Advertisements
Feeds:
Posts
Comments

Posts Tagged ‘AIDS’


Heroes in Medical Research: Dr. Robert Ting, Ph.D. and Retrovirus in AIDS and Cancer

Curator and Reporter: Stephen J. Williams, PhD

This is the second posting in this series in which I highlight the basic research which led to seminal breakthroughs in the medical field, brought on by the result of basic inquiry, thorough and detailed investigation, meticulously following the scientific method, and eventually leading to development of important medical therapies.

In his autobiography, Virus Hunting: AIDS, Cancer & the Human Retrovirus: A Story of Scientific Discovery, Dr. Robert Gallo, M.D. describes a wonderful story of the history behind, scientific biographies, and chronology of the discoveries which led he and his colleagues (including co-discoverer Dr. Luke Montagnier) to recognize retroviruses (in particular HIV) as the leading culprit for the cause of AIDS and in the etiology of Kaposi’s sarcoma.   For anyone who appreciates the history behind scientific discoveries and appreciates learning about the multitude of individual efforts which are the crux of seminal research, this book is a must read.

Recommendations from the back cover include:

Virus Hunting will be read and reread, for years to come.” —New York Newsday

“Provides a human, revealing look into the arcane, usually secret confines of laboratory science.”

Martin Delany, Project Inform

..as well as others.

While a fascinating aspect of this book is the description, like fitting pieces of a puzzle, of the important discoveries throughout history which are the necessary foundations for further investigations and discoveries, more important is a telling, personal narrative of the people involved in those initial and subsequent discoveries.  In fact, the book has over 396 colleagues, mentors, technicians, students, and even critiques who are given credit, in one form or another, for the ultimate discovery of HIV as a causative agent for the development of AIDS. The book is a literal Who’s Who in Science and shows how important personal collaboration and friendships are in the process of scientific discovery.

In 1972, Dr. Seymour Perry had appointed the young Dr. Robert Gallo as head of a new department, the Human Tumor Cell Biology Branch, renamed the Laboratory of Tumor Cell Biology.  The lab was carrying on the work on tRNA that Dr. Gallo had performed in Dr. Sid Perska’s group at NIH.  However, with the help of new lab members Dr. David Gillespie, Dr. Flossie Wong-Staal, and Dr. Marjorie Robert-Guroff the lab focused on the search for disease-causing retroviruses, especially in human leukemias.  This was, in part, due to conversations with Dr. Robert Huebner and Todaro, who insisted that

“within the genetic makeup of this endogenous retroviral material was, they suggested, a special gene, the oncogene, that was the parent of the cancer-causing protein”

which may explain some of the early work by Rous concerning the Rous sarcoma virus.

Enter in Gallo’s good friend Dr. Bob Ting.  Dr. Gallo had known Dr. Ting socially since 1966, shortly after Gallo had arrived at NIH.  Dr. Bob Ting was a well-established NCI investigator, who was doing work on DNA and RNA oncogenic viruses of animals.  Originally from a large and wealthy family in Hong Kong, Dr. Ting had worked with Nobel Prize winners Salvatore Luria (who worked on phages) and Renato Dulbecco, who, along with his well-known cell culture media, had made the seminal discoveries that led to our knowledge how some DNA viruses can transform normal animal cells into neoplastic-like cells in culture.

Bob Ting gave a talk on these oncogenic viruses and Gallo was very interested in his observations that oncogenic viruses like Rous and Maloney, could transform cells in vitro in a matter of days.

A friendship developed between the two over tennis matches and Chinese food.  During this time, Dr. Ting made the important suggestion that they both collaborate and use the viral systems developed by Dulbecco.  Ting also introduced him to RNA viruses, Dr. Robert Huebner, and Dr. Howard Temin.  It was, in part, due to these associations that Gallo started looking, in earnest, at the possibility of RNA retroviruses in leukemias. Thus, just like the internet today, connections and networking provided new insights into current research, and helped lead the advent of new discoveries, therapies, and scientific disciplines.

Therefore, “after some late-night discussion with Bob Ting, I decided to enter the fray. My own laboratory, … would immediately be set up to compare the properties of reverse transcriptase enzymes from many different animal retroviruses”.

