Where Do “New” Viruses Come From?

Every year there seems to be a new virus that just popped up out of nowhere to cause us a great deal of pain and suffering. Is it the work of a mad scientist vying for global domination? Are these viruses coming back to life after being frozen for millennia? Are they hitching a ride to Earth via meteorites?

The truth is many of these viruses are not so new – but we are creating new opportunities for them to infect us. Many viruses jump from other animals into people – a process known as “zoonotic transmission” – and some of our actions roll out the red carpet for the virus. Let’s take a closer look at where some of these “new” viruses may have originated and how they spiral out of control.

Zika

Microcephaly is a term used to describe babies born with much smaller head size than normal, which is indicative of incomplete brain development. In Brazil, this birth defect occurs about 150 times per year. However, in the past 4 months, nearly 4,000 babies have been born with microcephaly - a dramatic spike that has set off alarm bells.

Photo of a child born with microcephaly, which has been linked to the Zika virus.

While evidence is still circumstantial, the primary culprit is a previously obscure virus called Zika, named after the forest in Uganda where it was first identified in a rhesus monkey back in 1947. Zika is transmitted through mosquitoes, which basically operate like flying dirty syringes. If they fed on an infected person, they can transmit the virus to the next person they bite.

Global warming and increased travel have conspired to create excellent opportunities for viruses like Zika to spread. It only takes one infected person to attend a major spectacle (for example, the 2014 FIFA World Cup in Brazil) to start a chain reaction of viral transmission. Viruses need no passports and can jet set around the world in unprecedented time. Global warming is an issue because it has allowed the species of mosquito that carries these viruses to thrive in areas that used to be too cold. Even El Niño has been catching some of the blame for helping to spread Zika.

Ebola

While Zika jumped to humans from other primates, the African filovirus Ebola is thought to have originated in fruit bats. Bats can transmit a number of other deadly viruses, including rabies. Bats happen to be a source of food in several of the areas where Ebola outbreaks have occurred, consistent with the idea that bats are the culprits. Once Ebola infects a human, it can spread quite easily to other people through bodily fluids.

Bats like this one are now considered to be a major carrier capable of spreading the Ebola virus to people.

Ebola first appeared in humans in 1976 in the Sudan and the Democratic Republic of Congo. The initial outbreak killed an estimated 600 people, but the latest outbreak that began in 2014 in West Africa has been the worst in history, killing over 11,000 people. This wasn’t due to an enormous fruit bat invasion, but rather human-to-human transmission. Genetic studies indicated that the entire epidemic likely stemmed from just a single infected child in Guinea, the so-called “Patient Zero”. A catastrophic mix of poor health facilities and unsanitary practices ignited to spread the virus like wildfire.




The 2014 Ebola outbreak started with a toddler who fell sick in Meliandou village in Guinea. Source.
Credit: Live Science

MERS

MERS, Middle East Respiratory Syndrome, first made headlines in 2012. This life-threatening respiratory virus reared its ugly head in Saudi Arabia first, but has since been reported in 25 other countries, including those not in the Middle East (due to unwitting travelers carrying more than their luggage). MERS is caused by a coronavirus, so the causative agent is typically referred to as MERS-CoV. Like many other respiratory viruses, coughing in close proximity can spread MERS-CoV between people.

But how did MERS-CoV get into people in the first place? According to the World Health Organization:  “It is believed that humans can be infected through direct or indirect contact with infected dromedary camels in the Middle East. Strains of MERS-CoV have been identified in camels in several countries, including Egypt, Oman, Qatar and Saudi Arabia.”

It is easy to understand the respect and admiration one can have for a noble creature like the camel. But getting a little too intimate with a camel may literally leave you breathless.

So stay away from coughing camels! In some areas, camels are butchered for food and their milk and urine (yes, urine) is consumed. These practices provide additional avenues for possible transmission of MERS-CoV to humans.


UPDATE (3/1/16): A new study suggests that we have bats to thank once again for spreading MERS-CoV to camels.

HIV

Human Immunodeficiency Virus (HIV), which causes AIDS, wasn’t on anyone’s radar until an unusually large number of people starting suffering from rare diseases with strange names like Kaposi’s sarcoma, toxoplasmosis, and pneumocystis. These diseases are hardly ever seen in people with normal, healthy immune systems. Turns out they were secondary infections – the primary infection was HIV, which was destroying the very immune cells that are needed to keep those other illnesses at bay.

Historical records have placed the earliest cases of HIV infection to the 1950s, which suggests it has been moving through humans slowly through the decades prior to its explosion in the early 1980s. An increase in international travel, unsafe sexual practices, and intravenous drug use are all factors that have contributed to accelerating the epidemic.

HIV (yellow particles) is a cunning foe that destroys the immune cells (blue) designed to protect us from foreign invaders.

