Test ID: HTLVI
Human T-Cell Lymphotropic Virus Types I and II (HTLV-I/-II) Antibody Screen with Confirmation, Serum
NY State Approved 
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Qualitative detection of human T-cell lymphotropic virus types I and II (HTLV-I and HTLV-II)-specific antibodies with confirmation and differentiation between HTLV-I and HTLV-II infection.
Reflex Tests Lists test(s) that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial test(s)
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| HTLVL | HTLV-I/-II Ab Confirmation, S | Yes | No |
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
If HTLV-I/-II antibody by EIA is reactive, HTLV-I/-II antibody confirmation by line immunoassay will be performed at an additional charge.
Method Name A short description of the method used to perform the test
HTLVI/9539: Enzyme Immunoassay (EIA)
HTLVL/83277: Line Immunoassay (LIA)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Collection Container/Tube: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild reject; Gross reject |
| Lipemia | Mild reject; Gross reject |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum SST | Frozen (preferred) | |
| Refrigerated | 7 days | |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Human T-cell lymphotropic virus types I and II (HTLV-I and HTLV-II) are closely related exogenous human retroviruses. HTLV-I was first isolated in 1980 from a patient with a cutaneous T-cell lymphoma, while HTLV-II was identified from a patient with hairy cell leukemia in 1982.
HTLV-I infection is endemic in southwestern Japan, Caribbean basin, Melanesia, and parts of Africa, where HTLV-I seroprevalence rates are as high as 15% in the general population. In the United States, the combined HTLV-I and HTLV-II seroprevalence rate is about 0.016% among voluntary blood donors. About half of these infected blood donors are infected with HTLV-I, with most of them reporting a history of birth in HTLV-I-endemic countries or sexual contact with persons from the Caribbean or Japan. Smaller percentages report a history of either injection drug use or blood transfusion. Transmission of HTLV-I occurs from mother to fetus, sexual contact, blood transfusion, and sharing of contaminated needles. Two diseases are known to be caused by HTLV-I infection: adult T-cell leukemia or lymphoma (ATL), and a chronic degenerative neurologic disease known as HTLV-I-associated myelopathy (HAM) or tropical spastic paraparesis (TSP). Cases of polymyositis, chronic arthropathy, panbronchiolitis, and uveitis also have been reported in HTLV-I-infected patients.
HTLV-II is prevalent among injection drug users in the United States and in Europe, and >80% of HTLV infections in drug users in the United States are due to HTLV-II. HTLV-II also appears to be endemic in Native American populations, including the Guaymi Indians in Panama and Native Americans in Florida and New Mexico. HTLV-II-infected blood donors most often report either a history of injection drug use or a history of sexual contact with an injection drug user. A smaller percentage of infected individuals report a history of blood transfusion. HTLV-II is transmitted similarly to HTLV-I, but much less is known about the specific modes and efficiency of transmission of HTLV-II. The virus can be transmitted by transfusion of cellular blood products (whole blood, red blood cells, and platelets). HTLV-II infection has been associated with hairy-cell leukemia, but definitive evidence is lacking on a viral etiologic role. HTLV-II has also been linked with neurodegenerative disorders characterized by spastic paraparesis and variable degrees of ataxia.
Infection by these viruses results in the appearance of specific antibodies against the viruses that can be detected by serologic tests such as enzyme immunoassays (EIA). For accurate diagnosis of HTLV-I or HTLV-II infection, all initially screening test-reactive results should be verified by a confirmatory test, such as Western blot or line immunoassay.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Negative
Interpretation Provides information to assist in interpretation of the test results
Negative screening results indicate the absence of both human T-cell lymphotropic virus types I and II (HTLV-I- and HTLV-II)-specific IgG antibodies in serum.
A reactive screening test result is suggestive of infection with either HTLV-I or HTLV-II. However, this result does not confirm infection (eg, low specificity), and it cannot differentiate between HTLV-I and HTLV-II infection.
Specimens with reactive screening test results will be tested automatically by the line immunoassay (LIA) confirmatory test. Positive LIA results provide confirmatory evidence of infection with HTLV-I or HTLV-II.
-Positive results for HTLV-I antibodies indicate the confirmed presence of HTLV-I IgG antibodies in serum, based on 2 visible antibody bands that include gp21-I/-II band, or 3 or more bands, and the sum of the gp46-I and p19-I band intensity is greater than the gp46-II band intensity.
-Positive results for HTLV-II antibodies indicate the confirmed presence of HTLV-II IgG antibodies in serum, based on 2 visible antibody bands that include gp21-I/-II band, or 3 or more bands, and the gp46-II band intensity is a) greater than the gp46-I band intensity and b) > or =the sum of the gp46-I and p19-I band intensity.
Indeterminate LIA results indicate the presence of gp21-I/-II band only or combination of any 2 bands without a detectable gp21-I/-II band. Patients with indeterminate test results with known risk factors for HTLV-I or HTLV-II infection should undergo repeat confirmatory antibody testing in 1 to 2 months to determine final infection status.
When the LIA band intensity pattern does not meet the criteria of a positive HTLV-I- or HTLV-II-antibody band intensity pattern, differentiation of HTLV-I and HTLV-II infection is not possible (ie, nontypeable HTLV antibodies).