Although the rest is more history, this early friendship, collaboration, and mentoring by Bob Ting had “transformed” Gallo’s research efforts to set him up to make some of the important discoveries eventually leading to the discovery of the role of HIV in AIDS.

A video interviewing Dr. Gallo can be found here:

VIEW VIDEO

https://www.youtube.com/watch?v=ELRlXLGWu4I

A very nice writeup/obituary for Dr. Ting was written by Patricia Sullivan of the Washington Post and is included below.

Robert Ting, 77; Biotech Pioneer

ME/Ting-ob

Dr. Robert Ting’s biotech company in Rockville developed the first FDA-approved diagnostic test kits to test for HIV antibodies. (By Gerald Martineau — The Washington Post)

 

By Patricia Sullivan

Washington Post Staff Writer
Friday, September 22, 2006

Robert C.Y. Ting, 77, a research scientist who started one of the early biotechnology companies in the Washington area, died Sept. 11 of complications after cardiac surgery at the Cleveland Clinic in Cleveland.

Dr. Ting founded Biotech Research Laboratories Inc. in Rockville in 1973, producing cells for government scientists to use in research. Eleven years later, his firm obtained a federal license to develop and produce the first FDA-approved diagnostic test kits for HIV antibody confirmation.

Robert C. Gallo, who co-discovered the HIV virus as the cause of AIDS, called Dr. Ting a pioneer in the field who popularized the term “biotechnology” when he moved from research to entrepreneurship.

“He introduced me to virology, and he did it twice,” said Gallo, director of the Institute of Human Virology in Baltimore. The men had known each other since the 1960s, and while playing tennis one day, Dr. Ting advised the cancer researcher to look at new research in viruses. Later, when Gallo was studying leukemia, Dr. Ting directed him to animal research in leukemia. “First he showed me how viruses change cells. Then he introduced me to retrovirology. . . . I went into retrovirology solely because of those discussions with Bob Ting on tennis courts,” Gallo said.

Dr. Ting, whom Gallo described as a quiet, modest man, was born in Shanghai, the son of a physician to Gen. Chiang Kai-Shek. His family fled the country during the Japanese invasion of China during World War II and moved to Hong Kong. Soon after, he moved to the United States, where he received a bachelor’s degree and in 1956 a master’s degree in genetics from Amherst College.

He received a doctoral degree in microbiology and biochemistry from the University of Illinois in 1960 under Salvador E. Luria, who later won the 1969 Nobel Prize in Medicine and Physiology. Dr. Ting spent the next two years on a postdoctoral fellowship at the California Institute of Technology, working with Renato Dulbecco, who later won the 1975 Nobel Prize in Medicine and Physiology. Their work focused on how viruses cause tumors.

“A lot of molecular biology developed from this,” Dr. Ting told The Washington Post in 1984 from his Rockville office, cluttered with scientific journals, awards and a large blackboard. “There was so much evidence in animal systems [that viruses cause tumors], that the next question was obvious — can you find the equivalent in humans.”

Dr. Ting joined the National Institutes of Health in 1962 as a visiting fellow and then a senior research scientist at the National Cancer Institute. From 1966 to 1968, he was an associate editor for the Journal of the National Cancer Institute.

In 1969, he joined Litton Bionetics Inc. in Rockville as director of experimental oncology, leading a project funded by the institute to search for viruses in human leukemia patients. He became scientific director of the cancer research branch the next year.

With academic, government and private business experience under his belt, Dr. Ting decided to go into business on his own and in 1973 started Biotech Research Laboratories in Rockville. It was a profitable supplier of research services and supplies until 1981, when it went public and produced the HIV diagnostic test kits. It became one of the most successful public biotech companies in the area in the mid-1980s.

The Economic Development Board of Singapore invited him to return to Asia to start a biotech company, which he did in 1985, forming Diagnostic Biotechnology Ltd. He also joined the Institute of Molecular and Cell Biology at the National University of Singapore, which Gallo called “the most prominent Asian academic biotechnology center.”

He returned to the United States in 1998 to join the board of Cell Works Inc. in Baltimore, and became chair and chief executive of a joint venture, Cell Works Asia Limited, in 2000.

Most recently, Dr. Ting was the founding president and chief executive of Profectus Biosciences Inc. of Baltimore, previously known as Maryland BioTherapeutics Inc.

