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AAV-expressed eCD4-Ig provides durable protection from multiple SHIV challenges.

ABSTRACT: Long-term in vivo expression of a broad and potent entry inhibitor could circumvent the need for a conventional vaccine for HIV-1. Adeno-associated virus (AAV) vectors can stably express HIV-1 broadly neutralizing antibodies (bNAbs). However, even the best bNAbs neutralize 10-50% of HIV-1 isolates inefficiently (80% inhibitory concentration (IC80) > 5 ?g ml(-1)), suggesting that high concentrations of these antibodies would be necessary to achieve general protection. Here we show that eCD4-Ig, a fusion of CD4-Ig with a small CCR5-mimetic sulfopeptide, binds avidly and cooperatively to the HIV-1 envelope glycoprotein (Env) and is more potent than the best bNAbs (geometric mean half-maximum inhibitory concentration (IC50) < 0.05 ?g ml(-1)). Because eCD4-Ig binds only conserved regions of Env, it is also much broader than any bNAb. For example, eCD4-Ig efficiently neutralized 100% of a diverse panel of neutralization-resistant HIV-1, HIV-2 and simian immunodeficiency virus isolates, including a comprehensive set of isolates resistant to the CD4-binding site bNAbs VRC01, NIH45-46 and 3BNC117. Rhesus macaques inoculated with an AAV vector stably expressed 17-77 ?g ml(-1) of fully functional rhesus eCD4-Ig for more than 40 weeks, and these macaques were protected from several infectious challenges with SHIV-AD8. Rhesus eCD4-Ig was also markedly less immunogenic than rhesus forms of four well-characterized bNAbs. Our data suggest that AAV-delivered eCD4-Ig can function like an effective HIV-1 vaccine.

SUBMITTER: Gardner MR

PROVIDER: S-EPMC4352131 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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AAV-expressed eCD4-Ig provides durable protection from multiple SHIV challenges.

Gardner Matthew R MR Kattenhorn Lisa M LM Kondur Hema R HR von Schaewen Markus M Dorfman Tatyana T Chiang Jessica J JJ Haworth Kevin G KG Decker Julie M JM Alpert Michael D MD Bailey Charles C CC Neale Ernest S ES Fellinger Christoph H CH Joshi Vinita R VR Fuchs Sebastian P SP Martinez-Navio Jose M JM Quinlan Brian D BD Yao Annie Y AY Mouquet Hugo H Gorman Jason J Zhang Baoshan B Poignard Pascal P Nussenzweig Michel C MC Burton Dennis R DR Kwong Peter D PD Piatak Michael M Lifson Jeffrey D JD Gao Guangping G Desrosiers Ronald C RC Evans David T DT Hahn Beatrice H BH Ploss Alexander A Cannon Paula M PM Seaman Michael S MS Farzan Michael M

Nature 20150218 7541

Long-term in vivo expression of a broad and potent entry inhibitor could circumvent the need for a conventional vaccine for HIV-1. Adeno-associated virus (AAV) vectors can stably express HIV-1 broadly neutralizing antibodies (bNAbs). However, even the best bNAbs neutralize 10-50% of HIV-1 isolates inefficiently (80% inhibitory concentration (IC80) > 5 μg ml(-1)), suggesting that high concentrations of these antibodies would be necessary to achieve general protection. Here we show that eCD4-Ig, a ...[more]

PMID: 25707797

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Project description:The engineered antibody-like entry inhibitor eCD4-Ig neutralizes every human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus isolate it has been tested against. The exceptional breadth of eCD4-Ig derives from its ability to closely and simultaneously emulate the HIV-1 receptor CD4 and coreceptors, either CCR5 or CXCR4. Here we investigated whether viral escape from eCD4-Ig is more difficult than that from CD4-Ig or the CD4-binding site antibody NIH45-46. We observed that a viral swarm selected with high concentrations of eCD4-Ig was increasingly resistant to but did not fully escape from eCD4-Ig. In contrast, viruses selected under the same conditions with CD4-Ig or NIH45-46 fully escaped from those inhibitors. eCD4-Ig-resistant viruses acquired unique changes in the V2 apex, V3, V4, and CD4-binding regions of the HIV-1 envelope glycoprotein (Env). Most of the alterations did not directly affect neutralization by eCD4-Ig or neutralizing antibodies. However, alteration of Q428 to an arginine or lysine resulted in markedly greater resistance to eCD4-Ig and CD4-Ig, with correspondingly dramatic losses in infectivity and greater sensitivity to a V3 antibody and to serum from an infected individual. Compensatory mutations in the V3 loop (N301D) and in the V2 apex (K171E) partially restored viral fitness without affecting serum or eCD4-Ig sensitivity. Collectively, these data suggest that multiple mutations will be necessary to fully escape eCD4-Ig without loss of viral fitness.IMPORTANCE HIV-1 broadly neutralizing antibodies (bNAbs) and engineered antibody-like inhibitors have been compared for their breadths, potencies, and in vivo half-lives. However, a key limitation in the use of antibodies to treat an established HIV-1 infection is the rapid emergence of fully resistant viruses. Entry inhibitors of similar breadths and potencies can differ in the ease with which viral escape variants arise. Here we show that HIV-1 escape from the potent and exceptionally broad entry inhibitor eCD4-Ig is more difficult than that from CD4-Ig or the bNAb NIH45-46. Indeed, full escape was not observed under conditions under which escape from CD4-Ig or NIH45-46 was readily detected. Moreover, viruses that were partially resistant to eCD4-Ig were markedly less infective and more sensitive to antibodies in the serum of an infected person. These data suggest that eCD4-Ig will be more difficult to escape and that even partial escape will likely extract a high fitness cost.

