<qa>  What is the purpose of this protocol?Study Design: The purpose of this protocol is to screen potential study volunteers with HIV infection to determine if they are suitable candidates for vaccine trials. Screening will be primarily for HIV vaccine trials, but may also be for screening HIV-infected adults to participate in trials of other kinds of vaccine studies that will be enrolling HIV-infected subjects. All work will be conducted at the National Institutes of Health. HIV-infected volunteers will be recruited and screened. This protocol will be used to determine if the volunteers meet eligibility requirements for participation in trials of vaccines in HIV-infected subjects. 