Dr. Ting was past chairman of the F.F. Fraternity, one of the oldest Chinese fraternities in the United States. He was also a member of the Organization of Chinese Americans in the D.C. area since its inception in the early 1970s. He enjoyed tennis, golf, ballroom dancing and international travel. He also was a wine connoisseur.

Survivors include his wife of 44 years, Sylvia Han Ting of Potomac; three children, Anthony Ting of Shaker Heights, Ohio, Andrew Ting of Beverly, Mass., and Jennifer Chow of Potomac; seven sisters; and seven grandchildren.

An obituary written from his son Anthony can be found here:

https://www.amherst.edu/aboutamherst/magazine/in_memory/1953/robertting

Sources:

http://www.amazon.com/Virus-Hunting-Retrovirus-Scientific-Discovery/dp/0465098150

http://www.washingtonpost.com/wp-dyn/content/article/2006/09/21/AR2006092101936.html

Other articles/postings related to this topic and HIV on this site includes:

Heroes in Medical Research: Barnett Rosenberg and the Discovery of Cisplatin

History of medicine, science, and society: 200 Years of the New England Journal of Medicine

Why did Pauling Lose the “Race” to James Watson and Francis Crick? How Crick Describes his Discovery in a Letter to his Son

John Randall’s MRC Research Unit and Rosalind Franklin’s role at Kings College

Interview with the co-discoverer of the structure of DNA: Watson on The Double Helix and his changing view of Rosalind Franklin

Otto Warburg, A Giant of Modern Cellular Biology

Inspiration From Dr. Maureen Cronin’s Achievements in Applying Genomic Sequencing to Cancer Diagnostics

Nanotechnology and HIV/AIDS treatment

HIV vaccine: Caltech puts us One step further

Getting Better: Documentary Videos on Medical Progress — in Surgery, Leukemia, and HIV/AIDS.

Advertisements

Read Full Post »


Nanotechnology and HIV/AIDS Treatment

Author: Tilda Barliya, PhD

 

AIDS was first reported in 1981 followed by the identification of HIV as the cause of the disease in 1983 and is now a global pandemic that has become the leading infectious killer of adults worldwide. By 2006, more than 65 million people had been infected with the HIV virus worldwide and 25 million had died of AIDS (Merson MH. The HIV-AIDS pandemic at 25 – the global response. (1, 2). This has caused tremendous social and economic damage worldwide, with developing countries, particularly Sub-Saharan Africa, heavily affected.

A cure for HIV/AIDS has been elusive in almost 30 years of research. Early treatments focused on antiretroviral drugs that were effective only to a certain degree. The first drug, zidovudine, was approved by the US FDA in 1987, leading to the approval of a total of 25 drugs to date, many of which are also available in fixed-dose combinations and generic formulations for use in resource-limited settings (to date, only zidovudine and didanosine are available as true generics in the USA).

However, it was the advent of a class of drugs known as protease inhibitors and the introduction of triple-drug therapy in the mid-1990s that revolutionized HIV/AIDS treatment (3,4). This launched the era of highly active antiretroviral therapy (HAART), where a combination of three or more different classes of drugs are administered simultaneously.

Challenges of HIV/AIDS treatment

  • HIV resides in latent cellular and anatomical reservoirs where current drugs are unable to completely eradicate the virus.
  • Macrophages are major cellular reservoirs, which also contribute to the generation of elusive mutant viral genotypes by serving as the host for viral genetic recombination.
  • Anatomical latent reservoirs include secondary lymphoid tissue, testes, liver, kidney, lungs, the gut and the brain.
  • The major challenge facing current drug regimens is that they do not fully eramacrdicate the virus from these reservoirs; requiring patients take medications for life. Under current treatment, pills are taken daily, resulting in problems of patient adherence. The drugs also have side effects and in some people the virus develops resistance against certain drugs.