We still don’t know how HIV leapt into the fabric of human DNA, but the evidence is very strong that it came from other primates. SIV, or simian immunodeficiency virus, has been found in African primates and is highly similar to HIV; it is easy to imagine that blood from infected primates, some of which are butchered for food or kept as pets, found its way into a person's open wound. Once in humans SIV evolved into HIV, transmissible to others through bodily fluids. HIV likely spread around Africa in its early days through the use of shared needles in impoverished hospitals.

It’s a virus world after all

As you can see from these examples, many “new” viruses were actually pre-existing in other animals and just made a “species jump” into humans. But how did these viruses get into the other animals in the first place? That question is a lot harder to answer.

Viruses are little more than a fragment of DNA or RNA, perhaps rogue genes that escaped a cell and became independent, infecting other cells in order to replicate and spread. Richard Dawkins coined the term, “the selfish gene”, and that is a very accurate description of viral DNA/RNA. What we do know is that viruses have been around a long, long time, perhaps before the dawn of life itself. There are even viruses that infect bacteria.

Once inside host cells, viruses replicate quickly, which means they are very adaptable. Their ability to evolve quickly is likely to be a key factor explaining why these selfish genes can make a reproductive factory out of a wide variety of different hosts…and why “new” viruses can appear to spring out of nowhere.

While viruses are a nuisance to us now, they may have been important drivers of evolutionary change in the past. It has been proposed that RNA viruses may have led to the formation of DNA and DNA replication mechanisms, without which we would not even be here to complain about them!

Contributed by:  Bill Sullivan, Ph.D.

Follow Bill on Twitter.

Simpson, D. (1964). Zika virus infection in man Transactions of the Royal Society of Tropical Medicine and Hygiene, 58 (4), 339-348 DOI: 10.1016/0035-9203(64)90201-9


Forterre P (2006). The origin of viruses and their possible roles in major evolutionary transitions. Virus research, 117 (1), 5-16 PMID: 16476498


Koonin EV, Senkevich TG, & Dolja VV (2006). The ancient Virus World and evolution of cells. Biology direct, 1 PMID: 16984643


Baize, S., Pannetier, D., Oestereich, L., Rieger, T., Koivogui, L., Magassouba, N., Soropogui, B., Sow, M., Keïta, S., De Clerck, H., Tiffany, A., Dominguez, G., Loua, M., Traoré, A., Kolié, M., Malano, E., Heleze, E., Bocquin, A., Mély, S., Raoul, H., Caro, V., Cadar, D., Gabriel, M., Pahlmann, M., Tappe, D., Schmidt-Chanasit, J., Impouma, B., Diallo, A., Formenty, P., Van Herp, M., & Günther, S. (2014). Emergence of Zaire Ebola Virus Disease in Guinea New England Journal of Medicine, 371 (15), 1418-1425 DOI: 10.1056/NEJMoa1404505

Ice, Ice Baby: Bringing Frozen Viruses Back To “Life”

Back in 2003, a new class of giant, ancient viruses were found that preyed upon unsuspecting amoebas in the Paleolithic.  

Earlier this year, scientists published a study describing how they revived another one of these giant viruses, which has been frozen in Siberian permafrost for 30,000 years! We’ll discuss why they did this in a bit, but let’s first talk about how they did this.

Over the years, lots of cool stuff has been found well-preserved in ice. Otzi, a 5,000 year old “ice man” was a historic find in 1991. He went on to become a spokesperson for the GEICO auto insurance company.

Viruses are minute obligate intracellular parasites. In other words, they cannot replicate outside of a host cell, an attribute that gives them the unflattering distinction of being the worst houseguest ever. That’s right:  viruses storm into your home – unannounced – take off their coat and make themselves right at home. They ransack the place and raid your fridge without even asking. As if that wasn’t bad enough, you come home one day and catch the virus in the act of making babies – lots and lots of babies. Finally, this unruly family blows up your house as they leave, without so much as a “thank you”, and go on their merry way to invade other homes in your neighborhood.

While we can feel the pain that they cause, especially during cold and flu season, we can’t see the culprits. Viruses are really, really tiny - most are smaller than the molecular complex cells use to make proteins.

Many viruses are under 100 nM (0.1 micron), but some (like Ebola) are almost 1.0 micron. Compared to viruses, even a bacterium is enormous. 

So how does one find a virus in thousands of miles of ice? Virus hunters take an approach similar to finding a needle in a haystack. But in this case, instead of a magnet, the scientists use amoebas as “bait” to lure out viruses that might be chilling out in the permafrost.

Amoebas are single-celled organisms called protozoa that, like most cells, fall prey to viruses. By putting permafrost into amoeba cultures, scientists were able to screen samples for those that could kill the amoebas. And they found a “big” surprise.



Thick membrane or no, Pithovirus invades amoebas. Who knows…with this discovery, maybe scientists can devise a new treatment that targets the deadly brain-eating amoeba, Naegleria.

