Can Zoloft Protect Us Against Ebola Virus Infection?

Repurposing drugs already approved by the FDA for different applications is highly attractive because these drugs have known pharmacology and toxicity profiles, as well as established manufacturing and formulation methods. That’s why thousands of existing drugs, those currently in use, are being screened by pharma companies for efficacy in other diseases of conditions. Some of these results are very surprising. Recently it was found that two known drugs that are already being used for other conditions might offer protection against infection by Ebola Virus. These findings are really significant since there is currently no effective treatment for Ebola infection. Vascor (Bepridil), a calcium channel blocker used to treat angina, and interestingly, Zoloft (Sertraline), a selective serotonin reuptake inhibitor (SSRI) used to treat anxiety and depression, were recently shown to inhibit virus replication in cells in tissue culture, and also to protect mice from virus infection.

First drugs were tested for their ability to prevent the virus from replicating/reproducing in cells in tissue culture. The cells were also tested for viability to make sure the drugs weren’t simply killing the cells. Several known drugs showed anti-virus activity in these experiments. The authors selected drugs with proven track records for safety in man as candidates for further studies. Two of the most promising were Vascor (Bepridil) and Zoloft (Sertraline).

Micrograph of ibroblasts in culture
Fibroblasts in culutre. Micrograph. Photo: Shutterstock.
Adding samples to an ELISA plate.
Adding samples to an ELISA plate. Photo: Shutterstock.

Next, the drugs were tested for their ability protect mice from infection with the virus. One hour after the mice were infected with the virus, drug treatment was started. Drugs were given to the mice for 10 days, and then the mice were observed for another 18 days. Zoloft treatment resulted in 70% survival (7/10) of the infected mice. Vascor (Bepridil) treatment resulted in 100% survival (10/10). In the Control groups, that is, mice infected with virus but not treated with a drug, no mice survived until day 10 post-infection (0/10, 0/10).

In a previous paper it was reported that two compounds that interfere with estrogen receptors also protected mice from infection with Ebola Virus. Clomiphene (brand names Clomid and Serophene) is used to treat female infertility due to anovulation. Toremifene (brand name Fareston) is approved for the treatment of advanced metastatic breast cancer. Treatment of mice with Clomiphene resulted in 90% (9/10) survival of the infected mice, while Toremifene resulted in 50% survival (5/10). Again, in the Control groups no mice survived until day 10 (0/10, 0/7).

Harvesting cells with a cell scraper.
Harvesting cells with a cell scraper. Photo: Shutterstock.

Finally, another in vitro (tissue culture) test was performed on artificially produced virus-like particles (VLPs) to study the mechanism by which the drugs inhibited the virus. From these experiments it was determined that both compounds inhibited the transport of virus components into the cells’ internal machinery, despite the fact the neither compound inhibited the ability of the intact virus particles to get into the cells. Although the exact mechanisms by which these drugs work in blocking Ebola Virus infection of cells, it seems likely that they are NOT working by the same molecular mechanisms that they use for their “real” jobs.

Thus, it is well worth the effort to continue to study known drugs for unexpected activity in situations other than those for which they are currently in use. Repurposing drugs will also save us lots of time and money with regard to drug development. Who can forget that the little blue pill, Viagra (Sildenafil) was originally developed to treat angina. To my knowledge it hasn’t been tested against Ebola yet, but if Vascor works, why not?!


Johansen LM, DeWald LE, Shoemaker CJ, Hoffstrom BG, Lear-Rooney CM, Stossel A, Nelson E, Delos SE, Simmons JA, Grenier JM, Pierce LT, Pajouhesh H, Lehár J, Hensley LE, Glass PJ, White JM, Olinger GG. 2015. A screen of approved drugs and molecular probes identifies therapeutics with anti-Ebola virus activity. Sci Transl Med. 7(290): 290ra89. doi: 10.1126/scitranslmed.aaa5597.

Johansen LM1, Brannan JM, Delos SE, Shoemaker CJ, Stossel A, Lear C, Hoffstrom BG, Dewald LE, Schornberg KL, Scully C, Lehár J, Hensley LE, White JM, Olinger GG. 2013. FDA-approved selective estrogen receptor modulators inhibit Ebola virus infection. Sci Transl Med. 5(190):190ra79. doi: 10.1126/scitranslmed.3005471.

