As a result of this interference, the virus goes by undetected. Herpes simplex virus, which causes recurrent cold sores, also interferes with the processing of the viral proteins into the immunologically stimulating peptide fragments, but in a different way. Adenoviruses, like the ones which cause colds, make themselves non immunogenic by interrupting the same process in another way. The problems with large numbers. This gives the virus the power to escape from both the killer cells and antibodies.
Some patients are more lucky than others, however.
The virus cannot mutate certain parts of its genes without damaging its ability to survive and replicate. Some people infected with HIV may be able to generate a more effective immune response to the virus if their particular HLA molecules happen to pick peptides from these 'conserved' regions. In the absence of a killer response HIV invades and kills the helper cells and multiplies rapidly so that progression to AIDS is fast. The rate of this failure depends on various factors including the intrinsic aggression of the infecting strain of HIV, the overall health of the individual, their ability to replenish stocks of helper cells and the vigour of the killer cell response. The strength of the killer cells in turn depends largely on ever-mutating virus.