using P-32-labe lled oligonucleotide probes.