Seppa, N. 2015. An antidepressant may protect against Ebola: Zoloft and another drug keep most mice alive after infection with the virus. Science News, Magazine of the Society for Science and the Public. JUNE 3, 2015.


What is Scarlet Fever?

I had heard of Scarlet Fever, but to be honest I didn’t know what it was. A faded memory from microbiology classes long past. Recently, a friend of mine got it so I decided to look it up. Scarlet Fever, it turns out, is a sequela (plural = sequelae) of Strep Throat. A sequela is a complication of another disease or condition, kind of like a side effect.

My friend’s young son got Strep Throat, and like a good parent, he got it too. Then he developed Scarlet Fever. Scarlet Fever is a rough, red rash on the skin. You can also get red bumps on your tongue that make it look like a strawberry.


Scarlet fever rash on the torso
Body Rash of Scarlet Fever. Wikimedia Commons.


Strawberry tongue of Scarlet Fever.
Strawberry tongue of Scarlet Fever. Wikimedia Commons.

That’s called—you guessed it–Strawberry tongue. It’s usually seen in young children, but my friend is one of the lucky adults to come down with it. Only a small percentage of people who get Strep Throat or another streptococcal disease develop Scarlet Fever. This suggests to me that there may be a host (or genetic) factor or factors that play a role in developing Scarlet Fever, but I don’t know that for sure.

Strep Throat is caused by a bacteria called Streptococcus pyogenes, or Strep pyogenes. Strep pyogenes is a member of a family of bacteria called Group A Strep. Strep pyogenes bacteria are commonly found on our skin. These bacteria cause a number of nasty diseases, such as Toxic Shock Syndrome, Rheumatic Fever, and necrotizing fasciitis, the flesh eating disease.

Long strings of spherical bacteria are characteristic of Streptococci.
Illustration of Streptococcus bacteria based on a photomicrograph. S. Anderson. Long strings of spherical bacteria are characteristic of Streptococci. Strepto = twisted chain; Coccus = spherical.

Strep pyogenes bacteria produce several toxins that help them cause disease. These toxins are known as virulence factors. The virulence factors that lead to Scarlet Fever are three toxins called SPE-A, SPE-B, and SPE-C. SPE stands for Streptococcal Pyrogenic Exotoxin. “Pyrogenic” means they cause fever. SPE-A, B, and C were formerly called erythrogenic toxins. “Erythrogenic” means “causing redness”, as seen in Scarlet Fever.

Strep Throat and Scarlet Fever are not normally serious or life-threatening, and can be treated with antibiotics like penicillin. However, if left untreated, they can lead to some serious sequelae (see what I did there) such as Rheumatic Fever, kidney disease, even lung infection, and arthritis. So if you think you or your child or loved one might have Strep Throat–GET TO THE DOCTOR!


Todar, K. Todar’s Online Textbook of Bacteriology Streptococcus pyogenes and Streptococcal Disease, p. 2. Accessed June 7, 2015.

Centers for Disease Control and Prevention (CDC). Scarlet Fever: A Group A Streptococcal Infection. Accessed June 7, 2015.

Streptococcus pyogenes. Accessed June 7, 2015.


Strawberry tongue of Scarlet Fever. Attribution: 6 Mar 2006: Erdbeerzunge Himbeerzunge Scharlach. Foto von Martin Kronawitter, Kellberg; 22 July 2013, color adjust by Jbarta; via Wikimedia Commons.

Body Rash of Scarlet Fever. Attribution: By The original uploader was Estreya at English Wikipedia (Transferred from en.wikipedia to Commons.) [CC BY 2.5 (, via Wikimedia Commons.

Lymphatic System Found in the Brain !

Lymphatic Vessel Location in the Brain
Diagram of the structure of the brain showing likely location of lymphatic vessels–my interpretation. Illustration: Shutterstock

Discovery of A Classical Lymphatic System in the Brain Will Revolutionize Neuro-Immunology

Until now, it was thought that the brain lacked the type of classical lymphatic drainage found in the rest of the body. Even though it was known that the brain was monitored by immune cells it wasn’t understood how they got there and moved around.

