Hair samples from subjects on antiretroviral therapy, both HIV- and HIV+ patients with HIV RNA <50copies/mL for >6 months will be analyzed to investigate the influence of race, hair color and hair treatment on ARV response.

A small thatch of hair (approximately 20 strands) will be collected from 85 participants who are currently taking antiretrovirals (ARVs). Hair collection will be evenly distributed into color cohorts: Black, Brown, Blonde and Grey. Participants will need to be >80% adherent to their medication and have had an undetectable HIV RNA VL within the previous 6 months. In the lab, samples will be used to develop IR-MALDESI MSI hair protocols for high sensitivity and accuracy to quantify ARVs in 5 therapeutic drug classes (Integrase Inhibitors, Nucleoside Reverse Transcriptase Inhibitors, Non-Nucleoside Reverse Transcriptase Inhibitors, Entry Inhibitors, Protease Inhibitors).

Inclusion Criteria:

• HIV Negative or HIV positive individuals, aged 18 years or older, who have been taking their ARV medication for at least 3 months and are adherent based on blood plasma HIV RNA of <50 copies/mL or HIV negative status.

Exclusion Criteria:

• Subjects non-adherent to anti-retroviral regimen
• Subjects not willing or able to provide head hair sample

Hair samples will be collected from HIV negative and positive individuals taking ARVs.