Transmission of Creutzfeldt-Jakob disease from human blood and urine into mice

Mouse inoculation studies reveal no transmissible agent in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) resembles the spongiform encephalopathies in its dual pattern of inherited and sporadic cases, its uniform prevalence in different populations, its late onset (suggestive of a long incubation period) and its pathological picture of neuronal degeneration without inflammation. There is a well-established protocol for primary transmission of scrapie and related diseases to mice. Using this, we inoculated four longlived, inbred, mouse strains with cord material fresh-frozen within three hours of death, from a case of ALS or a control case. No motor neuron loss, gliosis or tract demyelination was found in the experimental group. Fifty per cent of each group were observed for more than 600 days. Two types of lesions were found in these animals at death: widespread foci of white matter vacuolation and bilateral thalamic mineral deposits. They were present in the control group at the same incidence and severity as in the experimental group and were thus considered to represent an age-related change. Attention is drawn to them because they have been claimed as significant when found in a transgenic model of spongiform encephalopathy. The results of our carefully-controlled experiment suggest that it is unlikely that ALS is caused by a scrapie-like agent capable of transmission to mice.

Creutzfeldt-Jakob disease after liver transplantation

We report a 57-year-old woman who died from Creutzfeldt-Jakob disease 2 years after a liver transplantation. The liver donor had no history of neurological disease. In one albumin donor, possible Creutzfeldt-Jakob disease developed 3 years later. The patient initially had cerebellar symptoms. Neuropathology included "Kuru-type" plaques and prion protein (PrP) deposits involving the cerebellum predominantly. The patient was homozygote valine at codon 129 of the PrP gene while the liver was homozygote methionine. This observation raises the possibility of transmission of Creutzfeldt-Jakob disease by the graft itself or the associated albumin transfusions and, on a wider extent, by nonneural tissue.

Animal spongiform encephalopathies--an update. Part 1. Scrapie and lesser known animal spongiform encephalopathies

The present article (part I) reviews recent developments in animal spongiform encephalopathies (SEs), with the exception of bovine spongiform encephalopathy (BSE), which is dealt with in part II. The article focuses on scrapie and describes epidemiological aspects and the prospects for a preclinical diagnosis. Up to now, confirmatory diagnosis of scrapie depended on histological examination of the brain, collected during post-mortem examination from sheep with clinical signs of the disease. An altered protein, PrPSc, can be detected in the brain of diseased animals. The demonstration of the same protein in the spleen and in peripheral lymph nodes of infected animals seems to offer interesting possibilities of arriving at a method for a preclinical diagnosis, and thus a diagnosis in the live animal. Progress has also been made in our understanding of the relationship between the genetic constitution and susceptibility of the host. Susceptibility is expressed as the survival time of sheep inoculated with scrapie. This was thought to be determined by a single genetic locus designated the Sip gene (scrapie incubation period gene). Putative markers for the two alleles of the Sip gene, sA and pA, have been discovered, consisting of restriction fragment length polymorphisms (RFLPs). In field tests, however, the link between these markers and the length of incubation time was far from consistent. These RFLPs were found to be situated outside the prion-protein-coding region of the ovine gene. In later studies, RFLPs were detected inside this region. These markers appear to be more informative, i.e. they correspond with a difference in the length of the scrapie incubation period.(ABSTRACT TRUNCATED AT 250 WORDS)

Creutzfeld-Jakob disease: recommendations for infection control

Creutzfeld-Jakob disease, an infectious, progressive, degenerative neurologic disorder, has a presumably long incubation period but a rapid, fatal course. Brain tissue at autopsy resembles that seen in spongioform encephalopathies of other species. Creutzfeld-Jakob disease is transmitted by a proteinaceous infectious agent, or "prion." Epidemiologic patterns remain uncertain; various studies have reported conflicting risk factors in different populations, and genetic susceptibility may be involved. Although natural transmission routes are still unclear, both iatrogenic and nosocomial transmissions have been identified. Transmission has occurred through contaminated electrodes, contaminated biologic products from cadaveric brains, and infected donor tissues, including dura mater and corneas. Because the prion is difficult to eradicate, stringent sterilization precautions must be taken with all surgical instruments. Some tissues and body fluids (e.g., brain, ocular, central nervous system) from the patient with Creutzfeld-Jakob disease are highly infectious and must be contained or incinerated. Some body fluids, however, are not considered infectious. Persons with known or suspected Creutzfeld-Jakob disease, or with exposure to potential sources of iatrogenic infection, should not be considered as donors for any tissues or biologic products. Occupational transmission to health care and pathology workers is also possible. Therefore, specific preventive measures are necessary. Many questions remain regarding transmission and risk factors for Creutzfeld-Jakob syndrome, and the precautions presented here must be considered only preliminary.