Researchers at the University of Virginia Medical School have just discovered a functioning classical lymphatic system that serves the brain. In order to make this discovery a special technique for preparing and mounting brain tissue for microscopic examination was developed. Without this technique the presence of the brain’s lymphatic vessels would have been missed again. According to the researchers, the lymphatic structures in the brain are well-hidden which explains why they have remained undiscovered for so long.

The current work has been done primarily in mice, but similar structures in human brain tissues have already been identified. These findings will revolutionize our understanding of the connection between the central nervous system and the immune system, and has tremendous implication for the study of neuro-immunological diseases such as Alzheimer’s Disease, and Multiple Sclerosis.


Loveau A, Smirnov I, Keyes TJ, Eccles JD, Rouhani SJ, Peske JD, Derecki NC, Castle D, Mandell JW, Lee KS, Harris TH, and Kipnis J. 2015. Nature. Jun 1. doi: 10.1038/nature14432. [Epub ahead of print] PMID: 26030524

University of Virginia Health System. “Missing link found between brain, immune system; major disease implications.” ScienceDaily. (accessed June 5, 2015).

Plantibodies: Emerging Technology

Recently two healthcare workers infected with Ebola Virus (EBOV) were treated with a “mystery serum” which turned out to be a cocktail of monoclonal antibodies (Mabs) to EBOV, similar to receiving anti-venom for a snake bite. [see Mystery Serum Links below] What is unique about these Mabs is that they were produced in a plant, specifically, Nicotiana benthamiana, a relative of the tobacco plant. Antibodies produced in plants have been nicknamed “plantibodies”.


Why Make Proteins In Plants?

The ability to make mammalian, viral, and other proteins in plants has been around for about 25 years now. Early methods of expressing foreign proteins in plants were highly inefficient, but new methods have solved many of the early issues (ref). and produce high yields. Yields of 300mg/kg leaf fresh weight and 1-2 mg/g fresh weight (up to 10% of total soluble protein) have been reported (4,5). Some of the advantages of plant-based expression systems are (5):

  • Relatively inexpensive,  requiring no special culture equipment, bioreactors, media, components, or sterile environment.
  • Fast: can grow high yields of the desired protein within a few days to a weekThe material retains biological activity and immunogenicity.
  • Multi-vector systems consisting of replication-defective constructs can be used to minimize the chance of spurious replication.
  • Unique storage possibilities in that proteins can be stored in the form of seeds or in freeze-dried leaves.

In addition to EBOV antigens, proteins of Foot & Mouth Disease Virus, HIV-1, malaria, rotovirus, Influenza virus, HPV, Yersinia pestis, Dengue Virus, and HbsAg, and monoclonal antibodies all have been produced in plants (5).

How Do They Do It?

There are two key genetic components to the technology for expressing exogenous proteins in plants. The first is a plant expression vector derived from a plant virus. The two most popular types of vectors are based on Tobacco Mosaic Virus (TMV) or Potato Virus X (PVX) (1-7, Wikipedia).

The second is the bacterium Agrobacterium tumefaciens (Agrobacterium), that infects certain plants and causes tumors. Agrobacterium cultures are used as the gene transfer and delivery system to induce protein expression in the plants.

Here’s how it works:

  1. The gene of interest is cloned into a plant expression vector plasmid.
  2. The plasmid is introduced into Agrobacterium by transformation/conjugation.
  3. The plant is infected with Agrobacterium by a process called agroinfiltration.
  4. Agrobacterium then transfers the vector and gene of interest into the plant where it is expressed at high copy number, producing large quantities of the protein of interest.

SIDE BAR: Transient Expression by Agroinfiltration  (Wikipedia)

Agroinfiltration is a technique used to induce transient expression of genes in plants. A suspension of Agrobacterium tumefaciens is mechanically infused into the leaves of plants, where it transfers the desired gene to plant cells. The benefits of agroinfiltration compared to other plant transformation methods are speed and convenience. Once inside the leaf the Agrobacterium transfers the gene of interest in high copy numbers into the plant cells. The gene is then transiently expressed.

