Home Reports Health and Medicine Content

Marijuana as an anti-viral drug?

next article

15.09.2004

The active ingredient of cannabis, delta-9-tetrahydrocannibol (THC), can prevent the replication and activation of several forms of herpes known to cause cancer, according to an article published today in BMC Medicine. This finding could lead the way to the creation of anti-viral drugs based on non-psychoactive derivatives of THC.

The gamma herpes viruses, Kaposi’s Sarcoma Associated Herpes virus and Epstein-Barr virus (which causes glandular fever), predispose infected individuals to cancers such as Kaposi’s sarcoma, Burkitt’s lymphoma, and Hodgkin’s disease. Kaposi’s sarcoma is particularly prevalent in AIDS sufferers, and is now the most common form of cancer in Africa.

Once infected, it is almost impossible to get rid of the viruses, as they can lie dormant for long periods within lymphoid cells (a type of white blood cell of crucial importance to the immune system). The dormant viruses can also reactivate, bursting out of cells, spreading between individuals and causing the symptoms of disease.

Dr. Peter Medveczky and his colleagues from University of South Florida found that this reactivation was prevented if infected cells were grown in the presence of THC. In addition, though cultured cells that are infected with a mouse gamma herpes virus die as the virus reactivates, the cells can survive if they are cultured along with THC - further evidence that THC prevents viral reactivation.

The researchers showed that THC acts specifically on gamma herpes viruses, as the chemical was unable to prevent the reactivation of another related virus, herpes simplex-1, which causes cold sores.

Previous research has shown THC to be a more potent and selective antiviral agent against gamma herpes viruses than the commonly used acyclovir, gancicyclovir and foscarnet. Dr. Medveczky believes that THC has its inhibitory effect by directly or indirectly targeting a viral gene shared by gamma herpes viruses, called ORF50. By preventing activation of this gene, THC can prevent the replication of the virus that this gene controls.

"We believe that studies on cannabinoids and herpes viruses are important to continue because there are obvious benefits," write the authors. "Better understanding may lead to the development of specific non-psychoactive drugs that may inhibit reactivation of cancer-causing herpes viruses."

However, Dr. Medveczky also stresses that THC can act as an immunosuppressant. So smoking marijuana could cause more harm than good to patients infected with these viruses, who often have weakened immune systems already.

Whether THC would be predominantly beneficial can only be tested in experimental animals (e.g. mice infected with the murine gamma herpesvirus). "We have not evaluated the effect of THC in an animal model yet," he said. "Therefore, our findings do not recommend that people take pot to prevent or treat cancers associated with gamma herpesviruses."

This press release is based on the following article: Delta-9 tetrahydrocannabinol (THC) inbibits lytic replication of gamma oncogenic herpes viruses in vitro Maria M Medveczky, Tracy A Sherwood, Thomas W Klein, Herman Friedman and Peter G Medveczky BMC Medicine 2004, 2:34 To be published 15 September 2004

Grace Baynes | Source: Press BioMed Central
Further information: www.biomedcentral.com

next article