Neuroinvasion by a Creutzfeldt–Jakob disease agent in the absence of B cells and follicular dendritic cells

2002

J Virol

Self Cite

114

100

Neurons are often assumed to be the principal sites for replication of the infectious agents causing Creutzfeldt-Jakob disease (CJD), scrapie, and bovine spongiform encephalopathy because they express high levels of normal and pathological prion protein (PrP). However, isolated brain cell types have not been evaluated for either infection or gene expression. Microglia purified from CJD-infected mice showed infectivity comparable to that of starting brain homogenate but expressed ϳ50-fold less PrP. CJD-infected microglia also displayed morphological changes indicative of cellular activation. To determine the molecular pathways of activation, we evaluated pertinent transcripts, including those linked to inflammation. Semiquantitative reverse transcription-PCR showed a >4-fold increase in cathepsin S, an enzyme important in antigen presentation, the cytokine interleukin-1␤, and the chemokine B-lymphocyte chemoattractant. The profile of microglial changes induced by the CJD agent differed substantially from activation induced by bacterial lipopolysaccharide or by ␤-amyloid, a structure comparable to pathological PrP. These microglial studies emphasize migratory hematopoietic cells in the dispersion, and possibly replication, of the CJD agent. The low PrP levels in these highly infectious and activated cells further support the concept that pathological PrP is the result of infection rather than the infectious agent itself. Because microglia develop a specific pattern of responses to the CJD agent, microglial markers may be exploited in the diagnosis of these spongiform encephalopathies.Creutzfeldt-Jakob disease (CJD) and scrapie are neurodegenerative diseases caused by infectious agents that are incompletely characterized at the molecular level. The outbreak of bovine spongiform encephalopathy (BSE) and its link to variant CJD in humans makes it important to identify which types of cells carry the agent through the body. Many investigators emphasize neurons in agent spread because these cells accumulate abundant pathological prion protein (PrP), a host protein that aggregates with amyloid properties after infection. Although the contribution of other cell types in the brain, such as microglia, is unknown, such cells are often considered only reactive players. Nevertheless, these infectious agents can be recovered from circulating peripheral white blood cells that have no direct contact with neurons (20).More recent studies have suggested that B lymphocytes or B-cell-dependent follicular dendritic cells are required for infection from the periphery (4, 35). However, this conclusion is contradicted by positive infection in several different B-cellnull mouse models (28, 39). An alternative route for the agent would be through cells of the myeloid lineage (24). Myeloid cells are phenotypically flexible and can develop macrophage or related dendritic cell characteristics in response to environmental stimuli. We have shown that peripheral myeloid cells can carry and maintain the CJD agent for at least 5 weeks in vitro (28...

Section: Discussionmentioning

confidence: 99%

“…However, this conclusion is contradicted by positive infection in several different B-cellnull mouse models (28,39). An alternative route for the agent would be through cells of the myeloid lineage (24).…”

mentioning

confidence: 99%

Microglia from Creutzfeldt-Jakob Disease-Infected Brains Are Infectious and Show Specific mRNA Activation Profiles

Baker

Martín

2002

J Virol

Self Cite

114

100

“…route for both protection and challenge. We used this route because the challenge dose would be limited to the discrete pathways first encountered by SY, and blood can also be a conduit for these CJD agents (21)(22)(23)(24)(25). In this experiment, we used an 80-day interval between SY and FU challenge because peripheral inoculations are less efficient and yield longer incubation times.…”

Section: Resultsmentioning

confidence: 99%

Virus-like interference in the latency and prevention of Creutzfeldt–Jakob disease

Proc. Natl. Acad. Sci. U.S.A.

Lu²

2003

Self Cite

We previously showed that intracerebral (ic) inoculation of the attenuated SY strain of Creutzfeld-Jakob disease in mice could delay clinical signs and widespread neuropathology evoked by subsequent ic challenge with the more virulent FU strain. Using lower doses of SY and FU ic, we here demonstrate that mice can be protected well into old age without demonstrable neuropathology or pathologic prion protein (PrP-res). In contrast, parallel FU only controls became terminally diseased 1 year earlier. To determine whether factors elaborated in response to SY might be part of this effect, we evaluated brain and serum samples from additional parallel mice at 90 days after SY infection and just before FU challenge. The infectivity of FU preparations was significantly reduced by mixing with these fresh SY brain homogenates but not by mixing with SY serum samples, suggesting that brain cells were elaborating labile inhibitory factors that were part of the protective response. SY infectivity was too low to be detected in these brain homogenates. Although suppression could be overcome by higher FU doses ic, strong protection against maximal doses of FU was observed by using i.v. inoculations. Because myeloid microglia are infectious and also elaborate many factors in response to the foreign Creutzfeld-Jakob disease agent, it is likely that innate immunity underlies the profound protection shown here. In principle, it should be possible to artificially stimulate relevant myeloid pathways to better prevent and͞or delay the clinical and pathological sequelae of these infections. agent strains ͉ prion protein ͉ brain factors ͉ antibodies ͉ myeloid cells M any viruses, including those that evade classical immune responses, can evoke an interference response whereby infection with one viral strain can inhibit later superinfection by a second viral strain. In previous experiments, we showed that the slow SY agent, propagated from a typical ''sporadic'' case of Creutzfeldt-Jakob disease (CJD), could prevent superinfection by the more virulent and faster replicating FU agent from Japan (1). The suppression of FU was obvious, even with direct intracerebral (ic) injection of reasonably high doses of FU brain homogenates. Mice first inoculated with uninfected brain and later challenged with FU showed the same short incubation period as mice given only FU. In contrast, there was a dramatic Ϸ150-day delay in of CJD signs in mice first inoculated with SY. These SY-protected mice also exhibited a distinctive SY scratching syndrome, also seen in parallel SY only controls, but not in FU-infected mice. Furthermore, in 16 of 18 SY-protected mice, only the SY neuropathologic profile of minimal and highly localized lesions was seen without the widespread lesions evoked by the FU agent. Thus, it was apparent that the relatively avirulent SY agent itself, or a host response to this exogenous infectious agent, was capable of inhibiting and͞or clearing the more virulent FU agent.Interestingly, levels of abnormally folded prion protein (PrPres) were...

“…33 Such expensive instruments are destroyed by heat, bleach, 1M NaOH and other recommended TSE decontamination procedures, and standard decontamination with aldehydes is not sufficient to inactivate either conventional microorganisms or TSE agents. 34 Because BSE as well as other TSEs, including FU-CJD, also transmit via mucus membranes and the GI tract, 23,35,36 rapid nondestructive liquid treatments that can simultaneously prevent a variety of infectious agents are desirable. TSE agents are believed to be extraordinarily resistant to inactivation as compared to other infectious agents such as bacteria and viruses, and hence their destruction may be extended to other viruses that are difficult to sterilize in a hospital setting, such as Hepatitis B.…”

Section: Introductionmentioning

confidence: 99%

Rapid chemical decontamination of infectious CJD and scrapie particles parallels treatments known to disrupt microbes and biofilms

Botsios

Tittman²,

2015

Virulence

Self Cite

Neurodegenerative human CJD and sheep scrapie are diseases caused by several different transmissible encephalopathy (TSE) agents. These infectious agents provoke innate immune responses in the brain, including lateonset abnormal prion protein (PrP-res) amyloid. Agent particles that lack detectable PrP sequences by deep proteomic analysis are highly infectious. Yet these agents, and their unusual resistance to denaturation, are often evaluated by PrP amyloid disruption. To reexamine the intrinsic resistance of TSE agents to denaturation, a paradigm for less resistant viruses and microbes, we developed a rapid and reproducible high yield agent isolation procedure from cultured cells that minimized PrP amyloid and other cellular proteins. Monotypic neuronal GT1 cells infected with the FU-CJD or 22L scrapie agents do not have complex brain changes that can camouflage infectious particles and prevent their disruption, and there are only 2 reports on infectious titers of any human CJD strain treated with chemical denaturants. Infectious titers of both CJD and scrapie were reduced by >4 logs with Thiourea-urea, a treatment not previously tested. A mere 5 min exposure to 4M GdnHCl at 22 C reduced infectivity by >5 logs. Infectious 22L particles were significantly more sensitive to denaturation than FU-CJD particles. A protocol using sonication with these chemical treatments may effectively decontaminate complicated instruments, such as duodenoscopes that harbor additional virulent microbes and biofilms associated with recent iatrogenic infections.