We employed an RNA-guided CRISPR/Cas9 DNA editing system to precisely remove the entire HIV-1 genome spanning between 5′ and 3′ LTRs of integrated HIV-1 proviral DNA copies from latently infected human CD4+ T-cells. Comprehensive assessment of whole-genome sequencing of HIV-1 eradicated cells ruled out any off-target effects by our CRISPR/Cas9 technology that might compromise the integrity of the host genome and further showed no effect on several cell health indices including viability, cell cycle and apoptosis. Persistent co-expression of Cas9 and the specific targeting guide RNAs in HIV-1-eradicated T-cells protected them against new infection by HIV-1. Lentivirus-delivered CRISPR/Cas9 significantly diminished HIV-1 replication in infected primary CD4+ T-cell cultures and drastically reduced viral load in ex vivo culture of CD4+ T-cells obtained from HIV-1 infected patients. Thus, gene editing using CRISPR/Cas9 may provide a new therapeutic path for eliminating HIV-1 DNA from CD4+ T-cells and potentially serve as a novel and effective platform toward curing AIDS.
Civilization is at last turning green, albeit only pale green. Our attention remains focused on the physical environment — on pollution, the shortage of fresh water, the shrinkage of arable land and, of course, the great, wrathful demon that threatens all our lives, human-forced climate change. But Earth’s living environment, including all its species and all the ecosystems they compose, has continued to receive relatively little attention. This is a huge strategic mistake. If we save the living environment of Earth, we will also save the physical, nonliving environment, because each depends on the other. But if we work to save only the physical environment, as we seem bent on doing, we will lose them both.
In The Origin of Species (1859), Charles Darwin asserts that “species and groups of species gradually disappear one after another, first from one spot, then from another, and finally from the world.” From the Darwinian perspective, species adaptation and extinction are not only inexorable natural forces, but are also necessary to sustain the astonishing biodiversity of this planet. Of course, Darwin was writing just at the cusp of the modern era, right before industrialization and other anthropogenic factors began to accelerate extinction rates beyond natural background levels. We are now in the midst of a global biodiversity crisis caused by interacting forces such as climate change, the illegal trade in endangered species, habitat loss and ongoing modernization around the globe. Indeed, the International Union for the Conservation of Nature (IUCN) believes that extinction is proceeding at up to 1,000 times or more the natural rate.
Is it heresy to suggest that Darwin’s understanding of extinction may no longer be entirely true? What if we now have the scientific tools to bring back at least some of those disappeared ghost species that haunt our imagination? De-extinction refers broadly to the use of biotechnological tools such as reproductive cloning, genome sequencing and assisted reproduction in the effort to “bring back” extinct species such as the woolly mammoth, the Tasmanian tiger (thylacine), or the moa. Critics worry that de-extinction distracts our focus from those species currently on-the-brink in favor of fantastical “resurrection” projects and contend that scarce conservation resources are best spent on those extant species that we could potentially save. Yet de-extinction done ethically could enrich global biodiversity by reintroducing “lost genes” to the global genome and re-instating keystone species that played an important role in maintaining healthy ecosystems that are now under threat. We do not have to pit conservation against de-extinction; instead, we need to start thinking now about how we can harness all of the tools at our disposal to reinvigorate the environmental movement and replenish nature.
The Genetic Rescue Foundation is an increasingly visible stakeholder in the de-extinction and bio-conservation debate. Started by David Iorns, an expat Kiwi who lives and works in Silicon Valley, the Genetic Rescue Foundation uses innovative methods such as crowdfunding and social media to generate broad public and financial support for the use of biotechnology in conservation. Recently, the Foundation launched The Kakapo 125 Project, which intends to sequence the genome of every remaining live kakapo in New Zealand. The information gleaned from the project will be invaluable in ensuring that this iconic Kiwi species has the best possible chance to survive into the 21st century.
The Genetic Rescue Foundation is also a key player in a collaborative effort to bring back the moa. Originally, the island that became New Zealand hosted nine different species of these flightless birds (Dinornithiformes). Approximately 600 years ago, the moa abruptly went extinct for reasons that have been scientifically contested. The dominant theory today, based on recent ancient DNA studies, suggests that the moa’s demise was caused primarily by the arrival of Polynesians who hunted them, though variables such as climate change, disease or volcanic eruptions have also been mooted. As early as 1922, the Dunedin Star newspaper noted that “one of the oldest and certainly one of the most heated scientific controversies that ever engaged the attention of the New Zealand public was that which raged over the question as to the date of extinction of the moa.” Archival analysis further suggests that Kiwi interest in the moa dovetailed with both the public dissemination of Darwinian ideas about evolution in the late 1800s, and again with the early stirrings of a national—as opposed to colonial—identity immediately following World War I.
Today the moa is considered an iconic species, associated with a lush, primeval New Zealand that teemed with kiwis, kakapos and giant eagles. The moa is also a species at the forefront of international efforts to accomplish de-extinction over the long-term. The elusive elixir that could make de-extinction possible for the moa (among other species) is so-called “ancient DNA.” Around the world, scientists are revisiting bones and other specimens long locked up in natural history museums to see if these talismans might contain fragments of viable DNA that can then be amplified in the lab and,potentially, used in reproductive cloning projects. Thus far, the news on this front is mixed, with a recent analysis of four moa samples by the UCSC Paleogenomics Lab indicating the samples are too degraded to yield anything but a minute amount of endogenous DNA that would be prohibitively expensive to sequence. At the moment, the search for a well-preserved moa bone goes on.
The idea of bringing back the moa—as with bringing back the thylacine or the woolly mammoth—is a controversial one that sparks a great deal of public and scientific debate. Of course, public attention to the extinction crisis is one of the most important things that an organization such as the Genetic Rescue Foundation can generate. Even if the moa project does not succeed, the dialogue that has ensued and the associated knowledge and projects that can spin off from this effort are themselves invaluable contributions to our natural heritage. De-extinction—complicated, controversial and conditional—has already succeeded in bringing new enthusiasm and sources of funding into the conservation arena. If we resist the notion that extant and extinct species are in competition with each other, and focus instead on biological and environmental enrichment in the deepest sense, de-extinction could prove a journey into the past that ensures our environmental future.
|Amy L. Fletcher, PHD
Associate Professor of Political Science (The University of Canterbury) and Advisory Board Member of The Moa Revival Project, 1 March 2016
Debates rage over what to do about genetically modified organisms, but we rarely stop to ask a more basic question: Do GMOs really exist? It’s an important question, because no one in this debate can tell you precisely what a GMO is. It’s a metaphor we use to talk about a set of ideas. It doesn’t map neatly onto any clear category in the physical world.
Will it one day be possible to bring a woolly mammoth or a Neanderthal back to life? If so, should we? How is climate change affecting the evolution and extinction of species?
These are some of the questions explored in science writer Maura O’Connor’s new book, Resurrection Science: Conservation, De-Extinction And The Precarious Future of Wild Things.
A great simplified overview of the complexities involved in genome comparison.