Protected endogenous retroviral sequences copurify with infectivity in experimental Creutzfeldt-Jakob disease

Scrapie and Creutzfeldt-Jakob disease (CJD) are caused by infectious agents that are defined phenomenologically. No agent-specific molecules or particles have been identified. Biological properties, such as exponential agent replication and strain variation, as well as physical characteristics of infectivity indicate a protected viral structure. A host membrane glycoprotein of 34 kDa ("prion" protein) that aggregates at end stages of disease is clearly important in pathology and susceptibility to infection, but has no demonstrable infectivity in any purified or recombinant form. Thus a characterization of more viral-like molecules is important. In order to identify viral-like nucleic acids we previously developed methods to substantially purify the human CJD agent from experimentally infected hamster brains, and demonstrated selected retroviral-like LTR bands at pg levels that were insufficient for sequencing. To further define these and other viral-like sequences we cloned nucleic acids from highly infectious CJD fractions, and tested the efficacy of our methods using a selected retroviral probe. RNA extracted from an infectious 120 S Gaussian peak, which is reproducibly purified approximately 100,000 fold with respect to starting nucleic acids, and contains approximately 20% of the initial brain infectivity, was used to generate a cDNA library in a sequence independent amplification strategy for low levels of RNA (< 6 ng). Reconstituted strong stop experiments using several retroviral tRNA primers had indicated that Syrian hamster IAP (SHIAP) sequences should be present in both CJD and uninfected control fractions. Because SHIAP particles are extremely resistant to denaturation, their representation in a cDNA library would imply adequate extraction of other protected RNAs of viral origin. At least 900 bases of the Syrian hamster retroviral IAP genome were unambiguously identified in the cDNA library, and in independent PCR walks with selected primers, all of which were based on our cloned sequences. Sequencing confirmed the presence of protected LTR and adjacent retroviral motifs. Because these sequences were also present in control preparations they may represent normal endogenous viral contaminants that cosediment with infectivity in size and density gradients. On the other hand, LTRs can drive the expression of many diverse sequences, and it remains to be seen if CJD specific sequences are either transduced, or copackaged with, protected IAP complexes. The effective extraction and amplification of highly protected SHIAP nucleic acids of significant length sets the stage for identifying additional protected viral elements that may specify the CJD agent.

Creutzfeldt-Jakob disease and blood transfusion

Epidemiological surveillance of Creutzfeldt-Jakob disease (CJD) in the UK identified 21 patients who had received a blood transfusion and 29 who had donated blood, out of a total of 202 definite and probable cases. This frequency of blood transfusion or donation did not differ from that in age and sex matched controls, and the clinical features in patients with a history of blood transfusion were similar to those of classical CJD and clearly distinct from CJD in recipients of human growth hormone. This evidence does not suggest that blood transfusion is a major risk factor for CJD.

Nuclease-resistant polyadenylated RNAs of significant size are detected by PCR in highly purified Creutzfeldt-Jakob disease preparations

The molecular nature of the 'unconventional viruses' that cause slow, progressive brain deterioration is still poorly understood. As part of a reinvestigation of potential agent-specific nucleic acids, we developed a protocol for enriching agent-specific sequences. This protocol uses extensive micrococcal nuclease digestion followed by rate zonal sucrose sedimentation. Most of the infectivity in the gradient (84%) had a characteristic mean size of approximately 120S, and was resolved from 70% of a host glycoprotein (PrP) that can cosediment with infectivity. In infectious size fractions, nucleic acids were reduced approximately one million-fold with respect to starting brain homogenate, and specific purification of infectivity was approximately 100,000-fold with respect to nucleic acid. Using a novel polymerase chain reaction strategy, we were able to amplify RNA species in these fractions. Remarkably, host polyadenylated sequences of 1 to over 4 kb were detected in the nuclease-protected infectious fractions. These strategies set the stage for the identification of similar nucleic acids that may be specific for the CJD agent.

Creutzfeldt-Jakob disease: implications for growth hormone deficient children

For over 25 years children with short stature due to growth hormone deficiency have been able to achieve normal height with the aid of human growth hormone (hGH) injections. Following reports of four deaths due to Creutzfeldt-Jakob disease (CJD) in young adults previously treated with hGH this treatment has ceased. There are major implications due to the potential risks of further cases of CJD and to the lack of a previously well-tried therapeutic substitute.