Melitina y una esperanza en la lucha contra el HIV

[Invitado Anoshvan]

Esta es una noticia que hace días circula por los medios...

 

Desde su descubrimiento, en 1981, hasta la actualidad, el Sida (síndrome de inmunodeficiencia adquirida) mató a más de 30 millones de personas en todo el mundo. Además, se calcula que otras 33,4 millones se encuentran hoy infectadas con este temible virus. Sin embargo, aunque afortundamente se encuentra parcialmente controlado, pudiendo los pacientes infectados gozar de una vida relativamente normal, el miedo continúa. Después de todo, no existe una cura... hasta ahora.

 

Sucede que investigadores de la Escuela de Medicina de la Universidad de Washington, en Estados Unidos, descubieron que existe un veneno capaz de matar el VIH (virus de la inmunodeficiencia humana), causante del Sida. Lo que abre la esperanza de desarrollar un gel vaginal para prevenir la propagación del VIH y un tratamiento vía intravenosa para ayudar a las personas infectadas.

 

La investigación -puede leerse aquí-, que fue publicada en la edición de Antiviral Therapy, explica que el veneno que puede encuentrarse en las abejas contiene una potente toxina llamada melitina que puede hacer unos agujeros en la envoltura protectora que rodea al VIH, según informa The Huffington Post. Además de acabar con el virus, los científicos descubrieron que la melitina cargada en nanopartículas también puede ser eficaz a la hora de atacar células tumorales.

 

Los científicos añadieron una protección sobre la superficie de las nanopartículas, que cuando entran en contacto con las células normales, las partículas simplemente rebotan. Pero cuando encuentran el virus destruyen su capa protectora y lo eliminan. Por el contrario, aunque la mayoría de los medicamentos contra el VIH inhiben la capacidad del virus para replicarse, no hacen nada para detener la infección inicial, por lo que algunas cepas del virus acaban encontrando formas de evitar estos medicamentos y reproducirse de todos modos.

 

Este estudio viene de la mano con la noticia de que un bebé en Misisipí, EE.UU., que había nacido con VIH fue curado. Su madre fue diagnosticada con el virus durante el parto y el bebé recibió un tratamiento de tres fármacos 30 horas después de haber nacido.

 

La medicina moderna permite a los infectados llevar una vida relativamente normal, con pocos efectos secundarios. Sin embargo, deben permanecer esclavizados al medicamento, gastando enormes cantidades de dinero. La táctica resultó ser tan exitosa en las pruebas in vitro realizadas dentro del laboratorio, que el Consejo de Investigación Danés otorgó 1,5 millones de dólares al equipo para continuar con su labor en ensayos clínicos. Tuvieron la oportunidad de ver como reacciona el procedimiento en 15 pacientes, de los cuales todos se han curado de VIH.

 

Sin embargo, todavía no descorchemos botellas. El Dr. Søgaard, líder del equipo que realizó el estudio, adviertió que aunque el resultado fue exitoso, no equivale a una vacuna preventiva. “Crear conciencia acerca del SEXO desprotegido y el compartir de agujas permanece de suma importancia para combatir el SIDA”, agregó el profesional.

 

fuente: Clarin.

 

 

 

La misma noticia (por si las moscas...) desde otro portal:

 

Nanoparticles containing bee venom toxin melittin can destroy human immunodeficiency virus (HIV) while at the same time leaving surrounding cells unharmed, scientists from Washington University School of Medicine reported in the March 2013 issue of Antiviral Therapy.

 

The researchers said that their finding is a major step toward creating a vaginal gel that can prevent HIV spread. HIV is the virus that causes AIDS.

 

Joshua L. Hood, MD, PhD, a research instructor in medicine, said:

"Our hope is that in places where HIV is running rampant, people could use this gel as a preventive measure to stop the initial infection."

