The western blot test is one of those medical–lab terms people usually meet after a first screening test. You do an ELISA or EIA. It comes back positive or unclear. Then the doctor says, “We’ll confirm it with a western blot.” That’s when people start searching: what is western blot test, is the western blot test accurate, where can I get a western blot test for herpes, how long does the western blot test take, and what does a western blot test for?
What Is a Western Blot Test?
A western blot test is a blood-based antibody test used to confirm the presence of a particular infection. It doesn’t just say “yes, antibodies” — it checks whether your blood reacts to several specific proteins from that infection. Because it’s so specific, it’s often done after a more general screening test.
So if someone asks “what is the western blot test” or “western blot test is used for what,” the short answer is:
- it is a serological (blood) test,
- it detects antibodies to individual proteins,
- it is used as a confirmatory test for infections like HIV, herpes, and Lyme disease.
How the Western Blot Test Works
What is procedure or which steps are involved in test? The core steps are the same everywhere.
Western Blot Test Steps
- Proteins from the virus or bacteria are separated in a gel.
- These proteins are transferred to a membrane (the “blot”).
- Your blood serum is added to the membrane.
- If your body has made antibodies to any of those proteins, the antibodies will bind.
- A detection system makes these bindings appear as visible bands.
So, “western blot test detects” antibodies against specific pathogen proteins — not the whole pathogen. The pattern of bands is what matters.
How Long Does the Western Blot Test Take?
There are two timelines:
- The lab can run the test in about a day.
- Your reported results can take a few days to a couple of weeks if the sample is sent to a reference lab (for example, for HSV western blot).
ELISA Test vs Western Blot
This is a very common questiont: “elisa test vs western blot,” or “elisa test positive western blot negative.”
The flow is:
- ELISA (or EIA) is the screening test. It is sensitive.
- Western blot is the confirmatory test. It is specific.
So, “ELISA and western blot test is used for” stepwise diagnosis: screen first, confirm second. If ELISA is positive but the western blot is negative, doctors may say the screening test was a false positive or that you tested too early and need to repeat later.
Western Blot Test for HIV
Historically, HIV is the classic example: “the western blot test is confirmatory for HIV because” it checks for antibodies to multiple HIV-specific proteins. HIV has characteristic proteins (like gp120/gp160 and p24). A true HIV infection will produce antibodies to more than one of these. Western blot looks for that pattern.
So:
- western blot test for HIV → confirmatory;
- HIV western blot test result → reported as positive, negative, or indeterminate based on bands;
- western blot test HIV window period → if you test very soon after exposure, antibodies may not have formed yet, so retesting after the window period is advised.
In one line you can say:
“Western blot is used to confirm HIV because it detects antibodies to several HIV-specific proteins, which reduces false positives from screening tests.”
Western Blot Test for Herpes (HSV-1 and HSV-2)
Routine HSV blood tests can sometimes produce false positives, especially for HSV-2. The HSV western blot is considered more specific and is often used when:
- a person got a low-positive HSV result and wants to confirm,
- or they want type-specific (HSV-1 vs HSV-2) clarity.
Where to Get a Western Blot Test for Herpes
Not every local lab runs it every day, so people search “western blot herpes test near me,” or “how to get western blot herpes test.” The usual path is:
- doctor or telehealth orders the test,
- blood is drawn locally,
- sample is shipped to a reference lab (commonly University of Washington).
Cost and Accuracy for HSV Western Blot
Because it’s a send-out and more specialized, it can cost more than standard STD screening.
On accuracy: “how accurate is the western blot test for herpes?” — western blot for HSV is considered one of the most accurate type-specific antibody tests available.
Western Blot Test for Lyme Disease
Here’s the clean explanation:
- Lyme testing is often two-tiered: screening test (ELISA/EIA) → western blot.
- The Lyme western blot looks for antibodies to specific Borrelia proteins.
- Results are usually split into IgM and IgG western blots.
- Only certain combinations of bands are considered positive.
How to Read Western Blot Test for Lyme Disease
Patients get confused because they see multiple bands. A user-friendly line:
“Lyme western blot test results are considered positive only if the required number of specific bands is present. Having a few nonspecific bands does not always mean Lyme disease.”
Accuracy and Timing
“how accurate is western blot test for lyme disease” → accuracy depends on when you test. Too early = antibodies haven’t formed yet. Too late without treatment = antibodies may have waned. Standard labs follow CDC/IDSA criteria; specialty labs (like Igenex) may report extra bands.
Cost of western blot test for lyme
Costs vary by lab and insurance. Standard two-tier testing is often covered; specialty or out-of-network labs can be higher.
How Accurate Is the Western Blot Test?
- western blot is more specific than the screening test that comes before it;
- accuracy still depends on testing at the right time (after the body has made antibodies);
- and on using the correct interpretation criteria for that disease (HIV vs HSV vs Lyme).
So we can say: “Yes, western blot is accurate when done in the right window and read by disease-specific criteria.”
Reading Western Blot Test Results
General principle:
- western blot results are shown as bands;
- each band is a reaction to a specific protein;
- the lab compares your bands to a reference list;
- if the required bands are present, the test is positive;
- if not, it’s negative or indeterminate;
- a “positive western blot test” means the test found the antibody pattern consistent with that infection.
Because this can get disease-specific, it’s best for patients to go over results with their provider.
Commonly Asked Questions
What does a western blot test for?
It tests for antibodies to specific proteins of an infection (like HIV, HSV, or Lyme) to confirm whether your immune system has responded to that infection.
Is western blot a blood test?
Yes. Western blot uses a blood sample (serum) to look for antibodies, so it is a serological test.
Why do doctors do ELISA and western blot test together?
ELISA/EIA is a sensitive screening test; western blot is a specific confirmatory test. Together they reduce false positives.
How long does the western blot test take?
The lab process can be done in a day, but final results may take several days or longer if the sample is sent to a reference lab.
How accurate is the western blot test for herpes?
HSV western blot is considered one of the most accurate type-specific herpes antibody tests, which is why people seek it when other HSV tests are unclear.
How accurate is western blot test for Lyme disease?
It is more specific than screening tests, but timing and correct interpretation of bands are crucial.
Where can I get a western blot test for herpes?
Usually through a provider or clinic that can send your sample to a reference lab (for example, the University of Washington herpes western blot).
How much does a western blot test cost?
Costs vary by infection, lab, and country. Specialized herpes or Lyme blots can be more expensive than routine tests.
What does it mean if ELISA is positive and western blot is negative?
Often it means the screening test was falsely positive or the test was done in the window period. Your provider may repeat testing later.
Is the western blot test used to confirm HIV?
Yes. Western blot became well known because it was used to confirm HIV after a positive screening test.
