The Scientist : NewsBlog Print: Silencing HIV
The Scientist: NewsBlog:
Silencing HIV
Posted by Megan Scudellari
[Entry posted at 7th August 2008 05:11 PM GMT]
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With the help of a new mouse model for HIV infection, scientists have shown that gene silencing with RNA interference (RNAi) may be effective in preventing viral entry and replication in T-cells, according to a study published online today (August 7th) in Cell.

Past studies have used RNAi to suppress HIV infection in cultured cells, but researchers did not have a good animal model simulating chronic HIV-infection in which to test the approach. Another challenge has been targeting the therapy specifically to T-cells within a living organism.

"What makes this paper special," says Ramesh Akkina, a microbiologist at Colorado State University who was not involved in the study, "is using an actual animal model." The treatment suppressed viral load and maintained high T-cell levels in mice with humanized immune systems infected with HIV.

The team used two different "humanized" HIV mouse models, both immunodeficient so that injected human cells are not rejected. The "old-fashioned" model, Hu-PBL (human peripheral blood lymphocyte) mice, according to Akkina, are injected with human white blood cells for short term experiments. The second model, Hu-HSC (human hematopoietic stem cell) mice, was first developed in 2004 and later shown by researchers in Japan, the U.S., and Switzerland to be a good model for HIV infection. Researchers can transplant hematopoietic stem cells into these mice, which then give rise to a variety of human immune cells, effectively reconstituting a human immune system in a mouse. The stem cells also provide a constant source of replenishment of T-cells so viremia can be tracked in the mouse for as long as a year.

The researchers targeted the siRNA to T-cells with an antibody that binds to a receptor on the T-cell surface. That receptor is often used as an antigen for T-cell therapies because it readily internalizes antibodies that bind to it. They attached a peptide to the antibody to bind the siRNA molecules, like a tow rope to haul the RNA molecules to the T-cells.

The siRNA molecules target three key genes: two highly-conserved HIV viral genes and one T-cell receptor gene, CCR5. "It's important to target different stages of the viral life cycle, such as viral entry and viral replication" said senior author Premlata Shankar, previously at the Immune Disease Institute at Harvard Medical School and now at Texas Tech University Health Sciences Center.

The researchers first tested the siRNA cocktail as a prophylactic regimen, injecting it in Hu-PBL mice with healthy human lymphocytes and then challenging the animal with HIV. Three out of four siRNA-treated mice retained essentially normal T-cells levels four weeks after infection. Next, they tested the therapy in T-cells already infected with clinical HIV by transplanting HIV-infected human T-cells into Hu-PBL mice and then treating with the siRNA. Again, they saw a drop in virus load and an increase in CD4 T-cell count.

Finally, the team used Hu-HSC mice, with a reconstituted human immune system from hematopoietic stem cells, to test the siRNA treatment. While control mice displayed viremia by the first week after infection, siRNA in naive T-cells protected the mice from infection. "The ones with antiviral siRNA had no sign of infection for about 2 months," said Priti Kumar, an instructor at Harvard Medical School and first author on the paper, after which time the experiment was stopped.

The approach has some drawbacks, said Akkina. For example, the siRNA must be injected repeatedly to maintain the treatment, and it's possible that an individual could develop an immune reaction to the delivering antibody. In 2003, Akkina's lab developed a gene therapy strategy using a lentivirus vector to deliver the siRNA into the genome of T-cells, therefore not requiring repeat administration of the therapy.

Kumar believes that the need for repeat injections is actually a benefit. siRNA can target to the cytoplasm of T-cells without being incorporated into the genome, where it could have unintended consequence, she explained. Also, she added, the siRNA cocktail could be changed as needed to keep up with mutations of the HIV virus during treatment.

"There is a lot of promise that RNAi can be another feasible therapy for HIV," said Kumar. The team's future goals include finding a method to increase the amount of siRNA that can be delivered and humanizing the delivery antibody (currently a mouse antibody) so that it could someday be used in clinical trials.



Correction (posted August 8th): The original version of this story contained a misleading sentence in the second paragraph and incomplete attributions for the development of Hu-HSC mice in the fourth paragraph. The Scientist has corrected the sections and regrets the errors.


 

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comment:
Second Big siRNA vs HIV story of the year
by Aaron Rowe ??[Not You?
[Comment posted 2008-08-14 05:25:05]

Excellent post, particularly in the context of the earlier Science paper, Identification of Host Proteins Required for HIV Infection Through a Functional Genomic Screen

Keep up the great work!




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comment:
CURE for HIV/AIDS....Ambush
by Apostle Mishe

[Comment posted 2008-08-13 19:41:34]


THE CURE for HIV/AIDS.......AMBUSH

THE IDEA that AMBUSH cures AIDS
is being proven by the more than 400 individuals who have taken a dose of 60 ml three times daily for 21 days. The result is that AMBUSH 'KILLS' the virus by causing the protein envelope to rupture and the viral particles are discarded by the white blood cells. AMBUSH is able to 'KILL' the virus that are 'hiding' in the lymph system by its 'natural radioactive' properties. This process allows the body to 'return to normal health' with a corresponding immunity to that or those strains of the virus.