Current treatment in HIV/AIDS

The use of the HAART regimen, particularly in the developed world, has resulted in tremendous success in improving the expectancy and quality of lives for patients. However, some HAART regimens have serious side effects and, in all cases, HAART has to be taken for a lifetime, with daily dosing of one or more pills. Due to the need to take the medication daily for a lifetime, patients fail to adhere to the treatment schedule, leading to ineffective drug levels in the body and rebound of viral replication.Some patients also develop resistance to certain combinations of drugs, resulting in failure of the treatment. The absence of complete cure under current treatment underscores the great need for continued efforts in seeking innovative approaches for treatment of HIV/AIDS.

Drug resistance is mainly caused by the high genetic diversity of HIV-1 and the continuous mutation it undergoes. This problem is being addressed with individualized therapy, whereby resistance testing is performed to select a combination of drugs that is most effective for each patient (5). In addition, side effects due to toxicities of the drugs are also a concern. There are reports that patients taking HAART experience increased rates of heart disease, diabetes, liver disease, cancer and accelerated aging. Most experts agree that these effects could be due to the HIV infection itself or co-infection with another virus, such as co-infection with hepatitis C virus resulting in liver disease. However, the toxicities resulting from the drugs used in HAART could also contribute to these effects.

Under current treatment, complete eradication of the virus from the body has not been possible. The major cause for this is that the virus resides in ‘latent reservoirs’ within memory CD4+ T cells and cells of the macrophage–monocyte lineage. A major study recently found that, in addition to acting as latent reservoirs, macrophages significantly contribute to the generation of elusive mutant viral genotypes by serving as the host for viral genetic recombination (6).  The cells that harbor latent HIV are typically concentrated in specific anatomic sites, such as secondary lymphoid tissue, testes, liver, kidney, lungs, gut and the CNS. The eradication of the virus from such reservoirs is critical to the effective long-term treatment of HIV/AIDS patients.

Therefore, there is a great need to explore new approaches for developing nontoxic, lower-dosage treatment modalities that provide more sustained dosing coverage and effectively eradicate the virus from the reservoirs, avoiding the need for lifetime treatments.

Nanotechnology for HIV/AIDS treatment

The use of nanotechnology platforms for delivery of drugs is revolutionizing medicine in many areas of disease treatment.

Nanotechnology-based platforms for systemic delivery of antiretroviral drugs could have similar advantages.

  • Controlled-release delivery systems can enhance their half-lives, keeping them in circulation at therapeutic concentrations for longer periods of time. This could have major implications in improving adherence to the drugs.
  • Nanoscale delivery systems also enhance and modulate the distribution of hydrophobic and hydrophilic drugs into and within different tissues due to their small size. This particular feature of nanoscale delivery systems appears to hold the most promise for their use in clinical treatment and prevention of HIV. Specifically, targeted delivery of antiretroviral drugs to CD4+ T cells and macrophages as well as delivery to the brain and other organ systems could ensure that drugs reach latent reservoirs
  • Moreover, by controlling the release profiles of the delivery systems, drugs could be released over a longer time and at higher effective doses to the specific targets. Figure 1. Various nanoscale drug delivery systems.

Optional treatments:

  •    Antiretroviral drugs
  •    Gene Therapy
  •    Immune Therapy
  •    Prevention

An external file that holds a picture, illustration, etc.Object name is nihms180336f1.jpg Object name is nihms180336f1.jpg

The use of nanotechnology systems for delivery of antiretroviral drugs has been extensively reviewed by Nowacek et al. and Amiji et al. (7,8).

In a recent study based on polymeric systems, nanosuspensions (200 nm) of the drug rilpivirine (TMC278) stabilized by polyethylene. A series of experiments by Dou et al. showed that nanosuspension of the drug indinavir can be stabilized by a surfactant system comprised of Lipoid E80 for effective delivery to various tissues. The indinavir nanosuspensions were loaded into macrophages and their uptake was investigated. Macrophages loaded with indinavir nanosuspensions were then injected intravenously into mice, resulting in a high distribution in the lungs, liver and spleen. More significantly, the intravenous administration of a single dose of the nanoparticle-loaded macrophages in a rodent mouse model of HIV brain infection resulted in significant antiviral activity in the brain and produced measureable drug levels in the blood up to 14 days post-treatment.polypropylene glycol (poloxamer 338) and PEGylated tocopheryl succinate ester (TPGS 1000) were studied in dogs and mice. A single-dose administration of the drug in nanosuspensions resulted in sustained release over 3 months in dogs and 3 weeks in mice, compared with a half-life of 38 h for free drug. These results serve as a proof-of-concept that nanoscale drug delivery may potentially lower dosing frequency and improve adherence.

