TWiEVO 5: Looking at straw colored fruit bats through a straw

TWiEVOOn episode #5 of the science show This Week in Evolution, Sara Sawyer and Kartik Chandran join Nels and Vincent to talk about how the filovirus receptor NPC1 regulates Ebolavirus susceptibility in bats.

You can find TWiEVO #5 at microbe.tv/twievo, or you can listen below.

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TWiV 309: Ebola email

On episode #309 of the science show This Week in Virology, the TWiVocytes answer questions about Ebola virus, including mode of transmission, quarantine, incubation period, immunity, and much more.

You can find TWiV #309 at www.microbe.tv/twiv.

Ebola virus arrives in New York City

This morning I received this email from President Lee Bollinger:

Dear fellow members of the Columbia community:

As you may have seen in the media, Dr. Craig Spencer is being treated for Ebola at Bellevue Hospital in Manhattan. Dr. Spencer, an emergency department physician at NewYork-Presbyterian/Columbia University Medical Center, recently returned from a humanitarian mission with Doctors Without Borders to one of the outbreak areas in Western Africa. We admire and appreciate all of those willing to do this vital and selfless public health work around the globe.

It’s critical to bear in mind what our public health and infectious disease experts have emphasized – that the risk to people in New York City and at Columbia remains extremely low. If you or anyone has any concerns, please visit the University’s Ebola Preparedness site or the New York City Department of Health Ebola update page. You may also contact Student Health Services or Workforce Health and Safety for Faculty/Staff with Hospital Responsibilities.

We must keep Dr. Spencer in our thoughts and wish him a full and speedy recovery, as we do the vulnerable populations he serves. We will also continue to keep the Columbia community informed as we learn more from City, State, and Federal health officials.

Sincerely,
Lee C. Bollinger

The transition between incubation period (when there are no symptoms) and the first clinical signs is a dangerous period. During this time the patient may continue to move around in public despite having fever and other indications of infection. It will be important to trace as many of this physician’s contacts as possible, a difficult task in a city of over 8 million people. Apparently the physician traveled around the city, using the subways, the night before having a fever. Whether any virus is shed during this time, in amounts sufficient to infect others, is unknown, but could be determined by studying the contacts of such infected individuals.

TWiV 297: Ebola! Don’t panic

On episode #297 of the science show This Week in Virology, the TWiVites present an all-ebolavirus episode, tackling virology, epidemiology, and approaches to prevention and cure that are in the pipeline.

You can find TWiV #297 at www.microbe.tv/twiv.

Ebolavirus vaccines and antivirals

guinea-liberia-sierra-leone-2014As the epidemic of Zaire ebolavirus in Western Africa continues (1,779 cases and 961 deaths in four countries), many are questioning why there are no means of preventing or stopping infection. In the past two decades there has been substantial research into developing and testing active and passive vaccines and antiviral drugs, although none have yet been licensed for use in humans.

Using antibodies to treat infection with ebolaviruses with antibodies is probably the best known therapy, because it was used to treat a two Americans who were infected while working in Liberia. They received a mixture of three monoclonal antibodies (called ZMapp) which had been previously shown to block infection of cells with ebolaviruses, and prevent lethal infection of non-human primates when given within 24-48 hours after infection. These are mouse monoclonal antibodies that have been ‘humanized’ so that when given to people they do not induce an antibody response against the antibodies. Humanization involves changing the amino acids of the antibody molecule from mouse to human, except in the part of the antibody that binds antigen. The antibodies are then synthesized in tobacco plants and purified. Administering anti-viral antibodies to patients, also called passive immunization, was done long before vaccines were available. Serum from patients who had recovered from a particular disease would be given to others who had recently been infected, in order to prevent disease. Such therapy was used to save the life of virologist Jordi Casals, who had become infected with Lassa virus while isolating the virus from the blood of a patient, Penny Pinneo. The serum administered to Casals was obtained from Pinneo, who had recovered from the infection. The American doctor infected with Zaire ebolavirus while working in Liberia was also given serum from a boy who had recovered from infection.

