Today, the U.S. Food and Drug Administration cleared for marketing four previously cleared tests with new indications to aid in the diagnosis of Lyme disease. The tests cleared today are the first time that a test has been indicated to follow a new testing paradigm in which two tests called enzyme immunoassays (EIA) are run concurrently or sequentially, rather than the current two-step process in which a separate protein test called a Western Blot must be run after the initial EIA test.
“Lyme disease can have a devastating impact on patients. With today’s action, clinicians have a new option to test for Lyme that is easier to interpret by a clinical laboratory due to the streamlined method of conducting the test. These tests may improve confidence in diagnosing a patient for a condition that requires the earliest possible treatment to ensure the best outcome for patients,” said Tim Stenzel, M.D., Ph.D., director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health.
Lyme borreliosis (LB) is a global tick-borne disease caused by infection with Borrelia burgdorferi sensu lato. The disorder develops in stages and has different manifestations that mainly involve the skin, nervous system, and joints. The blots were assessed blindly and, to minimize any variation in interpretation, were always assessed.
Lyme disease is caused by the bacteria Borrelia burgdorferi and is transmitted to humans through the bite of infected ticks. Typical symptoms include fever, headache, fatigue and skin rash called erythema migrans. If left untreated, infection can spread to joints, the heart and the nervous system. In 2017, the last year for which the Centers for Disease Control and Prevention (CDC) has published data, a total of 42,743 confirmed and probable cases of Lyme disease were reported to CDC, an increase of 17% from 2016.
Laboratory diagnosis of Lyme disease has traditionally used a two-tier process for detecting the presence of antibodies against Borrelia burgdorferi in a patient’s blood. Antibodies are proteins present in the blood when the body is responding to a specific infection. In the previous two-tier approach, different types of tests were used (EIA and Western blots) to confirm a clinical diagnosis. The tests cleared today involve a modified approach that uses only EIA technology-based tests.
The FDA reviewed data from clinical studies of the ZEUS ELISA Borrelia VlsE1/pepC10 IgG/IgM Test System, ZEUS ELISA Borrelia burgdorferi IgG/IgM Test System, ZEUS ELISA Borrelia burgdorferi IgM Test System, and the ZEUS ELISA Borrelia burgdorferi IgG Test System that showed this alternative approach, referred to as a modified two-tier test, is as accurate as current methods for detecting antibodies for assessing exposure to Borrelia burgdorferi, the causative agent of Lyme disease, over current methods.
CDC recommendations should be followed for the diagnosis of Lyme disease and for determining when laboratory tests are appropriate.
The enzyme immunoassay tests were reviewed through the premarket notification (510(k)) pathway. A 510(k) is a premarket submission made to the FDA to demonstrate that the device to be marketed is at least as safe and effective, that is, substantially equivalent, to a legally marketed device.
- Western blots are labor intensive and expensive, but provide a method of confirming the identity of a reactive antigen. Western blots are done by electrophoresis of antigen (i.e., purified virus) by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE).
- But the longer a tick stays attached to you, the more likely it is to transmit Borrelia burgdorferi (the bacteria that causes Lyme disease), if the tick is a carrier. If not found and treated, Lyme.
- Objective: Autoimmune destruction of the adrenal gland is the major cause of Idiopathic Addison's disease, but the significance of 21-hydroxylase autoantibodies and their correlation with the presence of other autoantibodies have not so far been investigated in a larger population of patients with Addison's disease. We have now characterized a cohort of patients with.
- There are currently no accepted criteria for positive Western blots in Lyme disease. In a retrospective analysis of 225 case and control subjects, the best discriminatory ability of test criteria was obtained by requiring at least 2 of the 8 most common IgM bands in early disease (18, 21, 28, 37, 41, 45, 58, and 93 kDa) and by requiring at least 5 of the 10 most frequent IgG.
The FDA granted clearance of the ZEUS ELISA enzyme immunoassay tests to ZEUS Scientific.
The FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements, products that give off electronic radiation, and for regulating tobacco products.
- FDA: Ticks and Lyme Disease: Symptoms, Treatment, and Prevention
- FDA: Premarket Clearances
- CDC: Lyme disease
Prion disease is a rare, progressive, neurodegenerative disorder that affects humans (vCJD, CJD), cows (BSE), sheep (Scrapie), and elk/deer (CWD). It leads to characteristic brain lesions and a rapid loss in neurological functions after a long latency period. The accumulation of an altered isoform of a normal cellular protein appears to be instrumental in the development of prion disease.
There are several ways to identify the presence of the abnormal prion protein - a bioassay, immunohistochemistry on diseased tissue samples, and with a faster, well-characterized, and sensitive Western blot.
The Western blot below shows Scrapie infected sheep brain lysates (Lanes 3&4) compared to normal sheep brain lysates (Lanes 1&2). The key to this particular Western assay is the use of Proteinase (PK) treatment on parallel sets of samples. Since the Scrapie associated form of the prion protein is resistant to digestion, it is possible to distinguish between normal cellular forms and abnormal prion protein in a sample based upon their sensitivity to PK.
Thus, it is possible to discriminate diseased samples from normal ones quickly and unambiguously on a Western blot. The absence of bands in lane 2 indicates that the normal form is present as compared to the bands visible in lane 4, which indicate the presence of the pathogenic form.
Figure 18: Detection of Scrapie Infected Sheep Brain. Bands in lane 4 indicate that the protease resistant form of the prion protein is present in the sample as compared to normal tissue in lane 2. Lanes 1&2: Uninfected sheep brain homogenate. Lanes 3&4: Scrapie-infected sheep brain homogenate. Lanes 1&3: No PK added. Lanes 2&4: Digested with PK.
Confirmation of HIV
In the diagnosis of HIV infection in patients, an ELISA is used first because it demonstrates 99 .5% specificity and is quick and easy to perform on a large number of samples. Western blotting is used as a supplementary assay because the ELISA is subject to false positives.
In order to perform this assay, patient serum samples are used as the source of antibodies for immunodetection, and blots containing HIV antigens, proteins, viral lysates, or peptides are used as the source of target antigen on the Western blot. If the HIV target proteins on the blot are detected by the patient serum then it indicates that the patient sample is a true positive for HIV infection, since an immune response has been mounted by the patient. A similar strategy is also used in tests for Lyme disease and autoimmune disease. Q shows picard the borg.
|Western Blot Example: Demonstrating Antibody Specificity.||Chapter 5: Western Blot Buffers|