AIDS is what happens when you T-cells get destroyed.
The HIVirus uses mainly the T-Cells to multiply, thus detroying the cells.

Without T-Cells your immune system breaks down,
opening the door for a variety of other viruses and bacteria.
Causing the symptoms of AIDS.

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Its like a virus detroying your PC virus protection and firewall.
The Trojans then entering will cause "PCAIDS"