As ZMapp has not yet been subjected to human clinical trials to determine its safety and efficacy, its use in an infected human is considered unusual. A phase I clinical trial needs to be done to ensure that the preparation of monoclonal antibodies is safe in humans. Determining whether monoclonal antibody therapy for ebolavirus infection is effective is more difficult. Such testing could only be done during an outbreak, during which it would not be ethical to withhold treatment from the control group. Nevertheless it is clear that such mixtures of monoclonal anti-viral antibodies could potentially save many lives during outbreaks.

While passive immunization has value in saving lives, its protection is temporary: the antibodies given to patients do not endure. A better approach is immunization, which not only induces anti-viral antibodies, but creates immune memory, so that subsequent infections are accompanied by another round of antibody production. The catch is that it takes about two weeks after immunization for antibodies to reach sufficient protective levels. Nevertheless, a vaccine would likely have had substantial impact on the current outbreak, which began in March 2014 and has continued for 5 months.

A number of experimental vaccines against ebolaviruses are in development. In one approach, the glycoprotein of vesicular stomatitis virus is replaced with the corresponding protein of different ebolaviruses. These vaccines protect non-human primates from lethal infection. A similar approach using an attenuated rabies virus to deliver the ebolavirus glycoprotein also protected non-human primates from infection, as did immunization with an adenovirus encoding the ebolavirus glycoprotein.  This vaccine candidate has been shown to be safe and immunogenic in phase I clinical trials. Another vaccine approach entails production of the ebolavirus glycoprotein in E. coli. Immunization of mice with the purified protein leads to the production of neutralizing antibodies. Because protein-based vaccines do not replicate, the immune response may need to be boosted by using an adjuvant that stimulates the innate immune system and leads to better antibody production. A double-stranded RNA adjuvant has been shown to augment the immune response against a non-infections, virus-like particle vaccine containing the Ebola virus glycoprotein but not the viral genome.

Antivirals certainly have a place in control of viral disease, and a number of promising candidates to control infection with ebolaviruses have been developed. One is a nucleoside analog which is incorporated into RNA by the viral RNA polymerase and leads to chain termination. It blocks replication of ebolaviruses in culture cells, and protects mice and nonhuman primates from lethal infection. This compound, called BCX4430, is a broad spectrum antiviral that inhibits the replication of not only members of the Filoviridae, but also Arenaviridae, Bunyaviridae, Orthomyxoviridae, Picornaviridae, Paramyxoviridae, Flaviviridae, Coronaviridae. Another inhibitor of viral RNA synthesis is favipiravir, which has the advantage of being in late stage clinical development for the treatment of influenza. This compound inhibits replication of ebolaviruses in cultured cells and reduces disease severity and mortality in a mouse model of disease.

It is likely that the extent of the current outbreak of Ebola virus disease, the largest to date, will provide impetus to move some of these treatments into human trials. But consider that all the research on active and passive vaccines and antivirals for ebolaviruses required work in BSL-4 laboratories. Those who call for the shuttering of BSl-4 laboratories need to take note and move away from their unrealistic and unreasonable position.

Zaire ebolavirus in West Africa

Dr. Tom Solomon is Director of the Institute for Infection and Global Health at the University of Liverpool. Here he speaks with Vincent Racaniello about the 2014 outbreak of Zaire ebolavirus in West Africa. Dr. Solomon discusses why the epidemic has spread, how it might be curtailed, the return of two infected health workers back to the United States for treatment, and the possibility that he might be traveling to the affected region to assist with medical care.

 
 

TWiV 283: No Reston for the weary

On episode #283 of the science show This Week in Virology, Jens Kuhn speaks with the TWiV team about filoviruses, including the recent Ebola virus outbreak in Guinea.

You can find TWiV #283 at www.microbe.tv/twiv.

A new rhabdovirus from a patient with hemorrhagic fever

Viral hemorrhagic fevers in AfricaHemorrhagic fevers are among the most graphic viral diseases, inspiring movies, novels, and a general fear of infection. They are characterized by an abrupt onset and a striking clinical course involving bleeding from the nose and mouth, vomiting with blood, and bloody diarrhea. The most famous hemorrhagic fevers are produced by infection with filoviruses like Ebola virus, but members of three other viral families – Arenaviridae, Bunyaviridae, and Flaviviridae – can also cause this syndrome. The isolation of a novel rhabdovirus from an African with hemorrhagic fever suggests that members of a fifth viral family can also cause this disease.