Project description:We sought to test whether vaccine-induced immune responses could protect rhesus macaques (RMs) against upfront heterologous challenges with an R5 simian-human immunodeficiency virus, SHIV-2873Nip. We immunized the RMs with recombinant Env proteins heterologous to the challenge virus. For induction of immune responses against Gag, Tat, and Nef, we explored a strategy of immunization with overlapping synthetic peptides (OSP). The immune responses against Gag and Tat were finally boosted with recombinant proteins. The vaccinees and a group of ten control animals were given five low-dose intrarectal (i.r.) challenges with SHIV-2873Nip. All controls and seven out of eight vaccinees became systemically infected; there was no significant difference in viremia levels of vaccinees vs. controls. Prevention of viremia was observed in one vaccinee which showed strong boosting of virus-specific cellular immunity during virus exposures. The protected animal showed no challenge virus-specific neutralizing antibodies in the TZM-bl or A3R5 cell-based assays and had low level ADCC activity after the virus exposures. Microarray data strongly supported a role for cellular immunity in the protected animal. Our study represents a case of protection against heterologous tier 2 SHIV-C by vaccine-induced, virus-specific cellular immune responses. For the protected RM, blood was collected before vaccination, on the day of first virus exposure and six weeks after last virus challenge. Lymph node and rectal pinch biopsies were performed before vaccination and six weeks after last virus challenge. Blood was collected in tempus tubes and processed immediately according to the manufacturer’s instructions and stored at -80C. The biopsy specimens were cut into small pieces and immediately placed into RNAlater solution (Qiagen, Valencia, CA) and also stored at -80C. Total RNA from blood, lymph node and rectal biopsies was extracted using RNAeasy extraction kits (Qiagen, Valencia, CA). cDNA labeling, hybridization, staining and scanning were performed according to the manufacturer’s instructions (Affymetrix, Santa Clara, CA) for rhesus gene expression arrays.

Project description:BackgroundRepeated use, coitus-independent microbicide gels that do not contain antiretroviral agents also used as first line HIV therapy are urgently needed to curb HIV spread. Current formulations require high doses (millimolar range) of antiretroviral drugs and typically only provide short-term protection in macaques. We used the macaque model to test the efficacy of a novel combination microbicide gel containing zinc acetate and micromolar doses of the novel non-nucleoside reverse transcriptase inhibitor MIV-150 for up to 24 h after repeated gel application.Methods and findingsRhesus macaques were vaginally challenged with SHIV-RT up to 24 h after repeated administration of microbicide versus placebo gels. Infection status was determined by measuring virologic and immunologic parameters. Combination microbicide gels containing 14 mM zinc acetate dihydrate and 50 µM MIV-150 afforded full protection (21 of 21 animals) for up to 24 h after 2 weeks of daily application. Partial protection was achieved with the MIV-150 gel (56% of control at 8 h after last application, 11% at 24 h), while the zinc acetate gel afforded more pronounced protection (67% at 8-24 h). Marked protection persisted when the zinc acetate or MIV-150/zinc acetate gels were applied every other day for 4 weeks prior to challenge 24 h after the last gel was administered (11 of 14 protected). More MIV-150 was associated with cervical tissue 8 h after daily dosing of MIV-150/zinc acetate versus MIV-150, while comparable MIV-150 levels were associated with vaginal tissues and at 24 h.ConclusionsA combination MIV-150/zinc acetate gel and a zinc acetate gel provide significant protection against SHIV-RT infection for up to 24 h. This represents a novel advancement, identifying microbicides that do not contain anti-viral agents used to treat HIV infection and which can be used repeatedly and independently of coitus, and underscores the need for future clinical testing of their safety and ability to prevent HIV transmission in humans.

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AAV-expressed eCD4-Ig provides durable protection from multiple SHIV challenges.

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AAV-expressed eCD4-Ig provides durable protection from multiple SHIV challenges.

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