How to stop Ebola?

The first reported appearance of Ebola virus took place in 1976 as two outbreaks in Sudan and Democratic Republic of Congo, which killed 280 people. The prevalence of the Ebola virus disease (EVD, which is also termed Ebola haemorrhagic fever)  is strongly correlated with the standard of living and it most often occurs in the poorest countries. This years’ outbreak started in Guinea and is concentrated in West Africa, mainly in Liberia, Sierra Leone and Nigeria. The epidemics resulted in 1,229 deaths (as of August 16^th). As the countries afflicted by the epidemic possess healthcare systems not capable of coping with the virus, the international community has engaged in fighting the disease. The European Union has already provided 11.9 million euro and decided to continue the support.

Genus Ebola virus belongs to Filoviridae family together with two other genera. It possesses five different species, among which Bundibugyo Ebola virus (BDBV), Zaire Ebola virus (EBOV) and Sudan Ebola virus (SUDV) are associated with Ebola epidemics in Africa in the past. Concerning the ongoing outbreak, patients were positive for the presence of EBOV. The EVD has an extraordinarily high case fatality rate, which is up to 90%. The illness is usually characterized by such symptoms as fever, intense weakness, muscle pain, nausea and sore throat. With time, vomiting, diarrhea, kidney and liver damage and in most severe cases internal and external bleedings may occur.

Due to the fact that Ebola virus’ natural reservoir has not yet been precisely confirmed, the scientific hypothesis assumes that the first patient was infected during the contact with blood, secretions or organs of infected animals, which are believed to be species of fruit bats occurring solely in Africa. It would explain, why all reported Ebola epidemics took place on this continent. When the virus is present in humans, it can spread in a few distinct ways including direct contact with an infected person’s blood or fluids (urine, saliva, feces, vomit or semen) or contaminated objects. In order to diagnose EVD, the following laboratory tests are applied: antibody-capture enzyme-linked immunosorbent assay (ELISA), antigen detection tests, serum neutralization tests, reverse transcriptase polymerase chain reaction (RT-PCR), electron microscopy or virus isolation by cell culture.

Currently used drugs only treat the worst symptoms of EVD, therefore, there is an emerging need of elaborating a cure or vaccine. The experimental drug therapies are under way, including application of serum with monoclonal antibodies that was administered to US doctor Kent Brandly and missionary Nancy Writebol (to date the drug was tested only in monkeys). The treatment is based on proteins that should prevent Ebola replication. In case of these two patients the experimental therapy gave positive results, however, a Spanish patient who received the same drug has died. The used substance is produced by Mapp Biopharmaceutical, which utilizes genetically modified plants to synthesize a mixture of antibodies called ZMapp involving three distinct molecules directed against particular surface structures present in EBOV. The experimental drug could be tried in Africa, however, it appeared that its available supply has ended. Additional important aspects are regulatory and ethical issues that need to be overcome at first.

The other way to struggle with the Ebola outbreak is to provide efficient vaccines. According to WHO, the vaccine can be expected even in the next year. However, this might be unduly optimistic as all of them must be thoroughly examined to ensure their safety. Currently, Viral Pathogenesis & Therapeutics at the Vaccine and Gene Therapy Institute of Florida (VGTI) is working on a novel approach to elaborate vaccine by computationally optimizing certain proteins expressed by different viruses, which may help in constructing viral antigens for immunization against Ebola. Moreover, the US Department of Defense supports two other ideas for putative Ebola treatment. One of them proposes the delivery of a multivalent filovirus vaccine by using a virus-like-particle platform. The second approach involves so called TKM-Ebola that comprises a mixture of small interfering RNAs that are formulated as stable nucleic acid lipid particles and target EBOV.

The ongoing Ebola outbreak being the deadliest in the history has forced the developed world to intervene and to financially support African countries. However, money is not everything. The crucial obstacles that prevent a lot of experimental therapy proposals cannot be tested due to numerous regulatory and ethical issues. Hopefully, in the nearest time a combined effort of research institutes will end up in efficient vaccine and drugs that can prevent or cure the Ebola virus.

Sources:

http://www.who.int/csr/don/2014_04_ebola/en/

http://www.who.int/mediacentre/factsheets/fs103/en/

http://www.cdc.gov/vhf/ebola/transmission/index.html

http://www.bbc.com/news/world-africa-26835233

http://www.genengnews.com/insight-and-intelligence/regulatory-supply-issues-haunt-ebola-drug-makers/77900237/?kwrd=ebola

http://www.european-biotechnology-news.com/news/news/2014-03/debate-around-ebola-drugs.html

http://www.vox.com/2014/8/4/5963751/the-real-cause-of-the-ebola-outbreak-its-not-what-you-think

http://www.euractiv.com/sections/development-policy/eu-concerned-over-ebola-outbreak-307802

Maciej Smolarz