Active targeting strategies have also been employed for antiretroviral drug delivery. Macrophages, which are the major HIV reservoir cells, have various receptors on their surface such as formyl peptide, mannose, galactose and Fc receptors, which could be utilized for receptor-mediated internalization. The drug stavudine was encapsulated using various liposomes (120–200 nm) conjugated with mannose and galactose, resulting in increased cellular uptake compared with free drug or plain liposomes, and generating significant level of the drug in liver, spleen and lungs. Stavudine is a water-soluble drug with a very short serum half-life (1 h). Hence, the increased cellular uptake and sustained release in the tissues afforded by targeted liposomes is a major improvement compared with free drug. The drug zidovudine, with half-life of 1 h and low solubility, was also encapsulated in a mannose-targeted liposome made from stearylamine, showing increased localization in lymph node and spleen. An important factor to consider here is that although most of the nucleoside drugs such as stavudine and zidovudine have short serum half-lives, the clinically relevant half-life is that of the intracellular triphosphate form of the drug. For example, despite zidovudine’s 1 h half-life in plasma, it is dosed twice daily based on intracellular pharmacokinetic and clinical efficacy data. Therefore, future nanotechnology-based delivery systems will have to focus in showing significant increase of the half-lives of the encapsulated drugs to achieve a less frequent dosing such as once weekly, once-monthly or even less.

Gene Therapy for HIV/AIDS

In addition to improving existing antiretroviral therapy, there are ongoing efforts to discover alternative approaches for treatment of HIV/AIDS. One promising alternative approach is gene therapy, in which a gene is inserted into a cell to interfere with viral infection or replication. Other nucleic acid-based compounds, such as DNA, siRNA, RNA decoys, ribozymes and aptamers or protein-based agents such as fusion inhibitors and zinc-finger nucleases can also be used to interfere with viral replication.

An external file that holds a picture, illustration, etc.Object name is nihms180336f2.jpg Object name is nihms180336f2.jpg

RNAi is also considered to have therapeutic potential for HIV/AIDS. Gene silencing is induced by double stranded siRNA, which targets for destruction

he mRNA of the gene of interest. For HIV/AIDS, RNAi can either target the various stages of the viral replication cycle or various cellular targets involved in viral infection such as CD4, CCR5, and/or CXCR4, the major cell surface co-receptors responsible for viral entry. HIV replicates by reverse transcription to form DNA and uses the DNA to produce copies of its mRNA for protein synthesis; siRNA therapy could be used to knock down this viral mRNA. As with other gene therapy techniques, delivery of siRNA to specific cells and tissues has been the major challenge in realizing the potential of RNAi.

New nanotechnology platforms are tackling this problem by providing nonviral alternatives for effective and safe delivery. The first nontargeted delivery of siRNA in humans via self-assembling, cyclodextrin polymer-based nanoparticles for cancer treatment have recently entered Phase I clinical trials.

Although at an early stage, nonviral delivery of siRNA for treatment of HIV infection is also gaining ground. A fusion protein, with a peptide transduction domain and a double stranded RNA-binding domain, was used to encapsulate and deliver siRNA to T cells in vivo. CD4- and CD8-specific siRNA delivery caused RNAi responses with no adverse effects such as cyto-toxicity or immune stimulation. Similarly, a protamine-antibody fusion protein-based siRNA delivery demonstrated that siRNA knockdown of the gag gene can inhibit HIV replication in primary T cells

Single-walled nanotubes were shown to deliver CXCR4 and CD4 specific siRNA to human T cells and peripheral blood mononuclear cells. Up to 90% knockdown of CXCR4 receptors and up to 60% knockdown of CD4 expression on T cells was observed while the knockdown of CXCR4 receptors on peripheral blood mononuclear cells was as high as 60%. In a separate study, amino-terminated carbosilane dendrimers (with interior carbon-silicon bonds) were used for delivery of siRNA to HIV-infected lymphocytes.

