I am not the only scientist wondering where all this interest might come from. In 1998 the Spanish physician Juan Gòmez-Alonso proposed in the top-tier journal Neurology that scary tales of vampires and werewolves, mythologized in Hollywood movies and TV shows, may have a factual basis – originating from stories of humans infected with the rabies virus.

The parallels are quite interesting:

Both rabies and vampirism are transmitted by a bite. Both cause face spasms, hydrophobia (a fear of water) and an inability to face one’s own reflection in a mirror. Both show a hypersexualized behavior, with male rabies patients ejaculating up to 30 times per day in the final stages of infection. Finally, contrary to the Hollywood interpretation of a vampire living for centuries, the earliest mythology put the life span of a vampire at about 40 days, similar to the time is takes untreated rabies to kill a human. Gòmez-Alonso also found more evidence when examining geography and culture: geographic areas that experienced particularly devastating epidemic rabies outbreaks in the past – like the Balkans – are rich in popular folkloric myths and legends about vampires and hematofages (animals feeding on blood) with different features and behaviors.

The rabies is a virus belonging to the Rhabdoviridae family. It is a highly fatal disease that causes acute encephalitis, responsible for approximately 55,000 deaths each year worldwide, mainly in Asia and Africa. In 2010, the United States reported 6,153 animal cases of rabies across all states (including Puerto Rico) with the exception of Hawaii. Luckily, human acquisition of rabies in the US is a relatively rare occurrence, with only 2 human cases recorded for the same year (CDC data).However, the yearly mortality rate in other countries is significantly higher; for example, in India more than 25,000 people fall victim to rabies each year.

The rabies virus reproduces in both humans and animals, and is found in not only nervous tissue, but also in saliva, making the transmission of the virus easier….a bite will do. Non-animal associated transmission of rabies is extremely rare, but has occurred by means of transplant surgery.

The normal mode of transmission of this disease is by direct contact between animal and man. The animal implicated most frequently is man’s best friend – the dog, causing 99% of human rabies deaths – but other common zoonotic reservoirs (zoonosis meaning that an infectious disease can be transmitted between species) of the disease include bats, foxes, and skunks. Transmission from bats occurs through direct bites, skin-to-skin contact and through inhalation of aerosolized bat feces (like in caves with high bat populations).

The primary wild reservoir of rabies in the US is Procyon lotor, or the common raccoon; and the highest density of raccoons in New York State is…. New York City! The rabies population is under tight observation by the city health department because New York City experienced a Rabies Outbreak in 2009–2010 in New York´s favorite dog-walking destinations Central Park and Inwood Hill Park. It took one year of trapping and vaccinating animals before the numbers significantly dropped back to 1 reported case in 2012.

The rabies virus reproduces in both human and animal reservoirs, and is found in not only nervous tissue, but also in saliva, making the transmission of the virus easier….a bite will do. Transmission from bats occurs through direct bites, skin-to-skin contact and through inhalation of aerosolized bat feces (like in caves with high bat populations).

Non-animal associated transmission of rabies is extremely rare.

After a typical human infection by a dog bite, rabies replicates in muscles and spreads from the bite wound into the peripheral nervous system, moving about 1–2cm per day.  It then travels along the nerves from the peripheral nervous system to the central nervous system (CNS), driven by an unknown mechanism. The period between the inoculation of the virus into the victim/host and its invasion of the CNS is the incubation period. The median incubation period is 85 days (range 40–150 days). During this phase, the virus causes quite diffuse and nonspecific symptoms within the host, including fever, sore throat, chills, malaise, anorexia, headache, nausea, vomiting, shortness of breath, cough, and weakness.

At this stage vaccination can still initiate cell-mediated immunity to prevent symptomatic rabies. But once the virus reaches the brain treatment is useless; it quickly causes encephalitis and more extreme symptoms appear. This is called the “prodromal” phase and patients die within weeks.

