Radical Eradication: A (Population) Crash Course in Genetic Engineering

Malaria is a life-threatening blood disease that plagues nearly two-thirds of the world’s population. The disease in manifested by parasites of the Plasmodium genus and transmitted to humans through the bite of female Anopheles mosquitoes, which serve as the primary disease vectors. Roughly 200 million people per year are infected with malaria, and approximately 400,000 deaths are reported annually, with children under the age of five comprising the majority of victims.

Africa disproportionately bears the global brunt of this devastating illness, with approximately 92% of all reported cases, as well as 93% of all reported deaths, originating from the continent. This can be partially attributed to the fact that the conditions for transmission are essentially ideal there: the principal vector species Anopheles gambiae are abundant in this region, and not only do they prefer to source their blood from humans over animals, but the mosquitoes also tend to have a longer lifespan, which allows the most common and deadly malaria parasite, Plasmodium falciparum, to complete its life cycle, which contributes to higher disease transmission efficacy.

Though malaria is a preventable disease, often the areas affected most lack access or resources, or are politically unstable, all factors that can contribute to the absence of consistent, functional malaria control programs. Though malaria is also a curable disease, it has long been debated whether eradication was even within the realm of possibility. There are four species of Plasmodium parasites responsible for the pathogenesis of malaria and each exhibit different forms of drug resistance and each responds differently to different medications. This alone makes the prospect of developing a single overarching vaccine for all strains of malaria an improbable achievement and the idea of eradication practically impossible.

A CRISP[E]R APPROACH

In a study recently published in Nature Biotechnology, a team of scientists were able to effectively implement a new, though indubitably controversial, type of genetic modification. The team was able to weaponize mosquitoes to take out…other mosquitoes! They were able to engineer male mosquitoes to rapidly pass down a fatal mutation through generations of their own species, effectively sterilizing all female offspring, eliminating the possibility of successful reproduction and resulting in a population crash.

Utilizing the dynamic technology known as CRISPR, the London-based team was able to genetically modify male mosquitoes of the malaria-transmitting species A. gambiae  with gene drive. The concept of gene drives and the idea to engineer them as a means of controlling insect populations that spread disease is not novel, however, up to this point in recent history, the technology to bring these ideas into reality has simply not existed.

In typical sexual reproduction, there are two possible versions of any given gene that the offspring can inherit, one from each parent. According to the traditional rules of genetics, there is then a 50% chance of the offspring inheriting either version of the gene. Gene drives completely negate these rules, and result in the rapid transmission of the desired engineered modification to almost all of the offspring.

The gene drive in this particular study selected a specific region of what is known in insects as the “doublesex” gene, which controls sexual determination and development. The region that they targeted would specifically impact female phenotypic sexual characteristics.

Female mosquitoes who initially have only one copy of the mutation would still present as healthy and normal, in terms of looks and behavior, and as a result were still reproductively able to continue spreading the mutation. Females born with two copies of the mutation would be phenotypically impacted, resulting in male-mouthed females that had lacked typical reproductive organs. These altered characteristics would render them sterile, unable to bite and by extension, unable to spread the malaria parasite.

For this research, two cage trials were run concurrently, utilizing 300 wild-type females, 150 wild-type males and 150 genetically-modified males. The aim of this experiment was for the gene drive to push the inheritance of this modified doublesex gene through multiple generations until the mutation reaches 100% prevalence in female offspring, leading to a population crash due to the inability to reproduce.

In the span of about six months, the team was able to achieve population crashes in both cage trials, as the populations reached 100% mutation frequency at generation 7 and generation 11, respectively.

GOING AU NATURALE 

Building upon the success of the initial study, a new phase of study, launched in Terni, Italy at the beginning of February, will get to test the model on a larger scale and under conditions designed to replicate as close to a natural environment as possible. Through this environmental imitation, the idea is for the surroundings to encourage natural behavior, thus providing more accurate insight into what the results of a gene drive release might look like if it were unfolding in their natural hot, humid habitats.

