F9170, an antiviral peptide derived from the HIV-1 envelope glycoprotein (amino acids 789-803), targets the LLP1 domain in the virus's envelope protein cytoplasmic tail. This interaction inhibits HIV-1 IIIB infection in MT-2 cells, evidenced by an EC50 value of 0.19 µM. Additionally, at a dosage of 3 mg/kg, F9170 significantly lowers plasma viral load in rhesus macaques infected with simian HIV (SHIV).