Human Immunodeficiency Virus Type 1 and Type 2 Antibodies

Synonym/acronym: HIV-1/HIV-2.

Common use

Test blood for the presence of antibodies that would indicate a human immunodeficiency virus (HIV) infection.

Specimen

Serum (1 mL) collected in a red-top tube. Place separated serum into a standard transport tube within 2 h of collection.

Normal findings

(Method: Enzyme immunoassay) Negative.

Description

HIV is the etiological agent of AIDS and is transmitted through bodily secretions, especially by blood or sexual contact. The virus preferentially binds to the T4 helper lymphocytes and replicates within the cells using viral reverse transcriptase, integrase and protease enzymes. Current assays detect antibodies to one or more of several viral proteins. Public health guidelines recommend CD4 counts and viral load testing upon initiation of care for HIV; 3 to 4 mo before commencement of ART; every 3 to 4 mo, but no later than 6 mo, thereafter; and if treatment failure is suspected or otherwise when clinically indicated. Additionally, viral load testing should be requested 2 to 4 wk, but no later than 8 wk, after initiation of ART to verify success of therapy. In clinically stable patients, CD4 testing may be recommended every 6 to 12 mo rather than every 3 to 6 mo. Guidelines also state that treatment of asymptomatic patients should begin when CD4 count is less than 350 cells/microL; treatment is recommended when the patient is symptomatic regardless of test results or when the patient is asymptomatic and CD4 count is between 350 and 500 cells/microL. Failure to respond to therapy is defined as a viral load greater than 200 copies/mL. Increased viral load may be indicative of viral mutations, drug resistance, or noncompliance to the therapeutic regimen. Testing for drug resistance is recommended if viral load is greater than 1,000 copies/mL. Initial screening is generally performed using a third-generation immunoassay for antibodies to HIV1/HIV2. The antibody screening tests most commonly used do not distinguish between HIV1 and HIV2. A reactive screen result is followed by repeat testing in duplicate. Positive or indeterminate results should be confirmed by Western blot assay where positive is defined by the Centers for Disease Control and Prevention (CDC) as presence of two of the three viral proteins: gp41, gp120 (from the viral membrane), and p24 (from the viral core). The newest HIV testing algorithm was developed jointly by the Association of Public Health Laboratories and the CDC. This new algorithm provides for earlier detection of acute infection as well as identification of established infection. Recommendations for initial screening call for the use of a fourth-generation immunoassay capable of the simultaneous detection of HIV antigen and antibody. The fourth-generation assays demonstrate the ability to detect infection 7 days earlier than third-generation assays. Positive initial screens should be followed by a rapid immunoassay that differentiates between HIV1 and HIV2 antibody. A negative or indeterminate supplemental antibody result should be followed by a nucleic acid amplification test (NAAT), during the period after infection has occurred but before the development of antibodies to the virus, to determine if HIV viral RNA is present. The HIV screening test is routinely recommended as part of a prenatal work-up and is required for evaluating donated blood units before release for transfusion. The CDC has structured its recommendations to increase identification of HIV-infected patients as early as possible; early identification increases treatment options, increases frequency of successful treatment, and can decrease further spread of disease. The CDC recommends the following:

Include HIV testing in routine medical care; screening of all patients between the ages of 13 and 64 years of age as part of routine medical care, unless the patient requests to opt out.
Implement new models to diagnose HIV infections outside medical settings; promote availability of rapid waived testing kits like OraQuick.
Prevent new infections by working with persons diagnosed with HIV and their partners; adapt a voluntary opt-out approach that includes elimination of pretest counseling and written consent requirements.
Further decrease prenatal transmission of HIV by incorporating HIV testing as a routine part of prenatal medical care and also perform third-trimester testing in areas with high rates of HIV infection among pregnant women.

HIV genotyping by polymerase chain reaction (PCR) methods may also be required to guide selection of medications for therapeutic regimens, assess potential for drug resistance, and monitor for transmission of drug resistant HIV. Genotyping is also useful to determine eligibility for new medications once resistance to conventional drugs has been identified.

This procedure is contraindicated for

N/A

Indications

Evaluate donated blood units before transfusion
Perform as part of prenatal screening
Screen organ transplant donors
Test individuals who have documented and significant exposure to other infected individuals
Test exposed high-risk individuals for detection of antibody (e.g., persons with multiple sex partners, persons with a history of other sexually transmitted diseases, IV drug users, infants born to infected mothers, allied health-care workers, public service employees who have contact with blood and blood products)

Potential diagnosis

Positive findings in:

HIV1 or HIV2 infection

Critical findings

N/A

Interfering factors

Drugs that may decrease HIV antibody levels include didanosine, dideoxycytidine, zalcitabine, and zidovudine.
Nonreactive HIV test results occur during the acute stage of the disease, when the virus is present but antibodies have not sufficiently developed to be detected. It may take up to 6 mo for the test to become positive. During this stage, the test for HIV antigen may not confirm an HIV infection.
Test kits for HIV are very sensitive. As a result, nonspecific reactions may occur, leading to a false-positive result.