Plantibodies: Plant-Generated Monoclonal Antibodies

Monoclonal antibodies (Mab), such as the anti-EBOV antibodies, can also be produced in plants by agroinfiltration. Expressing complete antibody molecules is trickier because you need to express two different polypeptide chains and get them to assemble into a molecule consisting of two heavy chains (HC) and two light chains (LC), and retain antigen-binding specificity and capability (6,7).

Step 1: Generate monoclonal antibodies by immunizing mice and making hybridomas producing the Mab by the standard methods for making Mabs.

Step 2: “Humanize” the antibody by swapping gene and protein sequences common to mouse antibodies with those found in human antibodies, to prevent or decrease the chance of the recipient producing an immune reaction against the MAbs.

Step 3: Clone the Mab genes into plant expression vectors such as TMV- or PVX-based vectors; infect plants and let them grow (for about a week). Seems to work best if the HC and LC are expressed from non-competing vector systems such as HC in a TMV-based vector and LC in a PVX-based vector.

Step 4: Harvest the plant material, extract and purify the MAbs.


Although the production of proteins and antibodies in plants has not received much attention to date, the successful use of the anti-EBOV cocktail to treat people infected by EBOV will most likely propel this technology into the limelight in the near future.

Mystery Serum Links

References—Want To Read More?

  1. Gelvin SB. 2003. Agrobacterium-mediated plant transformation: the biology behind the “gene-jockeying” tool. Microbiol Mol Biol Rev. 67(1):16-37. ⊂⊃
  2. Marillonnet S, Giritch A, Gils M, Kandzia R, Klimyuk V, Gleba Y. 2004. In planta engineering of viral RNA replicons: efficient assembly by recombination of DNA modules delivered by Agrobacterium. Proc Natl Acad Sci U S A. 101(18): 6852-6857. ⊂⊃
  3. Marillonnet S, Thoeringer C, Kandzia R, Klimyuk V, Gleba Y. 2005. Systemic Agrobacterium tumefaciens-mediated transfection of viral replicons for efficient transient expression in plants. Nat Biotechnol. 23(6): 718-723.  ⊂⊃
  4. Giritch A, Marillonnet S, Engler C, van Eldik G, Botterman J, Klimyuk V, and Gleba Y. 2006. Rapid high-yield expression of full-size IgG antibodies in plants coinfected with non-competing viral vectors. Proc Natl Acad Sci U S A. 103(40): 14701–14706.  ⊂⊃
  5. Hefferon KL. 2012. Plant virus expression vectors set the stage as production platforms for biopharmaceutical proteins. Virology 433: 1–6.  ⊂⊃
  6. Olinger GG, Pettitt J, Kim D, Working C, Bohorov O, Bratcher B, Hiatt E, Hume SD, Ashley K. Johnson AK, Morton J, Pauly M, Whaley KJ, Lear CM, Biggins JE, Scully C, Hensley L, and Zeitlin L. 2012. Delayed treatment of Ebola virus infection with plant-derived monoclonal antibodies provides protection in rhesus macaques. Proc Natl Acad Sci U S A. 109(44): 18030-18035.  ⊂⊃
  7. Pettitt J, Zeitlin L, Kim DH, Working C, Johnson JC, Bohorov O, Bratcher B, Hiatt E, Hume SD, Johnson AK, Morton J, Pauly MH, Whaley KJ, Ingram MF, Zovanyi A, Heinrich M, Piper A, Zelko J, and Olinger GG. 2013. Therapeutic Intervention of Ebola Virus Infection in Rhesus Macaques with the MB-003 Monoclonal Antibody Cocktail. Sci. Transl. Med. 5(199):199ra113, pp.1-6.  ⊂⊃

Wikipedia Sources

Companies Involved In Plantibody Research


Icon Genetics GmbH, Weinbergweg 22, 06120 Halle, Germany; and Bayer BioScience N.V., Technologiepark 38, B-9052 Gent, Belgium


Ebola Virus Part II: Infection And The Immune Response

Instead of hiding from your immune system Ebola Virus (EBOV) infects cells of your immune system first. A number of other viruses also do this, including Measles Virus (MV), and of course HIV. With EBOV, lymphocytes are NOT infected, but the infection eventually leads to their depletion.

Once the virus infects your immune cells and begins to replicate, it evolves to have an affinity for other cell types, especially liver cells. Many different cell surface proteins, found on many different types of cells, can act as receptors for the virus making it possible to infect many other cell types.

