A novel protein, p27SJ, extracted from a callus culture of the St. John's wort plant (Hypericum perforatum) suppresses HIV-1 expression and inhibits its replication, according to researchers at Temple University School of Medicine's department of neuroscience and Center for Neurovirology (CNV).
Their findings, "p27SJ, a novel protein in St. John's wort, that suppresses expression of HIV-1 genome," will be published online in the Oct. 27 issue of Gene Therapy.
Kamel Khalili, Ph.D., director of CNV, professor and acting chair of Temple's department of neuroscience, and the study's lead author, said the researchers were originally examining plant extracts from St. John's wort cultured in the laboratory to see if they had any effect on cell growth or the behavior of brain cells in vitro.
"During the course of that study, we also looked to see whether these plant extracts that we had isolated from the callus culture had any anti-viral activity," said Khalili. "We soon discovered that the plant extract inhibited HIV-1 gene expression and replication in infected cells."
Next, the team sought to isolate the protein from the plant extract responsible for the observed anti-viral activity. After identifying the protein, the group cloned the gene, which they realized was a novel protein and named p27SJ.
"It has unique characteristics," said Khalili. "Remember, it is a plant protein, and so far, to my knowledge, there is no similar protein to that in mammalian cells."
After cloning the gene, the researchers then were able to identify the molecular mechanism by which the protein is able to suppress HIV-1 gene expression and replication, according to Khalili.
It is the expression of the viral gene and the replication of the viral genome that leads to the development of AIDS in HIV-infected individuals.