Zika virus: Accelerating development of Medical Countermeasures by re-purposing licensed drugs

(submitted by Atherical Pharmaceutical, LLC to an upcoming conference on Zika)

R.W. Malone*1,2, V. Soloveva3,4, S. Bavari3,4

1. Atheric Pharmaceutical, LLC, Scottsville, VA, USA, 2. Class of 2016, Harvard Medical School Global Clinical Scholars Research Training Program, Boston, MA3. United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA. 4. United States Army Medical Research Institute of Infectious Diseases, Therapeutic Development Center, Frederick, MD, USA.

Purpose of the study: Antiviral agent development.  Clinical care for Zika virus infection is supportive, and there are no prophylactic or therapeutic drugs, vaccines, or other biologicals licensed for use to prevent or treat Zika virus infection and disease. A Zika virus threat assessment and evaluation of medical countermeasure development options has been completed; re-purposing existing licensed drugs was identified as the most efficient strategy for rapid development of licensed medical countermeasures suitable for prevention, treatment, or containment of the pathogen (1,2).

Methods/summarized description of the project: Hypothesis-driven high throughput re-purposed drug screening.  An iterative multi-step drug selection and screening algorithm was established; 1) drug targets involving inhibition of virus-host cell interactions were identified, 2) compounds with significant clinical pharmacokinetic and safety data (preferably including in pregnancy) which inhibit the pathways were selected, 3) selected pharmaceuticals were tested for inhibition of Zika virus infection and replication using multiple cell types and Zika viral isolates, 4) pharmaceuticals with single-digit micromolar to nanomolar IC50 and CC50/IC50 ratios consistent with anti-viral specificity were selected for subsequent development as prophylactic and therapeutic anti-Zika drug candidates. 

Results:  Re-purposed licensed drugs with anti-Zika activity which are safe for use in pregnancy. Three general mechanisms of action (including autophagy inhibition) have been identified and corresponding compounds have been screened.  Multiple re-purposed drugs have been identified which meet selection criteria for subsequent development. 

Conclusion: Hypothesis-driven high throughput re-purposed drug selection can expedite identification of emerging infectious disease medical countermeasure candidates.  A summary of the pathways targeted, drugs identified and viral inhibition results obtained will be presented.  Discussion: Zika infection of the recipient host requires viral envelope protein binding and particle uptake into susceptible cells, is mediated by specific receptors which include DC-SIGN, AXL, Tyro3, and TIM-1, and triggers transcriptional activation of Toll-like receptor 3 (TLR3), RIG-I, MDA5, interferon stimulated genes including OAS2, ISG15, and MX1, and beta interferon (4). Primarily infected cells include skin fibroblasts, epidermal keratinocytes, and skin dendritic cells. Zika virus subsequently exploits autophagy to facilitate uptake and replication8, and pharmacologic manipulation of Zika infected cells with 3-Methyladenine (3-MA), an inhibitor of autophagosome formation, strongly reduces viral copy numbers in infected fibroblasts (3). Based on prior murine studies involving Zika virus inoculation in mouse brain (5), autophagy of Zika virus has been postulated as playing a key role in the pathogenesis of Zika-associated primary microcephaly (6).  Pharmacological mechanisms of currently licensed 4-Aminoquinoline anti-malarial drugs include inhibition of autophagy and broad-spectrum cathepsin B-mediated inhibition of viruses which require endosomal acidification (7).

References:

 1. Malone RW, Homan J, Callahan MV, Glasspool-Malone J, Damodaran L, Schneider Ade B, Zimler R, Talton J, Cobb RR, Ruzic I, Smith-Gagen J, Janies D, Wilson J; Zika Response Working Group.  Zika Virus: Medical Countermeasure Development Challenges.  PLoS Negl Trop Dis. 2016 Mar 2;10(3):e0004530. doi: 10.1371/journal.pntd.0004530. PMID: 26934531

2. Longini IM Jr, Nizam A, Xu S, Ungchusak K, Hanshaoworakul W, Cummings DA, Halloran ME.  Containing pandemic influenza at the source.  Science. 2005 Aug 12;309(5737):1083-7. PMID: 16079251

3. Hamel R, Dejarnac O, Wichit S, Ekchariyawat P, Neyret A, Luplertlop N, et al. Biology of Zika Virus Infection in Human Skin Cells. J Virol. 2015; 89(17):8880–96. doi: 10.1128/JVI.00354-15 PMID: 26085147.

4. Carneiro LA, Travassos LH. Autophagy and viral diseases transmitted by Aedes aegypti and Aedesalbopictus. Microbes Infect. 2016. doi: 10.1016/j.micinf.2015.12.006 PMID: 26774331.

5. Bell TM, Field EJ, Narang HK. Zika virus infection of the central nervous system of mice. Arch Gesamte Virusforsch. 1971; 35(2):183–93. PMID: 5002906.

6. Tetro JA. Zika and microcephaly: Causation, correlation, or coincidence? Microbes Infect. 2016. doi: 10.1016/j.micinf.2015.12.010 PMID: 26774330.

7. Zilbermintz L, Leonardi W, Jeong SY, Sjodt M, McComb R, Ho CL, Retterer C, Gharaibeh D, Zamani R, Soloveva V, Bavari S, Levitin A, West J, Bradley KA, Clubb R3, Cohen SN, Gupta V, Martchenko M. Identification of agents effective against multiple toxins and viruses by host-oriented cell targeting.  Sci Rep. 2015 Aug 27;5:13476. doi: 10.1038/srep13476. PMID: 26310922