The incubation period for EBOV infection can be anywhere from 2-21 days

Pathogenic Mechanisms

EBOV has two main, and complementary, pathogenic mechanisms that make it so deadly:

  1. It turns on the inflammatory response full-blast. This results in increased vascular permeability, hemorrhage, shock, and ultimately, death.
  2. It turns off the activation of virus-specific immune responses so you get little-to-no anti-viral immunity to control the replication of the virus inside your body.

Ebola also has a liking for liver cells and causes liver failure. And guess what?! Most of the blood clotting factors are made in the liver. Bad news.

The infection process goes something like this:

  1. EBOV infects Dendritic Cells (DCs), monocytes, and macrophages (MO), and also activates neutrophils. These are all cells belonging to your early or “innate” immune system, which is your front-line defense against foreign invaders.
  2. These events cause the release of massive amounts of pro-inflammatory cytokines such as TNFa, which increase vascular permeability, fluid leakage, and shock. This effect is known as “cytokine storm”. Tissue Factor (TF) is also produced, which disrupts normal blood clotting and contributes to hemorrhaging.
  3. Virus replication escalates in the infected cells
  4. In the infected cells, the production of interferon-gamma (IFNg) is turned off. Downstream interactions of DCs and MO with lymphocytes (T cells and B cells) to initiate an anti-viral immune response, which are dependent on IFNg, are disrupted.
  5. The maturation of DCs into functional antigen-presenting cells is inhibited, which, along with the decrease in IFNg, blocks activation of T cells and B cells preventing development of virus-specific immunity.
  6. Virus replication is rampant in infected cells resulting in rapid spread internally, high viral loads, and nothing to keep the virus in check.
  7. The virus spreads to other cell types, in particular liver cells, eventually leading to liver failure, increasing the potential for hemorrhaging.
  8. Once symptoms appear, death typically occurs within 7-14 days. If the patient survives, recovery can be a very long and difficult process.

Ebola Infection Domino Effect

What About A Vaccine?

A wide variety of vaccine candidates and approaches have been tested or are currently being tested. These include killed viruses, live attenuated viruses, subunit vaccines, DNA vaccines, recombinant vaccines using other viruses as vectors. The approaches to create an Ebola vaccine are the same as those taken to produce a vaccine for other organisms, and the difficulties and pitfalls are also the same.  The primary issue is finding the balance between potency/efficacy and safety, especially in the case of live or recombinant vaccines. It is also clear that a durable and potent vaccine needs to generate both cellular (T cell-mediated) and humoral (antibody-mediated) immunity. Furthermore, variation and changes in the viral envelope protein (GP) make it difficult to neutralize with antibodies from either natural immunity or a vaccine. Work remains in progress.


Mansour Mohamadzadeh M, Chen L, and Schmaljohn AL. 2007. How Ebola and Marburg viruses battle the immune system. Nature Reviews Immunology 7: 556-567.

Ebola Virus Primer

Ebola Virus is in the news again. The latest Ebola outbreak in Africa has killed more than 670 people including a prominent Liberian doctor and two American doctors. World Health Organization (WHO) calls the latest outbreak the largest recorded outbreak to date.  Ebola virus always conjures up in my mind images of an inevitable and horrible death by bleeding out of every orifice. Despite being discovered in 1976, even before AIDS and HIV, I realized that I didn’t know very much about the virus or how it worked, other than the occasional blurbs that appear in the news at the time of an outbreak. So I decided to look into it. It’s not that the basic information is difficult to find—my primary sources were the WHO and CDC fact sheets about Ebola Hemorrhagic Fever, and of course, Wikipedia. I did, however, also look in the scientific literature for some review articles and to see what research is currently going on in the field. For this article, though, I will just present the basic facts about Ebola Virus and the disease it causes, and other information you might be interested in, such as how contagious is it, how lethal is it, and how do you treat it. I will follow up later with more scientific details for those who want to learn more.


Ebola Virus  is endemic to Central and West Africa near tropical rainforest areas. It is initially spread to humans by contact with infected animals, most likely fruit bats, which are thought to be the most likely reservoir.


