Why is a Western blot considered more specific than ELISA in confirming HIV infections?

Why is a Western blot considered more specific than ELISA in confirming HIV infections?

• A. It uses more viral antigens for detection
• B. It is less prone to false positives
• C. It requires fewer follow-up tests
• D. It is faster than other methods

Answer: (A)

A Western blot is considered more specific than ELISA primarily because it involves the use of multiple viral antigens to confirm the presence of antibodies against HIV. This method separates specific proteins on a gel and transfers them to a membrane, where they can be probed with serum samples. Because the test targets various specific proteins associated with HIV, it reduces the likelihood of cross-reactivity with antibodies against other non-HIV antigens. In contrast, while ELISA can be a sensitive initial screening tool for HIV, it may sometimes yield false positives due to its reliance on fewer epitopes and broader cross-reactivity with antibodies against various pathogens. Therefore, when used as a confirmatory test following a reactive ELISA, the Western blot provides a higher level of specificity and helps ensure that the antibodies detected are indeed specific to HIV. The other options do not accurately capture the reason for the specific advantages of the Western blot test. While it may be true that Western blots can be less prone to false positives, the underlying reason is largely due to the use of more viral antigens. Additionally, it is more time-consuming and may require multiple follow-up tests, and it is generally slower than ELISA rather than faster.

A Western blot is considered more specific than ELISA primarily because it involves the use of multiple viral antigens to confirm the presence of antibodies against HIV. This method separates specific proteins on a gel and transfers them to a membrane, where they can be probed with serum samples. Because the test targets various specific proteins associated with HIV, it reduces the likelihood of cross-reactivity with antibodies against other non-HIV antigens.

In contrast, while ELISA can be a sensitive initial screening tool for HIV, it may sometimes yield false positives due to its reliance on fewer epitopes and broader cross-reactivity with antibodies against various pathogens. Therefore, when used as a confirmatory test following a reactive ELISA, the Western blot provides a higher level of specificity and helps ensure that the antibodies detected are indeed specific to HIV.

The other options do not accurately capture the reason for the specific advantages of the Western blot test. While it may be true that Western blots can be less prone to false positives, the underlying reason is largely due to the use of more viral antigens. Additionally, it is more time-consuming and may require multiple follow-up tests, and it is generally slower than ELISA rather than faster.