Inhibition of HIV Virus by Neutralizing Vhh Attached to Dual Functional Liposomes Encapsulating Dapivirine

Abstract

Although highly active antiretroviral therapy (HAART) has greatly improved the life expectancy of HIV/AIDS patients, the treatment is not curative. It is a global challenge which fosters an urgent need to develop an effective drug or neutralizing antibody delivery approach for the prevention and treatment of this disease. Due to the low density of envelope spikes with restricted mobility present on the surface of HIV virus, which limit the antibody potency and allow virus mutation and escape from the immune system, it is important for a neutralizing antibody to form bivalent or multivalent bonds with the virus. Liposome constructs could fulfil this need due to the flexible mobility of the membrane with its attached antibodies and the capacity for drug encapsulation. In this study, we evaluated the neutralization activity of a range of liposome formulations in different sizes coated with anti-gp120 llama antibody fragments (Vhhs) conjugated via either non-covalent metal chelation or a covalent linkage. The non-covalent construct demonstrated identical binding affinity to HIV-1 envelope glycoprotein gp120 and neutralizing ability for HIV virus as free Vhh. Although covalently linked Vhh showed significant binding affinity to gp120, it unexpectedly had a lower neutralization potency. This may be due to the comparability in size of the viral and liposome particles restricting the number which can be bound to the liposome surface so involving only a fraction of the antibodies, whereas non-covalently attached antibodies dissociate from the surface after acting with gp120 and free the remainder to bind further viruses. Covalently conjugated Vhh might also trigger the cellular uptake of a liposome-virion complex. To explore the possible ability of the antibody-coated liposomes to have a further function, we encapsulated the hydrophobic antiviral drug dapivirine into both of the non-covalently and covalently conjugated liposome formulations, both of which revealed high efficacy in reducing viral replication in vitro. Thus, dual function liposomes may lead to a novel strategy for the prophylaxis of HIV/AIDS by combining the neutralizing activity of Vhh with antiviral effects of high drug concentrations.

Liposome‑delivered baicalein induction of myeloid leukemia K562 cell death via reactive oxygen species generation

“…The absorbance of BL was recorded at 278 nm by FLUOstar Omega (BMG Labtech). Phospholipid (PC) was detected in the liposomes by the Stewart assay ( 36 ). Drug encapsulation efficiency was determined by encapsulated BL divided by original BL corrected by PC concentration.…”

Single-Domain Antibodies and Their Formatting to Combat Viral Infections

“…Whereas non-covalent conjugation did not interfere with the neutralization by VHH J3, covalent conjugation of J3 to liposomes did. Although the reverse transcriptase inhibitor dapivirine encapsulated in liposomes had higher antiviral activity than free dapivirine, conjugation of J3 to dapivirine loaded liposomes did not further increase the antiviral activity [79]. Further optimization could potentially lead to a more pronounced antiviral therapy.…”

Development of nanoparticle-delivery systems for antiviral agents: A review

“…This phenomenon was attributed to the presence of the neutral PEG molecules, which inhibit the adhesive interactions of the nanoliposomes with mucus, thereby allowing them to pass through more easily. In another study, antibody-coated nanoliposomes ( d = 100–230 nm) were developed to increase the efficacy of an antiviral agent (dapivirine) against HIV [ 175 ]. These nanoliposomes could inhibit HIV through two complementary mechanisms: (i) the virus neutralizing effects of the antibodies (Vhhs); (ii) the antiviral activity of the dapivirine.…”