According to information published by The WHO and CDC, Ebola causes an acute and rapidly progressing hemorrhagic fever. The disease often begins with the sudden onset of fever, intense weakness, muscle pain, headache and sore throat. This is followed by vomiting, diarrhea, rash, impaired kidney and liver function, and in some cases, both internal and external bleeding (WHO). The incubation period, the time between infection and onset of symptoms, can be anywhere from 2 to 21 days, with an average of about 14 days. Disease progression and death are rapid, thus somewhat limiting the spread of an outbreak.

What is the treatment?

There is currently no treatment for Ebola hemorrhagic fever other than supportive therapy such as maintaining fluids and electrolytes. There are no drugs or anti-viral treatments.

How lethal is Ebola?

The mortality rate of Ebola hemorrhagic fever is 50-90%.

How contagious is it?

Ebola is highly contagious during outbreaks. It is spread by direct contact with  bodily fluids of an infected person. There is no evidence to date for natural spread of Ebola by an airborne route, but airborne transmission cannot be ruled out (4). People are infectious as long as their blood and secretions contain the virus. Ebola virus was isolated from semen 61 days after onset of illness in a man who was infected in a laboratory. (WHO).

Is there a vaccine?

There is no vaccine available yet, but work is in progress.



Ebola Virus is a member of the Filovirus family, along with the Marburg and Cueva viruses. There are five known species of Ebola: Zaire ebolavirus (EBOV), Sudan ebolavirus (SUDV), Reston ebolavirus (RESTV), Côte d’Ivoire ebolavirus (TAFV), and Bundibugyo ebolavirus (BDBV). The Reston virus was isolated from cynomolgous monkeys imported from the Philippines. The Reston virus infects humans, but does not cause disease—so far. (CDC)


The genome of Ebola Virus is a 19 Kb (-) sense RNA, most similar  in genome size and organization to mumps, measles, and Respiratory Syncytial Viruses (RSV). The (-) or negative sense of the RNA strand means the virus genome must be transcribed into a (+) sense strand which then serves as messenger RNA for the production of virus structural proteins. The virus codes for, and carries with its virions, an RNA-dependent RNA polymerase to carry out the transcription and replication process.


Photo credit: "Ebola virus virion" by CDC/Cynthia Goldsmith - Public Health Image Library, #10816 This media comes  from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL).
Photo credit: “Ebola virus virion” by CDC/Cynthia Goldsmith – Public Health Image Library, #10816 This media comes
from the Centers for Disease Control and Prevention’s Public Health Image Library (PHIL).

Ebola Viruses form long filamentous virions 80 nm in diameter, and  are highly variable in length, from 500-1400 nm. Ebola virions are usually seen with loops or knots at one end by electron microscopy (see photo).

Components of the Virus Particle (Virion)

Ebola virions consist of seven structural proteins: the nucleocapsid protein (NP), a polymerase co-factor VP35, a transcriptional activator VP30, two matrix proteins, VP40 and VP24, the envelope protein GP, and the RNA- dependent RNA polymerase L. The helical nucleocapsid core consists of the genomic (-) RNA surrounded by a sheath of nucleoproteins (NP), and is associated with the RNA-dependent RNA polymerase (L), with the other proteins present in the virion cores. The virions are surrounded by a lipid membrane derived from the host cell membrane as the particles bud from the cell. The membrane contains the envelope proteins GP which allow the newly formed viruses to recognize, bind to, and infect their target cells.

I will follow up later with more on the molecular biology of the virus and the mechanisms of pathogenesis, in particular, the interaction between the virus and the immune system.


  1. Ebola Virus Disease. WHO Fact Sheet.
  2. Ebola Hemorrhagic Fever. CDC Fact Page.
  3. Ebola Virus Disease. Wikipedia:
  4. Zumbrun EE, Abdeltawab NF, Bloomfield HA, Chance TB, Nichols DK, Harrison PE, Kotb M, and Nalca A. 2012. Development of a Murine Model for Aerosolized Ebolavirus Infection Using a Panel of Recombinant Inbred Mice.
  5. Viruses 4: 3468-3493.
  6. Sullivan N, Yang ZY, and Nabel GJ. 2003. Ebola Virus Pathogenesis: Implications for Vaccines and Therapies. J. Virol 77: 9733-9737.