Lymph nodal prion replication and neuroinvasion in mice devoid of follicular dendritic cells - PubMed (original) (raw)

Figure 1

Western blot analysis of brains and spleens, as well as determination of prion infectivity titers in spleens and lymph nodes of scrapie-challenged TNF- and LT-deficient mice. (A and B) Western blots of brain material electrophoresed natively (−), or after digestion with proteinase K (PK; +). Large amounts of PK-resistant prion protein (PrPSc) were detected in the brain of all mice that had developed scrapie (terminal sick), independently of the genotype. Clinical healthy mice deficient in LT signaling showed no PrPSc accumulation, excluding subclinical scrapie (A). (C) Western blots of spleen homogenates electrophoresed natively (−) or after digestion with proteinase K (PK) (+). TNFR1−/− and TNFα−/− mice accumulated lower amounts of PrPSc as compared with TNFR2−/− and wild-type mice. No PrPSc was detected in the spleens of clinical healthy LT-deficient mice. (D) Prion infectivity in lymphoid organs. Titers were determined in spleens (blue circles), inguinal (red circles), mesenteric (red crosses, x), and cervical (red inverted open triangles) lymph nodes at the time points indicated below. Mice were inoculated i.p. with 6 log LD50 or 4 log LD50 of scrapie prions as indicated. Standard deviations within groups are drawn only when exceeding ±0.75 log LD50. (a and b) In each of the two separate transmissions, one of the four tga20 mice died 24 h after inoculation, most probably because of i.c. bleeding after injection. (j and k) Intercurrent death during incubation time. Symbols on the abscissa indicate prion titers below detection limit (none of the four indicator mice developed scrapie). If one or more indicator mice survived >180 dpi, or the mean incubation time was over 120 days, titer was assumed to be close to the detection threshold of the bioassay. For these samples (labeled with small letters), the numbers of animals succumbing to scrapie of four inoculated tga20 mice and incubation time (in days in parentheses) to terminal scrapie were as follows: c, 1/4 (111); d, 3/4 (93, 117, 132); e, 2/4 (90, 95); f, 1/4 (126); g, 3/4 (112, 123, 128); h, 4/4 (106, 115, 124, 136); i, 3/4 (89, 102, 119); l, 4/4 (115, 115, 126, 135); m, 1/4 (98); n, 2/4 (74, 78); o, 2/4 (125, 151); p, 2/4 (131, 193); q, 3/4 (119, 125, 152); r, 2/4 (109, 117); s, 1/4 (108); t, 1/4 (71); u, 3/4 (80, 96, 98); and v, 2/4 (98, 98).