Rectal and vaginal tissue from intravenous VRC01 recipients show protection against ex vivo HIV-1 challenge.

Astronomo, Rena D; Lemos, Maria P; Narpala, Sandeep R; Czartoski, Julie; Ballweber Fleming, Lamar; Seaton, Kelly E; Prabhakaran, Madhu; Huang, Yunda; Lu, Yiwen; Westerberg, Katharine; Zhang, Lily; Gross, Mary K; Hural, John; Tieu, Hong-Van; Baden, Lindsey R; Hammer, Scott; Frank, Ian; Ochsenbauer, Christina; Grunenberg, Nicole; Ledgerwood, Julie E; Mayer, Kenneth; Tomaras, Georgia; McDermott, Adrian B; McElrath, M Juliana

BACKGROUND VRC01, a potent, broadly-neutralizing monoclonal antibody, inhibits simian-HIV infection in animal models. HVTN 104 assessed VRC01 safety and pharmacokinetics in humans. We extend the clinical evaluation to determine intravenous-infused VRC01 distribution and protective function at mucosal sites of HIV-1 entry. METHODS Healthy, HIV-1-uninfected men (n=7) and women (n=5) receiving VRC01 every two months provided mucosal and serum samples once, 4-13 days post-infusion. Eleven male and 8 female HIV-seronegative volunteers provided untreated control samples. VRC01 levels were measured in serum, secretions and tissue, and HIV-1 inhibition was determined in tissue explants. RESULTS Median VRC01 levels were quantifiable in serum (96.2 µg/ml or 1.3 pg/ng protein), rectal tissue (0.11 pg/ng protein), rectal secretions (0.13 pg/ng protein), vaginal tissue (0.1 pg/ng protein) and cervical secretions (0.44 pg/ng protein) from all recipients. VRC01/IgG ratios in male serum correlated with those in paired rectal tissue (r=0.893, P=0.012) and rectal secretions (r=0.9643, P=0.003). Ex vivo HIV-1Bal26 challenge infected 4/21 rectal explants from VRC01-infused versus 20/22 from controls (P=0.005); HIV-1 Du422.1 infected 20/21 rectal explants of VRC01 recipients and 12/12 from controls (P=0.639). HIV-1Bal26 infected 0/14 vaginal explants of VRC01 recipients compared to 23/28 control explants (P=0.003). CONCLUSION Intravenous VRC01 distributes into the female genital and male rectal mucosa and retains anti-HIV-1 functionality, inhibiting a highly neutralization-sensitive but not a highly-resistant HIV-1 strain in mucosal tissue. These findings lend insight into VRC01 mucosal infiltration and provide perspective to in vivo protective efficacy. FUNDING National Institute of Allergy and Infectious Diseases and Bill & Melinda Gates Foundation.