What is AMBUSH ?
AMBUSH is a radioactive isotope of uranium that is found in the 'palm' plant of which there are more than 3000 species. When ingested, AMBUSH causes the body temperature in the trunk area to rise to about 102 degrees when the individual is sleeping. The preparation takes four hours per batch, which is then given to the individuals for consumption 60 ml three times daily for 21 days. AMBUSH is a herbal preparation in this form but it contains an active ingredient which is a 'NEW' crystalline substance, a drug from the 'palm plant' similarly to ASPIRIN originating from the willow tree bark

RESULTS:
After 21 days on AMBUSH, ALL the individuals experienced a decrease in viral load to undetectable, an increase in cd4, increase in RBC, an improvement in general health such as more color to the face, decrease in Buffalo hump, an increase in gluteal muscles, a decrease to having no joint pains whereby individuals can bend to touch their toes, and walk up steps are but a few examples. There is also a dramatic increase in their sexual appetite beginning after the first week of therapy

DISCUSSION:
In any plant concoction such as percolated 'tea', there are 30-40,000 compounds, whi ch would take the scientific community twenty years to isolate one particular ingredient if they knew what they were looking for. The LORD GOD has given me seven steps to isolate the active ingredient, which is soft and metallic in nature and has a carbon- uranium-sulfur-(classified)-phentolamine configuration or structure. This is similar to Federick Kekule and the discovery of the benzene ring where he dreamt the structure.

As an antiviral and 'natural radioactivity' producing agent, AMBUSH is also effective against leukemia, lupus and HPV. Here I am saying that I have 'GIVEN' AMBUSH in the same 'strength' and dosage to patients with leukemia, lupus and HPV. A 35 year old male with HIV found it difficult to impossible to urinate was put on 'green tea' and water while the doctors contemplated prostrate surgery. One of the doctors gave him my number , I sent him a supply of AMBUSH an d he has not been given any more ARV's, since taking AMBUSH 18 months ago, is in 'good' health and has expressed a willingness to be examined by HIV investigators like many others who have taken AMBUSH.

I have sent this 'IDEA' to most HIV research agencies, scientist of the field, universities, hospitals, clinics, politicians and news agencies to which it is REJECTED because the name of THE LORD GOD is mentioned. He has steered me scientifically through the processes such as which plant and how to produce the active ingredient. What are the odds of a Florida Pharmacist picking a plant would contain the CURE for HIV/AIDS ?
I have never charged any of the people for their supply of AMBUSH but a life saving has been spent on the project with NO renumeration from any sources because AMBUSH falls outside the walls of modern medicine and research.

PROPOSAL:

My proposal is that I PROVE that AMBUSH CURES HIV/AIDS by giving it to a number of END-STAGE or DRUG-RESISTANT people and the scientific community watches their recovery. This proposal addresses the problem in that I have already outlaid the results to be obtained.

This IDEA is unconventional in that the scientific community has rejected AMBUSH because I say it is GOD given. Secondly if I wrote it according to certain standards, then it might be peer reviewed. However, THE LORD GOD has also shown me that there are five enzyme systems associated with the virus, reverse transcriptase, protease, fusion and two more of which causes the virus to be AIRBOURNE. This means that without DIVINE intervention mankind and ALL warm- blooded mammals will be extinct in a number of years.

The PROOF of what I am saying is found in scientific papers wherein it is found that when the protease cuts the viral strands, it cuts it at DIFFERENT lengths EVERY time, to which it should always be a valine at the end but is a different amino acid every time. This is why it is IMPOSSIBLE to produce a VACCINE.

Since this is NOT a hypothesis but there are about 400 individuals who have taken AMBUSH, here lies a vast area in which to check, recheck and confirm that AMBUSH CURES AIDS. Let it be mentioned that during the HIV reproductive cycle, reverse transcriptase converts viral RNA into DNA compatible to human genetic materials. Thus the human DNA has been 'hijacked' and since each person has a DIFFERENT DNA, then the new viral copy is unique to that person which shows that each individual has a DIFFERENT STRAIN of the virus. Consider two HIV positive people swapping viral strains and increasing its complexity with multiple partners.
It can also be proposed that they be revisited as proof that the strain or strains that they had were 'killed' at the time of taking AMBUSH considering that a person can catch as many different strains as there are people who are infected by HIV.
I am also willing to work with the scientific community in identifying those individuals who took AMBUSH and wish to be identified with this process notwithstanding that some are stigmatized while others are jubilant,

Once AMBUSH is verified as being able to accomplish that which is aforementioned then the next stage might be the natural and artificial synthesis of the substance.

Finally, if this is accepted or not, believed or not, THE LORD GOD always wins and this is the heavenly truth to which AMBUSH was divinely given to mankind for the CURE of HIV/AIDS and it will be here forever. Apostle Shada Mishe.

vapalmer@bellsouth.net

Here is a video taped presentation that I gave at t he Martin Luther King library in Washington



http://www.youtube.com/watch?v=8V53D1w__Po
http://www.youtube.com/watch?v=vPwuwlVBOV0
http://www.youtube.com/watch?v=ZejptOwMTzQ
http://www.youtube.com/watch?v=CqcTgIAhrhc
http://www.youtube.com/watch?v=f7HPKcT_iwY
http://www.youtube.com/watch?v=W9iQfgiYAnw
http://www.youtube.com/watch?v=i3RzRS6tJDM




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comment:
One problem though
by Alicia Prater

[Comment posted 2008-08-11 22:30:36]

Recent research has shown that long-term siRNA treatment can be toxic.

http://www.preclinica.com/content/articles/1103/02.pdf

http://www.the-scientist.com/news/display/23495/




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comment:
VERY PROMISING
by Vinod Nikhra

[Comment posted 2008-08-09 21:05:36]

The study really appears very promising. For one, it successfully used an actual animal model and actually showed that 'the treatment' was able to suppress viral load and maintain a high T-cell level in HIV-infected mice bearing humanized immune systems. Secondly, the study dealt with three key genes, two HIV viral genes and one T-cell receptor gene, CCR5. Thirdly, it tested the siRNA treatment and actually showed that, while control mice displayed viremia after infection, the 'treatment' protected the mice with antiviral siRNA from the infection. The only minus point is need of repeated injections. But as the authors point out,a siRNA cocktail can be used to keep up with mutations of the HIV virus during treatment.
It is a good and laudable study.





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