The virus spotted in these infected amoeba cultures resembled a so-called “pandoravirus” or “giant” virus. They are still microscopic of course, but considerably larger than the viruses we know of today (about 1.5 microns in length and 0.5 microns across). Not only are they larger in size, but they contain many more genes. By way of comparison, HIV contains less than 15 genes, but this giant virus has 500 genes. They christened this new giant virus “Pithovirus sibericum”, and it is the oldest virus ever to have been revived to date.

A “huge” find in the world of virology, Pithovirus is now growing in labs again after a 30,000 year slumber. Image taken from Legendre, et al.

Now why on earth would scientists bring a virus back from the dead? Are they mad? Are they trying to facilitate the apocalypse?

Of course not. As climate change continues to melt more and more ice, it is possible that these viruses are going to revive naturally. By resurrecting them in the lab in controlled conditions, researchers can get ahead of this curve by studying the virus. Study of the virus can help determine which one(s) pose a threat and, if so, vaccine and drug development efforts can get underway thanks to our knowledge of the virus. And don’t worry about Pithovirus – it was already found to be incapable of infecting animal cells.

Another reason these viruses are worthy of study is that they can reveal new insights into how cells evolved, since viruses can transfer their DNA to their hosts. They may even shed light on the greatest biological mystery:  the origin of DNA/RNA and how life came to be on Earth.

The same team of scientists isolated yet another ancient giant virus this year from the same permafrost and named it Mollivirus sibericum. You may also be wondering what Siberian virus hunters listen to while exploring those Hoth-like landscapes. I'll take a guess and hope that it is wrong...
 

Contributed by:  Bill Sullivan, Ph.D.
Follow Bill on Twitter.

Legendre, M., Lartigue, A., Bertaux, L., Jeudy, S., Bartoli, J., Lescot, M., Alempic, J., Ramus, C., Bruley, C., Labadie, K., Shmakova, L., Rivkina, E., Couté, Y., Abergel, C., & Claverie, J. (2015). In-depth study of , a new 30,000-y-old giant virus infecting Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1510795112

 

Legendre, M., Bartoli, J., Shmakova, L., Jeudy, S., Labadie, K., Adrait, A., Lescot, M., Poirot, O., Bertaux, L., Bruley, C., Coute, Y., Rivkina, E., Abergel, C., & Claverie, J. (2014). Thirty-thousand-year-old distant relative of giant icosahedral DNA viruses with a pandoravirus morphology Proceedings of the National Academy of Sciences, 111 (11), 4274-4279 DOI: 10.1073/pnas.1320670111

Weather Vs. Climate In Global Warming

Sharknado - more than enough said, but I can’t resist.

Without having seen the “film,” I don’t think I can give a

good review, but I know enough to know that a flood of

sharks would do more damage than a single tornado full

of sharks. As with all falls, it’s the landing that does the

damage, so I would guess there would be a lot of shark

parts to clean up later. Do you think a sharknado is

caused by global warning?

Here in the Midwest, the fall and winter of 2013-2014 was a doozie. There were ice storms, snowstorms, sleet storms, and at least one Sharknado. My shovel and patience got quite a work out. But this was followed by a particularly mild summer, which by coincidence has included a second Sharknado. As of mid-August, we’ve only had one day where the temperatures got above 90˚F (32.2˚C).

Some people say that this is proof that global warming is a government/liberal/ commie/hippie/satanic conspiracy. I hate to burst your Oliver Stone bubble, but that’s just not so – and it doesn’t prove global warming is true either. Let’s take a short look into climate and weather and see if we can pick out a few trends.

Number one, and this is a point for the conspiracy theorists, global warming and climate change are as natural as day following night, as dogs chasing cats, or as Justin Bieber doing something socially or morally reprehensible. The Earth has gone through countless shifts in climate.

The Cambrian Explosion took place 550 million years ago, and the average global temperature at the time was 25˚C (77˚F). This was the period when the number of types of multicellular animals increased greatly over a relatively short period of time. All of our current phyla of animals were born in this era, so speciation obviously doesn’t have a problem with heat.

During the Middle Carboniferous Period 330 million years ago, the average temperature on Earth decreased from about 20˚C to 15˚C. Yet animals grew to huge sizes, like dragonflies with 6-foot wing spans, even though the temperature was dropping. By the Permian period the average global temperature was only 10˚C (50˚F).

You can see that through geologic history, there have been

many warm and cold periods in Earth’s history. We can’t

blame human technology for all of them. But that doesn’t

mean we aren’t affecting our rate of temperature rise now.

You can see that we are now near a low point, and that’s

What humans evolved to live in. The next warming trend

will be our first – can we survive it?