There are two forms of canine rabies in the prodromal phase, a “furious” (encephalitic) or “dumb” (paralytic) form. Furious rabies is characterized by high fever, hyperactivity, hypersexuality, including an increase in sexual appetite and priapism (a painful medical condition, in which the erect penis or clitoris does not return to its flaccid state) of several days, along with dysfunction of the autonomic nervous system, and abnormal looking pupils (WHO). It is this form or rabies that people think of when they hear the word “rabies,” especially as the autonomic dysfunction also includes excess salivation, producing the famous “foaming at the mouth.”

The dumb form progresses from the peripheral weakness around the transmission area to a generalized craniospinal weakness and cumulates in final encephalitis (inflammation of the brain).

On a cellular level rabies can be diagnosed prior to the appearance of symptoms by the presence of Negri bodies (inclusion bodies found in nerve cells) and a direct fluorescent antibody test (dFA). However, the dFA test requires brain tissue, and is therefore performed post-mortem. It is the test of choice for the testing of rabid animals but for living humans it is necessary to perform several other tests to diagnose rabies before death. The two main tests are PCR-based tests on saliva, or testing the blood serum or spinal fluid for antibodies. Additionally, skin biopsy specimens of hair follicles may display a rabies antigen within skin nerves.

So, happy World Rabies Day and have fun at the movies – now you can watch the films as a scientist as well as a horror fan!

———————————————–

Further reading:

Juan Gomez-Alonso; Rabies : A possible explanation for the vampire legend, Neurology 1998;51;856

Rabid: A Cultural History of the World’s Most Diabolical Virus

by Bill Wasik, Monica Murphy, Viking, www.penguin.com

A boa constrictor with IBD, "mad snake disease".

Have you ever seen a sick boa constrictor? All of a sudden they start shedding, develop head tremors and secondary infections, twisting up into knots and wasting away. These poor animals may have acquired a fatal infectious disease called inclusion body disease (IBD). The disease can rapidly progress to the nervous system, with behavioral abnormalities such as disorientation, corkscrewing of the head and neck, holding the head in unnatural positions, or rolling onto the back. Affected snakes either die quickly or starve slowly over several years. The disease was first observed in captive snakes in zoos in the mid 1970s but the cause of the disease remained elusive. Unfortunately no treatment exists; snakes diagnosed with IBD are euthanized to stop transmission to other animals.

IBD is named after large eosinophilic inclusions (or “junk” in the form of huge protein aggregates) in the cytoplasms of nearly every cell in almost all tissues, possibly caused by replication of an unknown retrovirus. However it was unclear how the virus was transmitted.

Now the riddle has been solved and IBD treatments might be possible soon. And even more than that, by investigating the origin of IBD, the Joseph L. DeRisi lab at the University of California, San Francisco, identified a virus that shares characteristics with two known virus families that can cause fatal hemorrhagic fevers in humans!

It is well-established that some of the most medically important human diseases have origins in viruses from animal populations, or have animal reservoirs. Examples include HIV-1 and -2, influenza viruses, West Nile virus, severe acute respiratory virus (SARS), coronavirus, henipaviruses, rabies viruses, hantavirus, filoviruses, and arenaviruses. Therefore animal viruses and their hosts are excellent models for studying host-pathogen interactions and vaccine development.

To computationally identify the virus the researchers used high-throughput sequencing methods to search for candidate causes of IBD. Retroviruses are RNA viruses; each snake cell already contains 95% snake RNA needed for cell viability, plus the virus RNA. But how to separate the snake RNA from the virus RNA? The scientists simply compared sequences from the infected snake to sequences from a healthy snake to figure out what was foreign and therefore might belong to the virus. The problem was that the boa constrictor genome had not yet been sequenced. DeRisi organized the “Assemblathon 2” contest, in which teams competed to develop a computer program to assemble genetic sequences in a previously unknown animal genome, preferentially the boa constrictor genome.