These pioneering studies demonstrate that nonviral siRNA delivery is possible for HIV/AIDS treatment. However, more work needs to be done in optimizing the delivery systems and utilizing designs for efficient targeting and intracellular delivery. The recent developments in polymer- and liposome-based siRNA delivery systems could be optimized for targeting cells that are infected with HIV, such as T cells and macrophages. Moreover, since HIV mutates and has multiple strains with different genetic sequences, combination siRNA therapy targeting multiple genes should be pursued. For these applications, nanotechnology platforms with capability for co-delivery and targeting need to be developed specifically for HIV-susceptible cells. A macrophage and T-cell-targeted and nanotechnology-based combination gene therapy may be a promising platform for efficient HIV/AIDS treatment.

Immunotherapy for HIV/AIDS

The various treatment approaches described above focus on treating HIV/AIDS by directly targeting HIV at the level of the host cell or the virus itself. An alternative approach is immunotherapy aimed at modulating the immune response against HIV. CD8+ cytotoxic T-cell responses to acute HIV infection appear to be relatively normal, while neutralizing antibody production by B cells is delayed or even absent.

Immunotherapy is a treatment approach involving the use of immunomodulatory agents to modulate the immune response against a disease. Similar to vaccines, it is based on immunization of individuals with various immunologic formulations; however, the purpose is to treat HIV-infected patients as opposed to protect healthy individuals (preventive vaccines will be discussed in an upcoming section). The various immunotherapy approaches for HIV/AIDS could be based on delivering cytokines (such as IL-2, IL-7 and IL-15) or antigens. The development of cellular immunity, and to a large degree humoral immunity, requires antigen-presenting cells (APCs) to process and present antigens to CD4+and CD8+ T cells. Dendritic cells (DCs) are the quintessential professional APCs responsible for initiating and orchestrating the development of cellular and humoral (antibody) immunity.

Various polymeric systems have been explored for in vivo targeting of DCs and delivery of small molecules, proteins or DNAs showing potential for immunotherapy. Poly(ethylene glycol) (PEG) stabilized poly(propylene sulfide) polymer nanoparticles accumulated in DCs in lymph nodes. Following nanoparticle injection, DCs containing nanoparticles accumulated in lymph nodes, peaking at 4 days with 40–50% of DCs and other APCs having internalized nanoparticles.

In another study, nanoparticles of the copolymer poly(D,L-lacticide-co-glycolide) (PLGA) showed efficient delivery of antigens to murine bone marrow-derived DCs in vitro, suggesting their potential use in immunotherapy. More recently, a very interesting work showed that HIV p24 protein adsorbed on the surface of surfactant-free anionic poly(D,L-lactide) (PLA) nanoparticles were efficiently taken-up by mouse DCs, inducing DC maturation. he p24-nanoparticles induced enhanced cellular and mucosal immune responses in mice. Although this targeting is seen in ex vivo-generated DCs and not in vivo DCs, the efficient delivery of the antigen to DCs through the nanoparticles is an important demonstration that may eventually be applied to in vivo DC targeting.

Clinical Trial

he most clinically advanced application of nanotechnology for immunotherapy of HIV/AIDS is the DermaVir patch that has reached Phase II clinical trials (9). DermaVir is a targeted nanoparticle system based on polyethyleimine mannose (PEIm), glucose and HIV antigen coding DNA plasmid formulated into nanoparticles (~100 nm) and administered under a patch after a skin preparation. The nanoparticles are delivered to epidermal Langerhans cells that trap the nanoparticles and mature to become highly immunogenic on their way to the lymph nodes. Mature DCs containing the nanoparticles present antigens to T cells inducing cellular immunity. Preclinical studies and Phase I clinical trials showed safety and tolerability of the DermaVir patch, which led the progression to Phase II trials. This is the first nanotechnology-based immunotherapy for HIV/AIDS that has reached the clinic and encourages further work in this area.

Table 1

Summary of nanotechnology-based treatment approaches for HIV/AIDS.

