A new study published in the journal Mucosal Immunology found that cannabidiol (CBD) blocked several early steps involved in HIV-1 transmission in lab and tissue-based models, leading researchers to suggest that commercially available CBD products could potentially be repurposed as a form of pre-exposure prophylaxis.

According to the study, HIV-1 transmission depends heavily on the structure and immune-cell makeup of mucosal tissues, where the virus can infect CD4+ T-cells and macrophages directly, or be passed along indirectly by Langerhans cells and dendritic cells. Researchers examined whether CBD, a non-psychoactive compound found in marijuana, could interfere with that process.

They found that CBD activated the TRPV1 ion channel, a pathway already linked to protection against HIV transfer in certain immune cells. Through that mechanism, CBD inhibited direct HIV-1 infection in macrophages and CD4+ T-cells. It also reduced viral transfer to CD4+ T-cells from both Langerhans cells and dendritic cells.

The study says CBD’s effect in macrophages and in Langerhans cell-mediated viral transfer involved secretion of calcitonin gene-related peptide, or CGRP, a neuropeptide previously shown to hinder HIV transmission activity.

Researchers also tested CBD in ex-vivo human inner foreskin tissue, where they found it blocked early events tied to HIV-1 spread, including the formation of epidermal Langerhans cell and T-cell conjugates, along with the resulting infection of CD4+ T-cells.

According to the study, CBD inhibited infection of “all HIV-1 cellular targets” examined. Based on those findings, researchers say commercial CBD products “might be repositioned as novel HIV-1 pre-exposure prophylaxis,” referring to the concept as CBD PrEP.