Melittin destroys some viruses and malignant tumor cells

 

Melittin is a powerful toxin found in bee venom. It can poke holes in the protective viral envelope that surrounds the human immunodeficiency virus, as well as other viruses. Free melittin in large-enough quantities can cause considerable damage.

 

Senior author, Samuel A. Wickline, MD, the J. Russell Hornsby Professor of Biomedical Sciences, has demonstrated that nanoparticles loaded with melittin have anti-cancer properties and have the capacity to kill tumor cells. Linking bee venom with anticancer therapies is not new, in 2004 Croatian scientists reported in the Journal of the Science of Food and Agriculture that honey-bee products, including venom, could well have applications in cancer treatment and prevention.

 

Normal cells remain intact - the scientists showed that nanoparticles loaded with melittin do not harm normal, healthy cells. Protective bumpers were added to the nanoparticles surface, so that when they come into contact with normal cells (which tend to be much larger), the nanoparticles bounce off rather than attach themselves.

 

Scientists have discovered a powerful toxin in bee venom that could end up playing a crucial role in preventing the spread of HIV.

HIV is much smaller than the nanoparticles and fits in between the bumpers. When HIV comes across a nanoparticle it goes in between the bumpers and comes into direct contact with its surface, which is coated with the bee toxin, which destroys it.

 

Hood explained "Melittin on the nanoparticles fuses with the viral envelope. The melittin forms little pore-like attack complexes and ruptures the envelope, stripping it off the virus."

 

While most anti-HIV medications work on inhibiting the virus' ability to replicate, this one attacks a vital part of its structure. The problem with attacking a pathogen's ability to replicate is that it does not stop it from starting an infection. Some HIV strains have found ways to circumvent replication-inhibiting drugs, and reproduce regardless.

 

Hood said:

"We are attacking an inherent physical property of HIV. Theoretically, there isn't any way for the virus to adapt to that. The virus has to have a protective coat, a double-layered membrane that covers the virus."

Melittin nanoparticles may prevent and treat existing HIV infections

 

Hood believes that the melittin-loaded nanoparticles have the potential for two types of therapies:

• A vaginal gel to prevent the spread of HIV infection
  
• Therapy for existing HIV infections, particularly drug-resistant ones
  

In theory, if the nanoparticles were injected into the patient's bloodstream, they should be able to clear the blood of HIV.

 

Hood said "The basic particle that we are using in these experiments was developed many years ago as an artificial blood product. It didn't work very well for delivering oxygen, but it circulates safely in the body and gives us a nice platform that we can adapt to fight different kinds of infections."

 

Melittin attacks double-layered membranes indiscriminately, making it a potential for drug therapies beyond HIV infections. The hepatitis B and C viruses, among several others, rely on the same type of protective envelope and could be targeted and destroyed by administering melittin-loaded nanoparticles.

 

The gel also has the potential to target sperm, the researchers explained, making it a possible contraceptive medication. The study, however, did not look at contraception.

 

Hood said "We also are looking at this for couples where only one of the partners has HIV, and they want to have a baby. These particles by themselves are actually very safe for sperm, for the same reason they are safe for vaginal cells."

 

This study was carried out in cells in a laboratory environment. However, the nanoparticles are easy to produce - enough of them could easily be supplied for future human studies.

 

Recent research on HIV

 

Over the last few years, scientists have made strides in improving HIV/AIDS treatments and prevention strategies.

 

Baby "functionally cured" of HIV infection - researchers from Johns Hopkins Children's Center, the University of Mississippi Medical Center and the University of Massachusetts Medical School reported that a baby who was administered antiretroviral therapy thirty hours after being born was "functionally cured". A functional cure means that there is no detectable viral replication after retroviral therapy has stopped.

 

Ramping up HIV antiretroviral treatments worth the extra cost - investigators from Harvard University, USA, reported that scaling up HIV antiretroviral treatment in a remote province of South Africa (KwaZulu-Natal) reduced the risk of transmitting HIV to sexual partners by 96%.

 

fuente: medicalnewstoday