By Christian Nordqvist
Special to the Las Vegas Tribune
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 earlier this year in an issue of Antiviral
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
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.
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
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 anti-retroviral treatments worth the extra cost —
investigators from Harvard University 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 percent.
By Christian Nordqvist