Genetically Modified Plant may Help Prevent HIV

by VR Sreeraman on Aug 2 2007 11:43 AM

Researchers have genetically modified a plant to halt reproduction of cauliflower mosaic virus, and the study may help prevent HIV, for the plant virus and AIDS virus use the same process to multiply in their victims' cells and spread disease.

Cauliflower mosaic virus (CaMV) attacks a group of plants that includes the largest number of agriculturally important plants in the world.

The study was conducted by a team of researchers led by Zhixiang Chen at Purdue University.

The retrovirus HIV and the pararetrovirus CaMV both use reverse transcription to recruit the host's proteins in order to reproduce and spread infection.

Transcription in cells is the process in which a gene's DNA code is copied into RNA, which, in turn, carries the information to another part of the cell or to another cell. In reverse transcription the virus' RNA is copied into DNA after it latches on to a victim's cell. This allows the virus to easily integrate into the host's genome and then reproduce in other cells.

CaMV recruits a protein complex called CDKC. This is the same protein complex that HIV uses, known in humans as P-TEFb. Since both viruses use this same process to trigger transcription, the scientists now know that this protein complex and its related genes have passed from species to species as organisms evolved over millions of years.

Humans and organisms used for research, such as fruit flies and the tiny wormlike organism Caenorhabditis elegans, have only one gene in the protein complex that retroviruses use to activate transcription and these organisms die if that gene is completely blocked because of its essential role during transcription.

This makes it difficult to analyze the function the gene may have in the organisms' growth, development and survival. Unlike those other organisms, the plant protein complex involves two genes.

As part of the study, researchers studied CaMV and found that modified laboratory research plant Arabidopsis had two genes for the CDKC protein complexes.

"In Arabidopsis there are two genes for the CDKC protein complexes that trigger the transcription process. If we knock out one of these genes, the plants become resistant to CaMV and the plant is still growing," Chen said.

Researchers suggested that the mustard plant Arabidopsis is a better organism than others for studying how the proteins regulate gene function and transcription.

The findings of the study were published in journal The Plant Cell.