Final answer:
HIV is the most serious incurable STI that attacks specific immune system cells, weakening the body's defense against pathogens.
Explanation:
The most serious incurable STI which attacks specific immune system cells preventing the body from defending itself against pathogens is the human immunodeficiency virus (HIV). HIV infects and destroys helper T cells of the immune system, leading to a weakened immune response. If left untreated, HIV can progress to acquired immunodeficiency syndrome (AIDS), a severe condition that develops in individuals with untreated HIV infections.
Learn more about STIs and their impact on the immune system here:
https://brainly.com/question/43412974
