Western blot vs. Elisa: which of these two tests is the most accurate for HIV testing?

Today, advanced medical research and innovative molecular diagnostic technologies can efficiently control, treat and even cure many deadly diseases. Among them is the Human Immunodeficiency Virus, commonly known as HIV, which, as the name suggests, attacks our immune system. Often confused with AIDS (we debunk this myth in one of our previous articles), HIV develops into AIDS – a fatal malady when left untreated.

Regular testing and early diagnosis evince a greater possibility of preventing and treating HIV so that it does not spiral into AIDS. Early identification of HIV demands attention, as the virus is highly transmissible during the first stage (Acute HIV infection).

The Western Blot and ELISA tests have been the gold standard of HIV testing for many labs. Today, we shed light on these two lab testing methods and compare them to understand which is the most accurate for HIV testing.

But before that, here is a quick recap of what we do.

Helvetica Health Care (HHC) is a trusted name in the supply of high-quality and essential lab testing products. We are known for the ZeptoMetrix WESTERN BLOT for in vitro detection of antibodies to SIV (Simian Immunodeficiency Virus, the lentivirus most closely related to Human HIV) in serum or plasma, available in 10 or 30-strip kit formats.

We also provide a wide range of ELISA kits ready to use with break-apart wells that include

• The RETROTEK™ range is designed for the detection and quantitation of retroviral antigens from the retroviruses HIV-1, SIV and HTLV found in cell culture, serum, plasma or other biological fluids

• IMMUNOTEK™ kits can detect and quantify various immunoglobulins from many species, including Humans, Chicken, Cow, Goat, Rabbit, Rat and Mouse. We also provide HHV-6 IgG antibody and KSHV/HHV8 IgG antibody ELISA kits.

Now that we have established our expertise let’s look at the two commonly applied HIV testing methods – ELISA and Western Blot.

What is ELISA?

The enzyme-linked immunosorbent assay or ELISA is a widely used and affordable test that helps scientists study antibodies, antigens, proteins, and glycoproteins. It’s a top choice in immune testing because it’s super sensitive and straightforward. Researchers often use ELISAs to determine if certain proteins are present in samples like urine, blood serum, or cell cultures. ELISAs are very useful in detecting HIV antibodies and antigens in blood samples.

The immune system produces certain proteins known as antibodies, which help our body fight diseases. When foreign bodies, such as viruses, are present in the body, our immune system reacts by producing antibodies. Antigens, on the other hand, are any foreign material that the body encounters and to which the immune system reacts.

What is Western Blot?

Western blotting, called protein immunoblotting, is a common cell and molecular biology technique. It’s used to find out if certain proteins are present in a sample, ascertain their size, and relative strength which can indicate the phase of HIV infection.

How does the ELISA testing for HIV work?

ELISAs are the typical testing method to detect HIV antibodies by checking for proteins the body makes in response to the virus. The viral protein antigen will be included in a cassette with the blood sample. If the blood contains HIV antibodies, they will bind to the antigen and change the colour of the cassette’s contents. The first commonly used test for HIV was this very sensitive one.

Highly sensitive, ELISAs were the first and are still the most widely used diagnostic technique in the detection of HIV. ELISA tests are usually performed in 96 well test plates, which means that a large number of tests can be performed in each run, making it quick and cost effective. ELISA tests also lend themselves well to automation, and many laboratories now employ fully automated, robotic systems.

What is the role of the Western Blotting technique in HIV testing?

Typically, labs would run the Western blotting procedure following an ELISA to confirm a positive test result. However, since alternative tests have become more trustworthy and provide a speedier diagnosis, the Western blot test is less often recommended.

In this technique, the blood samples are taken in the same way as the ELISA tests, but the sample collected is then divided by an electrical current and transferred to blotting paper. Here, adding an enzyme results in colour alterations that indicate the presence of HIV antibodies.

As we established earlier, the detection of HIV in the first or the acute infection stage is critical as there lies a higher risk of HIV transmission from one individual to another during this period compared to confirmed HIV patients. Despite being a gold standard for molecular diagnostics in the past, Western blotting is less often recommended due to the following limitations:

• Inability to detect acute infection
• Potential misclassification of HIV-2 infection as an HIV-1 infection
• Delayed lab processes due to the need for batches or the need to outsource samples for testing
• Possibility of false-negative or inconclusive outcomes in acute and early stages of seroconversion.
• Difficulty in interpreting results.

ELISA vs Western blotting for HIV testing 

When comparing ELISA and Western Blotting for HIV testing, ELISA assays are far superior to Western blotting testing in terms of blood screening, in terms of cost, efficiency and practicality.  

With the number of diseases on the rise, one cannot stress more on the importance of testing which is the first step towards efficient health management of patients. If you are a lab or a lab technician, let us help you make your lab processes more accurate and efficient.

Call us now to find out more about our products.