Zika virus: A neglected disease with no specifically designed drugs


I was shocked to see in recent weeks how a potential connection between a virus infection and  pregnant women have led to a global concern for the association with a high number of babies being born with microencephaly, initially in Brazil but with other cases shown worldwide, and it has even been associated to the rare Guillain-Barré Syndrome (1). Children with these syndromes are likely to have shorter life expectancies. A recent opinion article (2) with extensive research on this particular virus is analised in this blog.

After the epidemic outbreak of the Ebola virus in 2014-2015 which killed thousands of people in Africa and risked to generate a pandemic crisis, mobilising the World Health Organisation (WHO) and Governments, we have been exposed to another case of unprepared health concern with serious global implications.

Zika virus (ZIKV) is a virus from the Flaviviridae family with genetically similarities with the ones responsible for the Dengue Fever and the Yellow Fever. ZIKV was isolated and reported over 60 years ago and since then the small number of publications, the lack of a crystal structure, the abscence of reports of molecules having been screened either in vitro or in vivo in animal models, and the lack of patents covering drugs targeting ZIK virus (although there are some focused in compounds addressing the Dengue Fever), has left it as an undoubtedly case of a “Neglected Disease”.

So, despite of having some knowledge of the virus, little if not nothing seems to have been done in order to understand its risks, exposing under this circumstances, right now, its danger after the outbreak. The WHO has had to move faster than 2 years ago with the Ebola epidemic, and has  issued a Public Health Emergency of International Concern (PHEIC).

Ekins and co-workers(2), after extensive research on related viruses and taking into consideration antivirals and non-related drugs, suggest to create a fast-track plan of action in order to tackle the problem with more urgency, leadership and preparation. This could be applicable to other future outbreaks and put us in a better situation to fight future epidemics.

With the information we have on other closely related virus like the Dengue, the immediately plan of action against this outbreak should have to start with the use of already FDA-approved antivirals profiled against related viruses (with a safety and efficacy profile proved) as a starting point in fighting the ZIKV, and test other drugs, non antivirals and compounds from commercial sources (eg. Libraries) in a descendent order of priority as shown in Fig 1.

jose1

Figure 1. Compounds and chemical libraries suggested to be tested against Zika virus

Without much further do, the authors propose the following Drug Discovery plan:

  1. To develop a cell or ZIKV-target based in vitro assay, which might have to be done in special protective environments, limiting the number of companies or organisations capable of such as assays.
  2. The immediate test of all kind of available drugs (up to 48 FDA approved known antivirals) into the previously generated and validated assay, capable to produce some results against the absence of any other treatment, as reflected in Table 1.
  3. To study and understand the genome of the ZIKV and how a chemotherapy approach could lead to effectively target the virus.
  4. To develop and use “homology models” showing the suggested protein sequence based in similar/ related viruses with known molecule action-modes using target prediction software, such as SWISS-MODEL.
  5. To establish a pharmacological profile with a suitable/ ethical animal model

jose2

Table 1. List of potential compounds to tes.t

Equally important and without leaving it off the schedule, the scientific community should undertake efforts to reveal the virus structure, its function and physiology and establish the relationship between the infection and the human neurological abnormalities.

Despite of getting even better co-ordinating resources through management organisations like WHO, more should be addressed in an emergency outbreak from National Governments and Health Institutions through funding (eg. from the FDA repurposing approved drugs, from big pharmaceutical companies through the donation of chemicals to be tested, from biotechs investing in the development of ZIKV-based in vitro assays, from ground-field-experienced organisations like Medecins Sans Frontieres, etc…)

We need to retain alert against highly likely-to happen diseases lurking upon us at any time and learn from past actions to make us better prepared to fight them.

Blog written by: Jose Gascon

References

  1. Oehler E, Watrin L, Larre P, Leparc-Foffart I, Lastere S, Valour F, Baudouin L, Mallet HP, Musso D, Ghawche; Zika virus infection complicated by GuillainBarre syndrome–case report, French Polynesia, December 2013. Euro Surveill. 2014; 19(9): 20720
  2. Ekins S, Mietchen D, Coffee M, Stratton TP, Freundlich JS, Freitas-Junior L, Muratov E, Siqueira-neto J, Williams AJ, Andrade C; Open drug discovery for the Zika virus. F1000Research 2016, 5:150

 

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