Type of therapy Therapeutic agent (drug or gene) Nanotechnology delivery platform Development stage Refs.
Antiretroviral therapy Rilpivirine (TMC278) Poloxamer 338/TPGS 1000 Preclinical [35]
Indinavir Liposome-laden macrophages Preclinical [3638]
Stavudine Mannose- and galactose-targeted liposome Preclinical [3941]
Zidovudine Mannose-targeted liposome Preclinical [42]
Efavirenz Mannose-targeted dendrimer Preclinical [43,45]
Lamivudine Mannose-targeted dendrimer Preclinical [46]
Nanomaterials Fullerene derivatives Preclinical [4955]
Dendrimers Preclinical [56,57]
Silver nanoparticles Preclinical [58,59]
SDC-1721/gold nanoparticles Gold nanoparticles Preclinical [60]
Gene therapy siRNA Peptide fusion proteins, protamine–antibody fusion proteins, dendrimers, single walled carbon nanotubes, peptide–antibody conjugates Preclinical [7781]
Immunotherapy P24 protein Poly (D,L-lactide) nanoparticles/dendritic cells Preclinical [98]
Plasmid DNA Mannose-targeted polyethyleimine polymers Phase II clinical trials [99]

Note:  to open the references in the table 1, please go to ref 1 in this post to see full ref info.

Nanotechnology for HIV/AIDS prevention

The search for a safe and effective HIV/AIDS vaccine has been challenging in the almost three decades since the discovery of the disease. Recently, high-profile clinical trial failures have prompted great debate over the vaccine research, with some suggesting the need for a major focus on fundamental research, with fewer efforts on clinical trials.

The major challenges in the development of a preventive HIV/AIDS vaccine have been the extensive viral strain and sequence diversity, viral evasion of humoral and cellular immune responses, coupled with the lack of methods to elicit broadly reactive neutralizing antibodies and cytotoxic T cells. The challenge associated with delivery of any exogenous antigen (such as nanoparticles) to APCs, is that exogenous antigens require specialized ‘cross-presentation’ in order to be presented by MHC class I and activate CD8+cytotoxic T cells.

his requirement for cytosolic delivery of antigens and cross-presentation represents yet another hurdle for HIV intracellular antigen vaccine, but potentially an advantage of nanodelivery. Humoral responses (neutralizing antibodies produced by B cells) are generated to intact antigen presented on the surface for the virus, or nanoparticles, but these humoral responses typically require ‘help’ from CD4+ T cells, but rather both. Nanoparticles have potential as adjuvants and delivery systems for vaccines. Table 2 present the different approaches.

Table 2

Summary of nanotechnology developments for prevention of HIV/AIDS.

Type of preventive agent Antigen/adjuvant or drug Nanotechnology platform Development stage Refs.
Protein or peptide vaccine gp41, gp120, gp160, p24, Env, Gag, Tat Liposomes, nanoemulsion, MF59, PLA nanoparticles, poly(γ-glutamic acid) nanoparticles Preclinical [108111]
[119120]
[122125]
[128130]
DNA vaccine env, rev, gag, tat, CpG ODN Liposomes, nanoemulsion, PLA nanoparticles Preclinical [115,121]
Inactivated viral particle Inactivated HIV viral particle Polystyrene nanospheres Preclinical [126127]
Microbicides L-lysine dendrimer L-lysine dendrimer Phase I/II [136138]
PLGA nanoparticles
PSC-RANTES PLGA Preclinical [139]
siRNA Nanoparticles, lipids, cholesterol conjugation Preclinical [141144]

ODN: Oligonucleotides; PLA: Poly(D,L-lactide); PLGA: Poly(D,L-lacticide-co-glycolide).

Note:  to open the references in the table 2, please go to ref 1 in this post to see full ref info.

 

Summary

Nanotechnology can impact the treatment and prevention of HIV/AIDS with various innovative approaches. Treatment options may be improved using nanotechnology platforms for delivery of antiretroviral drugs. Controlled and sustained release of the drugs could improve patient adherence to drug regimens, increasing treatment effectiveness.

While there is exciting potential for nanomedicine in the treatment of HIV/AIDS, challenges remain to be overcome before the potential is realized. These include toxicity of nanomaterials, stability of nanoparticles in physiological conditions and their scalability for large-scale production. These are challenges general to all areas of nanomedicine and various works are underway to tackle them.