Nursing Implications and Procedure

Potential nursing problems

Problem	Signs & Symptoms	Interventions
Knowledge (Related to the emotional nature of the disease; new condition or diagnosis; lack of familiarity or understanding with disease and treatment; treatment complexity; fear; misinterpretation provided information)	Lack of interest or questions; multiple questions; anxiety in relation to disease process and management; verbalization of inaccurate information; lack of follow-through with directions	Identify patient’s, family’s, and significant others’ concerns about HIV infection; explain the importance of receiving a hepatitis B vaccine, annual influenza vaccine and pneumococcal vaccine to protect health; assist patient to identify at-risk behaviors (sexual activities and IV drug use); instruct to avoid raw foods that can cause infection from bacteria and protozoa in compromised individuals; avoid emptying cat litter boxes to avoid organism exposure; discuss safe sex practices, ways to express intimacy without infection exposure; discuss the importance of using safe needles for recreational drug use; encourage drug rehabilitation and provide contact information; explain the importance of refraining from blood donation
Infection (Related to decreased CD4 cells; detectable viral load; confirmed HIV antibody secondary to HIV infection)	Fever; swollen lymph glands in the armpit, neck, and groin; sore throat; rash; unexplained fatigue; achy muscles and joints with pain; headache; weight loss; fever and night sweats; diarrhea lasting more than a week; mouth, anal, and genital sores; pneumonia; blotches (red, brown, pink, or purplish) on or under the skin located in the mouth, or nose; depression; memory loss; neurologic disorders	Monitor and trend vial load and CD4 laboratory results; explain the purpose of antiviral medication; administer prescribed antiviral medication (nucleoside and nonnucleoside reverse transcriptase inhibitors, protease inhibitors, integrase strand transfer inhibitors, fusion inhibitors); ensure legal regulations regarding testing are adhered to; reinforce the necessity of strict adherence to the designated treatment plan
Nutrition (Related to fatigue; no appetite; oral candidiasis; nausea; vomiting; malabsorption; secondary to HIV infection)	Weight loss; pale dry skin; dry mucous membranes; documented inadequate caloric intake; loss of subcutaneous tissue, muscle, fat; hair pulls out easily; loss of muscle; decreased body mass index	Record accurate daily weight at the same time each day with the same scale; obtain an accurate nutritional history; assess for nausea and administer prescribed medication; inspect the mouth and assess for oral candidiasis infection; administer prescribed medications antimonilial, anabolic steroids, testosterone supplements, human growth hormones, dronabinol; administer prescribed medications to enhance nutrient absorption within the gastrointestinal (GI) tract; discuss the patient use of total parenteral nutrition (TPN) to support nutrition with the health-care provider (HCP); assess attitude toward eating; promote a dietary consult to evaluate current eating habits and best method of nutritional supplementation; develop short- and long-term eating strategies; monitor nutritional laboratory values such as albumin, transferrin, red blood cells (RBC), white blood cells (WBC), and serum electrolytes; encourage cultural home foods; provide a pleasant environment for eating; alter food seasoning to enhance flavor; ensure appropriate use of recommended vitamin supplements

Pretest

Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
Patient Teaching: Inform the patient that this laboratory test can assist in evaluating for HIV infection.
Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
Obtain a history of the patient’s immune system, a history of high-risk behaviors, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
Note that there are no food, fluid, or medication restrictions unless by medical direction.

Intratest

Potential complications: N/A
Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
Promptly transport the specimen to the laboratory for processing and analysis.

Post-Test

Inform that patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
Warn the patient that false-positive results occur and that the absence of antibody does not guarantee absence of infection, because the virus may be latent or may not have produced detectable antibody at the time of testing.
Social and Cultural Considerations: Recognize anxiety related to test results, and be supportive of impaired activity related to weakness, perceived loss of independence, and fear of shortened life expectancy. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services. Provide contact information, if desired, for AIDS information provided by the National Institutes of Health (www.aidsinfo.nih.gov) or the CDC (www.cdc.gov).
Social and Cultural Considerations: Counsel the patient, as appropriate, regarding risk of transmission and proper prophylaxis, and reinforce the importance of strict adherence to the treatment regimen, including consultation with a pharmacist.
Social and Cultural Considerations: Inform patient that positive findings must be reported to local health department officials, who will question him or her regarding sexual partners.
Social and Cultural Considerations: Offer support, as appropriate, to patients who may be the victims of rape or sexual assault. Educate the patient regarding access to counseling services. Provide a nonjudgmental, nonthreatening atmosphere for a discussion during which risks of sexually transmitted diseases are explained. It is also important to discuss problems the patient may experience (e.g., guilt, depression, anger).
Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
Patient Education
- Inform the patient that retesting may be necessary.
- Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
- Provide information regarding vaccine-preventable diseases where indicated (e.g., hepatitis B, human papillomavirus). Provide contact information, if desired, for the CDC (www.cdc.gov/vaccines/vpd-vac) and (www.cdc.gov/DiseasesConditions).
- Instruct the patient in the use of home test kits approved by the U.S. Food and Drug Administration, if prescribed. Answer any questions or address any concerns voiced by the patient or family.
Expected Patient Outcomes
- Knowledge
- States understanding of the importance of avoiding activities that can cause exposure to infecting organisms.
- States understanding that donating infected blood can put others at risk, and that donation is prohibited.
- Skills
- Accurately describes interventions that can prevent exposure to opportunistic infections.
- Proficiently self-administers prescribed medication to treat or prevent opportunistic infection.
- Attitude
- Complies with the recommendation to take precautions during sexual activity to avoid placing others at risk.
- Complies with suggested dietary changes and takes the recommended medication designed to improve caloric intake.

Related Monographs

Related tests include biopsy bone marrow, bronchoscopy, CD4/CD8 enumeration, Chlamydia group antibody, CBC, CBC platelet count, CBC WBC count and differential, culture and smear mycobacteria, culture viral, cytology sputum, CMV, culture skin, gallium scan, HBV antibody and antigen, HCV antibody, human T-cell lymphotropic virus types I and II, laparoscopy abdominal, LAP, lymphangiogram, MRI musculoskeletal, mediastinoscopy, β₂-microglobulin, newborn screening, and syphilis serology.
Refer to the Immune System table at the end of the book for related tests by body system.

Human Immunodeficiency Virus Type 1 and Type 2 Antibodies