This notice announces the government's intent to award sole source modifications to the existing National NeuroHIV Tissue Consortium (NNTC) clinical site contracts held by UC San Diego and Washington University. The UCSD contract will increase by $269,941 to a total value of $13,774,419 through August 22, 2027, while the WashU contract will increase by $543,301.63 to $8,322,165.63 through September 22, 2027. The modifications support continued clinical research on HIV-associated CNS complications, including participant recruitment, clinical assessments, and biospecimen collection and distribution, with a focus on advancing HIV cure research. This is not a competitive solicitation, though interested parties may submit capability statements and objections for consideration.