The result of the RNA comparison shocked the scientists.

The foreign RNA sequences that were not present in the boa constrictor genome had several similarities to arenavirus genes. These similarities revealed the cause of the illness to be a completely new set of two arenaviruses. These viruses looked like distant relatives of other arenaviruses but had protein coats that were more similar to those of Ebola viruses. While nasty arenaviruses are common in rodents and cause infections in other mammals, we were unaware that they could infect reptiles. Like arenaviruses, Ebola viruses can cause fatal hemorrhagic fever or encephalitis when transmitted to humans. Neither of those viruses had ever been known to infect reptiles, and although it had been postulated that they shared a common ancestor, no link had ever been discovered.

The next step was genome assembly (building a complete genome out of raw data) using open access bioinformatics software, and then comparison with the RNA data. They found that the sequences from the snake virus belonged to four genes—one of which was most similar to genes found in filoviruses.

Turning back to the sick snakes, the scientists found the newly identified virus in six of eight snakes with IBD, and were able to isolate the virus.

Now the team had to find a way to grow the virus so that it could be studied further. They generated Boa constrictor cell lines to perform in vitro virus culture. When the virus was introduced into healthy boa constrictor cells, the virus replicated and the cells became clogged with giant protein aggregates like those in snakes with IBD. Antibodies aimed against the virus showed that these clumps were indeed derived from arenavirus protein, further strengthening the association of this new virus and the deadly disease. A final proof of this hypothesis will be a “challenge study,” where researchers intentionally infect boa constrictors and other captive snakes with the virus in order to induce and study IBD.

IBD is a very important disease of captive snakes. In solving this longstanding veterinary mystery and enabling the first steps towards treatment, vaccines, and perhaps even eradication of this disease, these scientists also discovered an unexpected new branch of virus biology: the viruses they found appear to be a combination of arenavirus and filovirus, neither of which had been known to infect reptiles. Their existence in reptiles raises an array of important questions about host range, evolution, basic biology and emergence of new diseases associated with this poorly understood branch of viral phylogeny.

—————

Further information:

The article, “Identification, characterization, and in vitro culture of highly divergent arenaviruses from boa constrictors and annulated tree boas: a candidate etiological agent for snake inclusion body disease (IBD)” by Mark D. Stenglein, Chris Sanders, Amy L. Kistler, J. Graham Ruby, Jessica Y. Franco, Drury R. Reavill, Freeland Dunker, and Joseph L. DeRisi is published in the open access journal mBio.

Press release video:

This week in virology podcast:

http://www.twiv.tv/2012/08/19/twiv-196-an-arena-for-snakes/

Vincent Racaniello´s virology blog:

http://www.virology.ws/

And how does this relate to the issue of scientific publishing and biosecurity? Read on…

Flu – or influenza – is a serious respiratory illness (not to be confused with common cold) caused by the influenza A and B viruses. Influenza claims a death toll of about 250,000 to 500,000 people worldwide every year. Medical advances have helped understand and combat one of history’s worst killers. From 1918 to 2012 the number of death from influenza has significantly decreased.

Box 1: Facts About Influenza. Source: www.flu.gov

Source: Wikipedia commons http://commons.wikimedia.org/wiki/Mustela_putoriu

 

Because the influenza virus can constantly mutate, it remains a highly challenging illness: there is no other vaccine that has to be changed on a yearly basis. Viruses evolve at a much faster rate than other organisms and scientists and pharmaceutical companies therefore have to keep updating their vaccines in response. And because evolution has produced variable strains of influenza, there is always a risk of predicting and targeting the wrong strain, which might result in an ineffective vaccine. Usually, the vaccine strains for the Northern hemisphere for the following season are picked in early spring based on data from the latest flu isolates from the Southern hemisphere and vice versa in fall. (This is the reason why vaccine strains for the Northern hemisphere are often called Brisbane or Perth – after the city in which they were isolated in Australia).