Three cases of hemorrhagic fever that occurred in the spring of 2009 were noteworthy because none of the typical viral suspects could be detected in one patient. Two were young (13, 15 year old) students in the village of Mangala, Bas-Congo province, Democratic Republic of Congo. They lived near each other and went to the same school. Both arrived at the local health center with typical symptoms of hemorrhagic fever, and both died 2-3 days later. The third case was a 32 year old male nurse at the health center who was involved in the care of the other two patients. He developed symptoms of hemorrhagic fever but recovered within a few days.

Deep sequence analysis of RNA extracted from the serum of patient #3 revealed the presence of a novel rhabdovirus, provisionally named Bas-Congo virus (BASV). Phylogenetic analyses reveal that BASV is substantially diverged from the two main human rhabdoviruses, rabies virus and Chandipura virus (ten of the 160 known species of rhabdoviruses have been isolated from humans). BASV is more related to viruses of the Tibrogargan group and the Ephemerovirus genus, which contain arthropod-borne viruses that infect cattle, but clusters separately in an independent branch of the phylogenetic tree.

Antibodies to BASV were detected in the serum of patient #3 and also in the serum of an asymptomatic nurse who had cared for this patient. However, no antibodies to this virus were found in 43 other serum samples from individuals with hemorrhagic fever of unknown origin. These samples came from individuals who lived in 9 of the 11 provinces of the DRC, including Bas-Congo. Nor were antiviral antibodies detected in plasma from 50 random blood donors in one DRC province.

Although the viral genome sequence was determined from RNA extracted from patient serum (where there were 1 million copies per ml of the viral RNA), the virus did not replicate in cell cultures from monkey, rabbit, and mosquito, or in suckling mice. These findings are in contrast to those obtained with a newly discovered coronavirus in humans. It is likely that the samples had not been kept sufficiently cold to maintain viral infectivity. It should be possible to recover virus from a cloned DNA copy of the viral genome.

These data suggest, but do not prove, that BASV caused hemorrhagic fever in the 3 patients. All three cases occurred in a 3 week period within the same small village. BASV nucleic acid and antibodies were detected in the third patient. Given that viruses of the closely related Tibrogargan group and the Ephemerovirus genus are transmitted to cattle by biting midges, it is possible that the initial infections were transmitted by such an arthropod vector. Human to human transmission of the virus could have taken place when the nurse was infected by one or both pediatric patients. However, it should be noted that infection with BASV was not confirmed in either of the first two cases as no clinical samples were available. Other etiologies for this outbreak of hemorrhagic fever should not be ruled out.

Rhabdoviruses are known to cause encephalitis, vesicular stomatitis, or flu-like illness in humans, not hemorrhagic fevers. But these viruses clearly have the potential to cause this disease: members of the Novirhabdovirus genus cause hemorrhagic septicemia in fish. As long as there are viruses to discover, any rules we make about them should be considered breakable.

G Gerard, JN Fair, D Lee, E Silkas, I Steffen, J Muyembe, T Sittler, N Veerarghavan, J Ruby, C Wang, M Makuwa, P Mulembakani, R Tesh, J Mazet, A Rimoin, T Taylor, B Schneider, G Simmons, E Delwart, N Wolfe, C Chiu, E Leroy. 2012. A novel rhabdovirus associated with acute hemorrhagic fever in central Africa. PLoS Pathogens  8.

Behind the scenes: TWiV 200 at the NEIDL

We celebrated the 200th episode of TWiV by visiting the National Emerging Infectious Diseases Laboratories at Boston University Medical Center, where we met with Elke, Paul, and Ron to talk about building and working in a BSL4 facility. It was an amazing visit that will be fully documented in an upcoming video. Here are some behind-the-scenes photographs of two memorable days.

TWiV 200: Threading the NEIDL

TWiV Team in BSL4 suitsOn episode #200 of the science show This Week in Virology, Vincent, Alan, and Rich visit the National Emerging Infectious Diseases Laboratories at Boston University Medical Center, where they meet with Elke, Paul, and Ron to talk about building and working in a BSL4 facility.

You can find TWiV #200 at www.microbe.tv/twiv.