A reactive screening result with a negative or indeterminate confirmatory test result suggests either a false-reactive screening test result or a seroconverting HTLV infection. Repeat testing in 1 to 2 months can clarify the final infection status. Persistently indeterminate confirmatory test results indicate absence of HTLV infection.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test is not offered as a screening or confirmatory test for serum specimens from blood, human cells, tissues, or solid organ donors.
This test is not intended for screening blood, human cells, tissues, or solid-organ donors.
A negative test result does not exclude the possibility of exposure to human T-cell lymphotropic virus types I and II (HTLV-I or HTLV-II). Levels of total antibodies to these viruses may be undetectable in early infection.
Performance characteristics have not been established for serum specimens that are hemolyzed, lipemic, icteric, or contain particulate matter.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Centers for Disease Control and Prevention: Guidelines for counseling persons infected with human T-lymphotropic virus type I (HTLV-I) and type II (HTLV-II). MMWR Morb Mortal Wkly Rep 1993;42(RR-9):1-13
2. Murphy E, Roucoux D: The epidemiology and disease outcome of human T-lymphotropic virus type II. AIDS Rev 2004;6:144-154
3. Projetti FA, Carneiro-Projetti AB, Catalan-Soares BC, et al: Global epidemiology of HTLV-I infection and associated diseases. Oncogene 2005;24:6058-6068
Method Description Describes how the test is performed and provides a method-specific reference
EIA Screen:
In the MP Diagnostics, HTLV-I/-II ELISA 4.0, the wells of the polystyrene microplate strips are coated with a mixture of 3 different human T-cell lymphotropic virus (HTLV) recombinant proteins, which correspond to the highly antigenic segments of HTLV-I and HTLV-II viruses. Human sera diluted in a diluent containing the conjugate are incubated in these coated wells. The conjugate is based on a trifusion recombinant protein, which is labeled with horseradish peroxidase. The trifusion antigen is generated by cloning 3 cDNA fragments coding for the 3 HTLV recombinant proteins into a single vector. HTLV-I/-II-specific antibodies (IgA, IgG, and IgM), if present, will bind to both the antigens immobilized on the solid phase and the trifusion antigen of the conjugate. After incubation, the wells are thoroughly washed to remove unbound materials. A colorless substrate solution containing chromogen 3,3',5,5'-tetramethylbenzidine (TMB) is then added to each well. The presence of specific antibodies is indicated by the presence of a blue color after incubation, which changes to yellow when the color reaction is terminated by the addition of sulfuric acid. The intensity of the resulting yellow product is measured at 450 nm using a spectrophotometer and is proportional to the amount of antibodies present in the specimen. Initially reactive specimens will be retested in duplicate. Specimens that do not react in either of the duplicate repeat tests are called "nonreactive" for antibodies to HTLV-I/-II. Specimens that are reactive in either of the duplicate tests are considered "repeatedly reactive." (Package insert: HTLV-I/-II ELISA 4.0, revision 4; MP Biomedicals Asia Pacific Pte. Limited. Singapore)
Line Immunoassay (LIA) Confirmation:
INNO-LIA HTLV I/II is a line immunoassay that uses well-defined antigens derived from HTLV-I and HTLV-II immunodominant proteins. The antigens used are either recombinant proteins or synthetic peptides, highly purified and fixed on a nylon membrane strip. The sequences are selected to allow the detection of antibodies with a wide specificity to all known isolates of the HTLV strains. The antigenicity exhibited by these proteins and peptides is either common to both HTLV-I and HTLV-II, or type-specific to 1 of the 2 viruses to allow confirmation and discrimination in a single assay. Two gag (p19-I/II, p24-I/II) and 2 env (gp46-I/II, gp21-I/II) bands are applied as nontype-specific antigens, which are used to confirm the presence of antibodies against HTLV-I/II. The type-specific antigens for HTLV-I (gag p19-I, env gp46-I) and for HTLV-II (env gp46-II) are applied to differentiate between HTLV-I and HTLV-II infections. In addition, 4 control lines are coated: 1 negative control (streptavidin), and 3 positive control lines, a strong (antihuman IgG), a moderate (human IgG), and a weak (human IgG) line.
This assay is based on the enzyme immunoassay principle. Specific anti-HTLV antibodies, if present in the clinical sample, will bind to the HTLV antigen lines on the strip. Subsequently, goat antihuman IgG antibodies labeled with alkaline phosphatase are added and will bind to any HTLV antigen-antibody complex previously formed. Incubation with a chromogenic substrate produces a dark brown color in proportion to the amount of specific antibodies present in the sample. The color development is stopped with sulfuric acid. If the sample contains no HTLV-specific antibodies, only a low background color develops.
Every sample is classified as negative, indeterminate, or positive, then further classified as HTLV-I, HTLV-II, or untypeable-positive according to the antibody band reactivity. (Package insert: INNO-LIA HTLV I/II Score kit 25957 v5; INNOGENETICS N.V., Gent, Belgium)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
HTLV-I/-II Antibody Screen: Monday through Friday; varies
HTLV-I/-II Antibody Confirmation: Wednesday; 3:00 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
86687-HTLV-I/-II
86689-Confirmation (if appropriate)
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 9539 | HTLV-I/-II Ab Screen, S | 29901-6 |
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