Researchers might soon concoct the perfect drug for HIV – one that acts as preventive drug while also being efficient on infected patients. Salk Gene Expression Laboratory scientists have come a step closer to manufacturing such a drug by making use of a defense system exhibited by bacteria.
A senior author of the paper published in the journal Nature Communications, Juan Carlos Izpisua Belmonte, who is also a professor of Salk’s Gene Expression Laboratory, stated that:-
“Evolution has led to some of the most astonishing mechanisms for protecting organisms against their natural pathogens. Understanding the immune responses by which bacteria protect themselves against viral infections has allowed us to engineer novel platforms for the targeting of devastating viruses, such as HIV, in human patients.”
One of the main troubles with existing drugs is that they do not remove copies of the HIV virus from the DNA of the hosts’ cells. As a consequence, the copies remain inside the body, ready to be activated again after periods of dormancy. Therefore, the patients are forever dependent on drugs which they need to take regularly enough because of the latent HIV. This costs time, effort and money, according to the first author of the paper, Hsin-Kai (Ken) Liao.
To counter this predicament, the team of researchers set out to exploit the molecular defense system known as CRISPR used by bacteria to chip off foreign DNA to edit genes. This system has an embedded defensive ability that the researchers programmed to cut and destroy viruses found inside human cells.
CRISPR uses guided RNAs to control the chipping process. The scientists therefore built guide RNAs that are able to stick to specific points of the HIV virus. They produced a system that incorporated CRISPR, the guide RNAs and other molecules into immune cells infeced with HIV. The CRISPR was found to cause cuts at the right spots in the HIV genes, thereby deactivating the virus. The virus was thus removed from 72 % of the cells. The system cut loose copies of the virus that had just infected cells and those copies that were hidden and dormant inside the DNA of the host cells.
“The main advantage of this technology is not only that viral DNA integrated into the human genome can be eliminated but perhaps, most importantly, the prophylactic application,” says Izpisua Belmonte. “By eliminating the virus at the early steps of its life cycle, we can altogether prevent the infection of human cells in an analogous manner to how conventional vaccines work.”
But, will this work on human patients? And, will the HIV ultimately evolve to counter the system? More research needs to be done to attend to these queries.
“The HIV virus can mutate very quickly,” says Liao. “If we target multiple regions at the same time, we reduce the chance that the virus can develop resistance.”