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Background: HIV remains a major public health issue, especially in Eastern and Southern Africa. Pre-exposure prophylaxis is highly effective when adhered to, but its effectiveness is limited by cost, user acceptability and uptake. The cost of a non-inferiority phase III trial is likely to be prohibitive, and thus, it is essential to select the best possible drug, dose and schedule in advance. The aim of this study, the Combined HIV Adolescent PrEP and Prevention Study (CHAPS), is to investigate the drug, dose and schedule of pre-exposure prophylaxis (PrEP) required for the protection against HIV and the acceptability of PrEP amongst young people in sub-Saharan Africa, and hence to inform the choice of intervention for future phase III PrEP studies and to improve strategies for PrEP implementation., Methods: We propose a mixed-methods study amongst young people aged 13-24 years. The first component consists of qualitative research to identify the barriers and motivators towards the uptake of PrEP amongst young people in South Africa, Uganda and Zimbabwe. The second component is a randomised clinical trial (ClinicalTrials.gov NCT03986970, June 2019) using a novel ex vivo HIV challenge method to investigate the optimal PrEP treatment (FTC-TDF vs FTC-TAF), dose and schedule. We will recruit 144 amongst HIV-negative uncircumcised men aged 13-24 years from voluntary male medical circumcision clinics in two sites (South Africa and Uganda) and randomise them into one of nine arms. One group will receive no PrEP prior to surgery; the other arms will receive either FTC-TDF or FTC-TAF, over 1 or 2 days, and with the final dose given either 6 or 20 h prior to surgery. We will conduct an ex vivo HIV challenge on their resected foreskin tissue., Discussion: This study will provide both qualitative and quantitative results to help decide the optimum drug, dose and schedule for a future phase III trial of PrEP. The study will also provide crucial information on successful strategies for providing PrEP to young people in sub-Saharan Africa., Trial Registration: ClinicalTrials.gov NCT03986970 . Registered on 14 June 2019.

Antibodies to Human Immunodeficiency Virus type 1 (HIV-1) and type 2 (HIV-2) were investigated, using site-directed enzyme immunoassay (ELISA), in 320 specimens obtained from three remote, African tribes during 1969-1971. Using HIV-1 E34/E32 ELISA and HIV-2 149 ELISA, assay were conducted on 101 serum specimens from the Korekore tribe of Zimbabwe, 93 specimens from the Mano tribe of Liberia, and 126 specimens from the Turkana tribe of Kenya; specimens which tested positive in ELISA were further tested by radioimmunoprecipitation assay (RIPA) and Western blot (WB). Two serum specimens from the Mano tribe of Liberia gave OD 492 nm values greater than 0.2 in HIV E34/E32 ELISA in all three runs. These two specimens reacted with HIV-1 envelope proteins gp160 and gp120 and the internal protein p24 in RIPA and WB; however, the reactivity was uncostant. All other serum specimens were negative for HIV-1 and HIV-2 antibodies. Site directed ELISA serology for HIV-1 and HIV-2 gave very low rates of false positive reactivity. Thus, reaction with HIV-1 antigen was identified in two persons of one tribe in Liberia in 1971, but HIV-2 antibodies were not detected in this tribe; HIV-1 and HIV-2 antibodies were absent during the late 1960's and early 1970's from two African tribes resident in Zimbabwe and Kenya.