To set the stage for this experiment in the lab, the team of scientists are utilizing six huge cages that will each contain individual populations of A. gambiae mosquitoes. Every wall of each cage is lined floor to ceiling with mosquito netting, and each cage is supplied with stacks of hollow cylinders comprised of moist clay for the mosquitoes to utilize as shelter and heated canisters of cow’s blood, to help the specimens simulate drawing blood from a live animal.

Photo Credit: Firkin

Each chamber is additionally equipped with large black boxes with white backgrounds, and computer-regulated lighting systems. The boxes and their backgrounds play an important role in this experiment, as they are meant to mimic swarming, a key part of the mosquito mating ritual, and the controlled lighting is critical in simulating day and night cycles, particularly sunset as that is the typical time mating occurs.

To initiate the study, lab technicians methodically introduced small glass dishes to each mosquito-infested chamber. These glass dishes contained dozens of pupal-stage modified mosquitoes, which will quickly develop and assimilate into the already-thriving populations of the hundreds of normal mosquitoes that inhabit each cage. Two of the cages received an amount of modified insects equivalent to 25% of the normal population, another two received an amount of modified mosquitoes equivalent to approximately 50% of the normal population and the final two received no modified mosquito pupals and will serve as control populations.

Scientists will be collecting thousands of eggs from the chambers every week to monitor the spread of the lethal sterilizing mutation throughout each model population, and hoping that after about six months to a year, they will be able to see the effects of the engineered mutation play out.

EXAMINING EXPERIMENTATION EFFORTS

At least one thing has been made clear from these studies. The gravity of this situation – with just how controversial this technology and the implication of its successes in the laboratory is – is emphatically not lost on any of the scientists involved with these projects, which is a good indicator that this technology is in the best possible hands

As with most new and groundbreaking technologies, CRISPR carries the weight of great power but those who use it must also bear the baggage of great responsibility. Part of that responsibility is the thorough examination of the pros and cons and meticulous analysis of every “what if”.

When it comes to the decision to move this experimentation out of the lab and into real world applications, there is obviously some rightful pushback. This is not a topic to be taken lightly, and there is a very real possibility that we could see severe consequences, should anyone decide to continue full-speed ahead without evaluating all the possibilities.

It’s almost too easy to build a case against the advancement of these genetic engineering mechanisms simply by looking at the magnitude of all the unknown factors. Because there really is no precedent for this applied technology, there seem to be innumerable potential risks no matter which way you slice it.

From a con point of view, let’s say we were to press on with this particular experimentation in real-world environments. The potential eradication of the A. gambiae mosquitoes using this technology could present a variety of plausible undesirable effects. Delicate ecosystems could be thrown out of whack. The technology could stretch beyond the desired species and inadvertently lead to the destruction of non-disease-transmitting mosquitoes, or even the destruction of important pollinators.

Furthermore, what if the population crash of A. gambiae leaves an empty niche in an ecosystem that could be filled by another more problematic disease-peddling species?  And on an even broader scale, what if this gene-editing technology falls into the wrong hands? What if those wrong hands belong to terrorists who use the technology to develop biological warfare agents?

Photo Credit: GDJ

Though all these unknowns are valid questions that undeniably should be posed and thoroughly discussed, its equally important to not get so absorbed in what could go wrong, that we can no longer see what could go right. What if the large scale study is wildly successful? What if we can then apply the study to real life populations, and we eliminate huge populations of malaria-causing A. gambiae, effectively eliminating, if not entirely eradicating, the disease? We could then turn our focus to ending other insect-borne diseases plaguing humanity, such as Zika, Lyme Disease, West Nile, sleeping sickness, and yellow fever. What if we are able to spare millions of people from agonizing, unnecessary suffering?

What if we start to apply the gene drive model to other categories of global-scale issues? We could help endangered ecosystems thrive again, by targeting invasive rodents, fungi and plants. We could clean up harmful oil spills in our oceans utilizing genetically modified bacteria. We could engineer more efficient crops to aide the global hunger crisis, and minimize the need for harmful pesticides and herbicides by modifying bugs to stop consuming crops in the first place.

Depending on your perspective, everywhere you look you could either see potential problems or see potential solutions. Don’t disregard the problems as they arise–welcome them! Sit with them, make them a cup of tea, get to know them better. Just try to keep your eyes on the solutions–the advances, the unveiling of previous mysteries, the cures–as those are what make the pursuit of science worthwhile.

“We’re From NASA”: How Citizen Science Helped Find Ultima Thule

The science world is a-twitter with excitement lately, following the recent arrival of the New Horizons spacecraft at 2014 MU69, dubbed “Ultima Thule” by popular vote. The name means “beyond the borders of the known world”, signifying Ultima Thule’s status as the most distant object ever visited by Earthly spacecraft. Ultima Thule is a dark reddish rock in the Kuiper belt, a contact binary formed by two smaller rocks coming together in what was presumably a gentle fashion.

Do you wanna build a snowman? Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Reaching this space snowman 6.5 billion kilometers away from Earth took brains, dedication, ingenuity and the help of an unnamed Argentinian man and his daughter.

To successfully intercept Ultima Thule, the New Horizons mission team needed to answer some questions, such as “What trajectory is Ultima Thule on?” and “Is there any space debris around Ultima Thule that will destroy our spacecraft?” Being so small (~30km diameter at its widest point), observing Ultima Thule directly from this far away would be too difficult, so the team relied on data gathered during stellar occultations, i.e., when Ultima Thule passed in front of a star.

One of these occultations occurred on July 17, 2017, in the Patagonia region of Argentina. The team had already struck out twice in trying to observe Ultima Thule passing over a star: once in South Africa, and again using the airborne telescope SOFIA over the Pacific Ocean, so tension was already running high.

On this particular night, it happened to be very windy where the observation team was, which is bad news when you’re trying to hold steady focus on a tiny object that’s really far away. The team found themselves needing help to shield the telescopes they had brought with them from wind vibrations, and get the data from the star “without it jiggling around all over the place”, as planetary scientist Anne Verbiscer puts it.

Where does one find volunteers for an astronomical observation? Well, apparently even in Argentina NASA is known and loved, and help can be found just by walking into the community. “If you just started out with ‘We’re from NASA,’ people started coming out of the woodwork,” said Dr. Verbiscer. And that is how one Argentinian man and his daughter ended up spending their evening blocking the wind from a telescope using a truck, a tarp and some plywood, allowing the NASA folks to collect the data they needed to send New Horizons to Ultima Thule.

Want to learn more about the search for Ultima Thule? Check out the episode of NOVA that inspired this blog!

2019: International Year of the Periodic Table

Periodic table of the elements

From the inside covers of elementary science textbooks to the walls of chemistry labs all around the world, the periodic table is one of the most pivotal and enduring tools of modern science. To honor the 150th anniversary of its discovery, the United Nations General Assembly and UNESCO have declared 2019 to be the International Year of the Periodic Table of Chemical Elements.

As with all scientific progress, Dmitri Mendeleev’s periodic table was the result of decades—centuries, even—of research performed by scientists all over the world. Aristotle first theorized the existence of basic building blocks of matter over 2,500 years ago, which later were believed to be earth, air, fire and water. Alchemist Hennig Brand is credited with discovering phosphorus in the late 17th century, sparking chemists to begin pursuing these basic atomic elements.

Continue reading “2019: International Year of the Periodic Table”

5 of Our Favorite Blogs from 2018

We have published 130 blogs here at Promega this year (not including this one). I diligently reviewed every single one and compiled a list of the best 8.5%, then asked my coworkers to vote on the top 5 out of that subset. Here are their picks:

1. The Amazing, Indestructible—and Cuddly—Tardigrade

No surprises here, everyone loves water bears. Kelly Grooms knows what the people want.

The face of a creature that is nigh un-killable.

Continue reading “5 of Our Favorite Blogs from 2018”

Could Your Appendix Predispose You to Parkinson’s Disease?

Image of span of vagal nerve, humans.
The vagal nerve could serve as conduit for transit of alpha-synuclein from appendix to brain.

Since about 2000 we’ve learned a lot about the bacteria in our guts. We’ve learned that the right bacterial communities in our gastrointestinal system can make us feel better, think better and even help avoid obesity (1). My colleague Isobel has previously blogged about how certain gut bacteria can improve immunotherapy outcomes.

Conversely, the wrong bacteria in our guts can have negative consequences on health and cognition.

Along the way we’ve learned that gut bacterial flora can be influenced by what we eat, certain medications like antibiotics, and even stressful events. We now know that fermented foods like yogurt, sauerkraut, kombucha and that horrible-smelling stuff (kimchi) that another colleague eats are happy food for the good gut bacteria.

And you might guess that fried foods, saturated fats and certain carbohydrates can support the growth of gut bacteria that are doing us no favors when present in large quantities in our gastrointestinal system. Continue reading “Could Your Appendix Predispose You to Parkinson’s Disease?”

Finding Its Place: The Biohealth Industry in Wisconsin

On October 9, the 2018 Wisconsin Biohealth Summit was held in Madison, WI, hosted by BioForward, an organization that supports the growth of the biohealth industry in the state. This day-long event covered topics such as how diversifying your team can build better leadership, discovering new markets for existing products, and biomanufacturing. One of the panels on the schedule was “Examining the Economic Impact of Wisconsin’s Biohealth Industry,” and Penny Patterson, our Vice President of Communications, was one of the panel participants. We spoke after the summit to learn what came out of the panel discussion and the topics of interest raised by the biohealth industry attendees.

As we talked, Penny explained many topics were discussed, but ultimately focused around how to attract talented individuals to the biohealth industry in Wisconsin. This concern stemmed in part from the lower profile of the biohealth industry in Wisconsin compared to the more prominent and well-known East and West coasts. Of note, education and quality of life are important tools for recruiting candidates to join the biohealth industry. Continue reading “Finding Its Place: The Biohealth Industry in Wisconsin”

MSI Analysis and the Application of Therapies Based on 2018 Nobel Immuno-Oncology Work

The 2018 Nobel Prize in Physiology and Medicine was awarded to James P. Allison of the United States and Tasuku Honjo of Japan for their work to identify pathways in the immune system that can be used to attack cancer cells (1). Although immunotherapy for cancer has been a goal for many decades, Dr. Allison and Dr. Honjo succeeded through their manipulation of “checkpoint inhibitor” pathways to target cancer cells.

Immune checkpoint inhibitor drugs have been effective in cancers such as aggressive metastatic melanoma, some lung cancers, kidney, bladder and head and neck cancers. These therapies have succeeded in pushing many aggressive cancers below detectable limits, though these cases are notably not relapse-free or necessarily “cured” (2,3).

One challenge in implementing immunotherapy in a cancer treatment regime is the need to understand the genetic makeup of the tumor. Certain tumors, with specific genetic features, are far more likely to respond to immune checkpoint therapy than others. For this reason, Microsatellite Instability (MSI) analysis has become an increasingly relevant tool in genetic and immuno-oncology research.

What is MSI Analysis?

Continue reading “MSI Analysis and the Application of Therapies Based on 2018 Nobel Immuno-Oncology Work”

Conflict, CRISPR and the Scientific Method

Scientific inquiry is a process that is revered as much as it is misunderstood. As I listed to a TED talk about the subject, I was reminded that for the general public the foundation of science is the scientific method—the linear process of making an observation, asking a question, forming an hypothesis, making a prediction and testing the hypothesis.

While this process is integral to doing science, what gives scientific findings credibility and value is consensus from the scientific community. Building consensus is the time-consuming process that includes peer review, publication and replication of results. It is also the part of scientific inquiry that so often leads the public to misunderstand and mistrust scientific findings.

Continue reading “Conflict, CRISPR and the Scientific Method”

Could Your Dog Meds End Malaria or Zika Infections?

Mosquito photo
Will the sun soon be setting on dangerous mosquito populations?

Could that once-monthly beef-flavored pill you give your dog to kill fleas and ticks save thousands of human lives in Zika virus- and malaria-infected areas of the world?

That’s the hypothesis examined in a 2018 publication “Repurposing isoxazoline veterinary drugs for control of vector-borne human diseases”, published by Miglianico, et al., in PNAS.

