Researchers from Temple University have used the CRISPR/Cas9 gene editing tool to clear out the entire HIV-1 genome from a patient’s infected immune cells. It’s a remarkable achievement that could have profound implications for the treatment of AIDS and other retroviruses.
It’s a little early to break out the champagne, but while medication for HIV has done wonders – HIV is notoriously good at hiding in the body. That’s where news like this brings hope that HIV positive people could one day be truly cured.
For the approximately 37 million people worldwide who are infected with HIV (human immunodeficiency virus), the newest cocktails of anti-retroviral drugs have come a long way in beating back the retrovirus and keeping an infection in check. Still, those drugs are no cure. While the treatments snarl the viral assembly line and thwart new infectious particles from invading the body’s cells, HIV itself is still there, hunkered in the DNA of a patient’s genome until there’s an opportunity for a comeback—say, when a patient goes off their medication.
We know that we don’t “use” a lot of the genes inside our cells, but our DNA is strung with relics. But what are those relics, and what if they come back to haunt us? Here’s what you’re carrying around, and why it’s not as irrevocably part of the past as you think it is.
Case Western Reserve researchers are part of an international team that has discovered that a common herpes drug reduces HIV-1 levels — even when patients do not have herpes.
Published online in Clinical Infectious Diseases, the finding rebuts earlier scientific assumptions that Valacyclovir (brand name, Valtrex) required the presence of the other infection to benefit patients with HIV-1.
The result not only means that Valacyclovir can be used effectively with a broader range of HIV-1 patients, but also suggests promising new avenues for the development of HIV-fighting drugs. This insight is particularly significant given that some forms of HIV-1 have become resistant to existing medications.
…HIV-1 can lead to the immune deficiency known as AIDS. The herpes simplex virus 2 (HSV-2) causes periodic recurrence of genital herpes lesions, which increase the likelihood that a herpes sufferer may contract HIV through intimate contact. HSV-2 outbreaks are treated with either Acyclovir or the newer generation Valacyclovir, which requires less frequent dosing.
Wouldn’t be the first time a drug showed this type of cross-reactivity. Lamivudine started as an anti-HIV drug and ended up being effective as an anti-HBV drug as well. HIV is a retrovirus and HBV is a pararetrovirus – both of which have reverse transcriptase but HBV exists as a DNA virus outside the host cell while HIV exists as a RNA virus outside the host cell. This is important because RNA is more prone to mutations (thus the viral proteins made from the viral RNA avoid the antibodies custom made by the immune system from vaccines) while DNA is more stable in structure (the antibodies are able to target the common motif of the viral proteins made from the viral DNA and kill them before they have a chance to infect the organism). This explains why we have a HBV vaccine, but not an HIV vaccine.
Recent research also suggests that the chickenpox vaccine may help with herpes. Which shouldn’t be much of a surprise – chickenpox is a form of herpes.
Researchers have long been aware that endogenous retroviruses constitute around five per cent of our DNA. For many years, they were considered junk DNA of no real use, a side-effect of our evolutionary journey.
In the current study, Johan Jakobsson and his colleagues show that retroviruses seem to play a central role in the basic functions of the brain, more specifically in the regulation of which genes are to be expressed, and when. The findings indicate that, over the course of evolution, the viruses took an increasingly firm hold on the steering wheel in our cellular machinery. The reason the viruses are activated specifically in the brain is probably due to the fact that tumours cannot form in nerve cells, unlike in other tissues.