The AIDS Virus

Artist's conception of three mutant forms of the AIDS virus, HIV, illustrating subtle differences in the shape of the virus' surface glycoprotein (gp120). Although similar enough in overall shape to allow all viruses to remain infectious, the surface proteins vary in their conformation (three-dimensional geometry). Similar variation is also found in the virus' internal proteins, which are not shown in this view. Each virus' outer membrane is derived from a cell that it had previously infected. As shown in the circled protein on the surface of the right-most virus, only a very small fragment of the viral protein (in blue) is ultimately recognized by cytotoxic T cells, part of the immune system's viral defense

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