Vector-Borne Diseases Under Siege
Mosquito-transmitted diseases, such as malaria and Zika virus, and sand fly-transmitted leishmaniasis are major causes of mortality in sub-tropical regions. Although with a lower mortality incidence, mosquito-borne West Nile virus has spread in temperate regions such as Europe and the United States. Continue reading “Could Your Dog Meds End Malaria or Zika Infections?”

“GenEthics” – The Implications of Genomic Data

I majored in genetics because I love Punnett Squares. Don’t get me wrong, I was fascinated by the groundbreaking research going on in fields like oncology and agriculture, but there was something about the simple and logical nature of calculating inheritance patterns that really drew me in. At the time when I confusingly wandered into my advisor’s office to make this life changing academic decision, I had no idea that this degree would help me see the more complicated, “gray area”, of science, changing the way that I look at the world today.

What is “GenEthics” ?

As I’m sure you’ve already guessed, “GenEthics” is the intersection between the fields of genetics and ethics. A broad term involving questions related to the implications of a variety of different topics in genetic research; “GenEthics” covers everything from the modification of stem cells, to gene therapy and GMOs. Since this term encompasses such a large array of topics, I’m going to focus on some of the ethical questions related to your genome.

Genomic data and its applications

If you’ve ever heard of 23andMe or Ancestry.com then you’ve already had an introduction to genomic data. These direct-to-consumer genetic testing companies are a result of advancements in technology that have made the genotyping process relatively cheap and quick. When you submit a sample, they send it to a lab, extract the DNA, and test it for various markers. What’s returned to you is a report of what markers (alleles) you do and don’t have. These reports can tell you everything from what percent German you are, to your status for any of the many alleles of several genes that may increase risk for Alzheimer’s disease. Genomic data has affected a variety of fields; knowledge of the genome has allowed us to catch famous criminals like the Golden State Killer and has provided us with diagnostic markers for serious diseases. But even with all the good that genomic data has done and will do, there is a “gray area” where many questions regarding safety, equality, and privacy lie.

Safety – Should everyone have their genomes sequenced?

Some believe this is the future of healthcare, that everyone will have their genomes sequenced at birth and put into a national database. This would have amazing implications in the research world; access to endless data, and the ability to form conclusions about everything from human disease to intelligence.

This question also brings up a plethora of others, some pertaining to identity safety. In particular, what if this fictitious database is hacked? There have already been smaller-scale database breaches, the most recent being on the MyHeritage website. These breaches are potentially dangerous; the entirety of your personal health information is housed in your genome. With proper scientific guidance, hackers could infer your: gender, ethnicity, disease status, etc. DNA is not like a credit card, there is no way to obtain a new set of genes.

Equality – How do we ensure that everyone benefits from the advancements that genomic data has to offer?

There are many studies being done with the goal of eradicating cancer using precision medicine. This involves finding common tumor-causing variants in patients’ DNA sequences, and treating them based on their genes. These types of studies have the potential to contribute greatly to the field of personalized medicine, but caution needs to be taken to ensure that multiple populations are represented in the study. Ethnic groups have evolved on separate continents and their genetic sequences contain different variations, one set of conclusions about a disease might not apply to all populations.

Privacy: Who has a right to your genetic information?

The Genetic Nondiscrimination Act (GINA) was passed in 2008 to prevent your genetic test results from affecting your qualification for health insurance, or employment prospects. However, this is but a scratch on the surface of possible genomics-related legal issues; the ownership of a DNA sequence is a complete question mark at this time. There are no laws regarding an organization or family members’ right to an individual’s sequence.

Genomic data has the ability to save lives and prevent devastating disease, but it also can cause disputes within families, and between organizations and individuals. The question of DNA ownership brings up many others: if you test positive for a condition, should you inform other at risk family members? Do you have sole claim on your DNA when you have family members that share most of your sequence? When you submit your DNA to an organization what ownership rights do they have?

The Future…

We have come a long way since completion of the Human Genome Project back in 2003, and we will continue to make amazing advances thanks to the field of genetics. The questions I have posed are just a few that lie in the “gray area” we will be venturing into in the future. These questions may seem as if they are just for researchers, doctors, and lawyers, but they really are for everyone. The social and ethical implications of science affect us all; it’s important that we all join the conversation!