Additionally, animal influenza viruses jump from time to time into the human population, and can cause new pandemics. Candidates for such viruses are mostly avian viruses, most prominently the highly pathogenic H5N1 virus or “bird flu” (first isolated in Hong Kong in 1997) but also H9N2 and H7N7 viruses that infect humans sporadically. This scenario of avian viruses jumping into humans caused the pandemics of 1918, 1957 and 1968 (see Box 1) and can be imagined quite realistically in the recent movie, Contagion.

However, the avian H5N1 virus is unable to spread from human to human, an ability that is crucial for viruses to cause a pandemic. So how does a pandemic of avian flu occur?

Two research groups, Ron Fouchier’s group in Rotterdam in the Netherlands and Yoshihiro Kawaoka’s group in Madison, Wisconsin, addressed this question. They used ferrets as a model to look at what it takes to make the virus transmissible from human to human. They found that just a couple of mutations were necessary to enable the virus to spread from ferret to ferret. Ferrets are commonly used as model animals for influenza virus since they react to the infection in almost the same ways as humans. All of the mutations found in the mutant virus were also found in H5N1 viruses isolated from waterfowl and humans, but have never been found together on one virus.

So far, this is a pretty straightforward story of scientists figuring out how a virus works and developing a vaccine and efficient countermeasures to prevent it. But here’s the twist to this story, where researchers’ right to publish classed with government concerns about biosecurity.

Fouchier and Kawaoka simultaneously sent their manuscripts to the journals Nature and Science to share their findings with their international colleagues. However, strong concerns by the National Science Advisory Board for Biosecurity (NSABB) in the US about safety and bioterrorism forced both research groups to omit crucial information about the mutations from their manuscripts. The NSABB recommended giving access to the full information to a small group of approved scientists, but not the public.

This decision to forbid researchers to publish in full created debate and raised opposing viewpoints around the globe.

On the one hand, the US government takes the possible use of viruses in bioterrorism very seriously, especially as such a virus could easily be developed. The scientific community, on the other hand, considers the current situation as a crucial “catch-up” to help plan for future vaccines.  In the January 2012 issue of Nature the restriction of access to the scientific methods and data is stated as “akin to censorship, and counter to science, progress and public health.”

In a huge effort researchers from all over the world monitor and sequence hundreds of influenza samples from all kinds of animals and humans on a daily basis. Since these dangerous mutations are now known, the scientific community can react quickly in case similar mutations are found in an isolated virus. The earlier such a virus is identified, the faster countermeasures can be taken, and the faster vaccines and antivirals can be produced. However, if the necessary information is restricted and not available to the scientific community this will slow down identification of highly transmissible forms of influenza and would delay countermeasures taken by health agencies.

Now, the scientific community around the globe has to find a way to cope with both, biosafety concerns on the one hand and scientific progress and benefits for public health on the other hand. Withholding important information from scientific colleagues may not be the solution but biosafety concerns have to be addressed as well. A scientific advisory board of leading influenze researchers could potentially judge how to deal with the release of crucial but delicate data.

This is an astonishing example of a new virus is changing scientific culture and human behavior without infecting a single individual. The current international debate about the free flow of scientific information and how to balance public health and biosecurity has the potential to change life science forever.

Links to background information and controversy comments over the H5N1 research result:

Most recent letters to Science by active participants of the discussion (January, 19th, 2012):

Ron Fouchier (Author of one of the H5N1 studies)

Daniel Perez (Influenza expert)

Michael T. Osterholm (NSABB board member)

Publications

Nature 480, 421–422 (22 December 2011) | doi:10.1038/480421a

Nature online 20 January 2012 | doi:10.1038/481443a

Science, Science Insider online 20 January 2012

Krammer, F. and Grabherr, G., 2010. Alternative influenza vaccines made by insect cells. Trends Mol Med. 2010 Jul;16(7):313-20.

Blog

Vincent Racaniello’s Virology blog and podcast: