Saturday, December 3, 2016

Genetic modification of Influenza A virus reveal a novel vaccine production strategy

Researchers have developed a new type of vaccine. By genetically modifying the genome of Influenza A virus to require a non-standard amino acid (Ne-2-azidoethyloxycarbonyl-L-lysine which has been used in synthetic biology previously) that some microbes use. What makes this amino acid unique is its codon (three base RNA sequence that signals what the amino acid should be). In most organisms, the codon used (UAG) is actually what is known as a stop codon (it stops production of the protein chain), so this means that any gene that contains that codon will stop prematurely unless grown in an organism with that non-standard amino acid. A lot of work went into finding places in the viral protein that the non-standard amino acid could be inserted without interfering with the function of the protein. Once several sites were identified, the researchers grew the virus in kidney cells that had been genetically modified to use the non-standard amino acid. The end result was genetically stable progeny viruses that required the non-standard amino acid.

When the altered influenza virus was injected into mice, it did not replicate and the mice developed a strong immune response to the virus. Researchers were able to safely inject the mice with a dose of the modified virus that was about 100,000 times the dose of the wild-type virus that would kill half of the mice injected (LD50). The modified virus also interfered with the wild-type influenza virus in co-infections of the two.  

The implications for this development could be astounding. With this, researchers could develop a vaccine that uses a fully infectious virus that has been modified to need this amino acid to replicate. However, caution is warranted at this point. A lot of work still remains to develop this into a functional vaccine. It must go through further trials to see if it works in primates and then there are all the human clinical trials that are needed. This work is promising and certainly should be pursued further.

This negative stained transmission electron microscopic (TEM) image shows recreated 1918 influenza virions that were collected from supernatants of 1918-infected Madin-Darby Canine Kidney (MDCK) cells cultures 18 hours after infection. Photo credit: Cynthia Goldsmith courtesy of the CDC.

Friday, December 2, 2016

Poinsettias and pathogens

Poinsettias are a very interesting plant. Originally, this plant grows as either a small shrub or a tree in its native range (Mexico). However, the little potted poinsettias that can be bought at the store never grow close to that size. There is a good reason for this: the potted poinsettias are infected with a pathogen known as a phytoplasma. Phytoplasmas are small bacteria that lack a cell wall and are limited to the phloem tissue within plants. They are spread by vegetative propagation, grafting and by sap-sucking insects that feed in the phloem. Normally phytoplasmas are associated with severe disease in plants by altering the structure of plants, such as causing the petals of flowers to develop into leaves instead of petals. One such disease is aster yellows which infects over 300 different plant species in 38 families (see picture below).
Aster yellows on the Purple coneflower (Echinacea purpura). Via wikipedia
But what does this have to do with poinsettias? It turns out that the phytoplasma that infects the potted poinsettias also causes stunting, but doesn't cause severe distortion of the leaves. Not only is the plant stunted, but it produces additional branches where normally the plant has a single branch. The trait has been used since the 1920's to sell poinsettias during November/December in North America. This trait was found to be transferable by grafting but could be lost when the plant was subjected to heat treatment or tissue culture techniques. It was thought that another pathogen that is common in poinsettias was the cause of the stunting, Poinsettia mosaic virus, but it wasn't until the 1990's that a phytoplasma was shown to be the causal agent of the stunting. Previous work found that the virus wasn't completely associated with this trait as plants without the virus developed stunting and free branching. This article contains further information on the history of poinsettias and the work to determine why commercial poinsettias are stunted and free branching. This article discusses how to care for poinsettias.

A poinsettia tree in Mexico. Via Petal Passion

A potted poinsettia. Via pixabay.

The phytoplasma infecting poinsettias is a perfect example of how not all pathogenic organisms are bad and that they might be of benefit. This is certainly the case in the ornamental industry as it is the basis of the entire ornamental poinsettia industry.

Wednesday, November 2, 2016

Does Zika damage the testicles? Maybe

A lab mouse. Picture via Pixabay

A new study is causing quite the stir. Researchers used a mouse-adapted African strain of Zika to examine if the virus damages the testicles, as Zika has been detected in the sperm for up to 10 weeks post infection. In this latest study, severe damage and significantly smaller testicles were observed in infected mice. By day 21 the damage was much more extensive. Starting at day 14, sperm count and sperm motility dropped and by day 42, the differences were large. Overall, the fertility of infected mice dropped from around 80% to roughly 25% and the number of viable fetuses from the sperm of infected males dropped from 25 (from uninfected sperm) to 10. The researchers also tested this with mice infected with Dengue and an isolate of the Asian strain of Zika, but Dengue didn't damage the testes and the Asian strain caused less damage. The researchers hypothesize that the difference seen between the African and Asian strains is due to the Asian strain not being adapted to mice whereas the African strain was (it replicated less efficiently than the African strain in the mouse model).

Mouse testicles either infected with Zika or not, after 7 (a), 14 (b) or 21 days (c) post infection. Adapted from Govero et al., 2016; doi: 10.1038/nature20556

This study, although valuable, does have some limitations. First, a mouse-adapted strain was used which could result in mutations that make the virus different than the ones circulating in humans. Second, the work was done in a mouse model and sometimes research in mice doesn't translate to humans. However, this was just a preliminary study and something of concern was noted. These findings more than justify further work to examine if Zika causes damage to human testicles and if it can reduce fertility. 

Saturday, October 29, 2016

Zika causes birth defects (another case of Moms Across America ignoring science for ideology)

A friend of mine (Iida from Thoughtscapism <FB; website> sent me an interesting story that seems to be gaining steam in the anti-GMO world: Zika doesn't cause birth defects. Before I get started on debunking their claims, it's important to give a proper background on what Moms Across America truly represents and why they are not a valid source of information on anything related to science.

Moms Across America started off as an organization that was opposed to genetically engineered crops (colloquially known as GMOs). They rabidly oppose agrochemicals (glyphosate is a favorite target of theirs) and are well known for outrageous claims that they found glyphosate in X substance. They have claimed to find it in breastmilk, wine, granola bars and more recently vaccines. The group has recently branched out as being opposed to vaccines (although in all fairness, Zen said this was her personal belief and not necessarily the views of the organization), they have acted as a lobby wing and advertiser for organic food, and it now appears to be anti-science in general with their latest post. Researchers have taken the time to look at the methods used in the case of their breastmilk-glyphosate study and even tried to replicate it using proper testing protocols. They have also faced backlash for their attacks on breastfeeding (apparently to help market non-GMO formula, or rather that is what some suggest) and for parent-shaming those who do not "care" enough to feed their kids organic foods. In short, the positions of this group tend to be opposed to science and favor bad science over well designed and accurate studies and science. 

So what does this have to do with Zika and birth defects? In Zen's latest anti-science article she makes a series of claims (sourced from one Ian Trottier) that have no basis in science. She blames the "overblown" hysteria around Zika for allowing $1.9 billion in taxpayer dollars to go to Big Pharma for vaccines and Big Chemical for pesticides. Naturally, in her mind both vaccines and pesticides are far more dangerous than a virus, despite all the evidence to the contrary. First, I'll discuss her "evidence" and the four points that she tries to use to prove that Zika isn't a danger and then I'll discuss what the actual scientific evidence is for Zika causing birth defects (as she wrongly claims that there is no science to back up the idea that Zika causes birth defects). 

In the article, Zen tries to link to several "sources" to claim that Zika doesn't cause birth defects. The first link claims to have all sorts of evidence from science journals that Zika does not cause birth defects. This is what she says about the source: "The website sources articles from the New England Journal of Medicine, Lancet, PubMed, EPA, CDC and others. Additionally, site developer, Ian Hamilton Trottier, has conversed with experts at Lancaster University in the UK and the London School of Hygiene and Tropical Medicine. That includes experts based in the US." However, when you click the link you get the following:

Zen's first source that is "full" of scientific journal articles that "demonstrate" that Zika does not cause birth defects. 
Later in the article, she tries to cite as a source. However, when you click on that link, it is for a domain that is for sale:

Zen's second attempt at linking a source for her claims.

The third source does list the four claims that Zen mentions in her article, but lacks any sources to back up the assertions. 

The fourth time seemed to be the charm as when was linked, you get a website that has some sources. However, every source on that page deals with naled and does not back up the assertions that there is no credible scientific evidence that Zika causes birth defects. Furthermore, Zen claims that Dr. Michael Diamond "is essentially quoted as saying there is nothing that suggests detection of ZIKA as being the actual cause of MICROCEPHALY in the subjects he's studied. Dr Diamond recently published a review that links ZIKA to being present in tear ducts."
Dr. Diamond is indeed a flavivirus expert (the genus that Zika virus belongs to) and has published extensively on Zika (and other viruses and immunology in general). Since I cannot find the quote that Zen is alluding to and the fact that Dr. Diamond's work has been instrumental in confirming the link between Zika and birth defects, one is forced to assume that this quote is from the early days of the Zika outbreak in Brazil, when researchers did not know what we know now about Zika causing birth defects. This is a cherry picked quote that attempts to use an appeal to authority to confirm Zen's ideology despite the fact that the source has clearly demonstrated the opposite of what she is claiming.

The four points of the article basically boil down to "we don't know" and pesticides. She tries to link the use of the pesticides to both Monsanto and the Nazi bombing of France in a clear attempt to poison the well. Pesticides that have been ruled out as being involved with microcephaly, like 
pyriproxyfen, get mentioned as a possible cause. I won't get into that here as I've addressed pyripoxyfen before. It's sort of a rehashing of the claims that Mike Adams made about Zika that I also debunked previously, except Zen mentions paraoxonase as to why naled is really causing the birth defects attributed to Zika. However, her assertion that children have lower levels of paraoxonase in their liver does not automatically mean that the levels of this enzyme are the reason for birth defects. It ignores the fact that the mother's liver will help protect the growing baby. A study did find that lower maternal levels of one of the enzymes in this class did lead to a smaller head circumference, but it was nowhere near the level of reduction seen in babies born with congenital Zika disorder. I don't have the space to get further into the claims surrounding this enzyme as it is complicated.

But what about the evidence that supports the link between Zika infection during pregnancy and birth defects? How solid is the science on this? I'll outline just some of the key findings that support that Zika virus causes birth defects. The body of scientific literature is extensive on this topic and one only has to look to find it.

1) The Zika virus crosses the placental barrier
2) The complete genome of Zika has been recovered from the amniotic fluid and brain tissue of an infected fetus. 
3) Zika virus has been shown to disrupt brain organoid formation and deplete neural progenitor cells in vitro.
4) Case studies have shown a link between congenital Zika infection and birth defects.  
5) Zika virus infection caused birth defects in a mouse model. Specifically the Asian strain is more damaging than the African strain. 
6) A case-control study has demonstrated a clear link between congenital Zika virus infection and birth defects. 

Some of this work has been published since May 2016 when this article summarizing the evidence for congenital Zika virus infection and birth defects was published. This article concluded that the available evidence had met the criteria for a causal link to be established. Since then, the evidence supporting the link has only gotten stronger and at this point attempts to deny the link shows a clear lack of understanding of science. This infographic I made summarizes the evidence for Zika being a TORCH pathogen (TORCH pathogens cause birth defects).

The Zika virus is a TORCH pathogen that causes birth defects.

This article from Zen is a clear cut case of her ignoring the science that clearly demonstrates that the Zika virus causes birth defects. Although to be fair, it's entirely possible that she just doesn't understand the science. Based on her past history, that cannot be entirely discounted; however, not understanding science isn't an argument against it. The real moral here is that people need to be careful what they use as sources. Moms Across America, much like Natural News or Joseph Mercola, have clearly demonstrated that they are not a valid source when it comes to science. They cherry pick quotes and ignore all of the scientific evidence that contradicts their ideology. Moms Across America really shouldn't be used as a source for anything. 

Saturday, October 22, 2016

Sexual transmission of a bee virus

A queen honeybee. Via wiggledanceforme.

When sexually transmitted infections are discussed, one might think of human viruses, such as HIV or herpes. However, other organisms can become infected with viruses from sex. A new study describes how one of the more debilitating bee viruses, Deformed Wing Virus (DWV), can be sexually transmitted from infected male drones to otherwise healthy queens after mating. As the name might suggest, DWV severely deforms the wings of infected bees (see picture below) and impairs their cognitive function, specifically impairing the learning behavior and memory retention. Because of this, it wasn't known if infected drones would be successful at mating or not.

Carniolan honey bee with Deformed wing virus. Photo credit, Xolani90, via Wikipedia. 

In order to test this, the researchers took extensive steps to ensure that queen honeybees were free of viruses. They came from the same virus-tested colony as larvae and were then reared in nurse colonies that lacked a queen. That colony was screened for the varroa mite (300 bees were examined and none had the mite) and common bee viruses tested for in 60 worker bees. These include DWV, Black Queen Cell Virus, Sacbrood Virus, Chronic Bee Paralysis Virus and the ABPV complex made up of Acute Bee Paralysis Virus, Kashmir Bee Virus and Israeli Acute Paralysis Virus. A total of 30 queens met this criteria and were used in the study. They were then allowed to mate with DWV-infected male drones for at least 7 min; nine did not mate for the full time leaving 21 queens that fulfilled the requirements. If the drone's endophallus was still present in the queen after mating, then it was removed and tested for DWV; three of these had high levels of DWV. They found that seven of the queens developed high levels of systemic DWV infection; one of these queens died shortly after ovipositing (laying eggs) due to the infection. A further 15 queens had medium levels of DWV that varied in titer by tissue and eight queens had low levels of DWV.

This study answers an important question: can DWV-infected drones pass the virus on to queens by mating? The answer is a clear yes. Part of the reason why this study is important is because DWV is one of the major viruses associated with colony collapse disorder. Complicating matters, previous work has demonstrated that the varroa mite prefers drone brood (the varroa mite transmits all the viruses listed in this post to bees). 
Another issue is that if a queen dies, then the colony will be lost. Up to 25% of lost colonies are the result of loss of the queen. This new discovery could have implications for managing honeybees and lead to the development of strategies to mitigate these losses. 

Tuesday, October 18, 2016

Rift valley fever virus as a risk factor for miscarriage

Distribution of Rift valley fever virus via CDC.

New research has discovered that Rift valley fever virus(*more on this virus below) may be a risk factor for miscarriages. In a cross-sectional study of 130 pregnant women with fever in Sudan, it was found that 28 were infected with Rift valley fever virus and 31 with Chikungunya virus (also mosquito transmitted). In the women infected with Rift valley fever virus, 54% had a miscarriage compared to 12% in those not infected; this represents a 7-fold increase in miscarriage associated with the virus. Infection with Chikungunya virus did not result in a statistically significant increase in miscarriage, though the symptoms of this virus are quite unpleasant. The study does have some limitations, such as the smaller size, but these factors are hard to improve based on the system they are working with (it's not exactly ethical to infect large numbers of pregnant women with a virus to see if it causes miscarriages). However, this study does highlight how essential it is to try and prevent mosquito bites during pregnancy as there are several viruses of concern for pregnant women (such as Zika).

*Rift valley fever virus is a mosquito-transmitted virus in the genus Phlebovirus in the Bunyaviridae. It normally infects cattle and other domesticated animals, but also can be transmitted to humans, though this isn't as common; contact with infected animals is a known risk factor for this virus. The disease is normally mild, but in some cases, it can cause severe disease (1-3%). It is transmitted by Aedes species mosquitoes that also maintain the virus through vertical transmission (eggs are infected by the virus if the female mosquito is infected) but other mosquitoes can transmit the virus mechanically. The distribution is limited to Africa and the Middle East, but with the warming climate, researchers are worried that it could spread to new areas (as Aedes species mosquitoes like A. aegypti and A. albopictus are expanding their range) and one of the vector species is common in Europe. 

Monday, October 17, 2016

Misusing definitions is not the way to counter misinformation: Colony collapse disorder

European honeybee, Apis mellifera. Image via Wikipedia.

Anyone who has followed my page for awhile knows that one of my big pet peeves is bad science reporting. One of the ways that bad science reporting happens is when non-experts misuse definitions to draw incorrect conclusions. The best example of this is the reporting on colony collapse disorder (CCD). 

To give an example of some of the bad reporting around CCD, last year, Christopher Ingraham wrote an article for the Washington Post where he declared that the "beepocalypse" was over as the total number of hives has not gone down since CCD was first seen. To be fair, he's not the only one who has used this incorrect definition; Matt Miller used the same figures for his article in Slate. Their argument boils down to this: "Because the total number of hives haven't dropped means that the bees are doing just fine and any concerns about CCD are just overblown." This sounds like a fine conclusion until one realizes that they are not actually using a measurement that deals with CCD. When it comes to CCD, the total number of colonies does not matter. 

CCD is defined by the percentage of the adult bees that abandon the colony without leaving dead bodies in the hive while leaving brood and honey intact with the delayed invasion of the usual hive invaders (small hive beetle, wax moth, etc.). Typical losses in the winter range from 15-20%, so anything above 20% is classified as CCD. In 2014/15 the winter losses were 23.1%. However, the summer losses were much higher making the average losses for the year 42.1%. It's atypical to have high summer losses and it is very concerning. In 2015/16, the high summer losses continued with an average loss of 44% for the year. The losses the last two years are certainly above the threshold for CCD, so CCD is clearly still a problem. The article tried to gloss over it by using the wrong statistic and oversimplifying the problem. I find this distasteful as a science communicator as it misleads the public despite the issues with the authors argument being plain for those who are familiar with CCD.

In the comments on his article last year, Mr. Ingraham was taken to task by several beekeepers for his lack of understanding of CCD. However, rather than fact check his hypothesis by asking any entomologists or experts about it, he has doubled down with yet another article touting that the bees are just fine as the hive numbers are still high. He is facing yet more backlash in the comments. Some of them are incorrect and are lacking in any scientific basis. But not all of the comments were wrong. Several pointed out that the definition of CCD was being used incorrectly and that was leading to incorrect conclusions. One simply cannot try and disprove bad science by using bad science themselves. In science, definitions matter, especially if it is a disease or disorder that is being discussed. This is the same faulty understanding of science that leads people to question the effectiveness of vaccines or doubt that humans are contributing to the increasing global temperatures.   

But the problems with the article doesn't stop at misusing the definition of CCD. The author gives some solutions that are meant to negate the effect of CCD; however, neither solution is actually a long-term solution for CCD. From the article:

"So beekeepers have devised two main ways to replenish their stock. The first method involves splitting one healthy colony into two separate colonies: put half the bees into a new beehive, order them a new queen online (retail price: $25 or so), and voila: two healthy hives. The other method involves simply buying a bunch of bees to replace the ones you lost. You can buy 3 pounds of "packaged" bees, plus a queen, for about $100 or so."
There are several issues with the two solutions proposed. Splitting a sick or weak hive results in two sick/weak hives. It'll take time for each hive to build back up with a healthy hive that is split. Splitting weak hives is not a good solution. Buying more bees is just a temporary measure at best as eventually the hive will develop CCD if it's a commercial hive. Neither of these options really addresses what CCD is (remember, it's the loss of bees from a hive without dead bodies being near the hive), so these are akin to trying to put a band-aid on a serious wound. The author did get called out on this by several beekeepers, but their concerns weren't addressed and in fact he repeated these solutions in his second article.
An example of one of the comments from the article.

But what does it matter if one uses the wrong definition for CCD to discuss it or offers a solution that doesn't address the problem? CCD is still a major problem and is causing significant losses. What's worse is that if people truly believe what he is trying to say about CCD, funding for studying and ultimately finding a treatment for CCD could be in jeopardy. The solution of splitting hives or buying new bees isn't anything more than a temporary attempt at a solution. 
I get that this was an attempt to try and dispel the misinformation that surrounds CCD, but you cannot counter misinformation with more misinformation. 

But that doesn't mean that the bee situation is nearly as dire as some would have you believe. The reporting on the other side of the issue is equally atrocious. If we lost honeybees, there are other pollinators that are less efficient. Even if we lost pollinators altogether, we wouldn't starve. Almost all staple crops (wheat, corn, rice, potatoes, etc.) are either wind or self pollinated, so we wouldn't lose access to these food sources. We would lose many fruits and vegetables, such as apples, stone fruits and cucurbits, but we wouldn't starve. But this doesn't mean that losing the bees is something we should be okay with either. Bees play a huge role in agriculture and have for thousands of years. It would be a tremendous loss if they weren't around, even if it doesn't mean that we would starve.

I'll have a blog post soon discussing what some of the current research suggests is involved in causing CCD is. I'll give you a hint, viruses might be involved. But until then, there are some great places to get information on bees and CCD without having to wonder if the science is shaky. Scientific beekeeping is arguably one of the best resources for learning about the science of beekeeping and CCD. CCD is incredibly complex and there isn't a single definitive cause or easy solution for dealing with it.