Another important consideration in investigating nanotechnology-based systems for HIV/AIDS is the economic aspect, as the hardest hit and most vulnerable populations reside in underdeveloped and economically poor countries. In the case of antiretroviral therapy, nanotherapeutics may increase the overall cost of treatment, reducing the overall value. However, if the nanotherapeutics could improve patient adherence by reducing dosing frequency as expected, and furthermore, if they can eradicate viral reservoirs leading to a sterile immunity, these advantages may effectively offset the added cost.

 

Ref:

1. Mamo T, Moseman EA., Kolishetti N., Salvadoe-Morales C., Shi J., Kuritzkes DR., Langer R., von-Adrian U and Farokhzad OF.   Emerging nanotechnology approaches for HIV/AIDS treatment and prevention. Nanomedicine (Lond) 2010; 5(2): 269-295.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2861897/

2. Merson MH. The HIV-AIDS pandemic at 25 – the global response. N Engl J Med.2006;354(23):2414–2417

3. Walensky RP, Paltiel AD, Losina E, et al. The survival benefits of AIDS treatment in the United States. J Infect Dis. 2006;194(1):11–19

4. Richman DD, Margolis DM, Delaney M, Greene WC, Hazuda D, Pomerantz RJ. The challenge of finding a cure for HIV infection. Science. 2009;323(5919):1304–1307)

5.Sax PE, Cohen CJ, Kuritzkes DR. HIV Essentials. Physicians’ Press; Royal Oak, MI, USA: 2007.

6. Lamers SL, Salemi M, Galligan DC, et al. Extensive HIV-1 intra-host recombination is common in tissues with abnormal histopathology. PLoS One. 2009;4(3):E5065.

7. Vyas TK, Shah L, Amiji MM. Nanoparticulate drug carriers for delivery of HIV/AIDS therapy to viral reservoir sites. Expert Opin Drug Deliv. 2006;3(5):613–628.

8. Amiji MM, Vyas TK, Shah LK. Role of nanotechnology in HIV/AIDS treatment: Potential to overcome the viral reservoir challenge. Discov Med. 2006;6(34):157–162

9. Lori F, Calarota SA, Lisziewicz J. Nanochemistry-based immunotherapy for HIV-1. Curr Med Chem. 2007;14(18):1911–1919

Read Full Post »


Author and Curator: Chloe Thomas, Manager, Scientific Sessions and Education at Heart Rhythm Society

 

One step further towards an HIV vaccine

Statistics show that approximately 34 million people are infected with the Human Immunodeficiency Virus. Within the last years, important steps have been taken in finding treatments and medications against HIV. The study introduced in this article is a helpful contribution to the development of an HIV vaccine.

Cloning antibodies

Researchers working in the California Institute of Technology have focused more closely on the binding mechanism of the virus to the human cell. Leading a study which was published in the Science Magazine in 2011, they departed from the fact that a passive transfer of HIV neutralizing antibodies can prevent an infection and might therefore even be valuable for the creation of an HIV vaccine. As the number of naturally occurring antibodies is relatively low, the researchers intended to discover whether these antibodies belong to a larger group of molecules which might turn out useful studies of the infection. By cloning more than 500 HIV antibodies taken from four different infected individuals, they discovered that all of them produced a large number of potent HIV antibodies which mimic the binding to CD4. By isolating the potent anti-HIV antibodies of infected people, the scientists have begun to develop ways in order to neutralize subtypes of the infection. The researchers have found a strong version of an anti-HIV antibody, which is named NIH45-46. These antibodies that target the binding site of the host receptor (namely CD4) interact with the protein gp120. This protein sits on the viruses and helps the virus enter the cell, and thus mainly contributes to the infection process. The interaction between antibody and the protein leads to neutralizing the virus and thus may avoid infection. Knowing this, the scientists were able to develop an even stronger type, named NIH45-46G54W, which employs the described mechanism more effectively. The next step the researchers are advocating is a clinical testing period for the newly-created effective antibody. Through that, they hope to gain further information on understanding the neutralization of the virus which might even help in developing a vaccine against HIV.

Scientific research: a long process

Despite the success of the study, it is important to note that an analysis in the laboratories and a clinical testing phase has to be conducted over a long period of time in order to bring about representative results. Methods have to be considered, antibodies suppliers like here have to be contacted, and data have to be evaluated. For that reason, the development of an HIV vaccine cannot happen overnight, but should be furthered patiently.

Read Full Post »