Ice ages have been plentiful too, with multimillion year periods where the global temperature was low. Today, the average global temperature is about 14˚C (57.2 ˚F), so we’re much closer to another Disney movie about a sloth and a mammoth than we are to a period similar to an ant under the magnifying glass.

But don’t conclude that this means we have nothing to worry about. We are in a period of global warming. Over the last 100 years, the average global temperature has risen 1.53 degrees Celsius. This may not seem like much, but it’s faster than any time in the previous 1400 years, and we don’t know how high it might go.

Number two, even if global warming and cooling are natural events, the rate at which they occur doesn’t have to be. The number of things man is doing to influence the rate of global warming is staggering (called anthropogenic warming). Burning fossil fuels that release carbon dioxide and other gases that trap the heat radiating from the earth and not letting it escape to space is just the beginning.

As humans, we breathe, and after we stop breathing - we decay. These processes release greenhouse gases as well. O.K., these are natural, but with the population explosion, there‘s a lot more breathing and decaying going on.

And more people need more food. Livestock are great producers of greenhouse gases methane and CO₂ primarily (see this post). Even growing crops contributes to global warming. The fertilizers with nitrogen contribute to production of more nitrous oxide – right – laughing gas. This escapes to the atmosphere and is one of the worst greenhouse gases - not very funny.

We need to figure out to what degree human actions altering what might be a natural increase in temperature. The vast majority of scientists agree that we are accelerating the rate at which the temperatures around the world are rising. Many studies have compared the rate at which temperature rise and the amount of carbon dioxide in the atmosphere changed during historical periods of warming and now. They are going up faster now, and there doesn’t have to be a ceiling. Score one for the climate change supporters.

This sums up the difference between climate and weather

very well. The average weather, ie. what you expect for a

certain time of year, is the climate. What actually occurs on

any given day is the weather. The old song lyric, “It don’t

rain in Indianapolis in the summertime,“ refers to climate

not weather, because I got rained on today.

This brings us to point three – changes in global temperature aren’t given as one year compared to some other year in the last century, or any single year for that matter. The changes are best understood and are reported as deviations from what is considered normal over a longer period of time.

Here is the biggest point so far – climate and weather is not the same thing. Weather is what you see is happening when you stick your head out the window. Climate is considered an average of the weather for a certain place over the last 30 years. A single hot summer or single cold winter doesn’t really make much of a difference when it's included in a 30 year average. The trends over time are what are important.

Last year’s nasty winter or this year’s mild summer aren’t refutations of global warming any more than catching one 20 foot shark means that all the fish in the ocean are huge, deadly, and good movie material. It’s just one point of data that has to be looked at with all the others.

Things we can agree on: Global warming, whether natural, man made, or a combination of the two, can result in warmer weather. The warmest ten years on record have all occurred in the last three decades (calculated as rise over the 100 year average). Also, we can agree that the warmer weather can lead to stronger storms. Typhoons and hurricanes build up over warm ocean water; the warmer the water, the stronger the storms.

What isn’t so evident is whether global warming leads to an increase in the number of tropical storms. Two fairly recent papers (here and here) make opposite predictions. One says the increase in global temperature has and will lead to more storms. The other says the trend will be toward fewer storms as the temperatures rise.

Lake Erie is the shallowest of all the Great Lakes. The

deepest spot may be 210 feet, but it averages only 62 ft deep

overall. It’s almost the smallest of the Great Lakes (4^th of 5)

but is still the 10th largest lake in the world. Because of its

shallow depth, it freezes over almost every winter. Since

the Erie Canal was built for trade, this seems to have been

quite the cog in the works.

Global warming can even lead to stronger winter storms. In 2006, the huge amount of snowfall in the Ohio, Pennsylvania, and New York was attributed to the fact that Lake Erie didn’t freeze over – the first time this was ever recorded. Less ice cover meant more water was available to evaporate into the clouds and become lake effect snow. Therefore, one could just as easily argue that bad winters are support for the idea of global warming.

One last thing we should agree on – the Earth itself doesn’t care if it’s cold or hot. The Earth will go on, speciation will go on, with new species evolving in adaptation to new conditions and filling niches left by species that couldn’t hack it. If humans are going to adapt and survive, we’d better find a way to do it that doesn’t contribute to further warming – just turning the AC on high won’t help the situation.

Contributed by Mark E. Lasbury, MS, MSEd, PhD
As Many Exceptions As Rules

Bender MA, Knutson TR, Tuleya RE, Sirutis JJ, Vecchi GA, Garner ST, & Held IM (2010). Modeled impact of anthropogenic warming on the frequency of intense Atlantic hurricanes. Science (New York, N.Y.), 327 (5964), 454-8 PMID: 20093471

Knutson, T., Sirutis, J., Garner, S., Vecchi, G., & Held, I. (2008). Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions Nature Geoscience, 1 (6), 359-364 DOI: 10.1038/ngeo202